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dtls.c
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dtls.c
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/*! \file dtls.c
* \author Lorenzo Miniero <[email protected]>
* \copyright GNU General Public License v3
* \brief DTLS/SRTP processing
* \details Implementation (based on OpenSSL and libsrtp) of the DTLS/SRTP
* transport. The code takes care of the DTLS handshake between peers and
* the server, and sets the proper SRTP and SRTCP context up accordingly.
* A DTLS alert from a peer is notified to the plugin handling him/her
* by means of the hangup_media callback.
*
* \ingroup protocols
* \ref protocols
*/
#include "janus.h"
#include "debug.h"
#include "dtls.h"
#include "rtcp.h"
#include "events.h"
#include <openssl/err.h>
#include <openssl/bn.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <openssl/asn1.h>
const gchar *janus_get_dtls_srtp_state(janus_dtls_state state) {
switch(state) {
case JANUS_DTLS_STATE_CREATED:
return "created";
case JANUS_DTLS_STATE_TRYING:
return "trying";
case JANUS_DTLS_STATE_CONNECTED:
return "connected";
case JANUS_DTLS_STATE_FAILED:
return "failed";
default:
return NULL;
}
return NULL;
}
const gchar *janus_get_dtls_srtp_role(janus_dtls_role role) {
switch(role) {
case JANUS_DTLS_ROLE_ACTPASS:
return "actpass";
case JANUS_DTLS_ROLE_SERVER:
return "passive";
case JANUS_DTLS_ROLE_CLIENT:
return "active";
default:
return NULL;
}
return NULL;
}
const gchar *janus_get_dtls_srtp_profile(int profile) {
switch(profile) {
case SRTP_AES128_CM_SHA1_80:
return "SRTP_AES128_CM_SHA1_80";
case SRTP_AES128_CM_SHA1_32:
return "SRTP_AES128_CM_SHA1_32";
#ifdef HAVE_SRTP_AESGCM
case SRTP_AEAD_AES_256_GCM:
return "SRTP_AEAD_AES_256_GCM";
case SRTP_AEAD_AES_128_GCM:
return "SRTP_AEAD_AES_128_GCM";
#endif
default:
return NULL;
}
return NULL;
}
/* Helper to notify DTLS state changes to the event handlers */
static void janus_dtls_notify_state_change(janus_dtls_srtp *dtls) {
if(!janus_events_is_enabled())
return;
if(dtls == NULL)
return;
janus_ice_component *component = (janus_ice_component *)dtls->component;
if(component == NULL)
return;
janus_ice_stream *stream = component->stream;
if(stream == NULL)
return;
janus_ice_handle *handle = stream->handle;
if(handle == NULL)
return;
janus_session *session = (janus_session *)handle->session;
if(session == NULL)
return;
json_t *info = json_object();
json_object_set_new(info, "dtls", json_string(janus_get_dtls_srtp_state(dtls->dtls_state)));
json_object_set_new(info, "stream_id", json_integer(stream->stream_id));
json_object_set_new(info, "component_id", json_integer(component->component_id));
json_object_set_new(info, "retransmissions", json_integer(dtls->retransmissions));
janus_events_notify_handlers(JANUS_EVENT_TYPE_WEBRTC, JANUS_EVENT_SUBTYPE_WEBRTC_DTLS,
session->session_id, handle->handle_id, handle->opaque_id, info);
}
gboolean janus_is_dtls(char *buf) {
return ((*buf >= 20) && (*buf <= 64));
}
/* DTLS stuff */
#define DTLS_DEFAULT_CIPHERS "DEFAULT:!NULL:!aNULL:!SHA256:!SHA384:!aECDH:!AESGCM+AES256:!aPSK"
static const char *dtls_ciphers = DTLS_DEFAULT_CIPHERS;
/* Duration for the self-generated certs: 1 year */
#define DTLS_AUTOCERT_DURATION 60*60*24*365
/* NIST P-256 elliptic curve used for private key generation */
#define DTLS_ELLIPTIC_CURVE NID_X9_62_prime256v1
/* By default we always accept self-signed certificates (that's what almost
* all of the existing WebRTC implementations do today), but if told so we
* can be configured to reject them, and validate them instead */
static gboolean dtls_selfsigned_certs_ok = TRUE;
gboolean janus_dtls_are_selfsigned_certs_ok(void) {
return dtls_selfsigned_certs_ok;
}
/* DTLS timeout base to enforce: notice that this can currently only be
* modified if you're using BoringSSL, as OpenSSL uses 1s (1000ms) and
* that value cannot be modified (it will in OpenSSL v1.1.1) */
static guint16 dtls_timeout_base = 1000;
static SSL_CTX *ssl_ctx = NULL;
static X509 *ssl_cert = NULL;
static EVP_PKEY *ssl_key = NULL;
static gchar local_fingerprint[160];
gchar *janus_dtls_get_local_fingerprint(void) {
return (gchar *)local_fingerprint;
}
#if JANUS_USE_OPENSSL_PRE_1_1_API && !defined(HAVE_BORINGSSL)
/*
* DTLS locking stuff to make OpenSSL thread safe (not needed for 1.1.0)
*
* Note: this is an attempt to fix the infamous issue #316:
* https://github.com/meetecho/janus-gateway/issues/316
* that is the "tlsv1 alert decrypt error" randomly happening when
* doing handshakes that force Janus to be restarted (issue affecting
* OpenSSL but NOT BoringSSL, apparently). The cause might be related
* to race conditions, and in fact OpenSSL docs state that:
*
* "OpenSSL can safely be used in multi-threaded applications
* provided that at least two callback functions are set,
* locking_function and threadid_func."
*
* See here for the whole docs:
* https://www.openssl.org/docs/manmaster/crypto/threads.html
*
* The fix proposed here is heavily derived from a discussion related to
* RTPEngine:
* http://lists.sip-router.org/pipermail/sr-dev/2015-January/026860.html
* where it was mentioned the issue was fixed in this commit:
* https://github.com/sipwise/rtpengine/commit/935487b66363c9932684d8085f47450d65a8c37e
* which does indeed implement the callbacks the OpenSSL docs suggest.
*
*/
static pthread_mutex_t *janus_dtls_locks;
static void janus_dtls_cb_openssl_threadid(CRYPTO_THREADID *tid) {
/* FIXME Assuming pthread, which is fine as GLib wraps pthread and
* so that's what we use anyway? */
pthread_t me = pthread_self();
if(sizeof(me) == sizeof(void *)) {
CRYPTO_THREADID_set_pointer(tid, (void *) me);
} else {
CRYPTO_THREADID_set_numeric(tid, (unsigned long) me);
}
}
static void janus_dtls_cb_openssl_lock(int mode, int type, const char *file, int line) {
if((mode & CRYPTO_LOCK)) {
pthread_mutex_lock(&janus_dtls_locks[type]);
} else {
pthread_mutex_unlock(&janus_dtls_locks[type]);
}
}
#endif
static int janus_dtls_generate_keys(X509 **certificate, EVP_PKEY **private_key, gboolean rsa_private_key) {
static const int num_bits = 2048;
BIGNUM *bne = NULL;
RSA *rsa_key = NULL;
X509_NAME *cert_name = NULL;
EC_KEY *ecc_key = NULL;
JANUS_LOG(LOG_VERB, "Generating DTLS key / cert\n");
/* Create a private key object (needed to hold the RSA key). */
*private_key = EVP_PKEY_new();
if(!*private_key) {
JANUS_LOG(LOG_FATAL, "EVP_PKEY_new() failed\n");
goto error;
}
if(rsa_private_key) {
/* Create a big number object. */
bne = BN_new();
if(!bne) {
JANUS_LOG(LOG_FATAL, "BN_new() failed\n");
goto error;
}
if(!BN_set_word(bne, RSA_F4)) { /* RSA_F4 == 65537 */
JANUS_LOG(LOG_FATAL, "BN_set_word() failed\n");
goto error;
}
/* Generate a RSA key. */
rsa_key = RSA_new();
if(!rsa_key) {
JANUS_LOG(LOG_FATAL, "RSA_new() failed\n");
goto error;
}
/* This takes some time. */
if(!RSA_generate_key_ex(rsa_key, num_bits, bne, NULL)) {
JANUS_LOG(LOG_FATAL, "RSA_generate_key_ex() failed\n");
goto error;
}
if(!EVP_PKEY_assign_RSA(*private_key, rsa_key)) {
JANUS_LOG(LOG_FATAL, "EVP_PKEY_assign_RSA() failed\n");
goto error;
}
/* The RSA key now belongs to the private key, so don't clean it up separately. */
rsa_key = NULL;
} else {
/* Create key with curve dictated by DTLS_ELLIPTIC_CURVE */
if((ecc_key = EC_KEY_new_by_curve_name(DTLS_ELLIPTIC_CURVE)) == NULL) {
JANUS_LOG(LOG_FATAL, "EC_KEY_new_by_curve_name() failed\n");
goto error;
}
EC_KEY_set_asn1_flag(ecc_key, OPENSSL_EC_NAMED_CURVE);
/* This takes some time. */
if(EC_KEY_generate_key(ecc_key) == 0) {
JANUS_LOG(LOG_FATAL, "EC_KEY_generate_key() failed\n");
goto error;
}
if(EVP_PKEY_assign_EC_KEY(*private_key, ecc_key) == 0) {
JANUS_LOG(LOG_FATAL, "EVP_PKEY_assign_EC_KEY() failed\n");
goto error;
}
/* The EC key now belongs to the private key, so don't clean it up separately. */
ecc_key = NULL;
}
/* Create the X509 certificate. */
*certificate = X509_new();
if(!*certificate) {
JANUS_LOG(LOG_FATAL, "X509_new() failed\n");
goto error;
}
/* Set version 3 (note that 0 means version 1). */
X509_set_version(*certificate, 2);
/* Set serial number. */
ASN1_INTEGER_set(X509_get_serialNumber(*certificate), (long)g_random_int());
/* Set valid period. */
X509_gmtime_adj(X509_get_notBefore(*certificate), -1 * DTLS_AUTOCERT_DURATION); /* -1 year */
X509_gmtime_adj(X509_get_notAfter(*certificate), DTLS_AUTOCERT_DURATION); /* 1 year */
/* Set the public key for the certificate using the key. */
if(!X509_set_pubkey(*certificate, *private_key)) {
JANUS_LOG(LOG_FATAL, "X509_set_pubkey() failed\n");
goto error;
}
/* Set certificate fields. */
cert_name = X509_get_subject_name(*certificate);
if(!cert_name) {
JANUS_LOG(LOG_FATAL, "X509_get_subject_name() failed\n");
goto error;
}
X509_NAME_add_entry_by_txt(cert_name, "O", MBSTRING_ASC, (const unsigned char*)"Janus", -1, -1, 0);
X509_NAME_add_entry_by_txt(cert_name, "CN", MBSTRING_ASC, (const unsigned char*)"Janus", -1, -1, 0);
/* It is self-signed so set the issuer name to be the same as the subject. */
if(!X509_set_issuer_name(*certificate, cert_name)) {
JANUS_LOG(LOG_FATAL, "X509_set_issuer_name() failed\n");
goto error;
}
/* Sign the certificate with the private key. */
if(!X509_sign(*certificate, *private_key, EVP_sha1())) {
JANUS_LOG(LOG_FATAL, "X509_sign() failed\n");
goto error;
}
/* Free stuff and resurn. */
BN_free(bne);
return 0;
error:
if(bne)
BN_free(bne);
if(rsa_key && !*private_key)
RSA_free(rsa_key);
if(ecc_key && !*private_key)
EC_KEY_free(ecc_key);
if(*private_key)
EVP_PKEY_free(*private_key); /* This also frees the RSA key. */
if(*certificate)
X509_free(*certificate);
return -1;
}
static int janus_dtls_load_keys(const char *server_pem, const char *server_key, const char *password,
X509 **certificate, EVP_PKEY **private_key) {
FILE *f = NULL;
f = fopen(server_pem, "r");
if(!f) {
JANUS_LOG(LOG_FATAL, "Error opening certificate file\n");
goto error;
}
*certificate = PEM_read_X509(f, NULL, NULL, NULL);
if(!*certificate) {
JANUS_LOG(LOG_FATAL, "PEM_read_X509 failed\n");
goto error;
}
fclose(f);
f = fopen(server_key, "r");
if(!f) {
JANUS_LOG(LOG_FATAL, "Error opening key file\n");
goto error;
}
*private_key = PEM_read_PrivateKey(f, NULL, NULL, (void *)password);
if(!*private_key) {
JANUS_LOG(LOG_FATAL, "PEM_read_PrivateKey failed\n");
goto error;
}
fclose(f);
return 0;
error:
if(*certificate) {
X509_free(*certificate);
*certificate = NULL;
}
if(*private_key) {
EVP_PKEY_free(*private_key);
*private_key = NULL;
}
return -1;
}
/* Versioning info ( */
const char *janus_get_ssl_version(void) {
return OPENSSL_VERSION_TEXT;
}
/* DTLS-SRTP initialization */
gint janus_dtls_srtp_init(const char *server_pem, const char *server_key, const char *password,
const char *ciphers, guint16 timeout, gboolean rsa_private_key, gboolean accept_selfsigned) {
const char *crypto_lib = NULL;
#if JANUS_USE_OPENSSL_PRE_1_1_API && !defined(HAVE_BORINGSSL)
#if defined(LIBRESSL_VERSION_NUMBER)
crypto_lib = "LibreSSL";
#else
crypto_lib = "OpenSSL pre-1.1.0";
#endif
/* First of all make OpenSSL thread safe (see note above on issue #316) */
janus_dtls_locks = g_malloc0(sizeof(*janus_dtls_locks) * CRYPTO_num_locks());
int l=0;
for(l = 0; l < CRYPTO_num_locks(); l++) {
pthread_mutex_init(&janus_dtls_locks[l], NULL);
}
CRYPTO_THREADID_set_callback(janus_dtls_cb_openssl_threadid);
CRYPTO_set_locking_callback(janus_dtls_cb_openssl_lock);
#else
crypto_lib = "OpenSSL >= 1.1.0";
#endif
#ifdef HAVE_BORINGSSL
crypto_lib = "BoringSSL";
#endif
JANUS_LOG(LOG_INFO, "Crypto: %s\n", crypto_lib);
#ifndef HAVE_SRTP_AESGCM
JANUS_LOG(LOG_WARN, "The libsrtp installation does not support AES-GCM profiles\n");
#endif
/* Go on and create the DTLS context */
#if JANUS_USE_OPENSSL_PRE_1_1_API && !defined(HAVE_BORINGSSL)
#if defined(LIBRESSL_VERSION_NUMBER)
ssl_ctx = SSL_CTX_new(DTLSv1_method());
#else
ssl_ctx = SSL_CTX_new(DTLSv1_2_method());
#endif
#else
ssl_ctx = SSL_CTX_new(DTLS_method());
#endif
if(!ssl_ctx) {
JANUS_LOG(LOG_FATAL, "Ops, error creating DTLS context?\n");
return -1;
}
SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, janus_dtls_verify_callback);
SSL_CTX_set_tlsext_use_srtp(ssl_ctx,
#ifdef HAVE_SRTP_AESGCM
"SRTP_AEAD_AES_256_GCM:SRTP_AEAD_AES_128_GCM:SRTP_AES128_CM_SHA1_80:SRTP_AES128_CM_SHA1_32");
#else
"SRTP_AES128_CM_SHA1_80:SRTP_AES128_CM_SHA1_32");
#endif
if(!server_pem && !server_key) {
JANUS_LOG(LOG_WARN, "No cert/key specified, autogenerating some...\n");
if(janus_dtls_generate_keys(&ssl_cert, &ssl_key, rsa_private_key) != 0) {
JANUS_LOG(LOG_FATAL, "Error generating DTLS key/certificate\n");
return -2;
}
} else if(!server_pem || !server_key) {
JANUS_LOG(LOG_FATAL, "DTLS certificate and key must be specified\n");
return -2;
} else if(janus_dtls_load_keys(server_pem, server_key, password, &ssl_cert, &ssl_key) != 0) {
return -3;
}
if(!SSL_CTX_use_certificate(ssl_ctx, ssl_cert)) {
JANUS_LOG(LOG_FATAL, "Certificate error (%s)\n", ERR_reason_error_string(ERR_get_error()));
return -4;
}
if(!SSL_CTX_use_PrivateKey(ssl_ctx, ssl_key)) {
JANUS_LOG(LOG_FATAL, "Certificate key error (%s)\n", ERR_reason_error_string(ERR_get_error()));
return -5;
}
if(!SSL_CTX_check_private_key(ssl_ctx)) {
JANUS_LOG(LOG_FATAL, "Certificate check error (%s)\n", ERR_reason_error_string(ERR_get_error()));
return -6;
}
SSL_CTX_set_read_ahead(ssl_ctx,1);
unsigned int size;
unsigned char fingerprint[EVP_MAX_MD_SIZE];
if(X509_digest(ssl_cert, EVP_sha256(), (unsigned char *)fingerprint, &size) == 0) {
JANUS_LOG(LOG_FATAL, "Error converting X509 structure (%s)\n", ERR_reason_error_string(ERR_get_error()));
return -7;
}
char *lfp = (char *)&local_fingerprint;
unsigned int i = 0;
for(i = 0; i < size; i++) {
g_snprintf(lfp, 4, "%.2X:", fingerprint[i]);
lfp += 3;
}
*(lfp-1) = 0;
JANUS_LOG(LOG_INFO, "Fingerprint of our certificate: %s\n", local_fingerprint);
if(ciphers)
dtls_ciphers = ciphers;
if(SSL_CTX_set_cipher_list(ssl_ctx, dtls_ciphers) == 0) {
JANUS_LOG(LOG_FATAL, "Error setting cipher list (%s)\n", ERR_reason_error_string(ERR_get_error()));
return -8;
}
if(janus_dtls_bio_agent_init() < 0) {
JANUS_LOG(LOG_FATAL, "Error initializing BIO agent\n");
return -9;
}
dtls_timeout_base = timeout;
#ifndef HAVE_BORINGSSL
if(dtls_timeout_base != 1000) {
JANUS_LOG(LOG_WARN, "DTLS timeout set to %u ms, but not using BoringSSL: ignoring\n", timeout);
}
#endif
/* Initialize libsrtp */
if(srtp_init() != srtp_err_status_ok) {
JANUS_LOG(LOG_FATAL, "Ops, error setting up libsrtp?\n");
return -10;
}
/* Finally, let's set our policy with respect to DTLS self signed certificates */
dtls_selfsigned_certs_ok = accept_selfsigned;
if(!dtls_selfsigned_certs_ok) {
JANUS_LOG(LOG_WARN, "WebRTC PeerConnections with self-signed certificates will NOT be accepted\n");
}
return 0;
}
static void janus_dtls_srtp_free(const janus_refcount *dtls_ref) {
janus_dtls_srtp *dtls = janus_refcount_containerof(dtls_ref, janus_dtls_srtp, ref);
/* This stack can be destroyed, free all the resources */
dtls->component = NULL;
if(dtls->ssl != NULL) {
SSL_free(dtls->ssl);
dtls->ssl = NULL;
}
/* BIOs are destroyed by SSL_free */
dtls->read_bio = NULL;
dtls->write_bio = NULL;
if(dtls->srtp_valid) {
if(dtls->srtp_in) {
srtp_dealloc(dtls->srtp_in);
dtls->srtp_in = NULL;
}
if(dtls->srtp_out) {
srtp_dealloc(dtls->srtp_out);
dtls->srtp_out = NULL;
}
/* FIXME What about dtls->remote_policy and dtls->local_policy? */
}
g_free(dtls);
dtls = NULL;
}
void janus_dtls_srtp_cleanup(void) {
if(ssl_cert != NULL) {
X509_free(ssl_cert);
ssl_cert = NULL;
}
if(ssl_key != NULL) {
EVP_PKEY_free(ssl_key);
ssl_key = NULL;
}
if(ssl_ctx != NULL) {
SSL_CTX_free(ssl_ctx);
ssl_ctx = NULL;
}
#if JANUS_USE_OPENSSL_PRE_1_1_API && !defined(HAVE_BORINGSSL)
g_free(janus_dtls_locks);
#endif
}
janus_dtls_srtp *janus_dtls_srtp_create(void *ice_component, janus_dtls_role role) {
janus_ice_component *component = (janus_ice_component *)ice_component;
if(component == NULL) {
JANUS_LOG(LOG_ERR, "No component, no DTLS...\n");
return NULL;
}
janus_ice_stream *stream = component->stream;
if(!stream) {
JANUS_LOG(LOG_ERR, "No stream, no DTLS...\n");
return NULL;
}
janus_ice_handle *handle = stream->handle;
if(!handle || !handle->agent) {
JANUS_LOG(LOG_ERR, "No handle/agent, no DTLS...\n");
return NULL;
}
janus_dtls_srtp *dtls = g_malloc0(sizeof(janus_dtls_srtp));
g_atomic_int_set(&dtls->destroyed, 0);
janus_refcount_init(&dtls->ref, janus_dtls_srtp_free);
/* Create SSL context, at last */
dtls->srtp_valid = 0;
dtls->ssl = SSL_new(ssl_ctx);
if(!dtls->ssl) {
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Error creating DTLS session! (%s)\n",
handle->handle_id, ERR_reason_error_string(ERR_get_error()));
janus_refcount_decrease(&dtls->ref);
return NULL;
}
SSL_set_ex_data(dtls->ssl, 0, dtls);
SSL_set_info_callback(dtls->ssl, janus_dtls_callback);
dtls->read_bio = BIO_new(BIO_s_mem());
if(!dtls->read_bio) {
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Error creating read BIO! (%s)\n",
handle->handle_id, ERR_reason_error_string(ERR_get_error()));
janus_refcount_decrease(&dtls->ref);
return NULL;
}
BIO_set_mem_eof_return(dtls->read_bio, -1);
dtls->write_bio = BIO_janus_dtls_agent_new(dtls);
if(!dtls->write_bio) {
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Error creating write BIO! (%s)\n",
handle->handle_id, ERR_reason_error_string(ERR_get_error()));
janus_refcount_decrease(&dtls->ref);
return NULL;
}
SSL_set_bio(dtls->ssl, dtls->read_bio, dtls->write_bio);
/* The role may change later, depending on the negotiation */
dtls->dtls_role = role;
/* https://code.google.com/p/chromium/issues/detail?id=406458
* Specify an ECDH group for ECDHE ciphers, otherwise they cannot be
* negotiated when acting as the server. Use NIST's P-256 which is
* commonly supported.
*/
EC_KEY *ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
if(ecdh == NULL) {
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Error creating ECDH group! (%s)\n",
handle->handle_id, ERR_reason_error_string(ERR_get_error()));
janus_refcount_decrease(&dtls->ref);
return NULL;
}
const long flags = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | SSL_OP_NO_COMPRESSION | SSL_OP_SINGLE_ECDH_USE;
SSL_set_options(dtls->ssl, flags);
SSL_set_tmp_ecdh(dtls->ssl, ecdh);
EC_KEY_free(ecdh);
#ifdef HAVE_DTLS_SETTIMEOUT
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Setting DTLS initial timeout: %"SCNu16"ms\n", handle->handle_id, dtls_timeout_base);
DTLSv1_set_initial_timeout_duration(dtls->ssl, dtls_timeout_base);
#endif
dtls->ready = 0;
dtls->retransmissions = 0;
#ifdef HAVE_SCTP
dtls->sctp = NULL;
#endif
/* Done */
dtls->dtls_connected = 0;
dtls->component = component;
return dtls;
}
void janus_dtls_srtp_handshake(janus_dtls_srtp *dtls) {
if(dtls == NULL || dtls->ssl == NULL)
return;
if(dtls->dtls_state == JANUS_DTLS_STATE_CREATED) {
/* Starting the handshake now: enforce the role */
dtls->dtls_started = janus_get_monotonic_time();
if(dtls->dtls_role == JANUS_DTLS_ROLE_CLIENT) {
SSL_set_connect_state(dtls->ssl);
} else {
SSL_set_accept_state(dtls->ssl);
}
dtls->dtls_state = JANUS_DTLS_STATE_TRYING;
}
SSL_do_handshake(dtls->ssl);
/* Notify event handlers */
janus_dtls_notify_state_change(dtls);
}
int janus_dtls_srtp_create_sctp(janus_dtls_srtp *dtls) {
#ifdef HAVE_SCTP
if(dtls == NULL)
return -1;
janus_ice_component *component = (janus_ice_component *)dtls->component;
if(component == NULL)
return -2;
janus_ice_stream *stream = component->stream;
if(!stream)
return -3;
janus_ice_handle *handle = stream->handle;
if(!handle || !handle->agent)
return -4;
if(janus_flags_is_set(&handle->webrtc_flags, JANUS_ICE_HANDLE_WEBRTC_ALERT))
return -5;
dtls->sctp = janus_sctp_association_create(dtls, handle, 5000);
if(dtls->sctp == NULL) {
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Error creating SCTP association...\n", handle->handle_id);
return -6;
}
return 0;
#else
/* Support for datachannels hasn't been built in */
return -1;
#endif
}
void janus_dtls_srtp_incoming_msg(janus_dtls_srtp *dtls, char *buf, uint16_t len) {
if(dtls == NULL) {
JANUS_LOG(LOG_ERR, "No DTLS-SRTP stack, no incoming message...\n");
return;
}
janus_ice_component *component = (janus_ice_component *)dtls->component;
if(component == NULL) {
JANUS_LOG(LOG_ERR, "No component, no DTLS...\n");
return;
}
janus_ice_stream *stream = component->stream;
if(!stream) {
JANUS_LOG(LOG_ERR, "No stream, no DTLS...\n");
return;
}
janus_ice_handle *handle = stream->handle;
if(!handle || !handle->agent) {
JANUS_LOG(LOG_ERR, "No handle/agent, no DTLS...\n");
return;
}
if(janus_flags_is_set(&handle->webrtc_flags, JANUS_ICE_HANDLE_WEBRTC_ALERT)) {
JANUS_LOG(LOG_WARN, "[%"SCNu64"] Alert already triggered, clearing up...\n", handle->handle_id);
return;
}
if(!dtls->ssl || !dtls->read_bio) {
JANUS_LOG(LOG_ERR, "[%"SCNu64"] No DTLS stuff for component %d in stream %d??\n", handle->handle_id, component->component_id, stream->stream_id);
return;
}
if(dtls->dtls_started == 0) {
/* Handshake not started yet: maybe we're still waiting for the answer and the DTLS role? */
return;
}
int written = BIO_write(dtls->read_bio, buf, len);
if(written != len) {
JANUS_LOG(LOG_WARN, "[%"SCNu64"] Only written %d/%d of those bytes on the read BIO...\n", handle->handle_id, written, len);
} else {
JANUS_LOG(LOG_HUGE, "[%"SCNu64"] Written %d bytes on the read BIO...\n", handle->handle_id, written);
}
/* Try to read data */
char data[1500]; /* FIXME */
memset(&data, 0, 1500);
int read = SSL_read(dtls->ssl, &data, 1500);
JANUS_LOG(LOG_HUGE, "[%"SCNu64"] ... and read %d of them from SSL...\n", handle->handle_id, read);
if(read < 0) {
unsigned long err = SSL_get_error(dtls->ssl, read);
if(err == SSL_ERROR_SSL) {
/* Ops, something went wrong with the DTLS handshake */
char error[200];
ERR_error_string_n(ERR_get_error(), error, 200);
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Handshake error: %s\n", handle->handle_id, error);
return;
}
}
if(janus_flags_is_set(&handle->webrtc_flags, JANUS_ICE_HANDLE_WEBRTC_STOP) || janus_is_stopping()) {
/* DTLS alert triggered, we should end it here */
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Forced to stop it here...\n", handle->handle_id);
return;
}
if(!SSL_is_init_finished(dtls->ssl)) {
/* Nothing else to do for now */
JANUS_LOG(LOG_HUGE, "[%"SCNu64"] Initialization not finished yet...\n", handle->handle_id);
return;
}
if(dtls->ready) {
/* There's data to be read? */
JANUS_LOG(LOG_HUGE, "[%"SCNu64"] Any data available?\n", handle->handle_id);
#ifdef HAVE_SCTP
if(dtls->sctp != NULL && read > 0) {
JANUS_LOG(LOG_HUGE, "[%"SCNu64"] Sending data (%d bytes) to the SCTP stack...\n", handle->handle_id, read);
janus_sctp_data_from_dtls(dtls->sctp, data, read);
}
#else
if(read > 0) {
JANUS_LOG(LOG_WARN, "[%"SCNu64"] Data available but Data Channels support disabled...\n", handle->handle_id);
}
#endif
} else {
JANUS_LOG(LOG_VERB, "[%"SCNu64"] DTLS established, yay!\n", handle->handle_id);
/* Check the remote fingerprint */
X509 *rcert = SSL_get_peer_certificate(dtls->ssl);
if(!rcert) {
JANUS_LOG(LOG_ERR, "[%"SCNu64"] No remote certificate?? (%s)\n",
handle->handle_id, ERR_reason_error_string(ERR_get_error()));
} else {
unsigned int rsize;
unsigned char rfingerprint[EVP_MAX_MD_SIZE];
char remote_fingerprint[160];
char *rfp = (char *)&remote_fingerprint;
if(stream->remote_hashing && !strcasecmp(stream->remote_hashing, "sha-1")) {
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Computing sha-1 fingerprint of remote certificate...\n", handle->handle_id);
X509_digest(rcert, EVP_sha1(), (unsigned char *)rfingerprint, &rsize);
} else {
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Computing sha-256 fingerprint of remote certificate...\n", handle->handle_id);
X509_digest(rcert, EVP_sha256(), (unsigned char *)rfingerprint, &rsize);
}
X509_free(rcert);
rcert = NULL;
unsigned int i = 0;
for(i = 0; i < rsize; i++) {
g_snprintf(rfp, 4, "%.2X:", rfingerprint[i]);
rfp += 3;
}
*(rfp-1) = 0;
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Remote fingerprint (%s) of the client is %s\n",
handle->handle_id, stream->remote_hashing ? stream->remote_hashing : "sha-256", remote_fingerprint);
if(!strcasecmp(remote_fingerprint, stream->remote_fingerprint ? stream->remote_fingerprint : "(none)")) {
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Fingerprint is a match!\n", handle->handle_id);
dtls->dtls_state = JANUS_DTLS_STATE_CONNECTED;
dtls->dtls_connected = janus_get_monotonic_time();
/* Notify event handlers */
janus_dtls_notify_state_change(dtls);
} else {
/* FIXME NOT a match! MITM? */
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Fingerprint is NOT a match! got %s, expected %s\n", handle->handle_id, remote_fingerprint, stream->remote_fingerprint);
dtls->dtls_state = JANUS_DTLS_STATE_FAILED;
/* Notify event handlers */
janus_dtls_notify_state_change(dtls);
goto done;
}
if(dtls->dtls_state == JANUS_DTLS_STATE_CONNECTED) {
/* Which SRTP profile is being negotiated? */
const SRTP_PROTECTION_PROFILE *srtp_profile = SSL_get_selected_srtp_profile(dtls->ssl);
if(srtp_profile == NULL) {
/* Should never happen, but just in case... */
JANUS_LOG(LOG_ERR, "[%"SCNu64"] No SRTP profile selected...\n", handle->handle_id);
dtls->dtls_state = JANUS_DTLS_STATE_FAILED;
/* Notify event handlers */
janus_dtls_notify_state_change(dtls);
goto done;
}
JANUS_LOG(LOG_VERB, "[%"SCNu64"] %s\n", handle->handle_id, srtp_profile->name);
int key_length = 0, salt_length = 0, master_length = 0;
switch(srtp_profile->id) {
case SRTP_AES128_CM_SHA1_80:
case SRTP_AES128_CM_SHA1_32:
key_length = SRTP_MASTER_KEY_LENGTH;
salt_length = SRTP_MASTER_SALT_LENGTH;
master_length = SRTP_MASTER_LENGTH;
break;
#ifdef HAVE_SRTP_AESGCM
case SRTP_AEAD_AES_256_GCM:
key_length = SRTP_AESGCM256_MASTER_KEY_LENGTH;
salt_length = SRTP_AESGCM256_MASTER_SALT_LENGTH;
master_length = SRTP_AESGCM256_MASTER_LENGTH;
break;
case SRTP_AEAD_AES_128_GCM:
key_length = SRTP_AESGCM128_MASTER_KEY_LENGTH;
salt_length = SRTP_AESGCM128_MASTER_SALT_LENGTH;
master_length = SRTP_AESGCM128_MASTER_LENGTH;
break;
#endif
default:
/* Will never happen? */
JANUS_LOG(LOG_WARN, "[%"SCNu64"] Unsupported SRTP profile %lu\n", handle->handle_id, srtp_profile->id);
break;
}
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Key/Salt/Master: %d/%d/%d\n",
handle->handle_id, master_length, key_length, salt_length);
/* Complete with SRTP setup */
unsigned char material[master_length*2];
unsigned char *local_key, *local_salt, *remote_key, *remote_salt;
/* Export keying material for SRTP */
if(!SSL_export_keying_material(dtls->ssl, material, master_length*2, "EXTRACTOR-dtls_srtp", 19, NULL, 0, 0)) {
/* Oops... */
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Oops, couldn't extract SRTP keying material for component %d in stream %d?? (%s)\n",
handle->handle_id, component->component_id, stream->stream_id, ERR_reason_error_string(ERR_get_error()));
goto done;
}
/* Key derivation (http://tools.ietf.org/html/rfc5764#section-4.2) */
if(dtls->dtls_role == JANUS_DTLS_ROLE_CLIENT) {
local_key = material;
remote_key = local_key + key_length;
local_salt = remote_key + key_length;
remote_salt = local_salt + salt_length;
} else {
remote_key = material;
local_key = remote_key + key_length;
remote_salt = local_key + key_length;
local_salt = remote_salt + salt_length;
}
/* Build master keys and set SRTP policies */
/* Remote (inbound) */
switch(srtp_profile->id) {
case SRTP_AES128_CM_SHA1_80:
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(&(dtls->remote_policy.rtp));
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(&(dtls->remote_policy.rtcp));
break;
case SRTP_AES128_CM_SHA1_32:
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32(&(dtls->remote_policy.rtp));
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(&(dtls->remote_policy.rtcp));
break;
#ifdef HAVE_SRTP_AESGCM
case SRTP_AEAD_AES_256_GCM:
srtp_crypto_policy_set_aes_gcm_256_16_auth(&(dtls->remote_policy.rtp));
srtp_crypto_policy_set_aes_gcm_256_16_auth(&(dtls->remote_policy.rtcp));
break;
case SRTP_AEAD_AES_128_GCM:
srtp_crypto_policy_set_aes_gcm_128_16_auth(&(dtls->remote_policy.rtp));
srtp_crypto_policy_set_aes_gcm_128_16_auth(&(dtls->remote_policy.rtcp));
break;
#endif
default:
/* Will never happen? */
JANUS_LOG(LOG_WARN, "[%"SCNu64"] Unsupported SRTP profile %s\n", handle->handle_id, srtp_profile->name);
break;
}
dtls->remote_policy.ssrc.type = ssrc_any_inbound;
unsigned char remote_policy_key[master_length];
dtls->remote_policy.key = (unsigned char *)&remote_policy_key;
memcpy(dtls->remote_policy.key, remote_key, key_length);
memcpy(dtls->remote_policy.key + key_length, remote_salt, salt_length);
#if HAS_DTLS_WINDOW_SIZE
dtls->remote_policy.window_size = 128;
dtls->remote_policy.allow_repeat_tx = 0;
#endif
dtls->remote_policy.next = NULL;
/* Local (outbound) */
switch(srtp_profile->id) {
case SRTP_AES128_CM_SHA1_80:
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(&(dtls->local_policy.rtp));
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(&(dtls->local_policy.rtcp));
break;
case SRTP_AES128_CM_SHA1_32:
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32(&(dtls->local_policy.rtp));
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(&(dtls->local_policy.rtcp));
break;
#ifdef HAVE_SRTP_AESGCM
case SRTP_AEAD_AES_256_GCM:
srtp_crypto_policy_set_aes_gcm_256_16_auth(&(dtls->local_policy.rtp));
srtp_crypto_policy_set_aes_gcm_256_16_auth(&(dtls->local_policy.rtcp));
break;
case SRTP_AEAD_AES_128_GCM:
srtp_crypto_policy_set_aes_gcm_128_16_auth(&(dtls->local_policy.rtp));
srtp_crypto_policy_set_aes_gcm_128_16_auth(&(dtls->local_policy.rtcp));
break;
#endif
default:
/* Will never happen? */
JANUS_LOG(LOG_WARN, "[%"SCNu64"] Unsupported SRTP profile %s\n", handle->handle_id, srtp_profile->name);
break;
}
dtls->local_policy.ssrc.type = ssrc_any_outbound;
unsigned char local_policy_key[master_length];
dtls->local_policy.key = (unsigned char *)&local_policy_key;
memcpy(dtls->local_policy.key, local_key, key_length);
memcpy(dtls->local_policy.key + key_length, local_salt, salt_length);
#if HAS_DTLS_WINDOW_SIZE
dtls->local_policy.window_size = 128;
dtls->local_policy.allow_repeat_tx = 0;
#endif
dtls->local_policy.next = NULL;
/* Create SRTP sessions */
srtp_err_status_t res = srtp_create(&(dtls->srtp_in), &(dtls->remote_policy));
if(res != srtp_err_status_ok) {
/* Something went wrong... */
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Oops, error creating inbound SRTP session for component %d in stream %d??\n", handle->handle_id, component->component_id, stream->stream_id);
JANUS_LOG(LOG_ERR, "[%"SCNu64"] -- %d (%s)\n", handle->handle_id, res, janus_srtp_error_str(res));
goto done;
}
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Created inbound SRTP session for component %d in stream %d\n", handle->handle_id, component->component_id, stream->stream_id);
res = srtp_create(&(dtls->srtp_out), &(dtls->local_policy));
if(res != srtp_err_status_ok) {
/* Something went wrong... */
JANUS_LOG(LOG_ERR, "[%"SCNu64"] Oops, error creating outbound SRTP session for component %d in stream %d??\n", handle->handle_id, component->component_id, stream->stream_id);
JANUS_LOG(LOG_ERR, "[%"SCNu64"] -- %d (%s)\n", handle->handle_id, res, janus_srtp_error_str(res));
goto done;
}
dtls->srtp_profile = srtp_profile->id;
dtls->srtp_valid = 1;
JANUS_LOG(LOG_VERB, "[%"SCNu64"] Created outbound SRTP session for component %d in stream %d\n", handle->handle_id, component->component_id, stream->stream_id);
#ifdef HAVE_SCTP
if(janus_flags_is_set(&handle->webrtc_flags, JANUS_ICE_HANDLE_WEBRTC_DATA_CHANNELS)) {
/* Create SCTP association as well */
janus_dtls_srtp_create_sctp(dtls);
}
#endif
dtls->ready = 1;
}
done:
if(!janus_flags_is_set(&handle->webrtc_flags, JANUS_ICE_HANDLE_WEBRTC_ALERT) && dtls->srtp_valid) {
/* Handshake successfully completed */
janus_ice_dtls_handshake_done(handle, component);
} else {
/* Something went wrong in either DTLS or SRTP... tell the plugin about it */
janus_dtls_callback(dtls->ssl, SSL_CB_ALERT, 0);
janus_flags_set(&handle->webrtc_flags, JANUS_ICE_HANDLE_WEBRTC_CLEANING);
}
}
}
}
void janus_dtls_srtp_send_alert(janus_dtls_srtp *dtls) {
if(!dtls)
return;
/* Send alert */
janus_refcount_increase(&dtls->ref);
if(dtls != NULL && dtls->ssl != NULL) {
SSL_shutdown(dtls->ssl);
}
janus_refcount_decrease(&dtls->ref);
}
void janus_dtls_srtp_destroy(janus_dtls_srtp *dtls) {
if(!dtls || !g_atomic_int_compare_and_exchange(&dtls->destroyed, 0, 1))
return;
dtls->ready = 0;
dtls->retransmissions = 0;
#ifdef HAVE_SCTP
/* Destroy the SCTP association if this is a DataChannel */
if(dtls->sctp != NULL) {
janus_sctp_association_destroy(dtls->sctp);
dtls->sctp = NULL;
}
#endif
janus_refcount_decrease(&dtls->ref);
}
/* DTLS alert callback */
void janus_dtls_callback(const SSL *ssl, int where, int ret) {
/* We only care about alerts */
if(!(where & SSL_CB_ALERT)) {
return;
}
janus_dtls_srtp *dtls = SSL_get_ex_data(ssl, 0);
if(!dtls) {
JANUS_LOG(LOG_ERR, "No DTLS session related to this alert...\n");
return;
}
janus_ice_component *component = dtls->component;
if(component == NULL) {
JANUS_LOG(LOG_ERR, "No ICE component related to this alert...\n");
return;
}