| /* This Source Code Form is subject to the terms of the Mozilla Public |
| * License, v. 2.0. If a copy of the MPL was not distributed with this |
| * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| |
| /* |
| * DTLS Protocol |
| */ |
| |
| #include "ssl.h" |
| #include "sslimpl.h" |
| #include "sslproto.h" |
| |
| #ifndef PR_ARRAY_SIZE |
| #define PR_ARRAY_SIZE(a) (sizeof(a)/sizeof((a)[0])) |
| #endif |
| |
| static SECStatus dtls_TransmitMessageFlight(sslSocket *ss); |
| static void dtls_RetransmitTimerExpiredCb(sslSocket *ss); |
| static SECStatus dtls_SendSavedWriteData(sslSocket *ss); |
| |
| /* -28 adjusts for the IP/UDP header */ |
| static const PRUint16 COMMON_MTU_VALUES[] = { |
| 1500 - 28, /* Ethernet MTU */ |
| 1280 - 28, /* IPv6 minimum MTU */ |
| 576 - 28, /* Common assumption */ |
| 256 - 28 /* We're in serious trouble now */ |
| }; |
| |
| #define DTLS_COOKIE_BYTES 32 |
| |
| /* List copied from ssl3con.c:cipherSuites */ |
| static const ssl3CipherSuite nonDTLSSuites[] = { |
| #ifndef NSS_DISABLE_ECC |
| TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, |
| TLS_ECDHE_RSA_WITH_RC4_128_SHA, |
| #endif /* NSS_DISABLE_ECC */ |
| TLS_DHE_DSS_WITH_RC4_128_SHA, |
| #ifndef NSS_DISABLE_ECC |
| TLS_ECDH_RSA_WITH_RC4_128_SHA, |
| TLS_ECDH_ECDSA_WITH_RC4_128_SHA, |
| #endif /* NSS_DISABLE_ECC */ |
| TLS_RSA_WITH_RC4_128_MD5, |
| TLS_RSA_WITH_RC4_128_SHA, |
| TLS_RSA_EXPORT1024_WITH_RC4_56_SHA, |
| TLS_RSA_EXPORT_WITH_RC4_40_MD5, |
| 0 /* End of list marker */ |
| }; |
| |
| /* Map back and forth between TLS and DTLS versions in wire format. |
| * Mapping table is: |
| * |
| * TLS DTLS |
| * 1.1 (0302) 1.0 (feff) |
| * 1.2 (0303) 1.2 (fefd) |
| * 1.3 (0304) 1.3 (fefc) |
| */ |
| SSL3ProtocolVersion |
| dtls_TLSVersionToDTLSVersion(SSL3ProtocolVersion tlsv) |
| { |
| if (tlsv == SSL_LIBRARY_VERSION_TLS_1_1) { |
| return SSL_LIBRARY_VERSION_DTLS_1_0_WIRE; |
| } |
| if (tlsv == SSL_LIBRARY_VERSION_TLS_1_2) { |
| return SSL_LIBRARY_VERSION_DTLS_1_2_WIRE; |
| } |
| if (tlsv == SSL_LIBRARY_VERSION_TLS_1_3) { |
| return SSL_LIBRARY_VERSION_DTLS_1_3_WIRE; |
| } |
| |
| /* Anything other than TLS 1.1 or 1.2 is an error, so return |
| * the invalid version 0xffff. */ |
| return 0xffff; |
| } |
| |
| /* Map known DTLS versions to known TLS versions. |
| * - Invalid versions (< 1.0) return a version of 0 |
| * - Versions > known return a version one higher than we know of |
| * to accomodate a theoretically newer version */ |
| SSL3ProtocolVersion |
| dtls_DTLSVersionToTLSVersion(SSL3ProtocolVersion dtlsv) |
| { |
| if (MSB(dtlsv) == 0xff) { |
| return 0; |
| } |
| |
| if (dtlsv == SSL_LIBRARY_VERSION_DTLS_1_0_WIRE) { |
| return SSL_LIBRARY_VERSION_TLS_1_1; |
| } |
| if (dtlsv == SSL_LIBRARY_VERSION_DTLS_1_2_WIRE) { |
| return SSL_LIBRARY_VERSION_TLS_1_2; |
| } |
| if (dtlsv == SSL_LIBRARY_VERSION_DTLS_1_3_WIRE) { |
| return SSL_LIBRARY_VERSION_TLS_1_3; |
| } |
| |
| /* Return a fictional higher version than we know of */ |
| return SSL_LIBRARY_VERSION_TLS_1_2 + 1; |
| } |
| |
| /* On this socket, Disable non-DTLS cipher suites in the argument's list */ |
| SECStatus |
| ssl3_DisableNonDTLSSuites(sslSocket * ss) |
| { |
| const ssl3CipherSuite * suite; |
| |
| for (suite = nonDTLSSuites; *suite; ++suite) { |
| PORT_CheckSuccess(ssl3_CipherPrefSet(ss, *suite, PR_FALSE)); |
| } |
| return SECSuccess; |
| } |
| |
| /* Allocate a DTLSQueuedMessage. |
| * |
| * Called from dtls_QueueMessage() |
| */ |
| static DTLSQueuedMessage * |
| dtls_AllocQueuedMessage(PRUint16 epoch, SSL3ContentType type, |
| const unsigned char *data, PRUint32 len) |
| { |
| DTLSQueuedMessage *msg = NULL; |
| |
| msg = PORT_ZAlloc(sizeof(DTLSQueuedMessage)); |
| if (!msg) |
| return NULL; |
| |
| msg->data = PORT_Alloc(len); |
| if (!msg->data) { |
| PORT_Free(msg); |
| return NULL; |
| } |
| PORT_Memcpy(msg->data, data, len); |
| |
| msg->len = len; |
| msg->epoch = epoch; |
| msg->type = type; |
| |
| return msg; |
| } |
| |
| /* |
| * Free a handshake message |
| * |
| * Called from dtls_FreeHandshakeMessages() |
| */ |
| static void |
| dtls_FreeHandshakeMessage(DTLSQueuedMessage *msg) |
| { |
| if (!msg) |
| return; |
| |
| PORT_ZFree(msg->data, msg->len); |
| PORT_Free(msg); |
| } |
| |
| /* |
| * Free a list of handshake messages |
| * |
| * Called from: |
| * dtls_HandleHandshake() |
| * ssl3_DestroySSL3Info() |
| */ |
| void |
| dtls_FreeHandshakeMessages(PRCList *list) |
| { |
| PRCList *cur_p; |
| |
| while (!PR_CLIST_IS_EMPTY(list)) { |
| cur_p = PR_LIST_TAIL(list); |
| PR_REMOVE_LINK(cur_p); |
| dtls_FreeHandshakeMessage((DTLSQueuedMessage *)cur_p); |
| } |
| } |
| |
| /* Called only from ssl3_HandleRecord, for each (deciphered) DTLS record. |
| * origBuf is the decrypted ssl record content and is expected to contain |
| * complete handshake records |
| * Caller must hold the handshake and RecvBuf locks. |
| * |
| * Note that this code uses msg_len for two purposes: |
| * |
| * (1) To pass the length to ssl3_HandleHandshakeMessage() |
| * (2) To carry the length of a message currently being reassembled |
| * |
| * However, unlike ssl3_HandleHandshake(), it is not used to carry |
| * the state of reassembly (i.e., whether one is in progress). That |
| * is carried in recvdHighWater and recvdFragments. |
| */ |
| #define OFFSET_BYTE(o) (o/8) |
| #define OFFSET_MASK(o) (1 << (o%8)) |
| |
| SECStatus |
| dtls_HandleHandshake(sslSocket *ss, sslBuffer *origBuf) |
| { |
| /* XXX OK for now. |
| * This doesn't work properly with asynchronous certificate validation. |
| * because that returns a WOULDBLOCK error. The current DTLS |
| * applications do not need asynchronous validation, but in the |
| * future we will need to add this. |
| */ |
| sslBuffer buf = *origBuf; |
| SECStatus rv = SECSuccess; |
| |
| PORT_Assert(ss->opt.noLocks || ssl_HaveRecvBufLock(ss)); |
| PORT_Assert(ss->opt.noLocks || ssl_HaveSSL3HandshakeLock(ss)); |
| |
| while (buf.len > 0) { |
| PRUint8 type; |
| PRUint32 message_length; |
| PRUint16 message_seq; |
| PRUint32 fragment_offset; |
| PRUint32 fragment_length; |
| PRUint32 offset; |
| |
| if (buf.len < 12) { |
| PORT_SetError(SSL_ERROR_RX_MALFORMED_HANDSHAKE); |
| rv = SECFailure; |
| break; |
| } |
| |
| /* Parse the header */ |
| type = buf.buf[0]; |
| message_length = (buf.buf[1] << 16) | (buf.buf[2] << 8) | buf.buf[3]; |
| message_seq = (buf.buf[4] << 8) | buf.buf[5]; |
| fragment_offset = (buf.buf[6] << 16) | (buf.buf[7] << 8) | buf.buf[8]; |
| fragment_length = (buf.buf[9] << 16) | (buf.buf[10] << 8) | buf.buf[11]; |
| |
| #define MAX_HANDSHAKE_MSG_LEN 0x1ffff /* 128k - 1 */ |
| if (message_length > MAX_HANDSHAKE_MSG_LEN) { |
| (void)ssl3_DecodeError(ss); |
| PORT_SetError(SSL_ERROR_RX_MALFORMED_HANDSHAKE); |
| return SECFailure; |
| } |
| #undef MAX_HANDSHAKE_MSG_LEN |
| |
| buf.buf += 12; |
| buf.len -= 12; |
| |
| /* This fragment must be complete */ |
| if (buf.len < fragment_length) { |
| PORT_SetError(SSL_ERROR_RX_MALFORMED_HANDSHAKE); |
| rv = SECFailure; |
| break; |
| } |
| |
| /* Sanity check the packet contents */ |
| if ((fragment_length + fragment_offset) > message_length) { |
| PORT_SetError(SSL_ERROR_RX_MALFORMED_HANDSHAKE); |
| rv = SECFailure; |
| break; |
| } |
| |
| /* There are three ways we could not be ready for this packet. |
| * |
| * 1. It's a partial next message. |
| * 2. It's a partial or complete message beyond the next |
| * 3. It's a message we've already seen |
| * |
| * If it's the complete next message we accept it right away. |
| * This is the common case for short messages |
| */ |
| if ((message_seq == ss->ssl3.hs.recvMessageSeq) |
| && (fragment_offset == 0) |
| && (fragment_length == message_length)) { |
| /* Complete next message. Process immediately */ |
| ss->ssl3.hs.msg_type = (SSL3HandshakeType)type; |
| ss->ssl3.hs.msg_len = message_length; |
| |
| /* At this point we are advancing our state machine, so |
| * we can free our last flight of messages */ |
| dtls_FreeHandshakeMessages(&ss->ssl3.hs.lastMessageFlight); |
| ss->ssl3.hs.recvdHighWater = -1; |
| dtls_CancelTimer(ss); |
| |
| /* Reset the timer to the initial value if the retry counter |
| * is 0, per Sec. 4.2.4.1 */ |
| if (ss->ssl3.hs.rtRetries == 0) { |
| ss->ssl3.hs.rtTimeoutMs = INITIAL_DTLS_TIMEOUT_MS; |
| } |
| |
| rv = ssl3_HandleHandshakeMessage(ss, buf.buf, ss->ssl3.hs.msg_len); |
| if (rv == SECFailure) { |
| /* Do not attempt to process rest of messages in this record */ |
| break; |
| } |
| } else { |
| if (message_seq < ss->ssl3.hs.recvMessageSeq) { |
| /* Case 3: we do an immediate retransmit if we're |
| * in a waiting state*/ |
| if (ss->ssl3.hs.rtTimerCb == NULL) { |
| /* Ignore */ |
| } else if (ss->ssl3.hs.rtTimerCb == |
| dtls_RetransmitTimerExpiredCb) { |
| SSL_TRC(30, ("%d: SSL3[%d]: Retransmit detected", |
| SSL_GETPID(), ss->fd)); |
| /* Check to see if we retransmitted recently. If so, |
| * suppress the triggered retransmit. This avoids |
| * retransmit wars after packet loss. |
| * This is not in RFC 5346 but should be |
| */ |
| if ((PR_IntervalNow() - ss->ssl3.hs.rtTimerStarted) > |
| (ss->ssl3.hs.rtTimeoutMs / 4)) { |
| SSL_TRC(30, |
| ("%d: SSL3[%d]: Shortcutting retransmit timer", |
| SSL_GETPID(), ss->fd)); |
| |
| /* Cancel the timer and call the CB, |
| * which re-arms the timer */ |
| dtls_CancelTimer(ss); |
| dtls_RetransmitTimerExpiredCb(ss); |
| rv = SECSuccess; |
| break; |
| } else { |
| SSL_TRC(30, |
| ("%d: SSL3[%d]: We just retransmitted. Ignoring.", |
| SSL_GETPID(), ss->fd)); |
| rv = SECSuccess; |
| break; |
| } |
| } else if (ss->ssl3.hs.rtTimerCb == dtls_FinishedTimerCb) { |
| /* Retransmit the messages and re-arm the timer |
| * Note that we are not backing off the timer here. |
| * The spec isn't clear and my reasoning is that this |
| * may be a re-ordered packet rather than slowness, |
| * so let's be aggressive. */ |
| dtls_CancelTimer(ss); |
| rv = dtls_TransmitMessageFlight(ss); |
| if (rv == SECSuccess) { |
| rv = dtls_StartTimer(ss, dtls_FinishedTimerCb); |
| } |
| if (rv != SECSuccess) |
| return rv; |
| break; |
| } |
| } else if (message_seq > ss->ssl3.hs.recvMessageSeq) { |
| /* Case 2 |
| * |
| * Ignore this message. This means we don't handle out of |
| * order complete messages that well, but we're still |
| * compliant and this probably does not happen often |
| * |
| * XXX OK for now. Maybe do something smarter at some point? |
| */ |
| } else { |
| /* Case 1 |
| * |
| * Buffer the fragment for reassembly |
| */ |
| /* Make room for the message */ |
| if (ss->ssl3.hs.recvdHighWater == -1) { |
| PRUint32 map_length = OFFSET_BYTE(message_length) + 1; |
| |
| rv = sslBuffer_Grow(&ss->ssl3.hs.msg_body, message_length); |
| if (rv != SECSuccess) |
| break; |
| /* Make room for the fragment map */ |
| rv = sslBuffer_Grow(&ss->ssl3.hs.recvdFragments, |
| map_length); |
| if (rv != SECSuccess) |
| break; |
| |
| /* Reset the reassembly map */ |
| ss->ssl3.hs.recvdHighWater = 0; |
| PORT_Memset(ss->ssl3.hs.recvdFragments.buf, 0, |
| ss->ssl3.hs.recvdFragments.space); |
| ss->ssl3.hs.msg_type = (SSL3HandshakeType)type; |
| ss->ssl3.hs.msg_len = message_length; |
| } |
| |
| /* If we have a message length mismatch, abandon the reassembly |
| * in progress and hope that the next retransmit will give us |
| * something sane |
| */ |
| if (message_length != ss->ssl3.hs.msg_len) { |
| ss->ssl3.hs.recvdHighWater = -1; |
| PORT_SetError(SSL_ERROR_RX_MALFORMED_HANDSHAKE); |
| rv = SECFailure; |
| break; |
| } |
| |
| /* Now copy this fragment into the buffer */ |
| PORT_Assert((fragment_offset + fragment_length) <= |
| ss->ssl3.hs.msg_body.space); |
| PORT_Memcpy(ss->ssl3.hs.msg_body.buf + fragment_offset, |
| buf.buf, fragment_length); |
| |
| /* This logic is a bit tricky. We have two values for |
| * reassembly state: |
| * |
| * - recvdHighWater contains the highest contiguous number of |
| * bytes received |
| * - recvdFragments contains a bitmask of packets received |
| * above recvdHighWater |
| * |
| * This avoids having to fill in the bitmask in the common |
| * case of adjacent fragments received in sequence |
| */ |
| if (fragment_offset <= (unsigned int)ss->ssl3.hs.recvdHighWater) { |
| /* Either this is the adjacent fragment or an overlapping |
| * fragment */ |
| ss->ssl3.hs.recvdHighWater = fragment_offset + |
| fragment_length; |
| } else { |
| for (offset = fragment_offset; |
| offset < fragment_offset + fragment_length; |
| offset++) { |
| ss->ssl3.hs.recvdFragments.buf[OFFSET_BYTE(offset)] |= |
| OFFSET_MASK(offset); |
| } |
| } |
| |
| /* Now figure out the new high water mark if appropriate */ |
| for (offset = ss->ssl3.hs.recvdHighWater; |
| offset < ss->ssl3.hs.msg_len; offset++) { |
| /* Note that this loop is not efficient, since it counts |
| * bit by bit. If we have a lot of out-of-order packets, |
| * we should optimize this */ |
| if (ss->ssl3.hs.recvdFragments.buf[OFFSET_BYTE(offset)] & |
| OFFSET_MASK(offset)) { |
| ss->ssl3.hs.recvdHighWater++; |
| } else { |
| break; |
| } |
| } |
| |
| /* If we have all the bytes, then we are good to go */ |
| if (ss->ssl3.hs.recvdHighWater == ss->ssl3.hs.msg_len) { |
| ss->ssl3.hs.recvdHighWater = -1; |
| |
| rv = ssl3_HandleHandshakeMessage(ss, |
| ss->ssl3.hs.msg_body.buf, |
| ss->ssl3.hs.msg_len); |
| if (rv == SECFailure) |
| break; /* Skip rest of record */ |
| |
| /* At this point we are advancing our state machine, so |
| * we can free our last flight of messages */ |
| dtls_FreeHandshakeMessages(&ss->ssl3.hs.lastMessageFlight); |
| dtls_CancelTimer(ss); |
| |
| /* If there have been no retries this time, reset the |
| * timer value to the default per Section 4.2.4.1 */ |
| if (ss->ssl3.hs.rtRetries == 0) { |
| ss->ssl3.hs.rtTimeoutMs = INITIAL_DTLS_TIMEOUT_MS; |
| } |
| } |
| } |
| } |
| |
| buf.buf += fragment_length; |
| buf.len -= fragment_length; |
| } |
| |
| origBuf->len = 0; /* So ssl3_GatherAppDataRecord will keep looping. */ |
| |
| /* XXX OK for now. In future handle rv == SECWouldBlock safely in order |
| * to deal with asynchronous certificate verification */ |
| return rv; |
| } |
| |
| /* Enqueue a message (either handshake or CCS) |
| * |
| * Called from: |
| * dtls_StageHandshakeMessage() |
| * ssl3_SendChangeCipherSpecs() |
| */ |
| SECStatus dtls_QueueMessage(sslSocket *ss, SSL3ContentType type, |
| const SSL3Opaque *pIn, PRInt32 nIn) |
| { |
| SECStatus rv = SECSuccess; |
| DTLSQueuedMessage *msg = NULL; |
| |
| PORT_Assert(ss->opt.noLocks || ssl_HaveSSL3HandshakeLock(ss)); |
| PORT_Assert(ss->opt.noLocks || ssl_HaveXmitBufLock(ss)); |
| |
| msg = dtls_AllocQueuedMessage(ss->ssl3.cwSpec->epoch, type, pIn, nIn); |
| |
| if (!msg) { |
| PORT_SetError(SEC_ERROR_NO_MEMORY); |
| rv = SECFailure; |
| } else { |
| PR_APPEND_LINK(&msg->link, &ss->ssl3.hs.lastMessageFlight); |
| } |
| |
| return rv; |
| } |
| |
| /* Add DTLS handshake message to the pending queue |
| * Empty the sendBuf buffer. |
| * This function returns SECSuccess or SECFailure, never SECWouldBlock. |
| * Always set sendBuf.len to 0, even when returning SECFailure. |
| * |
| * Called from: |
| * ssl3_AppendHandshakeHeader() |
| * dtls_FlushHandshake() |
| */ |
| SECStatus |
| dtls_StageHandshakeMessage(sslSocket *ss) |
| { |
| SECStatus rv = SECSuccess; |
| |
| PORT_Assert(ss->opt.noLocks || ssl_HaveSSL3HandshakeLock(ss)); |
| PORT_Assert(ss->opt.noLocks || ssl_HaveXmitBufLock(ss)); |
| |
| /* This function is sometimes called when no data is actually to |
| * be staged, so just return SECSuccess. */ |
| if (!ss->sec.ci.sendBuf.buf || !ss->sec.ci.sendBuf.len) |
| return rv; |
| |
| rv = dtls_QueueMessage(ss, content_handshake, |
| ss->sec.ci.sendBuf.buf, ss->sec.ci.sendBuf.len); |
| |
| /* Whether we succeeded or failed, toss the old handshake data. */ |
| ss->sec.ci.sendBuf.len = 0; |
| return rv; |
| } |
| |
| /* Enqueue the handshake message in sendBuf (if any) and then |
| * transmit the resulting flight of handshake messages. |
| * |
| * Called from: |
| * ssl3_FlushHandshake() |
| */ |
| SECStatus |
| dtls_FlushHandshakeMessages(sslSocket *ss, PRInt32 flags) |
| { |
| SECStatus rv = SECSuccess; |
| |
| PORT_Assert(ss->opt.noLocks || ssl_HaveSSL3HandshakeLock(ss)); |
| PORT_Assert(ss->opt.noLocks || ssl_HaveXmitBufLock(ss)); |
| |
| rv = dtls_StageHandshakeMessage(ss); |
| if (rv != SECSuccess) |
| return rv; |
| |
| if (!(flags & ssl_SEND_FLAG_FORCE_INTO_BUFFER)) { |
| rv = dtls_TransmitMessageFlight(ss); |
| if (rv != SECSuccess) |
| return rv; |
| |
| if (!(flags & ssl_SEND_FLAG_NO_RETRANSMIT)) { |
| ss->ssl3.hs.rtRetries = 0; |
| rv = dtls_StartTimer(ss, dtls_RetransmitTimerExpiredCb); |
| } |
| } |
| |
| return rv; |
| } |
| |
| /* The callback for when the retransmit timer expires |
| * |
| * Called from: |
| * dtls_CheckTimer() |
| * dtls_HandleHandshake() |
| */ |
| static void |
| dtls_RetransmitTimerExpiredCb(sslSocket *ss) |
| { |
| SECStatus rv = SECFailure; |
| |
| ss->ssl3.hs.rtRetries++; |
| |
| if (!(ss->ssl3.hs.rtRetries % 3)) { |
| /* If one of the messages was potentially greater than > MTU, |
| * then downgrade. Do this every time we have retransmitted a |
| * message twice, per RFC 6347 Sec. 4.1.1 */ |
| dtls_SetMTU(ss, ss->ssl3.hs.maxMessageSent - 1); |
| } |
| |
| rv = dtls_TransmitMessageFlight(ss); |
| if (rv == SECSuccess) { |
| |
| /* Re-arm the timer */ |
| rv = dtls_RestartTimer(ss, PR_TRUE, dtls_RetransmitTimerExpiredCb); |
| } |
| |
| if (rv == SECFailure) { |
| /* XXX OK for now. In future maybe signal the stack that we couldn't |
| * transmit. For now, let the read handle any real network errors */ |
| } |
| } |
| |
| /* Transmit a flight of handshake messages, stuffing them |
| * into as few records as seems reasonable |
| * |
| * Called from: |
| * dtls_FlushHandshake() |
| * dtls_RetransmitTimerExpiredCb() |
| */ |
| static SECStatus |
| dtls_TransmitMessageFlight(sslSocket *ss) |
| { |
| SECStatus rv = SECSuccess; |
| PRCList *msg_p; |
| PRUint16 room_left = ss->ssl3.mtu; |
| PRInt32 sent; |
| |
| ssl_GetXmitBufLock(ss); |
| ssl_GetSpecReadLock(ss); |
| |
| /* DTLS does not buffer its handshake messages in |
| * ss->pendingBuf, but rather in the lastMessageFlight |
| * structure. This is just a sanity check that |
| * some programming error hasn't inadvertantly |
| * stuffed something in ss->pendingBuf |
| */ |
| PORT_Assert(!ss->pendingBuf.len); |
| for (msg_p = PR_LIST_HEAD(&ss->ssl3.hs.lastMessageFlight); |
| msg_p != &ss->ssl3.hs.lastMessageFlight; |
| msg_p = PR_NEXT_LINK(msg_p)) { |
| DTLSQueuedMessage *msg = (DTLSQueuedMessage *)msg_p; |
| |
| /* The logic here is: |
| * |
| * 1. If this is a message that will not fit into the remaining |
| * space, then flush. |
| * 2. If the message will now fit into the remaining space, |
| * encrypt, buffer, and loop. |
| * 3. If the message will not fit, then fragment. |
| * |
| * At the end of the function, flush. |
| */ |
| if ((msg->len + SSL3_BUFFER_FUDGE) > room_left) { |
| /* The message will not fit into the remaining space, so flush */ |
| rv = dtls_SendSavedWriteData(ss); |
| if (rv != SECSuccess) |
| break; |
| |
| room_left = ss->ssl3.mtu; |
| } |
| |
| if ((msg->len + SSL3_BUFFER_FUDGE) <= room_left) { |
| /* The message will fit, so encrypt and then continue with the |
| * next packet */ |
| sent = ssl3_SendRecord(ss, msg->epoch, msg->type, |
| msg->data, msg->len, |
| ssl_SEND_FLAG_FORCE_INTO_BUFFER | |
| ssl_SEND_FLAG_USE_EPOCH); |
| if (sent != msg->len) { |
| rv = SECFailure; |
| if (sent != -1) { |
| PORT_SetError(SEC_ERROR_LIBRARY_FAILURE); |
| } |
| break; |
| } |
| |
| room_left = ss->ssl3.mtu - ss->pendingBuf.len; |
| } else { |
| /* The message will not fit, so fragment. |
| * |
| * XXX OK for now. Arrange to coalesce the last fragment |
| * of this message with the next message if possible. |
| * That would be more efficient. |
| */ |
| PRUint32 fragment_offset = 0; |
| unsigned char fragment[DTLS_MAX_MTU]; /* >= than largest |
| * plausible MTU */ |
| |
| /* Assert that we have already flushed */ |
| PORT_Assert(room_left == ss->ssl3.mtu); |
| |
| /* Case 3: We now need to fragment this message |
| * DTLS only supports fragmenting handshaking messages */ |
| PORT_Assert(msg->type == content_handshake); |
| |
| /* The headers consume 12 bytes so the smalles possible |
| * message (i.e., an empty one) is 12 bytes |
| */ |
| PORT_Assert(msg->len >= 12); |
| |
| while ((fragment_offset + 12) < msg->len) { |
| PRUint32 fragment_len; |
| const unsigned char *content = msg->data + 12; |
| PRUint32 content_len = msg->len - 12; |
| |
| /* The reason we use 8 here is that that's the length of |
| * the new DTLS data that we add to the header */ |
| fragment_len = PR_MIN((PRUint32)room_left - (SSL3_BUFFER_FUDGE + 8), |
| content_len - fragment_offset); |
| PORT_Assert(fragment_len < DTLS_MAX_MTU - 12); |
| /* Make totally sure that we are within the buffer. |
| * Note that the only way that fragment len could get |
| * adjusted here is if |
| * |
| * (a) we are in release mode so the PORT_Assert is compiled out |
| * (b) either the MTU table is inconsistent with DTLS_MAX_MTU |
| * or ss->ssl3.mtu has become corrupt. |
| */ |
| fragment_len = PR_MIN(fragment_len, DTLS_MAX_MTU - 12); |
| |
| /* Construct an appropriate-sized fragment */ |
| /* Type, length, sequence */ |
| PORT_Memcpy(fragment, msg->data, 6); |
| |
| /* Offset */ |
| fragment[6] = (fragment_offset >> 16) & 0xff; |
| fragment[7] = (fragment_offset >> 8) & 0xff; |
| fragment[8] = (fragment_offset) & 0xff; |
| |
| /* Fragment length */ |
| fragment[9] = (fragment_len >> 16) & 0xff; |
| fragment[10] = (fragment_len >> 8) & 0xff; |
| fragment[11] = (fragment_len) & 0xff; |
| |
| PORT_Memcpy(fragment + 12, content + fragment_offset, |
| fragment_len); |
| |
| /* |
| * Send the record. We do this in two stages |
| * 1. Encrypt |
| */ |
| sent = ssl3_SendRecord(ss, msg->epoch, msg->type, |
| fragment, fragment_len + 12, |
| ssl_SEND_FLAG_FORCE_INTO_BUFFER | |
| ssl_SEND_FLAG_USE_EPOCH); |
| if (sent != (fragment_len + 12)) { |
| rv = SECFailure; |
| if (sent != -1) { |
| PORT_SetError(SEC_ERROR_LIBRARY_FAILURE); |
| } |
| break; |
| } |
| |
| /* 2. Flush */ |
| rv = dtls_SendSavedWriteData(ss); |
| if (rv != SECSuccess) |
| break; |
| |
| fragment_offset += fragment_len; |
| } |
| } |
| } |
| |
| /* Finally, we need to flush */ |
| if (rv == SECSuccess) |
| rv = dtls_SendSavedWriteData(ss); |
| |
| /* Give up the locks */ |
| ssl_ReleaseSpecReadLock(ss); |
| ssl_ReleaseXmitBufLock(ss); |
| |
| return rv; |
| } |
| |
| /* Flush the data in the pendingBuf and update the max message sent |
| * so we can adjust the MTU estimate if we need to. |
| * Wrapper for ssl_SendSavedWriteData. |
| * |
| * Called from dtls_TransmitMessageFlight() |
| */ |
| static |
| SECStatus dtls_SendSavedWriteData(sslSocket *ss) |
| { |
| PRInt32 sent; |
| |
| sent = ssl_SendSavedWriteData(ss); |
| if (sent < 0) |
| return SECFailure; |
| |
| /* We should always have complete writes b/c datagram sockets |
| * don't really block */ |
| if (ss->pendingBuf.len > 0) { |
| ssl_MapLowLevelError(SSL_ERROR_SOCKET_WRITE_FAILURE); |
| return SECFailure; |
| } |
| |
| /* Update the largest message sent so we can adjust the MTU |
| * estimate if necessary */ |
| if (sent > ss->ssl3.hs.maxMessageSent) |
| ss->ssl3.hs.maxMessageSent = sent; |
| |
| return SECSuccess; |
| } |
| |
| /* Compress, MAC, encrypt a DTLS record. Allows specification of |
| * the epoch using epoch value. If use_epoch is PR_TRUE then |
| * we use the provided epoch. If use_epoch is PR_FALSE then |
| * whatever the current value is in effect is used. |
| * |
| * Called from ssl3_SendRecord() |
| */ |
| SECStatus |
| dtls_CompressMACEncryptRecord(sslSocket * ss, |
| DTLSEpoch epoch, |
| PRBool use_epoch, |
| SSL3ContentType type, |
| const SSL3Opaque * pIn, |
| PRUint32 contentLen, |
| sslBuffer * wrBuf) |
| { |
| SECStatus rv = SECFailure; |
| ssl3CipherSpec * cwSpec; |
| |
| ssl_GetSpecReadLock(ss); /********************************/ |
| |
| /* The reason for this switch-hitting code is that we might have |
| * a flight of records spanning an epoch boundary, e.g., |
| * |
| * ClientKeyExchange (epoch = 0) |
| * ChangeCipherSpec (epoch = 0) |
| * Finished (epoch = 1) |
| * |
| * Thus, each record needs a different cipher spec. The information |
| * about which epoch to use is carried with the record. |
| */ |
| if (use_epoch) { |
| if (ss->ssl3.cwSpec->epoch == epoch) |
| cwSpec = ss->ssl3.cwSpec; |
| else if (ss->ssl3.pwSpec->epoch == epoch) |
| cwSpec = ss->ssl3.pwSpec; |
| else |
| cwSpec = NULL; |
| } else { |
| cwSpec = ss->ssl3.cwSpec; |
| } |
| |
| if (cwSpec) { |
| rv = ssl3_CompressMACEncryptRecord(cwSpec, ss->sec.isServer, PR_TRUE, |
| PR_FALSE, type, pIn, contentLen, |
| wrBuf); |
| } else { |
| PR_NOT_REACHED("Couldn't find a cipher spec matching epoch"); |
| PORT_SetError(SEC_ERROR_LIBRARY_FAILURE); |
| } |
| ssl_ReleaseSpecReadLock(ss); /************************************/ |
| |
| return rv; |
| } |
| |
| /* Start a timer |
| * |
| * Called from: |
| * dtls_HandleHandshake() |
| * dtls_FlushHAndshake() |
| * dtls_RestartTimer() |
| */ |
| SECStatus |
| dtls_StartTimer(sslSocket *ss, DTLSTimerCb cb) |
| { |
| PORT_Assert(ss->ssl3.hs.rtTimerCb == NULL); |
| |
| ss->ssl3.hs.rtTimerStarted = PR_IntervalNow(); |
| ss->ssl3.hs.rtTimerCb = cb; |
| |
| return SECSuccess; |
| } |
| |
| /* Restart a timer with optional backoff |
| * |
| * Called from dtls_RetransmitTimerExpiredCb() |
| */ |
| SECStatus |
| dtls_RestartTimer(sslSocket *ss, PRBool backoff, DTLSTimerCb cb) |
| { |
| if (backoff) { |
| ss->ssl3.hs.rtTimeoutMs *= 2; |
| if (ss->ssl3.hs.rtTimeoutMs > MAX_DTLS_TIMEOUT_MS) |
| ss->ssl3.hs.rtTimeoutMs = MAX_DTLS_TIMEOUT_MS; |
| } |
| |
| return dtls_StartTimer(ss, cb); |
| } |
| |
| /* Cancel a pending timer |
| * |
| * Called from: |
| * dtls_HandleHandshake() |
| * dtls_CheckTimer() |
| */ |
| void |
| dtls_CancelTimer(sslSocket *ss) |
| { |
| PORT_Assert(ss->opt.noLocks || ssl_HaveRecvBufLock(ss)); |
| |
| ss->ssl3.hs.rtTimerCb = NULL; |
| } |
| |
| /* Check the pending timer and fire the callback if it expired |
| * |
| * Called from ssl3_GatherCompleteHandshake() |
| */ |
| void |
| dtls_CheckTimer(sslSocket *ss) |
| { |
| if (!ss->ssl3.hs.rtTimerCb) |
| return; |
| |
| if ((PR_IntervalNow() - ss->ssl3.hs.rtTimerStarted) > |
| PR_MillisecondsToInterval(ss->ssl3.hs.rtTimeoutMs)) { |
| /* Timer has expired */ |
| DTLSTimerCb cb = ss->ssl3.hs.rtTimerCb; |
| |
| /* Cancel the timer so that we can call the CB safely */ |
| dtls_CancelTimer(ss); |
| |
| /* Now call the CB */ |
| cb(ss); |
| } |
| } |
| |
| /* The callback to fire when the holddown timer for the Finished |
| * message expires and we can delete it |
| * |
| * Called from dtls_CheckTimer() |
| */ |
| void |
| dtls_FinishedTimerCb(sslSocket *ss) |
| { |
| ssl3_DestroyCipherSpec(ss->ssl3.pwSpec, PR_FALSE); |
| } |
| |
| /* Cancel the Finished hold-down timer and destroy the |
| * pending cipher spec. Note that this means that |
| * successive rehandshakes will fail if the Finished is |
| * lost. |
| * |
| * XXX OK for now. Figure out how to handle the combination |
| * of Finished lost and rehandshake |
| */ |
| void |
| dtls_RehandshakeCleanup(sslSocket *ss) |
| { |
| dtls_CancelTimer(ss); |
| ssl3_DestroyCipherSpec(ss->ssl3.pwSpec, PR_FALSE); |
| ss->ssl3.hs.sendMessageSeq = 0; |
| ss->ssl3.hs.recvMessageSeq = 0; |
| } |
| |
| /* Set the MTU to the next step less than or equal to the |
| * advertised value. Also used to downgrade the MTU by |
| * doing dtls_SetMTU(ss, biggest packet set). |
| * |
| * Passing 0 means set this to the largest MTU known |
| * (effectively resetting the PMTU backoff value). |
| * |
| * Called by: |
| * ssl3_InitState() |
| * dtls_RetransmitTimerExpiredCb() |
| */ |
| void |
| dtls_SetMTU(sslSocket *ss, PRUint16 advertised) |
| { |
| int i; |
| |
| if (advertised == 0) { |
| ss->ssl3.mtu = COMMON_MTU_VALUES[0]; |
| SSL_TRC(30, ("Resetting MTU to %d", ss->ssl3.mtu)); |
| return; |
| } |
| |
| for (i = 0; i < PR_ARRAY_SIZE(COMMON_MTU_VALUES); i++) { |
| if (COMMON_MTU_VALUES[i] <= advertised) { |
| ss->ssl3.mtu = COMMON_MTU_VALUES[i]; |
| SSL_TRC(30, ("Resetting MTU to %d", ss->ssl3.mtu)); |
| return; |
| } |
| } |
| |
| /* Fallback */ |
| ss->ssl3.mtu = COMMON_MTU_VALUES[PR_ARRAY_SIZE(COMMON_MTU_VALUES)-1]; |
| SSL_TRC(30, ("Resetting MTU to %d", ss->ssl3.mtu)); |
| } |
| |
| /* Called from ssl3_HandleHandshakeMessage() when it has deciphered a |
| * DTLS hello_verify_request |
| * Caller must hold Handshake and RecvBuf locks. |
| */ |
| SECStatus |
| dtls_HandleHelloVerifyRequest(sslSocket *ss, SSL3Opaque *b, PRUint32 length) |
| { |
| int errCode = SSL_ERROR_RX_MALFORMED_HELLO_VERIFY_REQUEST; |
| SECStatus rv; |
| PRInt32 temp; |
| SECItem cookie = {siBuffer, NULL, 0}; |
| SSL3AlertDescription desc = illegal_parameter; |
| |
| SSL_TRC(3, ("%d: SSL3[%d]: handle hello_verify_request handshake", |
| SSL_GETPID(), ss->fd)); |
| PORT_Assert(ss->opt.noLocks || ssl_HaveRecvBufLock(ss)); |
| PORT_Assert(ss->opt.noLocks || ssl_HaveSSL3HandshakeLock(ss)); |
| |
| if (ss->ssl3.hs.ws != wait_server_hello) { |
| errCode = SSL_ERROR_RX_UNEXPECTED_HELLO_VERIFY_REQUEST; |
| desc = unexpected_message; |
| goto alert_loser; |
| } |
| |
| /* The version */ |
| temp = ssl3_ConsumeHandshakeNumber(ss, 2, &b, &length); |
| if (temp < 0) { |
| goto loser; /* alert has been sent */ |
| } |
| |
| if (temp != SSL_LIBRARY_VERSION_DTLS_1_0_WIRE && |
| temp != SSL_LIBRARY_VERSION_DTLS_1_2_WIRE) { |
| goto alert_loser; |
| } |
| |
| /* The cookie */ |
| rv = ssl3_ConsumeHandshakeVariable(ss, &cookie, 1, &b, &length); |
| if (rv != SECSuccess) { |
| goto loser; /* alert has been sent */ |
| } |
| if (cookie.len > DTLS_COOKIE_BYTES) { |
| desc = decode_error; |
| goto alert_loser; /* malformed. */ |
| } |
| |
| PORT_Memcpy(ss->ssl3.hs.cookie, cookie.data, cookie.len); |
| ss->ssl3.hs.cookieLen = cookie.len; |
| |
| |
| ssl_GetXmitBufLock(ss); /*******************************/ |
| |
| /* Now re-send the client hello */ |
| rv = ssl3_SendClientHello(ss, PR_TRUE); |
| |
| ssl_ReleaseXmitBufLock(ss); /*******************************/ |
| |
| if (rv == SECSuccess) |
| return rv; |
| |
| alert_loser: |
| (void)SSL3_SendAlert(ss, alert_fatal, desc); |
| |
| loser: |
| errCode = ssl_MapLowLevelError(errCode); |
| return SECFailure; |
| } |
| |
| /* Initialize the DTLS anti-replay window |
| * |
| * Called from: |
| * ssl3_SetupPendingCipherSpec() |
| * ssl3_InitCipherSpec() |
| */ |
| void |
| dtls_InitRecvdRecords(DTLSRecvdRecords *records) |
| { |
| PORT_Memset(records->data, 0, sizeof(records->data)); |
| records->left = 0; |
| records->right = DTLS_RECVD_RECORDS_WINDOW - 1; |
| } |
| |
| /* |
| * Has this DTLS record been received? Return values are: |
| * -1 -- out of range to the left |
| * 0 -- not received yet |
| * 1 -- replay |
| * |
| * Called from: dtls_HandleRecord() |
| */ |
| int |
| dtls_RecordGetRecvd(DTLSRecvdRecords *records, PRUint64 seq) |
| { |
| PRUint64 offset; |
| |
| /* Out of range to the left */ |
| if (seq < records->left) { |
| return -1; |
| } |
| |
| /* Out of range to the right; since we advance the window on |
| * receipt, that means that this packet has not been received |
| * yet */ |
| if (seq > records->right) |
| return 0; |
| |
| offset = seq % DTLS_RECVD_RECORDS_WINDOW; |
| |
| return !!(records->data[offset / 8] & (1 << (offset % 8))); |
| } |
| |
| /* Update the DTLS anti-replay window |
| * |
| * Called from ssl3_HandleRecord() |
| */ |
| void |
| dtls_RecordSetRecvd(DTLSRecvdRecords *records, PRUint64 seq) |
| { |
| PRUint64 offset; |
| |
| if (seq < records->left) |
| return; |
| |
| if (seq > records->right) { |
| PRUint64 new_left; |
| PRUint64 new_right; |
| PRUint64 right; |
| |
| /* Slide to the right; this is the tricky part |
| * |
| * 1. new_top is set to have room for seq, on the |
| * next byte boundary by setting the right 8 |
| * bits of seq |
| * 2. new_left is set to compensate. |
| * 3. Zero all bits between top and new_top. Since |
| * this is a ring, this zeroes everything as-yet |
| * unseen. Because we always operate on byte |
| * boundaries, we can zero one byte at a time |
| */ |
| new_right = seq | 0x07; |
| new_left = (new_right - DTLS_RECVD_RECORDS_WINDOW) + 1; |
| |
| for (right = records->right + 8; right <= new_right; right += 8) { |
| offset = right % DTLS_RECVD_RECORDS_WINDOW; |
| records->data[offset / 8] = 0; |
| } |
| |
| records->right = new_right; |
| records->left = new_left; |
| } |
| |
| offset = seq % DTLS_RECVD_RECORDS_WINDOW; |
| |
| records->data[offset / 8] |= (1 << (offset % 8)); |
| } |
| |
| SECStatus |
| DTLS_GetHandshakeTimeout(PRFileDesc *socket, PRIntervalTime *timeout) |
| { |
| sslSocket * ss = NULL; |
| PRIntervalTime elapsed; |
| PRIntervalTime desired; |
| |
| ss = ssl_FindSocket(socket); |
| |
| if (!ss) |
| return SECFailure; |
| |
| if (!IS_DTLS(ss)) |
| return SECFailure; |
| |
| if (!ss->ssl3.hs.rtTimerCb) |
| return SECFailure; |
| |
| elapsed = PR_IntervalNow() - ss->ssl3.hs.rtTimerStarted; |
| desired = PR_MillisecondsToInterval(ss->ssl3.hs.rtTimeoutMs); |
| if (elapsed > desired) { |
| /* Timer expired */ |
| *timeout = PR_INTERVAL_NO_WAIT; |
| } else { |
| *timeout = desired - elapsed; |
| } |
| |
| return SECSuccess; |
| } |
