size_t stun_agent_finish_message (StunAgent *agent, StunMessage *msg,
const uint8_t *key, size_t key_len)
{
uint8_t *ptr;
uint32_t fpr;
int saved_id_idx = 0;
uint8_t md5[16];
if (stun_message_get_class (msg) == STUN_REQUEST) {
for (saved_id_idx = 0; saved_id_idx < STUN_AGENT_MAX_SAVED_IDS; saved_id_idx++) {
if (agent->sent_ids[saved_id_idx].valid == FALSE) {
break;
}
}
}
if (saved_id_idx == STUN_AGENT_MAX_SAVED_IDS) {
stun_debug ("Saved ids full");
return 0;
}
if (msg->key != NULL) {
key = msg->key;
key_len = msg->key_len;
}
if (key != NULL) {
bool skip = FALSE;
if (msg->long_term_valid) {
memcpy (md5, msg->long_term_key, sizeof(msg->long_term_key));
} else if (agent->usage_flags & STUN_AGENT_USAGE_LONG_TERM_CREDENTIALS) {
uint8_t *realm = NULL;
uint8_t *username = NULL;
uint16_t realm_len;
uint16_t username_len;
realm = (uint8_t *) stun_message_find (msg,
STUN_ATTRIBUTE_REALM, &realm_len);
username = (uint8_t *) stun_message_find (msg,
STUN_ATTRIBUTE_USERNAME, &username_len);
if (username == NULL || realm == NULL) {
skip = TRUE;
} else {
stun_hash_creds (realm, realm_len,
username, username_len,
key, key_len, md5);
}
memcpy (msg->long_term_key, md5, sizeof(msg->long_term_key));
msg->long_term_valid = TRUE;
}
/* If no realm/username and long term credentials,
then don't send the message integrity */
if (skip == FALSE) {
ptr = stun_message_append (msg, STUN_ATTRIBUTE_MESSAGE_INTEGRITY, 20);
if (ptr == NULL) {
return 0;
}
if (agent->usage_flags & STUN_AGENT_USAGE_LONG_TERM_CREDENTIALS) {
if (agent->compatibility == STUN_COMPATIBILITY_RFC3489) {
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - 20, ptr, md5, sizeof(md5), TRUE);
} else if (agent->compatibility == STUN_COMPATIBILITY_WLM2009) {
size_t minus = 20;
if (agent->usage_flags & STUN_AGENT_USAGE_USE_FINGERPRINT)
minus -= 8;
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - minus, ptr, md5, sizeof(md5), TRUE);
} else {
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - 20, ptr, md5, sizeof(md5), FALSE);
}
} else {
if (agent->compatibility == STUN_COMPATIBILITY_RFC3489) {
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - 20, ptr, key, key_len, TRUE);
} else if (agent->compatibility == STUN_COMPATIBILITY_WLM2009) {
size_t minus = 20;
if (agent->usage_flags & STUN_AGENT_USAGE_USE_FINGERPRINT)
minus -= 8;
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - minus, ptr, key, key_len, TRUE);
} else {
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - 20, ptr, key, key_len, FALSE);
}
}
stun_debug (" Message HMAC-SHA1 message integrity:"
"\n key : ");
stun_debug_bytes (key, key_len);
stun_debug ("\n sent : ");
stun_debug_bytes (ptr, 20);
stun_debug ("\n");
}
}
if ((agent->compatibility == STUN_COMPATIBILITY_RFC5389 ||
agent->compatibility == STUN_COMPATIBILITY_WLM2009) &&
agent->usage_flags & STUN_AGENT_USAGE_USE_FINGERPRINT) {
ptr = stun_message_append (msg, STUN_ATTRIBUTE_FINGERPRINT, 4);
if (ptr == NULL) {
return 0;
}
fpr = stun_fingerprint (msg->buffer, stun_message_length (msg),
agent->compatibility == STUN_COMPATIBILITY_WLM2009);
memcpy (ptr, &fpr, sizeof (fpr));
stun_debug (" Message HMAC-SHA1 fingerprint: ");
stun_debug_bytes (ptr, 4);
stun_debug ("\n");
}
if (stun_message_get_class (msg) == STUN_REQUEST) {
stun_message_id (msg, agent->sent_ids[saved_id_idx].id);
agent->sent_ids[saved_id_idx].method = stun_message_get_method (msg);
agent->sent_ids[saved_id_idx].key = (uint8_t *) key;
agent->sent_ids[saved_id_idx].key_len = key_len;
memcpy (agent->sent_ids[saved_id_idx].long_term_key, msg->long_term_key,
sizeof(msg->long_term_key));
agent->sent_ids[saved_id_idx].long_term_valid = msg->long_term_valid;
agent->sent_ids[saved_id_idx].valid = TRUE;
}
msg->key = (uint8_t *) key;
msg->key_len = key_len;
return stun_message_length (msg);
}
StunValidationStatus stun_agent_validate (StunAgent *agent, StunMessage *msg,
const uint8_t *buffer, size_t buffer_len,
StunMessageIntegrityValidate validater, void * validater_data)
{
StunTransactionId msg_id;
uint32_t fpr;
uint32_t crc32;
int len;
uint8_t *username = NULL;
uint16_t username_len;
uint8_t *key = NULL;
size_t key_len;
uint8_t *hash;
uint8_t sha[20];
uint16_t hlen;
int sent_id_idx = -1;
uint16_t unknown;
int error_code;
int ignore_credentials = 0;
uint8_t long_term_key[16];
bool long_term_key_valid = FALSE;
len = stun_message_validate_buffer_length (buffer, buffer_len);
if (len == STUN_MESSAGE_BUFFER_INVALID) {
return STUN_VALIDATION_NOT_STUN;
} else if (len == STUN_MESSAGE_BUFFER_INCOMPLETE) {
return STUN_VALIDATION_INCOMPLETE_STUN;
} else if (len != (int) buffer_len) {
return STUN_VALIDATION_NOT_STUN;
}
msg->buffer = (uint8_t *) buffer;
msg->buffer_len = buffer_len;
msg->agent = agent;
msg->key = NULL;
msg->key_len = 0;
msg->long_term_valid = FALSE;
/* TODO: reject it or not ? */
if ((agent->compatibility == STUN_COMPATIBILITY_RFC5389 ||
agent->compatibility == STUN_COMPATIBILITY_WLM2009) &&
!stun_message_has_cookie (msg)) {
stun_debug ("STUN demux error: no cookie!\n");
return STUN_VALIDATION_BAD_REQUEST;
}
if ((agent->compatibility == STUN_COMPATIBILITY_RFC5389 ||
agent->compatibility == STUN_COMPATIBILITY_WLM2009) &&
agent->usage_flags & STUN_AGENT_USAGE_USE_FINGERPRINT) {
/* Looks for FINGERPRINT */
if (stun_message_find32 (msg, STUN_ATTRIBUTE_FINGERPRINT, &fpr) !=
STUN_MESSAGE_RETURN_SUCCESS) {
stun_debug ("STUN demux error: no FINGERPRINT attribute!\n");
return STUN_VALIDATION_BAD_REQUEST;
}
/* Checks FINGERPRINT */
crc32 = stun_fingerprint (msg->buffer, stun_message_length (msg),
agent->compatibility == STUN_COMPATIBILITY_WLM2009);
fpr = ntohl (fpr);
if (fpr != crc32) {
stun_debug ("STUN demux error: bad fingerprint: 0x%08x,"
" expected: 0x%08x!\n", fpr, crc32);
return STUN_VALIDATION_BAD_REQUEST;
}
stun_debug ("STUN demux: OK!\n");
}
if (stun_message_get_class (msg) == STUN_RESPONSE ||
stun_message_get_class (msg) == STUN_ERROR) {
stun_message_id (msg, msg_id);
for (sent_id_idx = 0; sent_id_idx < STUN_AGENT_MAX_SAVED_IDS; sent_id_idx++) {
if (agent->sent_ids[sent_id_idx].valid == TRUE &&
agent->sent_ids[sent_id_idx].method == stun_message_get_method (msg) &&
memcmp (msg_id, agent->sent_ids[sent_id_idx].id,
sizeof(StunTransactionId)) == 0) {
key = agent->sent_ids[sent_id_idx].key;
key_len = agent->sent_ids[sent_id_idx].key_len;
memcpy (long_term_key, agent->sent_ids[sent_id_idx].long_term_key,
sizeof(long_term_key));
long_term_key_valid = agent->sent_ids[sent_id_idx].long_term_valid;
break;
}
}
if (sent_id_idx == STUN_AGENT_MAX_SAVED_IDS) {
return STUN_VALIDATION_UNMATCHED_RESPONSE;
}
}
ignore_credentials =
(agent->usage_flags & STUN_AGENT_USAGE_IGNORE_CREDENTIALS) ||
(stun_message_get_class (msg) == STUN_ERROR &&
stun_message_find_error (msg, &error_code) ==
STUN_MESSAGE_RETURN_SUCCESS &&
(error_code == 400 || error_code == 401)) ||
(stun_message_get_class (msg) == STUN_INDICATION &&
(agent->usage_flags & STUN_AGENT_USAGE_NO_INDICATION_AUTH));
if (key == NULL &&
ignore_credentials == 0 &&
(stun_message_get_class (msg) == STUN_REQUEST ||
stun_message_get_class (msg) == STUN_INDICATION) &&
(((agent->usage_flags & STUN_AGENT_USAGE_SHORT_TERM_CREDENTIALS) &&
(!stun_message_has_attribute (msg, STUN_ATTRIBUTE_USERNAME) ||
!stun_message_has_attribute (msg, STUN_ATTRIBUTE_MESSAGE_INTEGRITY))) ||
((agent->usage_flags & STUN_AGENT_USAGE_LONG_TERM_CREDENTIALS) &&
stun_message_get_class (msg) == STUN_REQUEST &&
(!stun_message_has_attribute (msg, STUN_ATTRIBUTE_USERNAME) ||
!stun_message_has_attribute (msg, STUN_ATTRIBUTE_MESSAGE_INTEGRITY) ||
!stun_message_has_attribute (msg, STUN_ATTRIBUTE_NONCE) ||
!stun_message_has_attribute (msg, STUN_ATTRIBUTE_REALM))) ||
((agent->usage_flags & STUN_AGENT_USAGE_IGNORE_CREDENTIALS) == 0 &&
stun_message_has_attribute (msg, STUN_ATTRIBUTE_USERNAME) &&
!stun_message_has_attribute (msg, STUN_ATTRIBUTE_MESSAGE_INTEGRITY)))) {
return STUN_VALIDATION_UNAUTHORIZED_BAD_REQUEST;
}
if (stun_message_has_attribute (msg, STUN_ATTRIBUTE_MESSAGE_INTEGRITY) &&
((key == NULL && ignore_credentials == 0) ||
(agent->usage_flags & STUN_AGENT_USAGE_FORCE_VALIDATER))) {
username_len = 0;
username = (uint8_t *) stun_message_find (msg, STUN_ATTRIBUTE_USERNAME,
&username_len);
if (validater == NULL ||
validater (agent, msg, username, username_len,
&key, &key_len, validater_data) == FALSE) {
return STUN_VALIDATION_UNAUTHORIZED;
}
}
if (ignore_credentials == 0 && key != NULL && key_len > 0) {
hash = (uint8_t *) stun_message_find (msg,
STUN_ATTRIBUTE_MESSAGE_INTEGRITY, &hlen);
if (hash) {
/* We must give the size from start to the end of the attribute
because you might have a FINGERPRINT attribute after it... */
if (agent->usage_flags & STUN_AGENT_USAGE_LONG_TERM_CREDENTIALS) {
uint8_t *realm = NULL;
uint8_t *username = NULL;
uint16_t realm_len;
uint16_t username_len;
uint8_t md5[16];
if (long_term_key_valid) {
memcpy (md5, long_term_key, sizeof (md5));
} else {
realm = (uint8_t *) stun_message_find (msg, STUN_ATTRIBUTE_REALM, &realm_len);
username = (uint8_t *) stun_message_find (msg,
STUN_ATTRIBUTE_USERNAME, &username_len);
if (username == NULL || realm == NULL) {
return STUN_VALIDATION_UNAUTHORIZED;
}
stun_hash_creds (realm, realm_len,
username, username_len,
key, key_len, md5);
}
memcpy (msg->long_term_key, md5, sizeof(md5));
msg->long_term_valid = TRUE;
if (agent->compatibility == STUN_COMPATIBILITY_RFC3489) {
stun_sha1 (msg->buffer, hash + 20 - msg->buffer, hash - msg->buffer,
sha, md5, sizeof(md5), TRUE);
} else if (agent->compatibility == STUN_COMPATIBILITY_WLM2009) {
stun_sha1 (msg->buffer, hash + 20 - msg->buffer,
stun_message_length (msg) - 20, sha, md5, sizeof(md5), TRUE);
} else {
stun_sha1 (msg->buffer, hash + 20 - msg->buffer,
hash - msg->buffer, sha, md5, sizeof(md5), FALSE);
}
} else {
if (agent->compatibility == STUN_COMPATIBILITY_RFC3489) {
stun_sha1 (msg->buffer, hash + 20 - msg->buffer, hash - msg->buffer,
sha, key, key_len, TRUE);
} else if (agent->compatibility == STUN_COMPATIBILITY_WLM2009) {
stun_sha1 (msg->buffer, hash + 20 - msg->buffer,
stun_message_length (msg) - 20, sha, key, key_len, TRUE);
} else {
stun_sha1 (msg->buffer, hash + 20 - msg->buffer,
hash - msg->buffer, sha, key, key_len, FALSE);
}
}
stun_debug (" Message HMAC-SHA1 fingerprint:");
stun_debug ("\nkey : ");
stun_debug_bytes (key, key_len);
stun_debug ("\n expected: ");
stun_debug_bytes (sha, sizeof (sha));
stun_debug ("\n received: ");
stun_debug_bytes (hash, sizeof (sha));
stun_debug ("\n");
if (memcmp (sha, hash, sizeof (sha))) {
stun_debug ("STUN auth error: SHA1 fingerprint mismatch!\n");
return STUN_VALIDATION_UNAUTHORIZED;
}
stun_debug ("STUN auth: OK!\n");
msg->key = key;
msg->key_len = key_len;
} else if (!(stun_message_get_class (msg) == STUN_ERROR &&
stun_message_find_error (msg, &error_code) ==
STUN_MESSAGE_RETURN_SUCCESS &&
(error_code == 400 || error_code == 401))) {
stun_debug ("STUN auth error: No message integrity attribute!\n");
return STUN_VALIDATION_UNAUTHORIZED;
}
}
if (sent_id_idx != -1 && sent_id_idx < STUN_AGENT_MAX_SAVED_IDS) {
agent->sent_ids[sent_id_idx].valid = FALSE;
}
if (stun_agent_find_unknowns (agent, msg, &unknown, 1) > 0) {
if (stun_message_get_class (msg) == STUN_REQUEST)
return STUN_VALIDATION_UNKNOWN_REQUEST_ATTRIBUTE;
else
return STUN_VALIDATION_UNKNOWN_ATTRIBUTE;
}
return STUN_VALIDATION_SUCCESS;
}
size_t stun_agent_finish_message (StunAgent *agent, StunMessage *msg,
const uint8_t *key, size_t key_len)
{
uint8_t *ptr;
uint32_t fpr;
int saved_id_idx = 0;
uint8_t md5[16];
bool remember_transaction;
remember_transaction = (stun_message_get_class (msg) == STUN_REQUEST);
if (agent->compatibility == STUN_COMPATIBILITY_OC2007 &&
stun_message_get_method (msg) == STUN_SEND) {
/* As per [MS-TURN] Section 2.2.1, the TURN server doesn't send responses to
* STUN_SEND requests, so don't bother waiting for them. More details at
* https://msdn.microsoft.com/en-us/library/dd946797%28v=office.12%29.aspx.
*/
remember_transaction = FALSE;
}
if (remember_transaction) {
for (saved_id_idx = 0; saved_id_idx < STUN_AGENT_MAX_SAVED_IDS; saved_id_idx++) {
if (agent->sent_ids[saved_id_idx].valid == FALSE) {
break;
}
}
}
if (saved_id_idx == STUN_AGENT_MAX_SAVED_IDS) {
stun_debug ("WARNING: Saved IDs full. STUN message dropped.");
return 0;
}
if (msg->key != NULL) {
key = msg->key;
key_len = msg->key_len;
}
if (key != NULL) {
bool skip = FALSE;
if (msg->long_term_valid) {
memcpy (md5, msg->long_term_key, sizeof(msg->long_term_key));
} else if (agent->usage_flags & STUN_AGENT_USAGE_LONG_TERM_CREDENTIALS) {
uint8_t *realm = NULL;
uint8_t *username = NULL;
uint16_t realm_len;
uint16_t username_len;
realm = (uint8_t *) stun_message_find (msg,
STUN_ATTRIBUTE_REALM, &realm_len);
username = (uint8_t *) stun_message_find (msg,
STUN_ATTRIBUTE_USERNAME, &username_len);
if (username == NULL || realm == NULL) {
skip = TRUE;
} else {
stun_hash_creds (realm, realm_len,
username, username_len,
key, key_len, md5);
memcpy (msg->long_term_key, md5, sizeof(msg->long_term_key));
msg->long_term_valid = TRUE;
}
}
/* If no realm/username and long term credentials,
then don't send the message integrity */
if (skip == FALSE) {
ptr = stun_message_append (msg, STUN_ATTRIBUTE_MESSAGE_INTEGRITY, 20);
if (ptr == NULL) {
return 0;
}
if (agent->usage_flags & STUN_AGENT_USAGE_LONG_TERM_CREDENTIALS) {
if (agent->compatibility == STUN_COMPATIBILITY_RFC3489 ||
agent->compatibility == STUN_COMPATIBILITY_OC2007) {
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - 20, ptr, md5, sizeof(md5), TRUE);
} else if (agent->compatibility == STUN_COMPATIBILITY_WLM2009) {
size_t minus = 20;
if (agent->usage_flags & STUN_AGENT_USAGE_USE_FINGERPRINT)
minus -= 8;
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - minus, ptr, md5, sizeof(md5), TRUE);
} else {
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - 20, ptr, md5, sizeof(md5), FALSE);
}
} else {
if (agent->compatibility == STUN_COMPATIBILITY_RFC3489 ||
agent->compatibility == STUN_COMPATIBILITY_OC2007) {
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - 20, ptr, key, key_len, TRUE);
} else if (agent->compatibility == STUN_COMPATIBILITY_WLM2009) {
size_t minus = 20;
if (agent->usage_flags & STUN_AGENT_USAGE_USE_FINGERPRINT)
minus -= 8;
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - minus, ptr, key, key_len, TRUE);
} else {
stun_sha1 (msg->buffer, stun_message_length (msg),
stun_message_length (msg) - 20, ptr, key, key_len, FALSE);
}
}
stun_debug (" Message HMAC-SHA1 message integrity:");
stun_debug_bytes (" key : ", key, key_len);
stun_debug_bytes (" sent : ", ptr, 20);
}
}
if ((agent->compatibility == STUN_COMPATIBILITY_RFC5389 ||
agent->compatibility == STUN_COMPATIBILITY_WLM2009) &&
agent->usage_flags & STUN_AGENT_USAGE_USE_FINGERPRINT) {
ptr = stun_message_append (msg, STUN_ATTRIBUTE_FINGERPRINT, 4);
if (ptr == NULL) {
return 0;
}
fpr = stun_fingerprint (msg->buffer, stun_message_length (msg),
agent->compatibility == STUN_COMPATIBILITY_WLM2009);
memcpy (ptr, &fpr, sizeof (fpr));
stun_debug_bytes (" Message HMAC-SHA1 fingerprint: ", ptr, 4);
}
if (remember_transaction) {
stun_message_id (msg, agent->sent_ids[saved_id_idx].id);
agent->sent_ids[saved_id_idx].method = stun_message_get_method (msg);
agent->sent_ids[saved_id_idx].key = (uint8_t *) key;
agent->sent_ids[saved_id_idx].key_len = key_len;
memcpy (agent->sent_ids[saved_id_idx].long_term_key, msg->long_term_key,
sizeof(msg->long_term_key));
agent->sent_ids[saved_id_idx].long_term_valid = msg->long_term_valid;
agent->sent_ids[saved_id_idx].valid = TRUE;
}
msg->key = (uint8_t *) key;
msg->key_len = key_len;
return stun_message_length (msg);
}