X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fsptps.c;h=bdbfb89e61d7de3a64579f67b93c0b4582b5b1d9;hb=d7bf63c63ab397cf3e5ca4a065922364925788e7;hp=5088d65d388e71dfe8ab8ee347b7c40ed9ad20b1;hpb=65d6f023c46ac3a087f59b60762f87c869783f21;p=tinc

diff --git a/src/sptps.c b/src/sptps.c
index 5088d65d..bdbfb89e 100644
--- a/src/sptps.c
+++ b/src/sptps.c
@@ -54,8 +54,41 @@ static bool error(sptps_t *s, int s_errno, const char *msg) {
 	return false;
 }
 
+// Send a record (datagram version, accepts all record types, handles encryption and authentication).
+static bool send_record_priv_datagram(sptps_t *s, uint8_t type, const char *data, uint16_t len) {
+	char buffer[len + 23UL];
+
+	// Create header with sequence number, length and record type
+	uint32_t seqno = htonl(s->outseqno++);
+	uint16_t netlen = htons(len);
+
+	memcpy(buffer, &netlen, 2);
+	memcpy(buffer + 2, &seqno, 4);
+	buffer[6] = type;
+
+	// Add plaintext (TODO: avoid unnecessary copy)
+	memcpy(buffer + 7, data, len);
+
+	if(s->outstate) {
+		// If first handshake has finished, encrypt and HMAC
+		cipher_set_counter(&s->outcipher, &seqno, sizeof seqno);
+		if(!cipher_counter_xor(&s->outcipher, buffer + 6, len + 1UL, buffer + 6))
+			return false;
+
+		if(!digest_create(&s->outdigest, buffer, len + 7UL, buffer + 7UL + len))
+			return false;
+
+		return s->send_data(s->handle, buffer + 2, len + 21UL);
+	} else {
+		// Otherwise send as plaintext
+		return s->send_data(s->handle, buffer + 2, len + 5UL);
+	}
+}
 // Send a record (private version, accepts all record types, handles encryption and authentication).
 static bool send_record_priv(sptps_t *s, uint8_t type, const char *data, uint16_t len) {
+	if(s->datagram)
+		return send_record_priv_datagram(s, type, data, len);
+
 	char buffer[len + 23UL];
 
 	// Create header with sequence number, length and record type
@@ -85,7 +118,7 @@ static bool send_record_priv(sptps_t *s, uint8_t type, const char *data, uint16_
 }
 
 // Send an application record.
-bool send_record(sptps_t *s, uint8_t type, const char *data, uint16_t len) {
+bool sptps_send_record(sptps_t *s, uint8_t type, const char *data, uint16_t len) {
 	// Sanity checks: application cannot send data before handshake is finished,
 	// and only record types 0..127 are allowed.
 	if(!s->outstate)
@@ -102,6 +135,8 @@ static bool send_kex(sptps_t *s) {
 	size_t keylen = ECDH_SIZE;
 
 	// Make room for our KEX message, which we will keep around since send_sig() needs it.
+	if(s->mykex)
+		abort();
 	s->mykex = realloc(s->mykex, 1 + 32 + keylen);
 	if(!s->mykex)
 		return error(s, errno, strerror(errno));
@@ -124,13 +159,14 @@ static bool send_sig(sptps_t *s) {
 	size_t keylen = ECDH_SIZE;
 	size_t siglen = ecdsa_size(&s->mykey);
 
-	// Concatenate both KEX messages, plus tag indicating if it is from the connection originator
-	char msg[(1 + 32 + keylen) * 2 + 1];
+	// Concatenate both KEX messages, plus tag indicating if it is from the connection originator, plus label
+	char msg[(1 + 32 + keylen) * 2 + 1 + s->labellen];
 	char sig[siglen];
 
 	msg[0] = s->initiator;
 	memcpy(msg + 1, s->mykex, 1 + 32 + keylen);
-	memcpy(msg + 2 + 32 + keylen, s->hiskex, 1 + 32 + keylen);
+	memcpy(msg + 1 + 33 + keylen, s->hiskex, 1 + 32 + keylen);
+	memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
 
 	// Sign the result.
 	if(!ecdsa_sign(&s->mykey, msg, sizeof msg, sig))
@@ -219,6 +255,8 @@ static bool receive_kex(sptps_t *s, const char *data, uint16_t len) {
 	// Ignore version number for now.
 
 	// Make a copy of the KEX message, send_sig() and receive_sig() need it
+	if(s->hiskex)
+		abort();
 	s->hiskex = realloc(s->hiskex, len);
 	if(!s->hiskex)
 		return error(s, errno, strerror(errno));
@@ -238,11 +276,12 @@ static bool receive_sig(sptps_t *s, const char *data, uint16_t len) {
 		return error(s, EIO, "Invalid KEX record length");
 
 	// Concatenate both KEX messages, plus tag indicating if it is from the connection originator
-	char msg[(1 + 32 + keylen) * 2 + 1];
+	char msg[(1 + 32 + keylen) * 2 + 1 + s->labellen];
 
 	msg[0] = !s->initiator;
 	memcpy(msg + 1, s->hiskex, 1 + 32 + keylen);
-	memcpy(msg + 2 + 32 + keylen, s->mykex, 1 + 32 + keylen);
+	memcpy(msg + 1 + 33 + keylen, s->mykex, 1 + 32 + keylen);
+	memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
 
 	// Verify signature.
 	if(!ecdsa_verify(&s->hiskey, msg, sizeof msg, data))
@@ -264,7 +303,7 @@ static bool receive_sig(sptps_t *s, const char *data, uint16_t len) {
 	s->hiskex = NULL;
 
 	// Send cipher change record
-	if(!send_ack(s))
+	if(s->outstate && !send_ack(s))
 		return false;
 
 	// TODO: only set new keys after ACK has been set/received
@@ -282,13 +321,11 @@ static bool receive_sig(sptps_t *s, const char *data, uint16_t len) {
 			return false;
 	}
 
-	s->outstate = true;
-
 	return true;
 }
 
 // Force another Key EXchange (for testing purposes).
-bool force_kex(sptps_t *s) {
+bool sptps_force_kex(sptps_t *s) {
 	if(!s->outstate || s->state != SPTPS_SECONDARY_KEX)
 		return error(s, EINVAL, "Cannot force KEX in current state");
 
@@ -315,8 +352,16 @@ static bool receive_handshake(sptps_t *s, const char *data, uint16_t len) {
 			// If we already sent our secondary public ECDH key, we expect the peer to send his.
 			if(!receive_sig(s, data, len))
 				return false;
-			// s->state = SPTPS_ACK;
-			s->state = SPTPS_ACK;
+			if(s->outstate)
+				s->state = SPTPS_ACK;
+			else {
+				s->outstate = true;
+				if(!receive_ack(s, NULL, 0))
+					return false;
+				s->receive_record(s->handle, SPTPS_HANDSHAKE, NULL, 0);
+				s->state = SPTPS_SECONDARY_KEX;
+			}
+
 			return true;
 		case SPTPS_ACK:
 			// We expect a handshake message to indicate transition to the new keys.
@@ -331,8 +376,79 @@ static bool receive_handshake(sptps_t *s, const char *data, uint16_t len) {
 	}
 }
 
+// Receive incoming data, datagram version.
+static bool sptps_receive_data_datagram(sptps_t *s, const char *data, size_t len) {
+	if(len < (s->instate ? 21 : 5))
+		return error(s, EIO, "Received short packet");
+
+	uint32_t seqno;
+	memcpy(&seqno, data, 4);
+	seqno = ntohl(seqno);
+
+	if(!s->instate) {
+		if(seqno != s->inseqno) {
+			fprintf(stderr, "Received invalid packet seqno: %d != %d\n", seqno, s->inseqno);
+			return error(s, EIO, "Invalid packet seqno");
+		}
+
+		s->inseqno = seqno + 1;
+
+		uint8_t type = data[4];
+
+		if(type != SPTPS_HANDSHAKE)
+			return error(s, EIO, "Application record received before handshake finished");
+
+		return receive_handshake(s, data + 5, len - 5);
+	}
+
+	if(seqno < s->inseqno) {
+		fprintf(stderr, "Received late or replayed packet: %d < %d\n", seqno, s->inseqno);
+		return true;
+	}
+
+	if(seqno > s->inseqno)
+		fprintf(stderr, "Missed %d packets\n", seqno - s->inseqno);
+
+	s->inseqno = seqno + 1;
+
+	uint16_t netlen = htons(len - 21);
+
+	char buffer[len + 23];
+
+	memcpy(buffer, &netlen, 2);
+	memcpy(buffer + 2, data, len);
+
+	memcpy(&seqno, buffer + 2, 4);
+
+	// Check HMAC and decrypt.
+	if(!digest_verify(&s->indigest, buffer, len - 14, buffer + len - 14))
+		return error(s, EIO, "Invalid HMAC");
+
+	cipher_set_counter(&s->incipher, &seqno, sizeof seqno);
+	if(!cipher_counter_xor(&s->incipher, buffer + 6, len - 4, buffer + 6))
+		return false;
+
+	// Append a NULL byte for safety.
+	buffer[len - 14] = 0;
+
+	uint8_t type = buffer[6];
+
+	if(type < SPTPS_HANDSHAKE) {
+		if(!s->instate)
+			return error(s, EIO, "Application record received before handshake finished");
+		if(!s->receive_record(s->handle, type, buffer + 7, len - 21))
+			return false;
+	} else {
+		return error(s, EIO, "Invalid record type");
+	}
+
+	return true;
+}
 // Receive incoming data. Check if it contains a complete record, if so, handle it.
-bool receive_data(sptps_t *s, const char *data, size_t len) {
+bool sptps_receive_data(sptps_t *s, const char *data, size_t len) {
+	if(s->datagram)
+		return sptps_receive_data_datagram(s, data, len);
+
 	while(len) {
 		// First read the 2 length bytes.
 		if(s->buflen < 6) {
@@ -422,12 +538,13 @@ bool receive_data(sptps_t *s, const char *data, size_t len) {
 }
 
 // Start a SPTPS session.
-bool start_sptps(sptps_t *s, void *handle, bool initiator, ecdsa_t mykey, ecdsa_t hiskey, const char *label, size_t labellen, send_data_t send_data, receive_record_t receive_record) {
+bool sptps_start(sptps_t *s, void *handle, bool initiator, bool datagram, ecdsa_t mykey, ecdsa_t hiskey, const char *label, size_t labellen, send_data_t send_data, receive_record_t receive_record) {
 	// Initialise struct sptps
 	memset(s, 0, sizeof *s);
 
 	s->handle = handle;
 	s->initiator = initiator;
+	s->datagram = datagram;
 	s->mykey = mykey;
 	s->hiskey = hiskey;
 
@@ -435,11 +552,13 @@ bool start_sptps(sptps_t *s, void *handle, bool initiator, ecdsa_t mykey, ecdsa_
 	if(!s->label)
 		return error(s, errno, strerror(errno));
 
-	s->inbuf = malloc(7);
-	if(!s->inbuf)
-		return error(s, errno, strerror(errno));
-	s->buflen = 4;
-	memset(s->inbuf, 0, 4);
+	if(!datagram) {
+		s->inbuf = malloc(7);
+		if(!s->inbuf)
+			return error(s, errno, strerror(errno));
+		s->buflen = 4;
+		memset(s->inbuf, 0, 4);
+	}
 
 	memcpy(s->label, label, labellen);
 	s->labellen = labellen;
@@ -453,7 +572,7 @@ bool start_sptps(sptps_t *s, void *handle, bool initiator, ecdsa_t mykey, ecdsa_
 }
 
 // Stop a SPTPS session.
-bool stop_sptps(sptps_t *s) {
+bool sptps_stop(sptps_t *s) {
 	// Clean up any resources.
 	ecdh_free(&s->ecdh);
 	free(s->inbuf);