diff options
Diffstat (limited to 'plugins/ice/src/dtls_srtp.vala')
| -rw-r--r-- | plugins/ice/src/dtls_srtp.vala | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/plugins/ice/src/dtls_srtp.vala b/plugins/ice/src/dtls_srtp.vala new file mode 100644 index 00000000..0254351d --- /dev/null +++ b/plugins/ice/src/dtls_srtp.vala @@ -0,0 +1,356 @@ +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<Bytes> buffer_queue = new Gee.LinkedList<Bytes>(); + + 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) { + if (srtp_session.has_decrypt) { + try { + 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); + } catch (Error e) { + warning("%s (%d)", e.message, e.code); + return null; + } + } else if (component_id == 1) { + on_data_rec(data); + } + return null; + } + + public uint8[]? process_outgoing_data(uint component_id, uint8[] data) { + if (srtp_session.has_encrypt) { + try { + 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); + } catch (Error e) { + warning("%s (%d)", e.message, e.code); + return null; + } + } + 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.RSA, 2048); + 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() { + 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); + + Thread<int> thread = new Thread<int> (null, () => { + 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()); + Idle.add(setup_dtls_connection.callback); + return err; + }); + yield; + err = thread.join(); + buffer_mutex.lock(); + if (stop) { + stop = false; + running = false; + bool restart = restart; + buffer_mutex.unlock(); + if (restart) { + debug("Restarting DTLS handshake"); + return yield setup_dtls_connection(); + } + 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() { encryption_ns=Xmpp.Xep.JingleIceUdp.DTLS_NS_URI, encryption_name = "DTLS-SRTP", our_key=credentials.own_fingerprint, peer_key=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 +} + +} |