Merge pull request #592 from hrxi/gsoc_1

Add SOCKS5 bytestreams and a couple of other fixes

9 files changed, 1360 insertions, 172 deletions

diff --git a/xmpp-vala/CMakeLists.txt b/xmpp-vala/CMakeLists.txt
index 528c84a6..a0c15579 100644
--- a/xmpp-vala/CMakeLists.txt
+++ b/xmpp-vala/CMakeLists.txt
@@ -55,6 +55,7 @@ SOURCES
     "src/module/xep/0049_private_xml_storage.vala"
     "src/module/xep/0054_vcard/module.vala"
     "src/module/xep/0060_pubsub.vala"
+    "src/module/xep/0065_socks5_bytestreams.vala"
     "src/module/xep/0066_out_of_band_data.vala"
     "src/module/xep/0077_in_band_registration.vala"
     "src/module/xep/0082_date_time_profiles.vala"
@@ -68,6 +69,7 @@ SOURCES
     "src/module/xep/0199_ping.vala"
     "src/module/xep/0203_delayed_delivery.vala"
     "src/module/xep/0234_jingle_file_transfer.vala"
+    "src/module/xep/0260_jingle_socks5_bytestreams.vala"
     "src/module/xep/0261_jingle_in_band_bytestreams.vala"
     "src/module/xep/0280_message_carbons.vala"
     "src/module/xep/0313_message_archive_management.vala"
diff --git a/xmpp-vala/src/module/stanza_error.vala b/xmpp-vala/src/module/stanza_error.vala
index c108b02a..a5c3956c 100644
--- a/xmpp-vala/src/module/stanza_error.vala
+++ b/xmpp-vala/src/module/stanza_error.vala
@@ -75,7 +75,7 @@ namespace Xmpp {
                 error_node.put_node(new StanzaNode.build("text", ERROR_NS_URI)
                     .add_self_xmlns()
                     .put_attribute("xml:lang", "en")
-                    .put_node(new StanzaNode.text(text))
+                    .put_node(new StanzaNode.text(human_readable))
                 );
             }
         }
@@ -94,6 +94,9 @@ namespace Xmpp {
         public ErrorStanza.not_allowed(string? human_readable = null) {
             this.build(TYPE_CANCEL, CONDITION_NOT_ALLOWED, human_readable, null);
         }
+        public ErrorStanza.resource_constraint(string? human_readable = null) {
+            this.build(TYPE_WAIT, CONDITION_RESOURCE_CONSTRAINT, human_readable, null);
+        }
         public ErrorStanza.service_unavailable() {
             this.build(TYPE_CANCEL, CONDITION_SERVICE_UNAVAILABLE, null, null);
         }
diff --git a/xmpp-vala/src/module/xep/0047_in_band_bytestreams.vala b/xmpp-vala/src/module/xep/0047_in_band_bytestreams.vala
index 2650a194..9aa2d98c 100644
--- a/xmpp-vala/src/module/xep/0047_in_band_bytestreams.vala
+++ b/xmpp-vala/src/module/xep/0047_in_band_bytestreams.vala
@@ -14,7 +14,9 @@ public class Module : XmppStreamModule, Iq.Handler {
         stream.add_flag(new Flag());
         stream.get_module(Iq.Module.IDENTITY).register_for_namespace(NS_URI, this);
     }
-    public override void detach(XmppStream stream) { }
+    public override void detach(XmppStream stream) {
+        stream.get_module(Iq.Module.IDENTITY).unregister_from_namespace(NS_URI, this);
+    }
 
     public void on_iq_set(XmppStream stream, Iq.Stanza iq) {
         // the iq module ensures that there's only one child node
@@ -23,28 +25,28 @@ public class Module : XmppStreamModule, Iq.Handler {
         node = (node != null) ? node : iq.stanza.get_subnode("data", NS_URI);
         node = (node != null) ? node : iq.stanza.get_subnode("close", NS_URI);
         if (node == null) {
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("unknown IBB action")));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("unknown IBB action")) { to=iq.from });
             return;
         }
         string? sid = node.get_attribute("sid");
         if (sid == null) {
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("missing sid")));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("missing sid")) { to=iq.from });
             return;
         }
         Connection? conn = stream.get_flag(Flag.IDENTITY).get_connection(sid);
         if (node.name == "open") {
             if (conn == null) {
-                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.not_acceptable("unexpected IBB connection")));
+                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.not_acceptable("unexpected IBB connection")) { to=iq.from });
                 return;
             }
             if (conn.state != Connection.State.WAITING_FOR_CONNECT) {
-                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("IBB open for already open connection")));
+                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("IBB open for already open connection")) { to=iq.from });
                 return;
             }
             conn.handle_open(stream, node, iq);
         } else {
             if (conn == null || conn.state != Connection.State.CONNECTED) {
-                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.item_not_found()));
+                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.item_not_found()) { to=iq.from });
                 return;
             }
             if (node.name == "close") {
@@ -60,9 +62,8 @@ public class Module : XmppStreamModule, Iq.Handler {
 }
 
 public class Connection : IOStream {
-    // TODO(hrxi): Fix reference cycle
     public class Input : InputStream {
-        private Connection connection;
+        private weak Connection connection;
         public Input(Connection connection) {
             this.connection = connection;
         }
@@ -73,14 +74,14 @@ public class Connection : IOStream {
             return yield connection.read_async(buffer, io_priority, cancellable);
         }
         public override bool close(Cancellable? cancellable = null) throws IOError {
-            return connection.close_read(cancellable);
+            throw new IOError.NOT_SUPPORTED("can't do non-async closes on in-band bytestreams");
         }
         public override async bool close_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
             return yield connection.close_read_async(io_priority, cancellable);
         }
     }
     public class Output : OutputStream {
-        private Connection connection;
+        private weak Connection connection;
         public Output(Connection connection) {
             this.connection = connection;
         }
@@ -91,7 +92,7 @@ public class Connection : IOStream {
             return yield connection.write_async(buffer, io_priority, cancellable);
         }
         public override bool close(Cancellable? cancellable = null) throws IOError {
-            return connection.close_write(cancellable);
+            throw new IOError.NOT_SUPPORTED("can't do non-async closes on in-band bytestreams");
         }
         public override async bool close_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
             return yield connection.close_write_async(io_priority, cancellable);
@@ -150,25 +151,25 @@ public class Connection : IOStream {
         output = new Output(this);
     }
 
-    public void set_read_callback(SourceFunc callback, Cancellable? cancellable, int io_priority) throws IOError {
+    public void set_read_callback(owned SourceFunc callback, Cancellable? cancellable, int io_priority) throws IOError {
         if (read_callback != null) {
             throw new IOError.PENDING("only one async read is permitted at a time on an in-band bytestream");
         }
         if (cancellable != null) {
             read_callback_cancellable_id = cancellable.connect(trigger_read_callback);
         }
-        read_callback = callback;
+        read_callback = (owned)callback;
         read_callback_cancellable = cancellable;
         read_callback_priority = io_priority;
     }
-    public void set_write_callback(SourceFunc callback, Cancellable? cancellable, int io_priority) throws IOError {
+    public void set_write_callback(owned SourceFunc callback, Cancellable? cancellable, int io_priority) throws IOError {
         if (write_callback != null) {
             throw new IOError.PENDING("only one async write is permitted at a time on an in-band bytestream");
         }
         if (cancellable != null) {
             write_callback_cancellable_id = cancellable.connect(trigger_write_callback);
         }
-        write_callback = callback;
+        write_callback = (owned)callback;
         write_callback_cancellable = cancellable;
         write_callback_priority = io_priority;
     }
@@ -263,13 +264,6 @@ public class Connection : IOStream {
         return buffer.length;
     }
 
-    public bool close_read(Cancellable? cancellable = null) {
-        input_closed = true;
-        if (!output_closed) {
-            return true;
-        }
-        return close_impl(cancellable);
-    }
     public async bool close_read_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
         input_closed = true;
         if (!output_closed) {
@@ -277,13 +271,6 @@ public class Connection : IOStream {
         }
         return yield close_async_impl(io_priority, cancellable);
     }
-    public bool close_write(Cancellable? cancellable = null) {
-        output_closed = true;
-        if (!input_closed) {
-            return true;
-        }
-        return close_impl(cancellable);
-    }
     public async bool close_write_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
         output_closed = true;
         if (!input_closed) {
@@ -292,7 +279,7 @@ public class Connection : IOStream {
         return yield close_async_impl(io_priority, cancellable);
     }
     delegate void OnClose(bool success);
-    private bool close_impl(Cancellable? cancellable = null, OnClose? on_close = null) {
+    private bool close_impl(Cancellable? cancellable, OnClose on_close) {
         if (state == State.DISCONNECTING || state == State.DISCONNECTED || state == State.ERROR) {
             on_close(true);
             return true;
@@ -386,17 +373,17 @@ public class Connection : IOStream {
         string? stanza = open.get_attribute("stanza");
         if (block_size < 0 || (stanza != null && stanza != "iq" && stanza != "message")) {
             set_error("invalid open");
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("missing block_size or invalid stanza")));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("missing block_size or invalid stanza")) { to=iq.from });
             return;
         }
         if (stanza != null && stanza != "iq") {
             set_error("invalid open");
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.feature_not_implemented("cannot use message stanzas for IBB")));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.feature_not_implemented("cannot use message stanzas for IBB")) { to=iq.from });
             return;
         }
         if (block_size > this.block_size) {
             set_error("invalid open");
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.build(ErrorStanza.TYPE_CANCEL, ErrorStanza.CONDITION_RESOURCE_CONSTRAINT, "opening a connection with a greater than negotiated/acceptable block size", null)));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.build(ErrorStanza.TYPE_CANCEL, ErrorStanza.CONDITION_RESOURCE_CONSTRAINT, "opening a connection with a greater than negotiated/acceptable block size", null)) { to=iq.from });
             return;
         }
         this.block_size = block_size;
@@ -408,7 +395,7 @@ public class Connection : IOStream {
         assert(state == State.CONNECTED);
         if (input_closed) {
             set_error("unexpected data");
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.not_allowed("unexpected data")));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.not_allowed("unexpected data")) { to=iq.from });
             return;
         }
         int seq = data.get_attribute_int("seq");
@@ -417,12 +404,12 @@ public class Connection : IOStream {
         uint8[] content = Base64.decode(data.get_string_content());
         if (content.length > block_size) {
             set_error("data longer than negotiated block size");
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("data longer than negotiated block size")));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.bad_request("data longer than negotiated block size")) { to=iq.from });
             return;
         }
         if (seq < 0 || seq != remote_seq) {
             set_error("out of order data packets");
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.build(ErrorStanza.TYPE_CANCEL, ErrorStanza.CONDITION_UNEXPECTED_REQUEST, "out of order data packets", null)));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.build(ErrorStanza.TYPE_CANCEL, ErrorStanza.CONDITION_UNEXPECTED_REQUEST, "out of order data packets", null)) { to=iq.from });
             return;
         }
         remote_seq = (remote_seq + 1) % SEQ_MODULUS;
diff --git a/xmpp-vala/src/module/xep/0065_socks5_bytestreams.vala b/xmpp-vala/src/module/xep/0065_socks5_bytestreams.vala
new file mode 100644
index 00000000..1890aac3
--- /dev/null
+++ b/xmpp-vala/src/module/xep/0065_socks5_bytestreams.vala
@@ -0,0 +1,83 @@
+using Gee;
+using Xmpp;
+using Xmpp.Xep;
+
+namespace Xmpp.Xep.Socks5Bytestreams {
+
+internal const string NS_URI = "http://jabber.org/protocol/bytestreams";
+
+public class Proxy : Object {
+    public string host { get; private set; }
+    public Jid jid { get; private set; }
+    public int port { get; private set; }
+
+    public Proxy(string host, Jid jid, int port) {
+        this.host = host;
+        this.jid = jid;
+        this.port = port;
+    }
+}
+
+public class Module : XmppStreamModule, Iq.Handler {
+    public static Xmpp.ModuleIdentity<Module> IDENTITY = new Xmpp.ModuleIdentity<Module>(NS_URI, "0065_socks5_bytestreams");
+
+    public override void attach(XmppStream stream) {
+        stream.add_flag(new Flag());
+        query_availability(stream);
+    }
+    public override void detach(XmppStream stream) { }
+
+    public void on_iq_set(XmppStream stream, Iq.Stanza iq) { }
+
+    public Gee.List<Proxy> get_proxies(XmppStream stream) {
+        return stream.get_flag(Flag.IDENTITY).proxies;
+    }
+
+    private void query_availability(XmppStream stream) {
+        stream.get_module(ServiceDiscovery.Module.IDENTITY).request_items(stream, stream.remote_name, (stream, items_result) => {
+            foreach (Xep.ServiceDiscovery.Item item in items_result.items) {
+                stream.get_module(ServiceDiscovery.Module.IDENTITY).request_info(stream, item.jid, (stream, info_result) => {
+                    foreach (string feature in info_result.features) {
+                        if (feature == NS_URI) {
+                            StanzaNode query_ = new StanzaNode.build("query", NS_URI).add_self_xmlns();
+                            Iq.Stanza iq = new Iq.Stanza.get(query_) { to=item.jid };
+                            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq, (stream, iq) => {
+                                if (iq.is_error()) {
+                                    return;
+                                }
+                                StanzaNode? query = iq.stanza.get_subnode("query", NS_URI);
+                                StanzaNode? stream_host = query != null ? query.get_subnode("streamhost", NS_URI) : null;
+                                if (query == null || stream_host == null) {
+                                    return;
+                                }
+                                string? host = stream_host.get_attribute("host");
+                                string? jid_str = stream_host.get_attribute("jid");
+                                Jid? jid = jid_str != null ? Jid.parse(jid_str) : null;
+                                int port = stream_host.get_attribute_int("port");
+                                if (host == null || jid == null || port <= 0 || port > 65535) {
+                                    return;
+                                }
+                                stream.get_flag(Flag.IDENTITY).proxies.add(new Proxy(host, jid, port));
+                            });
+                        }
+                    }
+                });
+            }
+        });
+    }
+
+    public override string get_ns() { return NS_URI; }
+    public override string get_id() { return IDENTITY.id; }
+}
+
+public class Flag : XmppStreamFlag {
+    public static FlagIdentity<Flag> IDENTITY = new FlagIdentity<Flag>(NS_URI, "socks5_bytestreams");
+
+    public Gee.List<Proxy> proxies = new ArrayList<Proxy>();
+
+    public override string get_ns() { return NS_URI; }
+    public override string get_id() { return IDENTITY.id; }
+}
+
+
+}
diff --git a/xmpp-vala/src/module/xep/0166_jingle.vala b/xmpp-vala/src/module/xep/0166_jingle.vala
index ae872ac6..06e3d5c8 100644
--- a/xmpp-vala/src/module/xep/0166_jingle.vala
+++ b/xmpp-vala/src/module/xep/0166_jingle.vala
@@ -11,7 +11,9 @@ public errordomain IqError {
     BAD_REQUEST,
     NOT_ACCEPTABLE,
     NOT_IMPLEMENTED,
+    UNSUPPORTED_INFO,
     OUT_OF_ORDER,
+    RESOURCE_CONSTRAINT,
 }
 
 void send_iq_error(IqError iq_error, XmppStream stream, Iq.Stanza iq) {
@@ -22,13 +24,18 @@ void send_iq_error(IqError iq_error, XmppStream stream, Iq.Stanza iq) {
         error = new ErrorStanza.not_acceptable(iq_error.message);
     } else if (iq_error is IqError.NOT_IMPLEMENTED) {
         error = new ErrorStanza.feature_not_implemented(iq_error.message);
+    } else if (iq_error is IqError.UNSUPPORTED_INFO) {
+        StanzaNode unsupported_info = new StanzaNode.build("unsupported-info", ERROR_NS_URI).add_self_xmlns();
+        error = new ErrorStanza.build(ErrorStanza.TYPE_CANCEL, ErrorStanza.CONDITION_FEATURE_NOT_IMPLEMENTED, iq_error.message, unsupported_info);
     } else if (iq_error is IqError.OUT_OF_ORDER) {
         StanzaNode out_of_order = new StanzaNode.build("out-of-order", ERROR_NS_URI).add_self_xmlns();
         error = new ErrorStanza.build(ErrorStanza.TYPE_MODIFY, ErrorStanza.CONDITION_UNEXPECTED_REQUEST, iq_error.message, out_of_order);
+    } else if (iq_error is IqError.RESOURCE_CONSTRAINT) {
+        error = new ErrorStanza.resource_constraint(iq_error.message);
     } else {
         assert_not_reached();
     }
-    stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, error));
+    stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, error) { to=iq.from });
 }
 
 public errordomain Error {
@@ -40,34 +47,83 @@ public errordomain Error {
     TRANSPORT_ERROR,
 }
 
-StanzaNode get_single_node_anyns(StanzaNode parent, string node_name) throws IqError {
+StanzaNode? get_single_node_anyns(StanzaNode parent, string? node_name = null) throws IqError {
     StanzaNode? result = null;
     foreach (StanzaNode child in parent.get_all_subnodes()) {
-        if (child.name == node_name) {
+        if (node_name == null || child.name == node_name) {
             if (result != null) {
-                throw new IqError.BAD_REQUEST(@"multiple $(node_name) nodes");
+                if (node_name != null) {
+                    throw new IqError.BAD_REQUEST(@"multiple $(node_name) nodes");
+                } else {
+                    throw new IqError.BAD_REQUEST(@"expected single subnode");
+                }
             }
             result = child;
         }
     }
-    if (result == null) {
-        throw new IqError.BAD_REQUEST(@"missing $(node_name) node");
-    }
     return result;
 }
 
+class ContentNode {
+    public Role creator;
+    public string name;
+    public StanzaNode? description;
+    public StanzaNode? transport;
+}
+
+ContentNode get_single_content_node(StanzaNode jingle) throws IqError {
+    Gee.List<StanzaNode> contents = jingle.get_subnodes("content");
+    if (contents.size == 0) {
+        throw new IqError.BAD_REQUEST("missing content node");
+    }
+    if (contents.size > 1) {
+        throw new IqError.NOT_IMPLEMENTED("can't process multiple content nodes");
+    }
+    StanzaNode content = contents[0];
+    string? creator_str = content.get_attribute("creator");
+    // Vala can't typecheck the ternary operator here.
+    Role? creator = null;
+    if (creator_str != null) {
+        creator = Role.parse(creator_str);
+    } else {
+        // TODO(hrxi): now, is the creator attribute optional or not (XEP-0166
+        // Jingle)?
+        creator = Role.INITIATOR;
+    }
+
+    string? name = content.get_attribute("name");
+    StanzaNode? description = get_single_node_anyns(content, "description");
+    StanzaNode? transport = get_single_node_anyns(content, "transport");
+    if (name == null || creator == null) {
+        throw new IqError.BAD_REQUEST("missing name or creator");
+    }
+
+    return new ContentNode() {
+        creator=creator,
+        name=name,
+        description=description,
+        transport=transport
+    };
+}
+
+// This module can only be attached to one stream at a time.
 public class Module : XmppStreamModule, Iq.Handler {
     public static Xmpp.ModuleIdentity<Module> IDENTITY = new Xmpp.ModuleIdentity<Module>(NS_URI, "0166_jingle");
 
     private HashMap<string, ContentType> content_types = new HashMap<string, ContentType>();
     private HashMap<string, Transport> transports = new HashMap<string, Transport>();
 
+    private XmppStream? current_stream = null;
+
     public override void attach(XmppStream stream) {
         stream.add_flag(new Flag());
         stream.get_module(ServiceDiscovery.Module.IDENTITY).add_feature(stream, NS_URI);
         stream.get_module(Iq.Module.IDENTITY).register_for_namespace(NS_URI, this);
+        current_stream = stream;
+    }
+    public override void detach(XmppStream stream) {
+        stream.get_module(Iq.Module.IDENTITY).unregister_from_namespace(NS_URI, this);
     }
-    public override void detach(XmppStream stream) { }
 
     public void register_content_type(ContentType content_type) {
         content_types[content_type.content_type_ns_uri()] = content_type;
@@ -87,17 +143,25 @@ public class Module : XmppStreamModule, Iq.Handler {
         }
         return transports[ns_uri];
     }
-    public Transport? select_transport(XmppStream stream, TransportType type, Jid receiver_full_jid) {
+    public Transport? select_transport(XmppStream stream, TransportType type, Jid receiver_full_jid, Set<string> blacklist) {
+        Transport? result = null;
         foreach (Transport transport in transports.values) {
             if (transport.transport_type() != type) {
                 continue;
             }
-            // TODO(hrxi): prioritization
+            if (transport.transport_ns_uri() in blacklist) {
+                continue;
+            }
             if (transport.is_transport_available(stream, receiver_full_jid)) {
-                return transport;
+                if (result != null) {
+                    if (result.transport_priority() >= transport.transport_priority()) {
+                        continue;
+                    }
+                }
+                result = transport;
             }
         }
-        return null;
+        return result;
     }
 
     private bool is_jingle_available(XmppStream stream, Jid full_jid) {
@@ -106,14 +170,14 @@ public class Module : XmppStreamModule, Iq.Handler {
     }
 
     public bool is_available(XmppStream stream, TransportType type, Jid full_jid) {
-        return is_jingle_available(stream, full_jid) && select_transport(stream, type, full_jid) != null;
+        return is_jingle_available(stream, full_jid) && select_transport(stream, type, full_jid, Set.empty()) != null;
     }
 
     public Session create_session(XmppStream stream, TransportType type, Jid receiver_full_jid, Senders senders, string content_name, StanzaNode description) throws Error {
         if (!is_jingle_available(stream, receiver_full_jid)) {
             throw new Error.NO_SHARED_PROTOCOLS("No Jingle support");
         }
-        Transport? transport = select_transport(stream, type, receiver_full_jid);
+        Transport? transport = select_transport(stream, type, receiver_full_jid, Set.empty());
         if (transport == null) {
             throw new Error.NO_SHARED_PROTOCOLS("No suitable transports");
         }
@@ -121,8 +185,8 @@ public class Module : XmppStreamModule, Iq.Handler {
         if (my_jid == null) {
             throw new Error.GENERAL("Couldn't determine own JID");
         }
-        TransportParameters transport_params = transport.create_transport_parameters();
-        Session session = new Session.initiate_sent(random_uuid(), type, transport_params, receiver_full_jid, content_name);
+        TransportParameters transport_params = transport.create_transport_parameters(stream, my_jid, receiver_full_jid);
+        Session session = new Session.initiate_sent(random_uuid(), type, transport_params, my_jid, receiver_full_jid, content_name, send_terminate_and_remove_session);
         StanzaNode content = new StanzaNode.build("content", NS_URI)
             .put_attribute("creator", "initiator")
             .put_attribute("name", content_name)
@@ -146,51 +210,58 @@ public class Module : XmppStreamModule, Iq.Handler {
     }
 
     public void handle_session_initiate(XmppStream stream, string sid, StanzaNode jingle, Iq.Stanza iq) throws IqError {
-        Gee.List<StanzaNode> contents = jingle.get_subnodes("content");
-        if (contents.size == 0) {
-            throw new IqError.BAD_REQUEST("missing content node");
-        }
-        if (contents.size > 1) {
-            throw new IqError.NOT_IMPLEMENTED("can't process multiple content nodes");
+        ContentNode content = get_single_content_node(jingle);
+        if (content.description == null || content.transport == null) {
+            throw new IqError.BAD_REQUEST("missing description or transport node");
         }
-        StanzaNode content = contents[0];
-        string? name = content.get_attribute("name");
-        StanzaNode description = get_single_node_anyns(content, "description");
-        StanzaNode transport_node = get_single_node_anyns(content, "transport");
-        if (name == null) {
-            throw new IqError.BAD_REQUEST("missing name");
+        Jid? my_jid = stream.get_flag(Bind.Flag.IDENTITY).my_jid;
+        if (my_jid == null) {
+            throw new IqError.RESOURCE_CONSTRAINT("Couldn't determine own JID");
         }
-
-        Transport? transport = get_transport(transport_node.ns_uri);
+        Transport? transport = get_transport(content.transport.ns_uri);
         TransportParameters? transport_params = null;
         if (transport != null) {
-            transport_params = transport.parse_transport_parameters(transport_node);
+            transport_params = transport.parse_transport_parameters(stream, my_jid, iq.from, content.transport);
         } else {
             // terminate the session below
         }
 
-        ContentType? content_type = get_content_type(description.ns_uri);
+        ContentType? content_type = get_content_type(content.description.ns_uri);
         if (content_type == null) {
             // TODO(hrxi): how do we signal an unknown content type?
             throw new IqError.NOT_IMPLEMENTED("unknown content type");
         }
-        ContentParameters content_params = content_type.parse_content_parameters(description);
+        ContentParameters content_params = content_type.parse_content_parameters(content.description);
 
         TransportType type = content_type.content_type_transport_type();
-        Session session = new Session.initiate_received(sid, type, transport_params, iq.from, name);
+        Session session = new Session.initiate_received(sid, type, transport_params, my_jid, iq.from, content.name, send_terminate_and_remove_session);
         stream.get_flag(Flag.IDENTITY).add_session(session);
         stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
 
         if (transport == null || transport.transport_type() != type) {
             StanzaNode reason = new StanzaNode.build("reason", NS_URI)
                 .put_node(new StanzaNode.build("unsupported-transports", NS_URI));
-            session.terminate(stream, reason);
+            session.terminate(reason, "unsupported transports");
             return;
         }
 
         content_params.on_session_initiate(stream, session);
     }
 
+    private void send_terminate_and_remove_session(Jid to, string sid, StanzaNode reason) {
+        StanzaNode jingle = new StanzaNode.build("jingle", NS_URI)
+            .add_self_xmlns()
+            .put_attribute("action", "session-terminate")
+            .put_attribute("sid", sid)
+            .put_node(reason);
+        Iq.Stanza iq = new Iq.Stanza.set(jingle) { to=to };
+        current_stream.get_module(Iq.Module.IDENTITY).send_iq(current_stream, iq);
+
+        // Immediately remove the session from the open sessions as per the
+        // XEP, don't wait for confirmation.
+        current_stream.get_flag(Flag.IDENTITY).remove_session(sid);
+    }
+
     public void on_iq_set(XmppStream stream, Iq.Stanza iq) {
         try {
             handle_iq_set(stream, iq);
@@ -210,7 +281,7 @@ public class Module : XmppStreamModule, Iq.Handler {
         if (action == "session-initiate") {
             if (session != null) {
                 // TODO(hrxi): Info leak if other clients use predictable session IDs?
-                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.build(ErrorStanza.TYPE_MODIFY, ErrorStanza.CONDITION_CONFLICT, "session ID already in use", null)));
+                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.build(ErrorStanza.TYPE_MODIFY, ErrorStanza.CONDITION_CONFLICT, "session ID already in use", null)) { to=iq.from });
                 return;
             }
             handle_session_initiate(stream, sid, jingle, iq);
@@ -218,7 +289,7 @@ public class Module : XmppStreamModule, Iq.Handler {
         }
         if (session == null) {
             StanzaNode unknown_session = new StanzaNode.build("unknown-session", ERROR_NS_URI).add_self_xmlns();
-            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.item_not_found(unknown_session)));
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.error(iq, new ErrorStanza.item_not_found(unknown_session)) { to=iq.from });
             return;
         }
         session.handle_iq_set(stream, action, jingle, iq);
@@ -250,19 +321,26 @@ public enum Senders {
     }
 }
 
+public delegate void SessionTerminate(Jid to, string sid, StanzaNode reason);
+
 public interface Transport : Object {
     public abstract string transport_ns_uri();
     public abstract bool is_transport_available(XmppStream stream, Jid full_jid);
     public abstract TransportType transport_type();
-    public abstract TransportParameters create_transport_parameters();
-    public abstract TransportParameters parse_transport_parameters(StanzaNode transport) throws IqError;
+    public abstract int transport_priority();
+    public abstract TransportParameters create_transport_parameters(XmppStream stream, Jid local_full_jid, Jid peer_full_jid);
+    public abstract TransportParameters parse_transport_parameters(XmppStream stream, Jid local_full_jid, Jid peer_full_jid, StanzaNode transport) throws IqError;
 }
 
+
+// Gets a null `stream` if connection setup was unsuccessful and another
+// transport method should be tried.
 public interface TransportParameters : Object {
     public abstract string transport_ns_uri();
     public abstract StanzaNode to_transport_stanza_node();
-    public abstract void update_transport(StanzaNode transport) throws IqError;
-    public abstract IOStream create_transport_connection(XmppStream stream, Jid peer_full_jid, Role role);
+    public abstract void on_transport_accept(StanzaNode transport) throws IqError;
+    public abstract void on_transport_info(StanzaNode transport) throws IqError;
+    public abstract void create_transport_connection(XmppStream stream, Session session);
 }
 
 public enum Role {
@@ -276,12 +354,21 @@ public enum Role {
         }
         assert_not_reached();
     }
+
+    public static Role parse(string role) throws IqError {
+        switch (role) {
+            case "initiator": return INITIATOR;
+            case "responder": return RESPONDER;
+        }
+        throw new IqError.BAD_REQUEST(@"invalid role $(role)");
+    }
 }
 
 public interface ContentType : Object {
     public abstract string content_type_ns_uri();
     public abstract TransportType content_type_transport_type();
     public abstract ContentParameters parse_content_parameters(StanzaNode description) throws IqError;
+    public abstract void handle_content_session_info(XmppStream stream, Session session, StanzaNode info, Iq.Stanza iq) throws IqError;
 }
 
 public interface ContentParameters : Object {
@@ -290,79 +377,154 @@ public interface ContentParameters : Object {
 
 
 public class Session {
-    // INITIATE_SENT -> ACTIVE -> ENDED
-    // INITIATE_RECEIVED -> ACTIVE -> ENDED
+    // INITIATE_SENT -> CONNECTING -> [REPLACING_TRANSPORT -> CONNECTING ->]... ACTIVE -> ENDED
+    // INITIATE_RECEIVED -> CONNECTING -> [WAITING_FOR_TRANSPORT_REPLACE -> CONNECTING ->].. ACTIVE -> ENDED
     public enum State {
         INITIATE_SENT,
+        REPLACING_TRANSPORT,
         INITIATE_RECEIVED,
+        WAITING_FOR_TRANSPORT_REPLACE,
+        CONNECTING,
         ACTIVE,
         ENDED,
     }
 
     public State state { get; private set; }
 
+    public Role role { get; private set; }
     public string sid { get; private set; }
-    public Type type_ { get; private set; }
+    public TransportType type_ { get; private set; }
+    public Jid local_full_jid { get; private set; }
     public Jid peer_full_jid { get; private set; }
+    public Role content_creator { get; private set; }
     public string content_name { get; private set; }
 
-    // INITIATE_SENT | INITIATE_RECEIVED
-    TransportParameters? transport = null;
+    private Connection connection;
+    public IOStream conn { get { return connection; } }
 
-    // ACTIVE
-    public IOStream? conn { get; private set; }
+    public bool terminate_on_connection_close { get; set; }
 
-    // Only interesting in INITIATE_SENT.
-    // Signals that the session has been accepted by the peer.
-    public signal void accepted(XmppStream stream);
+    // INITIATE_SENT | INITIATE_RECEIVED | CONNECTING
+    Set<string> tried_transport_methods = new HashSet<string>();
+    TransportParameters? transport = null;
+
+    SessionTerminate session_terminate_handler;
 
-    public Session.initiate_sent(string sid, Type type, TransportParameters transport, Jid peer_full_jid, string content_name) {
+    public Session.initiate_sent(string sid, TransportType type, TransportParameters transport, Jid local_full_jid, Jid peer_full_jid, string content_name, owned SessionTerminate session_terminate_handler) {
         this.state = State.INITIATE_SENT;
+        this.role = Role.INITIATOR;
         this.sid = sid;
         this.type_ = type;
+        this.local_full_jid = local_full_jid;
         this.peer_full_jid = peer_full_jid;
+        this.content_creator = Role.INITIATOR;
         this.content_name = content_name;
+        this.tried_transport_methods = new HashSet<string>();
+        this.tried_transport_methods.add(transport.transport_ns_uri());
         this.transport = transport;
-        this.conn = null;
+        this.connection = new Connection(this);
+        this.session_terminate_handler = (owned)session_terminate_handler;
+        this.terminate_on_connection_close = true;
     }
 
-    public Session.initiate_received(string sid, Type type, TransportParameters? transport, Jid peer_full_jid, string content_name) {
+    public Session.initiate_received(string sid, TransportType type, TransportParameters? transport, Jid local_full_jid, Jid peer_full_jid, string content_name, owned SessionTerminate session_terminate_handler) {
         this.state = State.INITIATE_RECEIVED;
+        this.role = Role.RESPONDER;
         this.sid = sid;
         this.type_ = type;
+        this.local_full_jid = local_full_jid;
         this.peer_full_jid = peer_full_jid;
+        this.content_creator = Role.INITIATOR;
         this.content_name = content_name;
         this.transport = transport;
-        this.conn = null;
+        this.tried_transport_methods = new HashSet<string>();
+        if (transport != null) {
+            this.tried_transport_methods.add(transport.transport_ns_uri());
+        }
+        this.connection = new Connection(this);
+        this.session_terminate_handler = (owned)session_terminate_handler;
+        this.terminate_on_connection_close = true;
     }
 
     public void handle_iq_set(XmppStream stream, string action, StanzaNode jingle, Iq.Stanza iq) throws IqError {
+        // Validate action.
         switch (action) {
             case "session-accept":
-                if (state != State.INITIATE_SENT) {
-                    throw new IqError.OUT_OF_ORDER("got session-accept while not waiting for one");
-                }
-                handle_session_accept(stream, jingle, iq);
-                break;
+            case "session-info":
             case "session-terminate":
-                handle_session_terminate(stream, jingle, iq);
+            case "transport-accept":
+            case "transport-info":
+            case "transport-reject":
+            case "transport-replace":
                 break;
             case "content-accept":
             case "content-add":
             case "content-modify":
             case "content-reject":
             case "content-remove":
+            case "description-info":
             case "security-info":
-            case "transport-accept":
-            case "transport-info":
-            case "transport-reject":
-            case "transport-replace":
                 throw new IqError.NOT_IMPLEMENTED(@"$(action) is not implemented");
             default:
                 throw new IqError.BAD_REQUEST("invalid action");
         }
+        ContentNode? content = null;
+        StanzaNode? transport = null;
+        // Do some pre-processing.
+        if (action != "session-info" && action != "session-terminate") {
+            content = get_single_content_node(jingle);
+            verify_content(content);
+            switch (action) {
+                case "transport-accept":
+                case "transport-reject":
+                case "transport-replace":
+                case "transport-info":
+                    switch (state) {
+                        case State.INITIATE_SENT:
+                        case State.REPLACING_TRANSPORT:
+                        case State.INITIATE_RECEIVED:
+                        case State.WAITING_FOR_TRANSPORT_REPLACE:
+                        case State.CONNECTING:
+                            break;
+                        default:
+                            throw new IqError.OUT_OF_ORDER("transport-* unsupported after connection setup");
+                    }
+                    // TODO(hrxi): What to do with description nodes?
+                    if (content.transport == null) {
+                        throw new IqError.BAD_REQUEST("missing transport node");
+                    }
+                    transport = content.transport;
+                    break;
+            }
+        }
+        switch (action) {
+            case "session-accept":
+                if (state != State.INITIATE_SENT) {
+                    throw new IqError.OUT_OF_ORDER("got session-accept while not waiting for one");
+                }
+                handle_session_accept(stream, content, jingle, iq);
+                break;
+            case "session-info":
+                handle_session_info(stream, jingle, iq);
+                break;
+            case "session-terminate":
+                handle_session_terminate(stream, jingle, iq);
+                break;
+            case "transport-accept":
+                handle_transport_accept(stream, transport, jingle, iq);
+                break;
+            case "transport-reject":
+                handle_transport_reject(stream, jingle, iq);
+                break;
+            case "transport-replace":
+                handle_transport_replace(stream, transport, jingle, iq);
+                break;
+            case "transport-info":
+                handle_transport_info(stream, transport, jingle, iq);
+                break;
+        }
     }
-    void handle_session_accept(XmppStream stream, StanzaNode jingle, Iq.Stanza iq) throws IqError {
+    void handle_session_accept(XmppStream stream, ContentNode content, StanzaNode jingle, Iq.Stanza iq) throws IqError {
         string? responder_str = jingle.get_attribute("responder");
         Jid responder;
         if (responder_str != null) {
@@ -374,32 +536,168 @@ public class Session {
         if (!responder.is_full()) {
             throw new IqError.BAD_REQUEST("invalid responder JID");
         }
-        Gee.List<StanzaNode> contents = jingle.get_subnodes("content");
-        if (contents.size == 0) {
-            // TODO(hrxi): here and below, should we terminate the session?
-            throw new IqError.BAD_REQUEST("missing content node");
+        if (content.description == null || content.transport == null) {
+            throw new IqError.BAD_REQUEST("missing description or transport node");
         }
-        if (contents.size > 1) {
-            throw new IqError.NOT_IMPLEMENTED("can't process multiple content nodes");
-        }
-        StanzaNode content = contents[0];
-        StanzaNode description = get_single_node_anyns(content, "description");
-        StanzaNode transport_node = get_single_node_anyns(content, "transport");
-        if (transport_node.ns_uri != transport.transport_ns_uri()) {
+        if (content.transport.ns_uri != transport.transport_ns_uri()) {
             throw new IqError.BAD_REQUEST("session-accept with unnegotiated transport method");
         }
-        transport.update_transport(transport_node);
-        conn = transport.create_transport_connection(stream, peer_full_jid, Role.INITIATOR);
-        transport = null;
+        transport.on_transport_accept(content.transport);
+        StanzaNode description = content.description; // TODO(hrxi): handle this :P
         stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
-        state = State.ACTIVE;
-        accepted(stream);
+
+        state = State.CONNECTING;
+        transport.create_transport_connection(stream, this);
+    }
+    void connection_created(XmppStream stream, IOStream? conn) {
+        if (state != State.CONNECTING) {
+            return;
+        }
+        if (conn != null) {
+            state = State.ACTIVE;
+            transport = null;
+            tried_transport_methods.clear();
+            connection.set_inner(conn);
+        } else {
+            if (role == Role.INITIATOR) {
+                select_new_transport(stream);
+            } else {
+                state = State.WAITING_FOR_TRANSPORT_REPLACE;
+            }
+        }
     }
     void handle_session_terminate(XmppStream stream, StanzaNode jingle, Iq.Stanza iq) throws IqError {
+        connection.on_terminated_by_jingle("remote terminated jingle session");
+        state = State.ENDED;
+        stream.get_flag(Flag.IDENTITY).remove_session(sid);
+
         stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
         // TODO(hrxi): also handle presence type=unavailable
     }
+    void handle_session_info(XmppStream stream, StanzaNode jingle, Iq.Stanza iq) throws IqError {
+        StanzaNode? info = get_single_node_anyns(jingle);
+        if (info == null) {
+            // Jingle session ping
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
+            return;
+        }
+        ContentType? content_type = stream.get_module(Module.IDENTITY).get_content_type(info.ns_uri);
+        if (content_type == null) {
+            throw new IqError.UNSUPPORTED_INFO("unknown session-info namespace");
+        }
+        content_type.handle_content_session_info(stream, this, info, iq);
+    }
+    void select_new_transport(XmppStream stream) {
+        Transport? new_transport = stream.get_module(Module.IDENTITY).select_transport(stream, type_, peer_full_jid, tried_transport_methods);
+        if (new_transport == null) {
+            StanzaNode reason = new StanzaNode.build("reason", NS_URI)
+                .put_node(new StanzaNode.build("failed-transport", NS_URI));
+            terminate(reason, "failed transport");
+            return;
+        }
+        tried_transport_methods.add(new_transport.transport_ns_uri());
+        transport = new_transport.create_transport_parameters(stream, local_full_jid, peer_full_jid);
+        StanzaNode jingle = new StanzaNode.build("jingle", NS_URI)
+            .add_self_xmlns()
+            .put_attribute("action", "transport-replace")
+            .put_attribute("sid", sid)
+            .put_node(new StanzaNode.build("content", NS_URI)
+                .put_attribute("creator", "initiator")
+                .put_attribute("name", content_name)
+                .put_node(transport.to_transport_stanza_node())
+            );
+        Iq.Stanza iq = new Iq.Stanza.set(jingle) { to=peer_full_jid };
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq);
+        state = State.REPLACING_TRANSPORT;
+    }
+    void handle_transport_accept(XmppStream stream, StanzaNode transport_node, StanzaNode jingle, Iq.Stanza iq) throws IqError {
+        if (state != State.REPLACING_TRANSPORT) {
+            throw new IqError.OUT_OF_ORDER("no outstanding transport-replace request");
+        }
+        if (transport_node.ns_uri != transport.transport_ns_uri()) {
+            throw new IqError.BAD_REQUEST("transport-accept with unnegotiated transport method");
+        }
+        transport.on_transport_accept(transport_node);
+        state = State.CONNECTING;
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
+        transport.create_transport_connection(stream, this);
+    }
+    void handle_transport_reject(XmppStream stream, StanzaNode jingle, Iq.Stanza iq) throws IqError {
+        if (state != State.REPLACING_TRANSPORT) {
+            throw new IqError.OUT_OF_ORDER("no outstanding transport-replace request");
+        }
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
+        select_new_transport(stream);
+    }
+    void handle_transport_replace(XmppStream stream, StanzaNode transport_node, StanzaNode jingle, Iq.Stanza iq) throws IqError {
+        Transport? transport = stream.get_module(Module.IDENTITY).get_transport(transport_node.ns_uri);
+        TransportParameters? parameters = null;
+        if (transport != null) {
+            // Just parse the transport info for the errors.
+            parameters = transport.parse_transport_parameters(stream, local_full_jid, peer_full_jid, transport_node);
+        }
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
+        if (state != State.WAITING_FOR_TRANSPORT_REPLACE || transport == null) {
+            StanzaNode jingle_response = new StanzaNode.build("jingle", NS_URI)
+                .add_self_xmlns()
+                .put_attribute("action", "transport-reject")
+                .put_attribute("sid", sid)
+                .put_node(new StanzaNode.build("content", NS_URI)
+                    .put_attribute("creator", "initiator")
+                    .put_attribute("name", content_name)
+                    .put_node(transport_node)
+                );
+            Iq.Stanza iq_response = new Iq.Stanza.set(jingle_response) { to=peer_full_jid };
+            stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq_response);
+            return;
+        }
+        this.transport = parameters;
+        StanzaNode jingle_response = new StanzaNode.build("jingle", NS_URI)
+            .add_self_xmlns()
+            .put_attribute("action", "transport-accept")
+            .put_attribute("sid", sid)
+            .put_node(new StanzaNode.build("content", NS_URI)
+                .put_attribute("creator", "initiator")
+                .put_attribute("name", content_name)
+                .put_node(this.transport.to_transport_stanza_node())
+            );
+        Iq.Stanza iq_response = new Iq.Stanza.set(jingle_response) { to=peer_full_jid };
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq_response);
 
+        state = State.CONNECTING;
+        this.transport.create_transport_connection(stream, this);
+    }
+    void handle_transport_info(XmppStream stream, StanzaNode transport, StanzaNode jingle, Iq.Stanza iq) throws IqError {
+        this.transport.on_transport_info(transport);
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
+    }
+    void verify_content(ContentNode content) throws IqError {
+        if (content.name != content_name || content.creator != content_creator) {
+            throw new IqError.BAD_REQUEST("unknown content");
+        }
+    }
+    public void set_transport_connection(XmppStream stream, IOStream? conn) {
+        if (state != State.CONNECTING) {
+            return;
+        }
+        connection_created(stream, conn);
+    }
+    public void send_transport_info(XmppStream stream, StanzaNode transport) {
+        if (state != State.CONNECTING) {
+            return;
+        }
+        StanzaNode jingle = new StanzaNode.build("jingle", NS_URI)
+            .add_self_xmlns()
+            .put_attribute("action", "transport-info")
+            .put_attribute("sid", sid)
+            .put_node(new StanzaNode.build("content", NS_URI)
+                .put_attribute("creator", "initiator")
+                .put_attribute("name", content_name)
+                .put_node(transport)
+            );
+        Iq.Stanza iq = new Iq.Stanza.set(jingle) { to=peer_full_jid };
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq);
+    }
     public void accept(XmppStream stream, StanzaNode description) {
         if (state != State.INITIATE_RECEIVED) {
             return; // TODO(hrxi): what to do?
@@ -417,10 +715,8 @@ public class Session {
         Iq.Stanza iq = new Iq.Stanza.set(jingle) { to=peer_full_jid };
         stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq);
 
-        conn = transport.create_transport_connection(stream, peer_full_jid, Role.RESPONDER);
-        transport = null;
-
-        state = State.ACTIVE;
+        state = State.CONNECTING;
+        transport.create_transport_connection(stream, this);
     }
 
     public void reject(XmppStream stream) {
@@ -429,7 +725,7 @@ public class Session {
         }
         StanzaNode reason = new StanzaNode.build("reason", NS_URI)
             .put_node(new StanzaNode.build("decline", NS_URI));
-        terminate(stream, reason);
+        terminate(reason, "declined");
     }
 
     public void set_application_error(XmppStream stream, StanzaNode? application_reason = null) {
@@ -438,37 +734,254 @@ public class Session {
         if (application_reason != null) {
             reason.put_node(application_reason);
         }
-        terminate(stream, reason);
+        terminate(reason, "application error");
     }
 
-    public void close_connection(XmppStream stream) {
-        if (state != State.ACTIVE) {
-            return; // TODO(hrxi): what to do?
+    public void on_connection_error(IOError error) {
+        // TODO(hrxi): where can we get an XmppStream from?
+        StanzaNode reason = new StanzaNode.build("reason", NS_URI)
+            .put_node(new StanzaNode.build("failed-transport", NS_URI))
+            .put_node(new StanzaNode.build("text", NS_URI)
+                .put_node(new StanzaNode.text(error.message))
+            );
+        terminate(reason, @"transport error: $(error.message)");
+    }
+    public void on_connection_close() {
+        if (terminate_on_connection_close) {
+            StanzaNode reason = new StanzaNode.build("reason", NS_URI)
+                .put_node(new StanzaNode.build("success", NS_URI));
+            terminate(reason, "success");
         }
-        conn.close();
     }
 
-    public void terminate(XmppStream stream, StanzaNode reason) {
-        if (state != State.INITIATE_SENT && state != State.INITIATE_RECEIVED && state != State.ACTIVE) {
-            // TODO(hrxi): what to do?
+    public void terminate(StanzaNode reason, string? local_reason) {
+        if (state == State.ENDED) {
             return;
         }
         if (state == State.ACTIVE) {
-            conn.close();
+            if (local_reason != null) {
+                connection.on_terminated_by_jingle(@"local session-terminate: $(local_reason)");
+            } else {
+                connection.on_terminated_by_jingle("local session-terminate");
+            }
         }
 
-        StanzaNode jingle = new StanzaNode.build("jingle", NS_URI)
-            .add_self_xmlns()
-            .put_attribute("action", "session-terminate")
-            .put_attribute("sid", sid)
-            .put_node(reason);
-        Iq.Stanza iq = new Iq.Stanza.set(jingle) { to=peer_full_jid };
-        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq);
-
+        session_terminate_handler(peer_full_jid, sid, reason);
         state = State.ENDED;
-        // Immediately remove the session from the open sessions as per the
-        // XEP, don't wait for confirmation.
-        stream.get_flag(Flag.IDENTITY).remove_session(sid);
+    }
+}
+
+public class Connection : IOStream {
+    public class Input : InputStream {
+        private weak Connection connection;
+        public Input(Connection connection) {
+            this.connection = connection;
+        }
+        public override ssize_t read(uint8[] buffer, Cancellable? cancellable = null) throws IOError {
+            throw new IOError.NOT_SUPPORTED("can't do non-async reads on jingle connections");
+        }
+        public override async ssize_t read_async(uint8[]? buffer, int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+            return yield connection.read_async(buffer, io_priority, cancellable);
+        }
+        public override bool close(Cancellable? cancellable = null) throws IOError {
+            return connection.close_read(cancellable);
+        }
+        public override async bool close_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+            return yield connection.close_read_async(io_priority, cancellable);
+        }
+    }
+    public class Output : OutputStream {
+        private weak Connection connection;
+        public Output(Connection connection) {
+            this.connection = connection;
+        }
+        public override ssize_t write(uint8[] buffer, Cancellable? cancellable = null) throws IOError {
+            throw new IOError.NOT_SUPPORTED("can't do non-async writes on jingle connections");
+        }
+        public override async ssize_t write_async(uint8[]? buffer, int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+            return yield connection.write_async(buffer, io_priority, cancellable);
+        }
+        public override bool close(Cancellable? cancellable = null) throws IOError {
+            return connection.close_write(cancellable);
+        }
+        public override async bool close_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+            return yield connection.close_write_async(io_priority, cancellable);
+        }
+    }
+
+    private Input input;
+    private Output output;
+    public override InputStream input_stream { get { return input; } }
+    public override OutputStream output_stream { get { return output; } }
+
+    private weak Session session;
+    private IOStream? inner = null;
+    private string? error = null;
+
+    private bool read_closed = false;
+    private bool write_closed = false;
+
+    private class OnSetInnerCallback {
+        public SourceFunc callback;
+        public int io_priority;
+    }
+
+    Gee.List<OnSetInnerCallback> callbacks = new ArrayList<OnSetInnerCallback>();
+
+    public Connection(Session session) {
+        this.input = new Input(this);
+        this.output = new Output(this);
+        this.session = session;
+    }
+
+    public void set_inner(IOStream inner) {
+        assert(this.inner == null);
+        this.inner = inner;
+        foreach (OnSetInnerCallback c in callbacks) {
+            Idle.add((owned) c.callback, c.io_priority);
+        }
+        callbacks = null;
+    }
+
+    public void on_terminated_by_jingle(string reason) {
+        if (error == null) {
+            close_async.begin();
+            error = reason;
+        }
+    }
+
+    private void check_for_errors() throws IOError {
+        if (error != null) {
+            throw new IOError.CLOSED(error);
+        }
+    }
+    private async void wait_and_check_for_errors(int io_priority, Cancellable? cancellable = null) throws IOError {
+        while (true) {
+            check_for_errors();
+            if (inner != null) {
+                return;
+            }
+            SourceFunc callback = wait_and_check_for_errors.callback;
+            ulong id = 0;
+            if (cancellable != null) {
+                id = cancellable.connect(() => callback());
+            }
+            callbacks.add(new OnSetInnerCallback() { callback=(owned)callback, io_priority=io_priority});
+            yield;
+            if (cancellable != null) {
+                cancellable.disconnect(id);
+            }
+        }
+    }
+    private void handle_connection_error(IOError error) {
+        Session? strong = session;
+        if (strong != null) {
+            strong.on_connection_error(error);
+        }
+    }
+    private void handle_connection_close() {
+        Session? strong = session;
+        if (strong != null) {
+            strong.on_connection_close();
+        }
+    }
+
+    public async ssize_t read_async(uint8[]? buffer, int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+        yield wait_and_check_for_errors(io_priority, cancellable);
+        try {
+            return yield inner.input_stream.read_async(buffer, io_priority, cancellable);
+        } catch (IOError e) {
+            handle_connection_error(e);
+            throw e;
+        }
+    }
+    public async ssize_t write_async(uint8[]? buffer, int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+        yield wait_and_check_for_errors(io_priority, cancellable);
+        try {
+            return yield inner.output_stream.write_async(buffer, io_priority, cancellable);
+        } catch (IOError e) {
+            handle_connection_error(e);
+            throw e;
+        }
+    }
+    public bool close_read(Cancellable? cancellable = null) throws IOError {
+        check_for_errors();
+        if (read_closed) {
+            return true;
+        }
+        close_read_async.begin(GLib.Priority.DEFAULT, cancellable);
+        return true;
+    }
+    public async bool close_read_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+        yield wait_and_check_for_errors(io_priority, cancellable);
+        if (read_closed) {
+            return true;
+        }
+        read_closed = true;
+        IOError error = null;
+        bool result = true;
+        try {
+            result = yield inner.input_stream.close_async(io_priority, cancellable);
+        } catch (IOError e) {
+            if (error == null) {
+                error = e;
+            }
+        }
+        try {
+            result = (yield close_if_both_closed(io_priority, cancellable)) && result;
+        } catch (IOError e) {
+            if (error == null) {
+                error = e;
+            }
+        }
+        if (error != null) {
+            handle_connection_error(error);
+            throw error;
+        }
+        return result;
+    }
+    public bool close_write(Cancellable? cancellable = null) throws IOError {
+        check_for_errors();
+        if (write_closed) {
+            return true;
+        }
+        close_write_async.begin(GLib.Priority.DEFAULT, cancellable);
+        return true;
+    }
+    public async bool close_write_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+        yield wait_and_check_for_errors(io_priority, cancellable);
+        if (write_closed) {
+            return true;
+        }
+        write_closed = true;
+        IOError error = null;
+        bool result = true;
+        try {
+            result = yield inner.output_stream.close_async(io_priority, cancellable);
+        } catch (IOError e) {
+            if (error == null) {
+                error = e;
+            }
+        }
+        try {
+            result = (yield close_if_both_closed(io_priority, cancellable)) && result;
+        } catch (IOError e) {
+            if (error == null) {
+                error = e;
+            }
+        }
+        if (error != null) {
+            handle_connection_error(error);
+            throw error;
+        }
+        return result;
+    }
+    private async bool close_if_both_closed(int io_priority, Cancellable? cancellable = null) throws IOError {
+        if (read_closed && write_closed) {
+            handle_connection_close();
+            //return yield inner.close_async(io_priority, cancellable);
+        }
+        return true;
     }
 }
 
diff --git a/xmpp-vala/src/module/xep/0234_jingle_file_transfer.vala b/xmpp-vala/src/module/xep/0234_jingle_file_transfer.vala
index 2e636491..25fe3ce4 100644
--- a/xmpp-vala/src/module/xep/0234_jingle_file_transfer.vala
+++ b/xmpp-vala/src/module/xep/0234_jingle_file_transfer.vala
@@ -24,6 +24,19 @@ public class Module : Jingle.ContentType, XmppStreamModule {
     public Jingle.ContentParameters parse_content_parameters(StanzaNode description) throws Jingle.IqError {
         return Parameters.parse(this, description);
     }
+    public void handle_content_session_info(XmppStream stream, Jingle.Session session, StanzaNode info, Iq.Stanza iq) throws Jingle.IqError {
+        switch (info.name) {
+            case "received":
+                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
+                break;
+            case "checksum":
+                // TODO(hrxi): handle hash
+                stream.get_module(Iq.Module.IDENTITY).send_iq(stream, new Iq.Stanza.result(iq));
+                break;
+            default:
+                throw new Jingle.IqError.UNSUPPORTED_INFO(@"unsupported file transfer info $(info.name)");
+        }
+    }
 
     public signal void file_incoming(XmppStream stream, FileTransfer file_transfer);
 
@@ -45,13 +58,9 @@ public class Module : Jingle.ContentType, XmppStreamModule {
 
         Jingle.Session session = stream.get_module(Jingle.Module.IDENTITY)
             .create_session(stream, Jingle.TransportType.STREAMING, receiver_full_jid, Jingle.Senders.INITIATOR, "a-file-offer", description); // TODO(hrxi): Why "a-file-offer"?
+        session.terminate_on_connection_close = false;
 
-        SourceFunc callback = offer_file_stream.callback;
-        session.accepted.connect((stream) => {
-            session.conn.input_stream.close();
-            Idle.add((owned) callback);
-        });
-        yield;
+        yield session.conn.input_stream.close_async();
 
         // TODO(hrxi): catch errors
         yield session.conn.output_stream.splice_async(input_stream, OutputStreamSpliceFlags.CLOSE_SOURCE|OutputStreamSpliceFlags.CLOSE_TARGET);
@@ -69,7 +78,7 @@ public class Parameters : Jingle.ContentParameters, Object {
     public int64 size { get; private set; }
     public StanzaNode original_description { get; private set; }
 
-    public Parameters(Module parent, StanzaNode original_description, string? media_type, string? name, int64? size) {
+    public Parameters(Module parent, StanzaNode original_description, string? media_type, string? name, int64 size) {
         this.parent = parent;
         this.original_description = original_description;
         this.media_type = media_type;
@@ -91,12 +100,15 @@ public class Parameters : Jingle.ContentParameters, Object {
         string? size_raw = size_node != null ? size_node.get_string_content() : null;
         // TODO(hrxi): For some reason, the ?:-expression does not work due to a type error.
         //int64? size = size_raw != null ? int64.parse(size_raw) : null; // TODO(hrxi): this has no error handling
-        int64 size = -1;
-        if (size_raw != null) {
-            size = int64.parse(size_raw);
-            if (size < 0) {
-                throw new Jingle.IqError.BAD_REQUEST("negative file size is invalid");
-            }
+        if (size_raw == null) {
+            // Jingle file transfers (XEP-0234) theoretically SHOULD send a
+            // file size, however, we do require it in order to reliably find
+            // the end of the file transfer.
+            throw new Jingle.IqError.BAD_REQUEST("file offer without file size");
+        }
+        int64 size = int64.parse(size_raw);
+        if (size < 0) {
+            throw new Jingle.IqError.BAD_REQUEST("negative file size is invalid");
         }
 
         return new Parameters(parent, description, media_type, name, size);
@@ -107,6 +119,47 @@ public class Parameters : Jingle.ContentParameters, Object {
     }
 }
 
+// Does nothing except wrapping an input stream to signal EOF after reading
+// `max_size` bytes.
+private class FileTransferInputStream : InputStream {
+    InputStream inner;
+    int64 remaining_size;
+    public FileTransferInputStream(InputStream inner, int64 max_size) {
+        this.inner = inner;
+        this.remaining_size = max_size;
+    }
+    private ssize_t update_remaining(ssize_t read) {
+        this.remaining_size -= read;
+        return read;
+    }
+    public override ssize_t read(uint8[] buffer_, Cancellable? cancellable = null) throws IOError {
+        unowned uint8[] buffer = buffer_;
+        if (remaining_size <= 0) {
+            return 0;
+        }
+        if (buffer.length > remaining_size) {
+            buffer = buffer[0:remaining_size];
+        }
+        return update_remaining(inner.read(buffer, cancellable));
+    }
+    public override async ssize_t read_async(uint8[]? buffer_, int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+        unowned uint8[] buffer = buffer_;
+        if (remaining_size <= 0) {
+            return 0;
+        }
+        if (buffer.length > remaining_size) {
+            buffer = buffer[0:remaining_size];
+        }
+        return update_remaining(yield inner.read_async(buffer, io_priority, cancellable));
+    }
+    public override bool close(Cancellable? cancellable = null) throws IOError {
+        return inner.close(cancellable);
+    }
+    public override async bool close_async(int io_priority = GLib.Priority.DEFAULT, Cancellable? cancellable = null) throws IOError {
+        return yield inner.close_async(io_priority, cancellable);
+    }
+}
+
 public class FileTransfer : Object {
     Jingle.Session session;
     Parameters parameters;
@@ -115,14 +168,15 @@ public class FileTransfer : Object {
     public string? file_name { get { return parameters.name; } }
     public int64 size { get { return parameters.size; } }
 
-    public InputStream? stream { get { return session.conn != null ? session.conn.input_stream : null; } }
+    public InputStream? stream { get; private set; }
 
     public FileTransfer(Jingle.Session session, Parameters parameters) {
         this.session = session;
         this.parameters = parameters;
+        this.stream = new FileTransferInputStream(session.conn.input_stream, parameters.size);
     }
 
-    public void accept(XmppStream stream) {
+    public void accept(XmppStream stream) throws IOError {
         session.accept(stream, parameters.original_description);
         session.conn.output_stream.close();
     }
diff --git a/xmpp-vala/src/module/xep/0260_jingle_socks5_bytestreams.vala b/xmpp-vala/src/module/xep/0260_jingle_socks5_bytestreams.vala
new file mode 100644
index 00000000..e0542207
--- /dev/null
+++ b/xmpp-vala/src/module/xep/0260_jingle_socks5_bytestreams.vala
@@ -0,0 +1,533 @@
+using Gee;
+using Xmpp;
+using Xmpp.Xep;
+
+namespace Xmpp.Xep.JingleSocks5Bytestreams {
+
+private const string NS_URI = "urn:xmpp:jingle:transports:s5b:1";
+
+public class Module : Jingle.Transport, XmppStreamModule {
+    public static Xmpp.ModuleIdentity<Module> IDENTITY = new Xmpp.ModuleIdentity<Module>(NS_URI, "0260_jingle_socks5_bytestreams");
+
+    public override void attach(XmppStream stream) {
+        stream.get_module(Jingle.Module.IDENTITY).register_transport(this);
+        stream.get_module(ServiceDiscovery.Module.IDENTITY).add_feature(stream, NS_URI);
+    }
+    public override void detach(XmppStream stream) { }
+
+    public override string get_ns() { return NS_URI; }
+    public override string get_id() { return IDENTITY.id; }
+
+    public bool is_transport_available(XmppStream stream, Jid full_jid) {
+        bool? result = stream.get_flag(ServiceDiscovery.Flag.IDENTITY).has_entity_feature(full_jid, NS_URI);
+        return result != null && result;
+    }
+
+    public string transport_ns_uri() {
+        return NS_URI;
+    }
+    public Jingle.TransportType transport_type() {
+        return Jingle.TransportType.STREAMING;
+    }
+    public int transport_priority() {
+        return 1;
+    }
+    private Gee.List<Candidate> get_local_candidates(XmppStream stream) {
+        Gee.List<Candidate> result = new ArrayList<Candidate>();
+        int i = 1 << 15;
+        foreach (Socks5Bytestreams.Proxy proxy in stream.get_module(Socks5Bytestreams.Module.IDENTITY).get_proxies(stream)) {
+            result.add(new Candidate.proxy(random_uuid(), proxy, i));
+            i -= 1;
+        }
+        return result;
+    }
+    public Jingle.TransportParameters create_transport_parameters(XmppStream stream, Jid local_full_jid, Jid peer_full_jid) {
+        Parameters result = new Parameters.create(local_full_jid, peer_full_jid, random_uuid());
+        result.local_candidates.add_all(get_local_candidates(stream));
+        return result;
+    }
+    public Jingle.TransportParameters parse_transport_parameters(XmppStream stream, Jid local_full_jid, Jid peer_full_jid, StanzaNode transport) throws Jingle.IqError {
+        Parameters result = Parameters.parse(local_full_jid, peer_full_jid, transport);
+        result.local_candidates.add_all(get_local_candidates(stream));
+        return result;
+    }
+}
+
+public enum CandidateType {
+    ASSISTED,
+    DIRECT,
+    PROXY,
+    TUNNEL;
+
+    public static CandidateType parse(string type) throws Jingle.IqError {
+        switch (type) {
+            case "assisted": return CandidateType.ASSISTED;
+            case "direct": return CandidateType.DIRECT;
+            case "proxy": return CandidateType.PROXY;
+            case "tunnel": return CandidateType.TUNNEL;
+        }
+        throw new Jingle.IqError.BAD_REQUEST(@"unknown candidate type $(type)");
+    }
+
+    public string to_string() {
+        switch (this) {
+            case ASSISTED: return "assisted";
+            case DIRECT: return "direct";
+            case PROXY: return "proxy";
+            case TUNNEL: return "tunnel";
+        }
+        assert_not_reached();
+    }
+
+    private int type_preference_impl() {
+        switch (this) {
+            case ASSISTED: return 120;
+            case DIRECT: return 126;
+            case PROXY: return 10;
+            case TUNNEL: return 110;
+        }
+        assert_not_reached();
+    }
+    public int type_preference() {
+        return type_preference_impl() << 16;
+    }
+}
+
+public class Candidate : Socks5Bytestreams.Proxy {
+    public string cid { get; private set; }
+    public int priority { get; private set; }
+    public CandidateType type_ { get; private set; }
+
+    private Candidate(string cid, string host, Jid jid, int port, int priority, CandidateType type) {
+        base(host, jid, port);
+        this.cid = cid;
+        this.priority = priority;
+        this.type_ = type;
+    }
+
+    public Candidate.build(string cid, string host, Jid jid, int port, int local_priority, CandidateType type) {
+        this(cid, host, jid, port, type.type_preference() + local_priority, type);
+    }
+    public Candidate.proxy(string cid, Socks5Bytestreams.Proxy proxy, int local_priority) {
+        this.build(cid, proxy.host, proxy.jid, proxy.port, local_priority, CandidateType.PROXY);
+    }
+
+    public static Candidate parse(StanzaNode candidate) throws Jingle.IqError {
+        string? cid = candidate.get_attribute("cid");
+        string? host = candidate.get_attribute("host");
+        string? jid_str = candidate.get_attribute("jid");
+        Jid? jid = jid_str != null ? Jid.parse(jid_str) : null;
+        int port = candidate.get_attribute("port") != null ? candidate.get_attribute_int("port") : 1080;
+        int priority = candidate.get_attribute_int("priority");
+        string? type_str = candidate.get_attribute("type");
+        CandidateType type = type_str != null ? CandidateType.parse(type_str) : CandidateType.DIRECT;
+
+        if (cid == null || host == null || jid == null || port <= 0 || priority <= 0) {
+            throw new Jingle.IqError.BAD_REQUEST("missing or invalid cid, host, jid or port");
+        }
+
+        return new Candidate(cid, host, jid, port, priority, type);
+    }
+    public StanzaNode to_xml() {
+        return new StanzaNode.build("candidate", NS_URI)
+            .put_attribute("cid", cid)
+            .put_attribute("host", host)
+            .put_attribute("jid", jid.to_string())
+            .put_attribute("port", port.to_string())
+            .put_attribute("priority", priority.to_string())
+            .put_attribute("type", type_.to_string());
+    }
+}
+
+bool bytes_equal(uint8[] a, uint8[] b) {
+    if (a.length != b.length) {
+        return false;
+    }
+    for (int i = 0; i < a.length; i++) {
+        if (a[i] != b[i]) {
+            return false;
+        }
+    }
+    return true;
+}
+
+class Parameters : Jingle.TransportParameters, Object {
+    public Jingle.Role role { get; private set; }
+    public string sid { get; private set; }
+    public string remote_dstaddr { get; private set; }
+    public string local_dstaddr { get; private set; }
+    public Gee.List<Candidate> local_candidates = new ArrayList<Candidate>();
+    public Gee.List<Candidate> remote_candidates = new ArrayList<Candidate>();
+
+    Jid local_full_jid;
+    Jid peer_full_jid;
+
+    bool remote_sent_selected_candidate = false;
+    Candidate? remote_selected_candidate = null;
+    bool local_determined_selected_candidate = false;
+    Candidate? local_selected_candidate = null;
+    SocketConnection? local_selected_candidate_conn = null;
+    weak Jingle.Session? session = null;
+    XmppStream? hack = null;
+
+    string? waiting_for_activation_cid = null;
+    SourceFunc waiting_for_activation_callback;
+    bool waiting_for_activation_error = false;
+
+    private static string calculate_dstaddr(string sid, Jid first_jid, Jid second_jid) {
+        string hashed = sid + first_jid.to_string() + second_jid.to_string();
+        return Checksum.compute_for_string(ChecksumType.SHA1, hashed);
+    }
+    private Parameters(Jingle.Role role, string sid, Jid local_full_jid, Jid peer_full_jid, string? remote_dstaddr) {
+        this.role = role;
+        this.sid = sid;
+        this.local_dstaddr = calculate_dstaddr(sid, local_full_jid, peer_full_jid);
+        this.remote_dstaddr = remote_dstaddr ?? calculate_dstaddr(sid, peer_full_jid, local_full_jid);
+
+        this.local_full_jid = local_full_jid;
+        this.peer_full_jid = peer_full_jid;
+    }
+    public Parameters.create(Jid local_full_jid, Jid peer_full_jid, string sid) {
+        this(Jingle.Role.INITIATOR, sid, local_full_jid, peer_full_jid, null);
+    }
+    public static Parameters parse(Jid local_full_jid, Jid peer_full_jid, StanzaNode transport) throws Jingle.IqError {
+        string? dstaddr = transport.get_attribute("dstaddr");
+        string? mode = transport.get_attribute("mode");
+        string? sid = transport.get_attribute("sid");
+        if (mode != null && mode != "tcp") {
+            throw new Jingle.IqError.BAD_REQUEST(@"unknown transport method $(mode)");
+        }
+        if (dstaddr != null && dstaddr.length > 255) {
+            throw new Jingle.IqError.BAD_REQUEST("too long dstaddr");
+        }
+        Parameters result = new Parameters(Jingle.Role.RESPONDER, sid, local_full_jid, peer_full_jid, dstaddr);
+        foreach (StanzaNode candidate in transport.get_subnodes("candidate", NS_URI)) {
+            result.remote_candidates.add(Candidate.parse(candidate));
+        }
+        return result;
+    }
+    public string transport_ns_uri() {
+        return NS_URI;
+    }
+    public StanzaNode to_transport_stanza_node() {
+        StanzaNode transport = new StanzaNode.build("transport", NS_URI)
+            .add_self_xmlns()
+            .put_attribute("dstaddr", local_dstaddr);
+
+        if (role == Jingle.Role.INITIATOR) {
+            // Must not be included by the responder according to XEP-0260.
+            transport.put_attribute("mode", "tcp");
+        }
+
+        transport.put_attribute("sid", sid);
+        foreach (Candidate candidate in local_candidates) {
+            transport.put_node(candidate.to_xml());
+        }
+        return transport;
+    }
+    public void on_transport_accept(StanzaNode transport) throws Jingle.IqError {
+        Parameters other = Parameters.parse(local_full_jid, peer_full_jid, transport);
+        if (other.sid != sid) {
+            throw new Jingle.IqError.BAD_REQUEST("invalid sid");
+        }
+        remote_candidates = other.remote_candidates;
+        remote_dstaddr = other.remote_dstaddr;
+    }
+    public void on_transport_info(StanzaNode transport) throws Jingle.IqError {
+        StanzaNode? candidate_error = transport.get_subnode("candidate-error", NS_URI);
+        StanzaNode? candidate_used = transport.get_subnode("candidate-used", NS_URI);
+        StanzaNode? activated = transport.get_subnode("activated", NS_URI);
+        StanzaNode? proxy_error = transport.get_subnode("proxy-error", NS_URI);
+        int num_children = 0;
+        if (candidate_error != null) { num_children += 1; }
+        if (candidate_used != null) { num_children += 1; }
+        if (activated != null) { num_children += 1; }
+        if (proxy_error != null) { num_children += 1; }
+        if (num_children == 0) {
+            throw new Jingle.IqError.UNSUPPORTED_INFO("unknown transport-info");
+        } else if (num_children > 1) {
+            throw new Jingle.IqError.BAD_REQUEST("transport-info with more than one child");
+        }
+        if (candidate_error != null) {
+            handle_remote_candidate(null);
+        }
+        if (candidate_used != null) {
+            string? cid = candidate_used.get_attribute("cid");
+            if (cid == null) {
+                throw new Jingle.IqError.BAD_REQUEST("missing cid");
+            }
+            handle_remote_candidate(cid);
+        }
+        if (activated != null) {
+            string? cid = activated.get_attribute("cid");
+            if (cid == null) {
+                throw new Jingle.IqError.BAD_REQUEST("missing cid");
+            }
+            handle_activated(cid);
+        }
+        if (proxy_error != null) {
+            handle_proxy_error();
+        }
+    }
+    private void handle_remote_candidate(string? cid) throws Jingle.IqError {
+        if (remote_sent_selected_candidate) {
+            throw new Jingle.IqError.BAD_REQUEST("remote candidate already specified");
+        }
+        Candidate? candidate = null;
+        if (cid != null) {
+            foreach (Candidate c in local_candidates) {
+                if (c.cid == cid) {
+                    candidate = c;
+                    break;
+                }
+            }
+            if (candidate == null) {
+                throw new Jingle.IqError.BAD_REQUEST("unknown cid");
+            }
+        }
+        remote_sent_selected_candidate = true;
+        remote_selected_candidate = candidate;
+        try_completing_negotiation();
+    }
+    private void handle_activated(string cid) throws Jingle.IqError {
+        if (waiting_for_activation_cid == null || cid != waiting_for_activation_cid) {
+            throw new Jingle.IqError.BAD_REQUEST("unexpected proxy activation message");
+        }
+        Idle.add((owned)waiting_for_activation_callback);
+        waiting_for_activation_cid = null;
+    }
+    private void handle_proxy_error() throws Jingle.IqError {
+        if (waiting_for_activation_cid == null) {
+            throw new Jingle.IqError.BAD_REQUEST("unexpected proxy error message");
+        }
+        Idle.add((owned)waiting_for_activation_callback);
+        waiting_for_activation_cid = null;
+        waiting_for_activation_error = true;
+
+    }
+    private void try_completing_negotiation() {
+        if (!remote_sent_selected_candidate || !local_determined_selected_candidate) {
+            return;
+        }
+
+        Candidate? remote = remote_selected_candidate;
+        Candidate? local = local_selected_candidate;
+
+        int num_candidates = 0;
+        if (remote != null) { num_candidates += 1; }
+        if (local != null) { num_candidates += 1; }
+
+        if (num_candidates == 0) {
+            // Notify Jingle of the failed transport.
+            session.set_transport_connection(hack, null);
+            return;
+        }
+
+        bool remote_wins;
+        if (num_candidates == 1) {
+            remote_wins = remote != null;
+        } else {
+            if (local.priority < remote.priority) {
+                remote_wins = true;
+            } else if (local.priority > remote.priority) {
+                remote_wins = false;
+            } else {
+                // equal priority -> XEP-0260 says that the candidate offered
+                // by the initiator wins, so the one that the remote chose
+                remote_wins = role == Jingle.Role.INITIATOR;
+            }
+        }
+
+        if (!remote_wins) {
+            if (local_selected_candidate.type_ != CandidateType.PROXY) {
+                Jingle.Session? strong = session;
+                if (strong == null) {
+                    return;
+                }
+                strong.set_transport_connection(hack, local_selected_candidate_conn);
+            } else {
+                wait_for_remote_activation.begin(local_selected_candidate, local_selected_candidate_conn);
+            }
+        } else {
+            connect_to_local_candidate.begin(remote_selected_candidate);
+        }
+    }
+    public async void wait_for_remote_activation(Candidate candidate, SocketConnection conn) {
+        waiting_for_activation_cid = candidate.cid;
+        waiting_for_activation_callback = wait_for_remote_activation.callback;
+        yield;
+
+        Jingle.Session? strong = session;
+        if (strong == null) {
+            return;
+        }
+        if (!waiting_for_activation_error) {
+            strong.set_transport_connection(hack, conn);
+        } else {
+            strong.set_transport_connection(hack, null);
+        }
+    }
+    public async void connect_to_local_candidate(Candidate candidate) {
+        try {
+            SocketConnection conn = yield connect_to_socks5(candidate, local_dstaddr);
+
+            bool activation_error = false;
+            SourceFunc callback = connect_to_local_candidate.callback;
+            StanzaNode query = new StanzaNode.build("query", Socks5Bytestreams.NS_URI)
+                .add_self_xmlns()
+                .put_attribute("sid", sid)
+                .put_node(new StanzaNode.build("activate", Socks5Bytestreams.NS_URI)
+                    .put_node(new StanzaNode.text(peer_full_jid.to_string()))
+                );
+            Iq.Stanza iq = new Iq.Stanza.set(query) { to=candidate.jid };
+            hack.get_module(Iq.Module.IDENTITY).send_iq(hack, iq, (stream, iq) => {
+                activation_error = iq.is_error();
+                Idle.add((owned)callback);
+            });
+            yield;
+
+            if (activation_error) {
+                throw new IOError.PROXY_FAILED("activation iq error");
+            }
+
+            Jingle.Session? strong = session;
+            if (strong == null) {
+                return;
+            }
+            strong.send_transport_info(hack, new StanzaNode.build("transport", NS_URI)
+                .add_self_xmlns()
+                .put_attribute("sid", sid)
+                .put_node(new StanzaNode.build("activated", NS_URI)
+                    .put_attribute("cid", candidate.cid)
+                )
+            );
+
+            strong.set_transport_connection(hack, conn);
+        } catch (Error e) {
+            Jingle.Session? strong = session;
+            if (strong == null) {
+                return;
+            }
+            strong.send_transport_info(hack, new StanzaNode.build("transport", NS_URI)
+                .add_self_xmlns()
+                .put_attribute("sid", sid)
+                .put_node(new StanzaNode.build("proxy-error", NS_URI))
+            );
+            strong.set_transport_connection(hack, null);
+        }
+    }
+    public async SocketConnection connect_to_socks5(Candidate candidate, string dstaddr) throws Error {
+        SocketClient socket_client = new SocketClient() { timeout=3 };
+
+        string address = @"[$(candidate.host)]:$(candidate.port)";
+
+        size_t written;
+        size_t read;
+        uint8[] read_buffer = new uint8[1024];
+        ByteArray write_buffer = new ByteArray();
+
+        SocketConnection conn = yield socket_client.connect_to_host_async(address, 0);
+
+        // 05 SOCKS version 5
+        // 01 number of authentication methods: 1
+        // 00 nop authentication
+        yield conn.output_stream.write_all_async({0x05, 0x01, 0x00}, GLib.Priority.DEFAULT, null, out written);
+
+        yield conn.input_stream.read_all_async(read_buffer[0:2], GLib.Priority.DEFAULT, null, out read);
+        // 05 SOCKS version 5
+        // 01 success
+        if (read_buffer[0] != 0x05 || read_buffer[1] != 0x00) {
+            throw new IOError.PROXY_FAILED("wanted 05 00, got %02x %02x".printf(read_buffer[0], read_buffer[1]));
+        }
+
+        // 05 SOCKS version 5
+        // 01 connect
+        // 00 reserved
+        // 03 address type: domain name
+        // ?? length of the domain
+        // .. domain
+        // 00 port 0 (upper half)
+        // 00 port 0 (lower half)
+        write_buffer.append({0x05, 0x01, 0x00, 0x03});
+        write_buffer.append({(uint8)dstaddr.length});
+        write_buffer.append(dstaddr.data);
+        write_buffer.append({0x00, 0x00});
+        yield conn.output_stream.write_all_async(write_buffer.data, GLib.Priority.DEFAULT, null, out written);
+
+        yield conn.input_stream.read_all_async(read_buffer[0:write_buffer.len], GLib.Priority.DEFAULT, null, out read);
+        // 05 SOCKS version 5
+        // 00 success
+        // 00 reserved
+        // 03 address type: domain name
+        // ?? length of the domain
+        // .. domain
+        // 00 port 0 (upper half)
+        // 00 port 0 (lower half)
+        if (read_buffer[0] != 0x05 || read_buffer[1] != 0x00 || read_buffer[3] != 0x03) {
+            throw new IOError.PROXY_FAILED("wanted 05 00 ?? 03, got %02x %02x %02x %02x".printf(read_buffer[0], read_buffer[1], read_buffer[2], read_buffer[3]));
+        }
+        if (read_buffer[4] != (uint8)dstaddr.length) {
+            throw new IOError.PROXY_FAILED("wanted %02x for length, got %02x".printf(dstaddr.length, read_buffer[4]));
+        }
+        if (!bytes_equal(read_buffer[5:5+dstaddr.length], dstaddr.data)) {
+            string repr = ((string)read_buffer[5:5+dstaddr.length]).make_valid().escape();
+            throw new IOError.PROXY_FAILED(@"wanted dstaddr $(dstaddr), got $(repr)");
+        }
+        if (read_buffer[5+dstaddr.length] != 0x00 || read_buffer[5+dstaddr.length+1] != 0x00) {
+            throw new IOError.PROXY_FAILED("wanted port 00 00, got %02x %02x".printf(read_buffer[5+dstaddr.length], read_buffer[5+dstaddr.length+1]));
+        }
+
+        conn.get_socket().set_timeout(0);
+
+        return conn;
+    }
+    public async void try_connecting_to_candidates(XmppStream stream, Jingle.Session session) throws Error {
+        remote_candidates.sort((c1, c2) => {
+            // sort from priorities from high to low
+            if (c1.priority < c2.priority) { return 1; }
+            if (c1.priority > c2.priority) { return -1; }
+            return 0;
+        });
+        foreach (Candidate candidate in remote_candidates) {
+            if (remote_selected_candidate != null && remote_selected_candidate.priority > candidate.priority) {
+                // Don't try candidates with lower priority than the one the
+                // peer already selected.
+                break;
+            }
+            try {
+                SocketConnection conn = yield connect_to_socks5(candidate, remote_dstaddr);
+
+                local_determined_selected_candidate = true;
+                local_selected_candidate = candidate;
+                local_selected_candidate_conn = conn;
+                session.send_transport_info(stream, new StanzaNode.build("transport", NS_URI)
+                    .add_self_xmlns()
+                    .put_attribute("sid", sid)
+                    .put_node(new StanzaNode.build("candidate-used", NS_URI)
+                        .put_attribute("cid", candidate.cid)
+                    )
+                );
+                try_completing_negotiation();
+                return;
+            } catch (Error e) {
+                // An error in the connection establishment isn't fatal, just
+                // try the next candidate or respond that none of the
+                // candidates work.
+            }
+        }
+        local_determined_selected_candidate = true;
+        local_selected_candidate = null;
+        session.send_transport_info(stream, new StanzaNode.build("transport", NS_URI)
+            .add_self_xmlns()
+            .put_attribute("sid", sid)
+            .put_node(new StanzaNode.build("candidate-error", NS_URI))
+        );
+    }
+    public void create_transport_connection(XmppStream stream, Jingle.Session session) {
+        this.session = session;
+        this.hack = stream;
+        try_connecting_to_candidates.begin(stream, session);
+    }
+}
+
+}
diff --git a/xmpp-vala/src/module/xep/0261_jingle_in_band_bytestreams.vala b/xmpp-vala/src/module/xep/0261_jingle_in_band_bytestreams.vala
index dc2e8d7c..1a810ee8 100644
--- a/xmpp-vala/src/module/xep/0261_jingle_in_band_bytestreams.vala
+++ b/xmpp-vala/src/module/xep/0261_jingle_in_band_bytestreams.vala
@@ -30,28 +30,38 @@ public class Module : Jingle.Transport, XmppStreamModule {
     public Jingle.TransportType transport_type() {
         return Jingle.TransportType.STREAMING;
     }
-    public Jingle.TransportParameters create_transport_parameters() {
-        return new Parameters(random_uuid(), DEFAULT_BLOCKSIZE);
+    public int transport_priority() {
+        return 0;
     }
-    public Jingle.TransportParameters parse_transport_parameters(StanzaNode transport) throws Jingle.IqError {
-        return Parameters.parse(transport);
+    public Jingle.TransportParameters create_transport_parameters(XmppStream stream, Jid local_full_jid, Jid peer_full_jid) {
+        return new Parameters.create(peer_full_jid, random_uuid());
+    }
+    public Jingle.TransportParameters parse_transport_parameters(XmppStream stream, Jid local_full_jid, Jid peer_full_jid, StanzaNode transport) throws Jingle.IqError {
+        return Parameters.parse(peer_full_jid, transport);
     }
 }
 
 class Parameters : Jingle.TransportParameters, Object {
+    public Jingle.Role role { get; private set; }
+    public Jid peer_full_jid { get; private set; }
     public string sid { get; private set; }
     public int block_size { get; private set; }
-    public Parameters(string sid, int block_size) {
+    private Parameters(Jingle.Role role, Jid peer_full_jid, string sid, int block_size) {
+        this.role = role;
+        this.peer_full_jid = peer_full_jid;
         this.sid = sid;
         this.block_size = block_size;
     }
-    public static Parameters parse(StanzaNode transport) throws Jingle.IqError {
+    public Parameters.create(Jid peer_full_jid, string sid) {
+        this(Jingle.Role.INITIATOR, peer_full_jid, sid, DEFAULT_BLOCKSIZE);
+    }
+    public static Parameters parse(Jid peer_full_jid, StanzaNode transport) throws Jingle.IqError {
         string? sid = transport.get_attribute("sid");
         int block_size = transport.get_attribute_int("block-size");
         if (sid == null || block_size <= 0 || block_size > MAX_BLOCKSIZE) {
             throw new Jingle.IqError.BAD_REQUEST("missing or invalid sid or blocksize");
         }
-        return new Parameters(sid, block_size);
+        return new Parameters(Jingle.Role.RESPONDER, peer_full_jid, sid, block_size);
     }
     public string transport_ns_uri() {
         return NS_URI;
@@ -62,15 +72,18 @@ class Parameters : Jingle.TransportParameters, Object {
             .put_attribute("block-size", block_size.to_string())
             .put_attribute("sid", sid);
     }
-    public void update_transport(StanzaNode transport) throws Jingle.IqError {
-        Parameters other = Parameters.parse(transport);
+    public void on_transport_accept(StanzaNode transport) throws Jingle.IqError {
+        Parameters other = Parameters.parse(peer_full_jid, transport);
         if (other.sid != sid || other.block_size > block_size) {
             throw new Jingle.IqError.NOT_ACCEPTABLE("invalid IBB sid or block_size");
         }
         block_size = other.block_size;
     }
-    public IOStream create_transport_connection(XmppStream stream, Jid peer_full_jid, Jingle.Role role) {
-        return InBandBytestreams.Connection.create(stream, peer_full_jid, sid, block_size, role == Jingle.Role.INITIATOR);
+    public void on_transport_info(StanzaNode transport) throws Jingle.IqError {
+        throw new Jingle.IqError.UNSUPPORTED_INFO("transport-info not supported for IBBs");
+    }
+    public void create_transport_connection(XmppStream stream, Jingle.Session session) {
+        session.set_transport_connection(stream, InBandBytestreams.Connection.create(stream, peer_full_jid, sid, block_size, role == Jingle.Role.INITIATOR));
     }
 }
 
diff --git a/xmpp-vala/src/module/xep/0313_message_archive_management.vala b/xmpp-vala/src/module/xep/0313_message_archive_management.vala
index 00f8f99b..674224c9 100644
--- a/xmpp-vala/src/module/xep/0313_message_archive_management.vala
+++ b/xmpp-vala/src/module/xep/0313_message_archive_management.vala
@@ -39,7 +39,7 @@ public class Module : XmppStreamModule {
         }
         StanzaNode query_node = new StanzaNode.build("query", NS_VER(stream)).add_self_xmlns().put_node(data_form.get_submit_node());
         Iq.Stanza iq = new Iq.Stanza.set(query_node);
-        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq, (stream, iq) => { page_through_results(stream, iq, on_finished); });
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, iq, (stream, iq) => { page_through_results(stream, iq, (owned)on_finished); });
     }
 
     public override void attach(XmppStream stream) {
@@ -69,7 +69,7 @@ public class Module : XmppStreamModule {
                     )
                 )
             );
-        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, paging_iq, (stream, iq) => { page_through_results(stream, iq, on_finished); });
+        stream.get_module(Iq.Module.IDENTITY).send_iq(stream, paging_iq, (stream, iq) => { page_through_results(stream, iq, (owned)on_finished); });
     }
 
     private void query_availability(XmppStream stream) {