/*
sptps.c -- Simple Peer-to-Peer Security
- Copyright (C) 2014 Guus Sliepen <guus@meshlink.io>
+ Copyright (C) 2014-2017 Guus Sliepen <guus@meshlink.io>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include "prf.h"
#include "sptps.h"
-unsigned int sptps_replaywin = 16;
+unsigned int sptps_replaywin = 32;
/*
Nonce MUST be exchanged first (done)
*/
void sptps_log_quiet(sptps_t *s, int s_errno, const char *format, va_list ap) {
+ (void)s;
+ (void)s_errno;
+ (void)format;
+ (void)ap;
}
void sptps_log_stderr(sptps_t *s, int s_errno, const char *format, va_list ap) {
+ (void)s;
+ (void)s_errno;
vfprintf(stderr, format, ap);
fputc('\n', stderr);
}
}
// 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)
memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
// Sign the result.
- if(!ecdsa_sign(s->mykey, msg, sizeof msg, sig))
+ if(!ecdsa_sign(s->mykey, msg, sizeof(msg), sig))
return error(s, EINVAL, "Failed to sign SIG record");
// Send the SIG exchange record.
- return send_record_priv(s, SPTPS_HANDSHAKE, sig, sizeof sig);
+ return send_record_priv(s, SPTPS_HANDSHAKE, sig, sizeof(sig));
}
// Generate key material from the shared secret created from the ECDHE key exchange.
// Receive an ACKnowledgement record.
static bool receive_ack(sptps_t *s, const char *data, uint16_t len) {
+ (void)data;
if(len)
return error(s, EIO, "Invalid ACK record length");
memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
// Verify signature.
- if(!ecdsa_verify(s->hiskey, msg, sizeof msg, data))
+ if(!ecdsa_verify(s->hiskey, msg, sizeof(msg), data))
return error(s, EIO, "Failed to verify SIG record");
// Compute shared secret.
s->ecdh = NULL;
// Generate key material from shared secret.
- if(!generate_key_material(s, shared, sizeof shared))
+ if(!generate_key_material(s, shared, sizeof(shared)))
return false;
free(s->mykex);
static bool receive_handshake(sptps_t *s, const char *data, uint16_t len) {
// Only a few states to deal with handshaking.
switch(s->state) {
- case SPTPS_SECONDARY_KEX:
- // We receive a secondary KEX request, first respond by sending our own.
- if(!send_kex(s))
- return false;
- case SPTPS_KEX:
- // We have sent our KEX request, we expect our peer to sent one as well.
- if(!receive_kex(s, data, len))
- return false;
- s->state = SPTPS_SIG;
- return true;
- case SPTPS_SIG:
- // If we already sent our secondary public ECDH key, we expect the peer to send his.
- if(!receive_sig(s, data, len))
- return false;
- 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.
- if(!receive_ack(s, data, len))
+ case SPTPS_SECONDARY_KEX:
+ // We receive a secondary KEX request, first respond by sending our own.
+ if(!send_kex(s))
+ return false;
+ // fallthrough
+ case SPTPS_KEX:
+ // We have sent our KEX request, we expect our peer to sent one as well.
+ if(!receive_kex(s, data, len))
+ return false;
+ s->state = SPTPS_SIG;
+ return true;
+ case SPTPS_SIG:
+ // If we already sent our secondary public ECDH key, we expect the peer to send his.
+ if(!receive_sig(s, data, len))
+ return false;
+ 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;
- // TODO: split ACK into a VERify and ACK?
- default:
- return error(s, EIO, "Invalid session state %d", s->state);
+ }
+
+ return true;
+ case SPTPS_ACK:
+ // We expect a handshake message to indicate transition to the new keys.
+ if(!receive_ack(s, data, len))
+ return false;
+ s->receive_record(s->handle, SPTPS_HANDSHAKE, NULL, 0);
+ s->state = SPTPS_SECONDARY_KEX;
+ return true;
+ // TODO: split ACK into a VERify and ACK?
+ default:
+ return error(s, EIO, "Invalid session state %d", s->state);
}
}
// Check datagram for valid HMAC
-bool sptps_verify_datagram(sptps_t *s, const char *data, size_t len) {
- if(!s->instate || len < 21)
- return error(s, EIO, "Received short packet");
+bool sptps_verify_datagram(sptps_t *s, const void *data, size_t len) {
+ if(!s->instate)
+ return error(s, EIO, "SPTPS state not ready to verify this datagram");
- // TODO: just decrypt without updating the replay window
+ if(len < 21)
+ return error(s, EIO, "Received short packet in sptps_verify_datagram");
- return true;
+ uint32_t seqno;
+ memcpy(&seqno, data, 4);
+ seqno = ntohl(seqno);
+ // TODO: check whether seqno makes sense, to avoid CPU intensive decrypt
+
+ char buffer[len];
+ size_t outlen;
+ return chacha_poly1305_decrypt(s->incipher, seqno, data + 4, len - 4, buffer, &outlen);
}
// Receive incoming data, datagram version.
-static bool sptps_receive_data_datagram(sptps_t *s, const char *data, size_t len) {
+static bool sptps_receive_data_datagram(sptps_t *s, const void *vdata, size_t len) {
+ const char *data = vdata;
+
if(len < (s->instate ? 21 : 5))
- return error(s, EIO, "Received short packet");
+ return error(s, EIO, "Received short packet in sptps_receive_data_datagram");
uint32_t seqno;
memcpy(&seqno, data, 4);
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) {
+ } 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++)
+ for(uint32_t i = s->inseqno; i < seqno; i++)
s->late[(i / 8) % s->replaywin] |= 1 << i % 8;
}
}
} else if(type == SPTPS_HANDSHAKE) {
if(!receive_handshake(s, buffer + 1, len - 21))
abort();
- } else {
+ } else
return error(s, EIO, "Invalid record type %d", type);
- }
return true;
}
// 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");
} else if(type == SPTPS_HANDSHAKE) {
if(!receive_handshake(s, s->inbuf + 3, s->reclen))
return false;
- } else {
+ } else
return error(s, EIO, "Invalid record type %d", type);
- }
s->buflen = 0;
}
// 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) {
+ if(!s || !mykey || !hiskey || !label || !labellen || !send_data || !receive_record)
+ return error(s, EINVAL, "Invalid argument to sptps_start()");
+
// Initialise struct sptps
- memset(s, 0, sizeof *s);
+ memset(s, 0, sizeof(*s));
s->handle = handle;
s->initiator = initiator;
free(s->key);
free(s->label);
free(s->late);
- memset(s, 0, sizeof *s);
+ memset(s, 0, sizeof(*s));
return true;
}
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