using GnuTLS; namespace Dino.Plugins.Ice.DtlsSrtp { public class CredentialsCapsule { public uint8[] own_fingerprint; public X509.Certificate[] own_cert; public X509.PrivateKey private_key; } public class Handler { public signal void send_data(uint8[] data); public bool ready { get { return srtp_session.has_encrypt && srtp_session.has_decrypt; }} public Mode mode { get; set; default = Mode.CLIENT; } public uint8[] own_fingerprint { get; private set; } public uint8[] peer_fingerprint { get; set; } public string peer_fp_algo { get; set; } private CredentialsCapsule credentials; private Cond buffer_cond = Cond(); private Mutex buffer_mutex = Mutex(); private Gee.LinkedList buffer_queue = new Gee.LinkedList(); private bool running = false; private bool stop = false; private bool restart = false; private Crypto.Srtp.Session srtp_session = new Crypto.Srtp.Session(); public Handler.with_cert(CredentialsCapsule creds) { this.credentials = creds; this.own_fingerprint = creds.own_fingerprint; } public uint8[]? process_incoming_data(uint component_id, uint8[] data) throws Crypto.Error { if (srtp_session.has_decrypt) { if (component_id == 1) { if (data.length >= 2 && data[1] >= 192 && data[1] < 224) { return srtp_session.decrypt_rtcp(data); } return srtp_session.decrypt_rtp(data); } if (component_id == 2) return srtp_session.decrypt_rtcp(data); } else if (component_id == 1 && (data[0] >= 20 && data[0] <= 63)) { on_data_rec(data); } return null; } public uint8[]? process_outgoing_data(uint component_id, uint8[] data) throws Crypto.Error { if (srtp_session.has_encrypt) { if (component_id == 1) { if (data.length >= 2 && data[1] >= 192 && data[1] < 224) { return srtp_session.encrypt_rtcp(data); } return srtp_session.encrypt_rtp(data); } if (component_id == 2) return srtp_session.encrypt_rtcp(data); } return null; } public void on_data_rec(owned uint8[] data) { buffer_mutex.lock(); buffer_queue.add(new Bytes.take(data)); buffer_cond.signal(); buffer_mutex.unlock(); } internal static CredentialsCapsule generate_credentials() throws GLib.Error { int err = 0; X509.PrivateKey private_key = X509.PrivateKey.create(); err = private_key.generate(PKAlgorithm.ECDSA, 256); throw_if_error(err); var start_time = new DateTime.now_local().add_days(1); var end_time = start_time.add_days(2); X509.Certificate cert = X509.Certificate.create(); cert.set_key(private_key); cert.set_version(1); cert.set_activation_time ((time_t) start_time.to_unix ()); cert.set_expiration_time ((time_t) end_time.to_unix ()); uint32 serial = 1; cert.set_serial(&serial, sizeof(uint32)); cert.sign(cert, private_key); uint8[] own_fingerprint = get_fingerprint(cert, DigestAlgorithm.SHA256); X509.Certificate[] own_cert = new X509.Certificate[] { (owned)cert }; var creds = new CredentialsCapsule(); creds.own_fingerprint = own_fingerprint; creds.own_cert = (owned) own_cert; creds.private_key = (owned) private_key; return creds; } public void stop_dtls_connection() { buffer_mutex.lock(); stop = true; buffer_cond.signal(); buffer_mutex.unlock(); } public async Xmpp.Xep.Jingle.ContentEncryption? setup_dtls_connection() { MainContext context = MainContext.current_source().get_context(); var thread = new Thread("dtls-connection", () => { var res = setup_dtls_connection_thread(); Source source = new IdleSource(); source.set_callback(setup_dtls_connection.callback); source.attach(context); return res; }); yield; return thread.join(); } private Xmpp.Xep.Jingle.ContentEncryption? setup_dtls_connection_thread() { buffer_mutex.lock(); if (stop) { restart = true; buffer_mutex.unlock(); return null; } if (running || ready) { buffer_mutex.unlock(); return null; } running = true; restart = false; buffer_mutex.unlock(); InitFlags server_or_client = mode == Mode.SERVER ? InitFlags.SERVER : InitFlags.CLIENT; debug("Setting up DTLS connection. We're %s", mode.to_string()); CertificateCredentials cert_cred = CertificateCredentials.create(); int err = cert_cred.set_x509_key(credentials.own_cert, credentials.private_key); throw_if_error(err); Session? session = Session.create(server_or_client | InitFlags.DATAGRAM); session.enable_heartbeat(1); session.set_srtp_profile_direct("SRTP_AES128_CM_HMAC_SHA1_80"); session.set_credentials(GnuTLS.CredentialsType.CERTIFICATE, cert_cred); session.server_set_request(CertificateRequest.REQUEST); session.set_priority_from_string("NORMAL:!VERS-TLS-ALL:+VERS-DTLS-ALL:+CTYPE-CLI-X509"); session.set_transport_pointer(this); session.set_pull_function(pull_function); session.set_pull_timeout_function(pull_timeout_function); session.set_push_function(push_function); session.set_verify_function(verify_function); DateTime maximum_time = new DateTime.now_utc().add_seconds(20); do { err = session.handshake(); DateTime current_time = new DateTime.now_utc(); if (maximum_time.compare(current_time) < 0) { warning("DTLS handshake timeouted"); err = ErrorCode.APPLICATION_ERROR_MIN + 1; break; } if (stop) { debug("DTLS handshake stopped"); err = ErrorCode.APPLICATION_ERROR_MIN + 2; break; } } while (err < 0 && !((ErrorCode)err).is_fatal()); buffer_mutex.lock(); if (stop) { stop = false; running = false; bool restart = restart; buffer_mutex.unlock(); if (restart) { debug("Restarting DTLS handshake"); return setup_dtls_connection_thread(); } return null; } buffer_mutex.unlock(); if (err != ErrorCode.SUCCESS) { warning("DTLS handshake failed: %s", ((ErrorCode)err).to_string()); return null; } uint8[] km = new uint8[150]; Datum? client_key, client_salt, server_key, server_salt; session.get_srtp_keys(km, km.length, out client_key, out client_salt, out server_key, out server_salt); if (client_key == null || client_salt == null || server_key == null || server_salt == null) { warning("SRTP client/server key/salt null"); } debug("Finished DTLS connection. We're %s", mode.to_string()); if (mode == Mode.SERVER) { srtp_session.set_encryption_key(Crypto.Srtp.AES_CM_128_HMAC_SHA1_80, server_key.extract(), server_salt.extract()); srtp_session.set_decryption_key(Crypto.Srtp.AES_CM_128_HMAC_SHA1_80, client_key.extract(), client_salt.extract()); } else { srtp_session.set_encryption_key(Crypto.Srtp.AES_CM_128_HMAC_SHA1_80, client_key.extract(), client_salt.extract()); srtp_session.set_decryption_key(Crypto.Srtp.AES_CM_128_HMAC_SHA1_80, server_key.extract(), server_salt.extract()); } return new Xmpp.Xep.Jingle.ContentEncryption(Xmpp.Xep.JingleIceUdp.DTLS_NS_URI, "DTLS-SRTP", credentials.own_fingerprint, peer_fingerprint); } private static ssize_t pull_function(void* transport_ptr, uint8[] buffer) { Handler self = transport_ptr as Handler; self.buffer_mutex.lock(); while (self.buffer_queue.size == 0) { self.buffer_cond.wait(self.buffer_mutex); if (self.stop) { self.buffer_mutex.unlock(); debug("DTLS handshake pull_function stopped"); return -1; } } Bytes data = self.buffer_queue.remove_at(0); self.buffer_mutex.unlock(); uint8[] data_uint8 = Bytes.unref_to_data((owned) data); Memory.copy(buffer, data_uint8, data_uint8.length); // The callback should return 0 on connection termination, a positive number indicating the number of bytes received, and -1 on error. return (ssize_t)data_uint8.length; } private static int pull_timeout_function(void* transport_ptr, uint ms) { Handler self = transport_ptr as Handler; int64 end_time = get_monotonic_time() + ms * 1000; self.buffer_mutex.lock(); while (self.buffer_queue.size == 0) { self.buffer_cond.wait_until(self.buffer_mutex, end_time); if (self.stop) { self.buffer_mutex.unlock(); debug("DTLS handshake pull_timeout_function stopped"); return -1; } if (get_monotonic_time() > end_time) { self.buffer_mutex.unlock(); return 0; } } self.buffer_mutex.unlock(); // The callback should return 0 on timeout, a positive number if data can be received, and -1 on error. return 1; } private static ssize_t push_function(void* transport_ptr, uint8[] buffer) { Handler self = transport_ptr as Handler; self.send_data(buffer); // The callback should return a positive number indicating the bytes sent, and -1 on error. return (ssize_t)buffer.length; } private static int verify_function(Session session) { Handler self = session.get_transport_pointer() as Handler; try { bool valid = self.verify_peer_cert(session); if (!valid) { warning("DTLS certificate invalid. Aborting handshake."); return 1; } } catch (Error e) { warning("Error during DTLS certificate validation: %s. Aborting handshake.", e.message); return 1; } // The callback function should return 0 for the handshake to continue or non-zero to terminate. return 0; } private bool verify_peer_cert(Session session) throws GLib.Error { unowned Datum[] cert_datums = session.get_peer_certificates(); if (cert_datums.length == 0) { warning("No peer certs"); return false; } if (cert_datums.length > 1) warning("More than one peer cert"); X509.Certificate peer_cert = X509.Certificate.create(); peer_cert.import(ref cert_datums[0], CertificateFormat.DER); DigestAlgorithm algo; switch (peer_fp_algo) { case "sha-256": algo = DigestAlgorithm.SHA256; break; default: warning("Unkown peer fingerprint algorithm: %s", peer_fp_algo); return false; } uint8[] real_peer_fp = get_fingerprint(peer_cert, algo); if (real_peer_fp.length != this.peer_fingerprint.length) { warning("Fingerprint lengths not equal %i vs %i", real_peer_fp.length, peer_fingerprint.length); return false; } for (int i = 0; i < real_peer_fp.length; i++) { if (real_peer_fp[i] != this.peer_fingerprint[i]) { warning("First cert in peer cert list doesn't equal advertised one: %s vs %s", format_fingerprint(real_peer_fp), format_fingerprint(peer_fingerprint)); return false; } } return true; } } private uint8[] get_fingerprint(X509.Certificate certificate, DigestAlgorithm digest_algo) { uint8[] buf = new uint8[512]; size_t buf_out_size = 512; certificate.get_fingerprint(digest_algo, buf, ref buf_out_size); uint8[] ret = new uint8[buf_out_size]; for (int i = 0; i < buf_out_size; i++) { ret[i] = buf[i]; } return ret; } private string format_fingerprint(uint8[] fingerprint) { var sb = new StringBuilder(); for (int i = 0; i < fingerprint.length; i++) { sb.append("%02X".printf(fingerprint[i])); if (i < fingerprint.length - 1) { sb.append(":"); } } return sb.str; } public enum Mode { CLIENT, SERVER } }