FileProvider for aesgcm links

Co-authored-by: Thibaut Girka <thib@sitedethib.com>

2 files changed, 157 insertions, 0 deletions

diff --git a/plugins/omemo/src/file_provider.vala b/plugins/omemo/src/file_provider.vala
new file mode 100644
index 00000000..fb1c1d1e
--- /dev/null
+++ b/plugins/omemo/src/file_provider.vala
@@ -0,0 +1,155 @@
+using Gee;
+using Gtk;
+
+using Dino.Entities;
+using Xmpp;
+using Signal;
+
+namespace Dino.Plugins.Omemo {
+
+public class FileProvider : Dino.FileProvider, Object {
+    public string id { get { return "aesgcm"; } }
+
+    private StreamInteractor stream_interactor;
+    private Dino.Database dino_db;
+    private Regex url_regex;
+
+    private Gee.List<string> ignore_once = new ArrayList<string>();
+
+    public FileProvider(StreamInteractor stream_interactor, Dino.Database dino_db) {
+        this.stream_interactor = stream_interactor;
+        this.dino_db = dino_db;
+        this.url_regex = new Regex("""^aesgcm://(.*)#(([A-Fa-f0-9]{2}){48}|([A-Fa-f0-9]{2}){44})$""");
+
+        stream_interactor.get_module(MessageProcessor.IDENTITY).received_pipeline.connect(new ReceivedMessageListener(this));
+    }
+
+    private class ReceivedMessageListener : MessageListener {
+
+        public string[] after_actions_const = new string[]{ "STORE" };
+        public override string action_group { get { return ""; } }
+        public override string[] after_actions { get { return after_actions_const; } }
+
+        private FileProvider outer;
+        private StreamInteractor stream_interactor;
+
+        public ReceivedMessageListener(FileProvider outer) {
+            this.outer = outer;
+            this.stream_interactor = outer.stream_interactor;
+        }
+
+        public override async bool run(Entities.Message message, Xmpp.MessageStanza stanza, Conversation conversation) {
+            if (message.body.has_prefix("aesgcm://") && outer.url_regex.match(message.body)) {
+                yield outer.on_file_message(message, conversation);
+            }
+            return false;
+        }
+    }
+
+    private async void on_file_message(Entities.Message message, Conversation conversation) {
+        MatchInfo match_info;
+        this.url_regex.match(message.body, 0, out match_info);
+        string url_without_hash = match_info.fetch(1);
+
+        FileTransfer file_transfer = new FileTransfer();
+        file_transfer.account = conversation.account;
+        file_transfer.counterpart = message.counterpart;
+        file_transfer.ourpart = message.ourpart;
+        file_transfer.encryption = Encryption.NONE;
+        file_transfer.time = message.time;
+        file_transfer.local_time = message.local_time;
+        file_transfer.direction = message.direction;
+        file_transfer.file_name = url_without_hash.substring(url_without_hash.last_index_of("/") + 1);
+        file_transfer.mime_type = null;
+        file_transfer.size = -1;
+        file_transfer.state = FileTransfer.State.NOT_STARTED;
+        file_transfer.provider = 0;
+        file_transfer.info = message.id.to_string();
+
+        if (stream_interactor.get_module(FileManager.IDENTITY).is_sender_trustworthy(file_transfer, conversation)) {
+            ContentItem? content_item = stream_interactor.get_module(ContentItemStore.IDENTITY).get_item(conversation, 1, message.id);
+            if (content_item != null) {
+                stream_interactor.get_module(ContentItemStore.IDENTITY).set_item_hide(content_item, true);
+            }
+            yield get_meta_info(file_transfer);
+            file_incoming(file_transfer, conversation);
+        }
+    }
+
+    private async void get_meta_info(FileTransfer file_transfer) {
+        string url_body = dino_db.message.select({dino_db.message.body}).with(dino_db.message.id, "=", int.parse(file_transfer.info))[dino_db.message.body];
+        var session = new Soup.Session();
+        var head_message = new Soup.Message("HEAD", url_body);
+        if (head_message != null) {
+            yield session.send_async(head_message, null);
+
+            string? content_type = null, content_length = null;
+            head_message.response_headers.foreach((name, val) => {
+                if (name == "Content-Type") content_type = val;
+                if (name == "Content-Length") content_length = val;
+            });
+            file_transfer.mime_type = content_type;
+            file_transfer.size = int.parse(content_length);
+        }
+    }
+
+    public async void download(FileTransfer file_transfer, File file) {
+        try {
+            string url_body = dino_db.message.select({dino_db.message.body}).with(dino_db.message.id, "=", int.parse(file_transfer.info))[dino_db.message.body];
+            string url = "https://" + url_body.substring(9);
+            var session = new Soup.Session();
+            Soup.Request request = session.request(url);
+
+            file_transfer.input_stream = decrypt_file(yield request.send_async(null), url_body);
+            file_transfer.encryption = Encryption.OMEMO;
+
+            OutputStream os = file.create(FileCreateFlags.REPLACE_DESTINATION);
+            os.splice(file_transfer.input_stream, 0);
+            os.close();
+            file_transfer.path = file.get_basename();
+            file_transfer.input_stream = file.read();
+
+            file_transfer.state = FileTransfer.State.COMPLETE;
+        } catch (Error e) {
+            file_transfer.state = FileTransfer.State.FAILED;
+        }
+    }
+
+    public InputStream? decrypt_file(InputStream input_stream, string url) {
+        // Decode IV and key
+        MatchInfo match_info;
+        this.url_regex.match(url, 0, out match_info);
+        uint8[] iv_and_key = hex_to_bin(match_info.fetch(2).up());
+        uint8[] iv, key;
+        if (iv_and_key.length == 44) {
+            iv = iv_and_key[0:12];
+            key = iv_and_key[12:44];
+        } else {
+            iv = iv_and_key[0:16];
+            key = iv_and_key[16:48];
+        }
+
+        // Read data
+        uint8[] buf = new uint8[256];
+        Array<uint8> data = new Array<uint8>(false, true, 0);
+        size_t len = -1;
+        do {
+            len = input_stream.read(buf);
+            data.append_vals(buf, (uint) len);
+        } while(len > 0);
+
+        // Decrypt
+        return new MemoryInputStream.from_data(aes_decrypt(Cipher.AES_GCM_NOPADDING, key, iv, data.data));
+    }
+
+    private uint8[] hex_to_bin(string hex) {
+        uint8[] bin = new uint8[hex.length / 2];
+        const string HEX = "0123456789ABCDEF";
+        for (int i = 0; i < hex.length / 2; i++) {
+            bin[i] = (uint8) (HEX.index_of_char(hex[i*2]) << 4) | HEX.index_of_char(hex[i*2+1]);
+        }
+        return bin;
+    }
+}
+
+}
diff --git a/plugins/omemo/src/plugin.vala b/plugins/omemo/src/plugin.vala
index ab22651f..be6229cc 100644
--- a/plugins/omemo/src/plugin.vala
+++ b/plugins/omemo/src/plugin.vala
@@ -49,6 +49,8 @@ public class Plugin : RootInterface, Object {
             list.add(new StreamModule());
             this.own_notifications = new OwnNotifications(this, this.app.stream_interactor, account);
         });
+
+        app.stream_interactor.get_module(FileManager.IDENTITY).add_provider(new FileProvider(app.stream_interactor, app.db));
         Manager.start(this.app.stream_interactor, db, trust_manager);
 
         SimpleAction own_keys_action = new SimpleAction("own-keys", VariantType.INT32);