dino/plugins/ice/src/dtls_srtp.vala

357 lines
12 KiB
Vala

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(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
}
}