diff options
Diffstat (limited to 'plugins/ice/src/dtls_srtp.vala')
| -rw-r--r-- | plugins/ice/src/dtls_srtp.vala | 247 |
1 files changed, 247 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..a21c242b --- /dev/null +++ b/plugins/ice/src/dtls_srtp.vala @@ -0,0 +1,247 @@ +using GnuTLS; + +public class DtlsSrtp { + + public signal void send_data(uint8[] data); + + private X509.Certificate[] own_cert; + private X509.PrivateKey private_key; + private Cond buffer_cond = new Cond(); + private Mutex buffer_mutex = new Mutex(); + private Gee.LinkedList<Bytes> buffer_queue = new Gee.LinkedList<Bytes>(); + private uint pull_timeout = uint.MAX; + private string peer_fingerprint; + + private Crypto.Srtp.Session encrypt_session; + private Crypto.Srtp.Session decrypt_session; + + public static DtlsSrtp setup() throws GLib.Error { + var obj = new DtlsSrtp(); + obj.generate_credentials(); + return obj; + } + + internal string get_own_fingerprint(DigestAlgorithm digest_algo) { + return format_certificate(own_cert[0], digest_algo); + } + + public void set_peer_fingerprint(string fingerprint) { + this.peer_fingerprint = fingerprint; + } + + public uint8[] process_incoming_data(uint component_id, uint8[] data) { + if (decrypt_session != null) { + if (component_id == 1) return decrypt_session.decrypt_rtp(data); + if (component_id == 2) return decrypt_session.decrypt_rtcp(data); + } else if (component_id == 1) { + on_data_rec(data); + } + return null; + } + + public uint8[] process_outgoing_data(uint component_id, uint8[] data) { + if (encrypt_session != null) { + if (component_id == 1) return encrypt_session.encrypt_rtp(data); + if (component_id == 2) return encrypt_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(); + } + + private void generate_credentials() throws GLib.Error { + int err = 0; + + 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); + + own_cert = new X509.Certificate[] { (owned)cert }; + } + + public async void setup_dtls_connection(bool server) { + InitFlags server_or_client = server ? InitFlags.SERVER : InitFlags.CLIENT; + debug("Setting up DTLS connection. We're %s", server_or_client.to_string()); + + CertificateCredentials cert_cred = CertificateCredentials.create(); + int err = cert_cred.set_x509_key(own_cert, 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"); + return -1; + } + } while (err < 0 && !((ErrorCode)err).is_fatal()); + Idle.add(setup_dtls_connection.callback); + return err; + }); + yield; + err = thread.join(); + + 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"); + } + + Crypto.Srtp.Session encrypt_session = new Crypto.Srtp.Session(Crypto.Srtp.Encryption.AES_CM, Crypto.Srtp.Authentication.HMAC_SHA1, 10, Crypto.Srtp.Prf.AES_CM, 0); + Crypto.Srtp.Session decrypt_session = new Crypto.Srtp.Session(Crypto.Srtp.Encryption.AES_CM, Crypto.Srtp.Authentication.HMAC_SHA1, 10, Crypto.Srtp.Prf.AES_CM, 0); + + if (server) { + encrypt_session.setkey(server_key.extract(), server_salt.extract()); + decrypt_session.setkey(client_key.extract(), client_salt.extract()); + } else { + encrypt_session.setkey(client_key.extract(), client_salt.extract()); + decrypt_session.setkey(server_key.extract(), server_salt.extract()); + } + + this.encrypt_session = (owned)encrypt_session; + this.decrypt_session = (owned)decrypt_session; + } + + private static ssize_t pull_function(void* transport_ptr, uint8[] buffer) { + DtlsSrtp self = transport_ptr as DtlsSrtp; + + self.buffer_mutex.lock(); + while (self.buffer_queue.size == 0) { + self.buffer_cond.wait(self.buffer_mutex); + } + owned Bytes data = self.buffer_queue.remove_at(0); + self.buffer_mutex.unlock(); + + uint8[] data_uint8 = Bytes.unref_to_data(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.length; + } + + private static int pull_timeout_function(void* transport_ptr, uint ms) { + DtlsSrtp self = transport_ptr as DtlsSrtp; + + DateTime current_time = new DateTime.now_utc(); + current_time.add_seconds(ms/1000); + int64 end_time = current_time.to_unix(); + + self.buffer_mutex.lock(); + while (self.buffer_queue.size == 0) { + self.buffer_cond.wait_until(self.buffer_mutex, end_time); + + DateTime new_current_time = new DateTime.now_utc(); + if (new_current_time.compare(current_time) > 0) { + break; + } + } + 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) { + DtlsSrtp self = transport_ptr as DtlsSrtp; + 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) { + DtlsSrtp self = session.get_transport_pointer() as DtlsSrtp; + 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); + + string peer_fp_str = format_certificate(peer_cert, DigestAlgorithm.SHA256); + if (peer_fp_str.down() != this.peer_fingerprint.down()) { + warning("First cert in peer cert list doesn't equal advertised one %s vs %s", peer_fp_str, this.peer_fingerprint); + return false; + } + + return true; + } + + private string format_certificate(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); + + var sb = new StringBuilder(); + for (int i = 0; i < buf_out_size; i++) { + sb.append("%02x".printf(buf[i])); + if (i < buf_out_size - 1) { + sb.append(":"); + } + } + return sb.str; + } + + private uint8[] uint8_pt_to_a(uint8* data, uint size) { + uint8[size] ret = new uint8[size]; + for (int i = 0; i < size; i++) { + ret[i] = data[i]; + } + return ret; + } +}
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