diff options
Diffstat (limited to 'libdino/src/crypto/gnu')
| -rw-r--r-- | libdino/src/crypto/gnu/dtls_srtp.vala | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/libdino/src/crypto/gnu/dtls_srtp.vala b/libdino/src/crypto/gnu/dtls_srtp.vala new file mode 100644 index 00000000..f6f0a24e --- /dev/null +++ b/libdino/src/crypto/gnu/dtls_srtp.vala @@ -0,0 +1,245 @@ +using GnuTLS; + +namespace Dino.Crypto.DtlsSrtp { + +public class CredentialsCapsuleGnuTLS : CredentialsCapsule { + internal X509.Certificate[] own_cert; + internal X509.PrivateKey private_key; +} + +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; +} + +public 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 CredentialsCapsuleGnuTLS(); + creds.own_fingerprint = own_fingerprint; + creds.own_cert = (owned) own_cert; + creds.private_key = (owned) private_key; + + return creds; +} + +public class Handler : AbstractHandler { + + public Handler.with_cert(CredentialsCapsule creds) { + base.with_cert(creds); + } + + protected override Xmpp.Xep.Jingle.ContentEncryption? setup_dtls_connection_thread() { + InitFlags server_or_client = mode == Mode.SERVER ? InitFlags.SERVER : InitFlags.CLIENT; + debug("Setting up DTLS connection using GnuTLS. We're %s", mode.to_string()); + + CertificateCredentials cert_cred = CertificateCredentials.create(); + int err = cert_cred.set_x509_key(((CredentialsCapsuleGnuTLS)credentials).own_cert, ((CredentialsCapsuleGnuTLS)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; + } +} + +}
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