/*
sptps.c -- Simple Peer-to-Peer Security
- Copyright (C) 2011-2013 Guus Sliepen <guus@tinc-vpn.org>,
+ Copyright (C) 2011-2014 Guus Sliepen <guus@tinc-vpn.org>,
2010 Brandon L. Black <blblack@gmail.com>
This program is free software; you can redistribute it and/or modify
}
// 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) {
+static bool send_record_priv_datagram(sptps_t *s, uint8_t type, const void *data, uint16_t len) {
char buffer[len + 21UL];
// Create header with sequence number, length and record type
}
}
// 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) {
+static bool send_record_priv(sptps_t *s, uint8_t type, const void *data, uint16_t len) {
if(s->datagram)
return send_record_priv_datagram(s, type, data, len);
}
// Send an application record.
-bool sptps_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 void *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)
}
}
+static bool sptps_check_seqno(sptps_t *s, uint32_t seqno, bool update_state) {
+ // Replay protection using a sliding window of configurable size.
+ // s->inseqno is expected sequence number
+ // seqno is received sequence number
+ // s->late[] is a circular buffer, a 1 bit means a packet has not been received yet
+ // The circular buffer contains bits for sequence numbers from s->inseqno - s->replaywin * 8 to (but excluding) s->inseqno.
+ if(s->replaywin) {
+ if(seqno != s->inseqno) {
+ if(seqno >= s->inseqno + s->replaywin * 8) {
+ // Prevent packets that jump far ahead of the queue from causing many others to be dropped.
+ bool farfuture = s->farfuture < s->replaywin >> 2;
+ if (update_state)
+ s->farfuture++;
+ if(farfuture)
+ return error(s, EIO, "Packet is %d seqs in the future, dropped (%u)\n", seqno - s->inseqno, s->farfuture);
+
+ // Unless we have seen lots of them, in which case we consider the others lost.
+ warning(s, "Lost %d packets\n", seqno - s->inseqno);
+ if (update_state) {
+ // Mark all packets in the replay window as being late.
+ memset(s->late, 255, s->replaywin);
+ }
+ } else if (seqno < s->inseqno) {
+ // If the sequence number is farther in the past than the bitmap goes, or if the packet was already received, drop it.
+ if((s->inseqno >= s->replaywin * 8 && seqno < s->inseqno - s->replaywin * 8) || !(s->late[(seqno / 8) % s->replaywin] & (1 << seqno % 8)))
+ return error(s, EIO, "Received late or replayed packet, seqno %d, last received %d\n", seqno, s->inseqno);
+ } else if (update_state) {
+ // We missed some packets. Mark them in the bitmap as being late.
+ for(int i = s->inseqno; i < seqno; i++)
+ s->late[(i / 8) % s->replaywin] |= 1 << i % 8;
+ }
+ }
+
+ if (update_state) {
+ // Mark the current packet as not being late.
+ s->late[(seqno / 8) % s->replaywin] &= ~(1 << seqno % 8);
+ s->farfuture = 0;
+ }
+ }
+
+ if (update_state) {
+ if(seqno >= s->inseqno)
+ s->inseqno = seqno + 1;
+
+ if(!s->inseqno)
+ s->received = 0;
+ else
+ s->received++;
+ }
+
+ return true;
+}
+
// Check datagram for valid HMAC
-bool sptps_verify_datagram(sptps_t *s, const char *data, size_t len) {
+bool sptps_verify_datagram(sptps_t *s, const void *data, size_t len) {
if(!s->instate || len < 21)
return error(s, EIO, "Received short packet");
- // TODO: just decrypt without updating the replay window
+ uint32_t seqno;
+ memcpy(&seqno, data, 4);
+ seqno = ntohl(seqno);
+ if (!sptps_check_seqno(s, seqno, false))
+ return false;
- return true;
+ char buffer[len];
+ size_t outlen;
+ return chacha_poly1305_decrypt(s->incipher, seqno, data + 4, len - 4, buffer, &outlen);
}
// Receive incoming data, datagram version.
if(!chacha_poly1305_decrypt(s->incipher, seqno, data + 4, len - 4, buffer, &outlen))
return error(s, EIO, "Failed to decrypt and verify packet");
- // Replay protection using a sliding window of configurable size.
- // s->inseqno is expected sequence number
- // seqno is received sequence number
- // s->late[] is a circular buffer, a 1 bit means a packet has not been received yet
- // The circular buffer contains bits for sequence numbers from s->inseqno - s->replaywin * 8 to (but excluding) s->inseqno.
- if(s->replaywin) {
- if(seqno != s->inseqno) {
- if(seqno >= s->inseqno + s->replaywin * 8) {
- // Prevent packets that jump far ahead of the queue from causing many others to be dropped.
- if(s->farfuture++ < s->replaywin >> 2)
- return error(s, EIO, "Packet is %d seqs in the future, dropped (%u)\n", seqno - s->inseqno, s->farfuture);
-
- // Unless we have seen lots of them, in which case we consider the others lost.
- warning(s, "Lost %d packets\n", seqno - s->inseqno);
- // Mark all packets in the replay window as being late.
- memset(s->late, 255, s->replaywin);
- } else if (seqno < s->inseqno) {
- // If the sequence number is farther in the past than the bitmap goes, or if the packet was already received, drop it.
- if((s->inseqno >= s->replaywin * 8 && seqno < s->inseqno - s->replaywin * 8) || !(s->late[(seqno / 8) % s->replaywin] & (1 << seqno % 8)))
- return error(s, EIO, "Received late or replayed packet, seqno %d, last received %d\n", seqno, s->inseqno);
- } else {
- // We missed some packets. Mark them in the bitmap as being late.
- for(int i = s->inseqno; i < seqno; i++)
- s->late[(i / 8) % s->replaywin] |= 1 << i % 8;
- }
- }
-
- // Mark the current packet as not being late.
- s->late[(seqno / 8) % s->replaywin] &= ~(1 << seqno % 8);
- s->farfuture = 0;
- }
-
- if(seqno >= s->inseqno)
- s->inseqno = seqno + 1;
-
- if(!s->inseqno)
- s->received = 0;
- else
- s->received++;
+ if(!sptps_check_seqno(s, seqno, true))
+ return false;
// Append a NULL byte for safety.
buffer[len - 20] = 0;
if(!s->instate)
return error(s, EIO, "Application record received before handshake finished");
if(!s->receive_record(s->handle, type, buffer + 1, len - 21))
- abort();
+ return false;
} else if(type == SPTPS_HANDSHAKE) {
if(!receive_handshake(s, buffer + 1, len - 21))
- abort();
+ return false;
} else {
return error(s, EIO, "Invalid record type %d", type);
}
}
// Receive incoming data. Check if it contains a complete record, if so, handle it.
-bool sptps_receive_data(sptps_t *s, const char *data, size_t len) {
+bool sptps_receive_data(sptps_t *s, const void *data, size_t len) {
if(!s->state)
return error(s, EIO, "Invalid session state zero");
}
// Start a SPTPS session.
-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) {
+bool sptps_start(sptps_t *s, void *handle, bool initiator, bool datagram, ecdsa_t *mykey, ecdsa_t *hiskey, const void *label, size_t labellen, send_data_t send_data, receive_record_t receive_record) {
// Initialise struct sptps
memset(s, 0, sizeof *s);
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