/*
sptps.c -- Simple Peer-to-Peer Security
- Copyright (C) 2011 Guus Sliepen <guus@tinc-vpn.org>,
+ Copyright (C) 2011-2015 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
it under the terms of the GNU General Public License as published by
#include "system.h"
-#include "cipher.h"
+#include "chacha-poly1305/chacha-poly1305.h"
#include "crypto.h"
-#include "digest.h"
#include "ecdh.h"
#include "ecdsa.h"
+#include "logger.h"
#include "prf.h"
#include "sptps.h"
-char *logfilename;
-#include "utils.c"
+unsigned int sptps_replaywin = 16;
+
+/*
+ Nonce MUST be exchanged first (done)
+ Signatures MUST be done over both nonces, to guarantee the signature is fresh
+ Otherwise: if ECDHE key of one side is compromised, it can be reused!
+
+ Add explicit tag to beginning of structure to distinguish the client and server when signing. (done)
+
+ Sign all handshake messages up to ECDHE kex with long-term public keys. (done)
+
+ HMACed KEX finished message to prevent downgrade attacks and prove you have the right key material (done by virtue of Ed25519 over the whole ECDHE exchange?)
+
+ Explicit close message needs to be added.
+
+ Maybe do add some alert messages to give helpful error messages? Not more than TLS sends.
+
+ Use counter mode instead of OFB. (done)
+
+ Make sure ECC operations are fixed time (aka prevent side-channel attacks).
+*/
+
+void sptps_log_quiet(sptps_t *s, int s_errno, const char *format, va_list ap) {
+}
+
+void sptps_log_stderr(sptps_t *s, int s_errno, const char *format, va_list ap) {
+ vfprintf(stderr, format, ap);
+ fputc('\n', stderr);
+}
+
+void (*sptps_log)(sptps_t *s, int s_errno, const char *format, va_list ap) = sptps_log_stderr;
+
+// Log an error message.
+static bool error(sptps_t *s, int s_errno, const char *format, ...) {
+ if(format) {
+ va_list ap;
+ va_start(ap, format);
+ sptps_log(s, s_errno, format, ap);
+ va_end(ap);
+ }
-static bool error(sptps_t *s, int s_errno, const char *msg) {
- fprintf(stderr, "SPTPS error: %s\n", msg);
errno = s_errno;
return false;
}
-static bool send_record_priv(sptps_t *s, uint8_t type, const char *data, uint16_t len) {
- char plaintext[len + 23];
- char ciphertext[len + 19];
+static void warning(sptps_t *s, const char *format, ...) {
+ va_list ap;
+ va_start(ap, format);
+ sptps_log(s, 0, format, ap);
+ va_end(ap);
+}
- // Create header with sequence number, length and record type
- uint32_t seqno = htonl(s->outseqno++);
- uint16_t netlen = htons(len);
+// 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 void *data, uint16_t len) {
+ char buffer[len + 21UL];
- memcpy(plaintext, &seqno, 4);
- memcpy(plaintext + 4, &netlen, 2);
- plaintext[6] = type;
+ // Create header with sequence number, length and record type
+ uint32_t seqno = s->outseqno++;
+ uint32_t netseqno = ntohl(seqno);
- // Add plaintext (TODO: avoid unnecessary copy)
- memcpy(plaintext + 7, data, len);
+ memcpy(buffer, &netseqno, 4);
+ buffer[4] = type;
+ memcpy(buffer + 5, data, len);
- if(s->state) {
+ if(s->outstate) {
// If first handshake has finished, encrypt and HMAC
- if(!digest_create(&s->outdigest, plaintext, len + 7, plaintext + 7 + len))
- return false;
+ chacha_poly1305_encrypt(s->outcipher, seqno, buffer + 4, len + 1, buffer + 4, NULL);
+ return s->send_data(s->handle, type, buffer, len + 21UL);
+ } else {
+ // Otherwise send as plaintext
+ return s->send_data(s->handle, type, buffer, 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 void *data, uint16_t len) {
+ if(s->datagram)
+ return send_record_priv_datagram(s, type, data, len);
- if(!cipher_encrypt(&s->outcipher, plaintext + 4, sizeof ciphertext, ciphertext, NULL, false))
- return false;
+ char buffer[len + 19UL];
+
+ // Create header with sequence number, length and record type
+ uint32_t seqno = s->outseqno++;
+ uint16_t netlen = htons(len);
- return s->send_data(s->handle, ciphertext, len + 19);
+ memcpy(buffer, &netlen, 2);
+ buffer[2] = type;
+ memcpy(buffer + 3, data, len);
+
+ if(s->outstate) {
+ // If first handshake has finished, encrypt and HMAC
+ chacha_poly1305_encrypt(s->outcipher, seqno, buffer + 2, len + 1, buffer + 2, NULL);
+ return s->send_data(s->handle, type, buffer, len + 19UL);
} else {
// Otherwise send as plaintext
- return s->send_data(s->handle, plaintext + 4, len + 3);
+ return s->send_data(s->handle, type, buffer, len + 3UL);
}
}
-bool send_record(sptps_t *s, uint8_t type, const char *data, uint16_t len) {
+// Send an application record.
+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->state)
+ if(!s->outstate)
return error(s, EINVAL, "Handshake phase not finished yet");
- if(type & 128)
+ if(type >= SPTPS_HANDSHAKE)
return error(s, EINVAL, "Invalid application record type");
return send_record_priv(s, type, data, len);
}
+// Send a Key EXchange record, containing a random nonce and an ECDHE public key.
static bool send_kex(sptps_t *s) {
size_t keylen = ECDH_SIZE;
- size_t siglen = ecdsa_size(&s->mykey);
- char data[32 + keylen + siglen];
- // Create a random nonce.
- s->myrandom = realloc(s->myrandom, 32);
- if(!s->myrandom)
+ // Make room for our KEX message, which we will keep around since send_sig() needs it.
+ if(s->mykex)
+ return false;
+ s->mykex = realloc(s->mykex, 1 + 32 + keylen);
+ if(!s->mykex)
return error(s, errno, strerror(errno));
- randomize(s->myrandom, 32);
- memcpy(data, s->myrandom, 32);
+ // Set version byte to zero.
+ s->mykex[0] = SPTPS_VERSION;
+
+ // Create a random nonce.
+ randomize(s->mykex + 1, 32);
// Create a new ECDH public key.
- if(!ecdh_generate_public(&s->ecdh, data + 32))
- return false;
+ if(!(s->ecdh = ecdh_generate_public(s->mykex + 1 + 32)))
+ return error(s, EINVAL, "Failed to generate ECDH public key");
- // Sign the former.
- if(!ecdsa_sign(&s->mykey, data, 32 + keylen, data + 32 + keylen))
- return false;
+ return send_record_priv(s, SPTPS_HANDSHAKE, s->mykex, 1 + 32 + keylen);
+}
+
+// Send a SIGnature record, containing an Ed25519 signature over both KEX records.
+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, 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 + 1 + 33 + keylen, s->hiskex, 1 + 32 + keylen);
+ memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
- // Send the handshake record.
- return send_record_priv(s, 128, data, sizeof data);
+ // Sign the result.
+ 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);
}
-static bool generate_key_material(sptps_t *s, const char *shared, size_t len, const char *hisrandom) {
+// Generate key material from the shared secret created from the ECDHE key exchange.
+static bool generate_key_material(sptps_t *s, const char *shared, size_t len) {
// Initialise cipher and digest structures if necessary
- if(!s->state) {
- bool result
- = cipher_open_by_name(&s->incipher, "aes-256-ofb")
- && cipher_open_by_name(&s->outcipher, "aes-256-ofb")
- && digest_open_by_name(&s->indigest, "sha256", 16)
- && digest_open_by_name(&s->outdigest, "sha256", 16);
- if(!result)
- return false;
+ if(!s->outstate) {
+ s->incipher = chacha_poly1305_init();
+ s->outcipher = chacha_poly1305_init();
+ if(!s->incipher || !s->outcipher)
+ return error(s, EINVAL, "Failed to open cipher");
}
// Allocate memory for key material
- size_t keylen = digest_keylength(&s->indigest) + digest_keylength(&s->outdigest) + cipher_keylength(&s->incipher) + cipher_keylength(&s->outcipher);
+ size_t keylen = 2 * CHACHA_POLY1305_KEYLEN;
s->key = realloc(s->key, keylen);
if(!s->key)
// Create the HMAC seed, which is "key expansion" + session label + server nonce + client nonce
char seed[s->labellen + 64 + 13];
- strcpy(seed, "key expansion");
+ memcpy(seed, "key expansion", 13);
if(s->initiator) {
- memcpy(seed + 13, hisrandom, 32);
- memcpy(seed + 45, s->myrandom, 32);
+ memcpy(seed + 13, s->mykex + 1, 32);
+ memcpy(seed + 45, s->hiskex + 1, 32);
} else {
- memcpy(seed + 13, s->myrandom, 32);
- memcpy(seed + 45, hisrandom, 32);
+ memcpy(seed + 13, s->hiskex + 1, 32);
+ memcpy(seed + 45, s->mykex + 1, 32);
}
- memcpy(seed + 78, s->label, s->labellen);
+ memcpy(seed + 77, s->label, s->labellen);
// Use PRF to generate the key material
if(!prf(shared, len, seed, s->labellen + 64 + 13, s->key, keylen))
- return false;
+ return error(s, EINVAL, "Failed to generate key material");
return true;
}
+// Send an ACKnowledgement record.
static bool send_ack(sptps_t *s) {
- return send_record_priv(s, 128, "", 0);
+ return send_record_priv(s, SPTPS_HANDSHAKE, "", 0);
}
+// Receive an ACKnowledgement record.
static bool receive_ack(sptps_t *s, const char *data, uint16_t len) {
if(len)
- return false;
+ return error(s, EIO, "Invalid ACK record length");
- // TODO: set cipher/digest keys
- return error(s, ENOSYS, "receive_ack() not completely implemented yet");
+ if(s->initiator) {
+ if(!chacha_poly1305_set_key(s->incipher, s->key))
+ return error(s, EINVAL, "Failed to set counter");
+ } else {
+ if(!chacha_poly1305_set_key(s->incipher, s->key + CHACHA_POLY1305_KEYLEN))
+ return error(s, EINVAL, "Failed to set counter");
+ }
+
+ free(s->key);
+ s->key = NULL;
+ s->instate = true;
+
+ return true;
}
+// Receive a Key EXchange record, respond by sending a SIG record.
static bool receive_kex(sptps_t *s, const char *data, uint16_t len) {
+ // Verify length of the HELLO record
+ if(len != 1 + 32 + ECDH_SIZE)
+ return error(s, EIO, "Invalid KEX record length");
+
+ // Ignore version number for now.
+
+ // Make a copy of the KEX message, send_sig() and receive_sig() need it
+ if(s->hiskex)
+ return error(s, EINVAL, "Received a second KEX message before first has been processed");
+ s->hiskex = realloc(s->hiskex, len);
+ if(!s->hiskex)
+ return error(s, errno, strerror(errno));
+
+ memcpy(s->hiskex, data, len);
+
+ return send_sig(s);
+}
+
+// Receive a SIGnature record, verify it, if it passed, compute the shared secret and calculate the session keys.
+static bool receive_sig(sptps_t *s, const char *data, uint16_t len) {
size_t keylen = ECDH_SIZE;
- size_t siglen = ecdsa_size(&s->hiskey);
+ size_t siglen = ecdsa_size(s->hiskey);
// Verify length of KEX record.
- if(len != 32 + keylen + siglen)
+ if(len != siglen)
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 + s->labellen];
+
+ msg[0] = !s->initiator;
+ memcpy(msg + 1, s->hiskex, 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, data, 32 + keylen, data + 32 + keylen))
- return false;
+ if(!ecdsa_verify(s->hiskey, msg, sizeof msg, data))
+ return error(s, EIO, "Failed to verify SIG record");
// Compute shared secret.
char shared[ECDH_SHARED_SIZE];
- if(!ecdh_compute_shared(&s->ecdh, data + 32, shared))
- return false;
+ if(!ecdh_compute_shared(s->ecdh, s->hiskex + 1 + 32, shared))
+ return error(s, EINVAL, "Failed to compute ECDH shared secret");
+ s->ecdh = NULL;
// Generate key material from shared secret.
- if(!generate_key_material(s, shared, sizeof shared, data))
+ if(!generate_key_material(s, shared, sizeof shared))
return false;
- // Send cipher change record if necessary
- if(s->state)
- if(!send_ack(s))
- return false;
+ free(s->mykex);
+ free(s->hiskex);
- // TODO: set cipher/digest keys
+ s->mykex = NULL;
+ s->hiskex = NULL;
+
+ // Send cipher change record
+ if(s->outstate && !send_ack(s))
+ return false;
+
+ // TODO: only set new keys after ACK has been set/received
if(s->initiator) {
- bool result
- = cipher_set_key(&s->incipher, s->key, false)
- && digest_set_key(&s->indigest, s->key + cipher_keylength(&s->incipher), digest_keylength(&s->indigest))
- && cipher_set_key(&s->outcipher, s->key + cipher_keylength(&s->incipher) + digest_keylength(&s->indigest), true)
- && digest_set_key(&s->outdigest, s->key + cipher_keylength(&s->incipher) + digest_keylength(&s->indigest) + cipher_keylength(&s->outcipher), digest_keylength(&s->outdigest));
- if(!result)
- return false;
+ if(!chacha_poly1305_set_key(s->outcipher, s->key + CHACHA_POLY1305_KEYLEN))
+ return error(s, EINVAL, "Failed to set key");
} else {
- bool result
- = cipher_set_key(&s->outcipher, s->key, true)
- && digest_set_key(&s->outdigest, s->key + cipher_keylength(&s->outcipher), digest_keylength(&s->outdigest))
- && cipher_set_key(&s->incipher, s->key + cipher_keylength(&s->outcipher) + digest_keylength(&s->outdigest), false)
- && digest_set_key(&s->indigest, s->key + cipher_keylength(&s->outcipher) + digest_keylength(&s->outdigest) + cipher_keylength(&s->incipher), digest_keylength(&s->indigest));
- if(!result)
- return false;
+ if(!chacha_poly1305_set_key(s->outcipher, s->key))
+ return error(s, EINVAL, "Failed to set key");
}
return true;
}
+// Force another Key EXchange (for testing purposes).
+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");
+
+ s->state = SPTPS_KEX;
+ return send_kex(s);
+}
+
+// Receive a handshake record.
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 0:
- // We have sent our public ECDH key, we expect our peer to sent one as well.
+ 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 = 1;
+ s->state = SPTPS_SIG;
return true;
- case 1:
- // We receive a secondary key exchange request, first respond by sending our own public ECDH key.
- if(!send_kex(s))
- return false;
- case 2:
+ case SPTPS_SIG:
// If we already sent our secondary public ECDH key, we expect the peer to send his.
- if(!receive_kex(s, data, len))
+ if(!receive_sig(s, data, len))
return false;
- s->state = 3;
+ 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 3:
- // We expect an empty handshake message to indicate transition to the new keys.
+ case SPTPS_ACK:
+ // We expect a handshake message to indicate transition to the new keys.
if(!receive_ack(s, data, len))
return false;
- s->state = 1;
+ 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");
+ return error(s, EIO, "Invalid session state %d", s->state);
}
}
-bool receive_data(sptps_t *s, const char *data, size_t len) {
- while(len) {
- // First read the 2 length bytes.
- if(s->buflen < 6) {
- size_t toread = 6 - s->buflen;
- if(toread > len)
- toread = len;
-
- if(s->state) {
- if(!cipher_decrypt(&s->incipher, data, toread, s->inbuf + s->buflen, NULL, false))
- return false;
- } else {
- memcpy(s->inbuf + s->buflen, data, toread);
+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 update_state ? error(s, EIO, "Packet is %d seqs in the future, dropped (%u)\n", seqno - s->inseqno, s->farfuture) : false;
+
+ // Unless we have seen lots of them, in which case we consider the others lost.
+ if(update_state)
+ 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 update_state ? error(s, EIO, "Received late or replayed packet, seqno %d, last received %d\n", seqno, s->inseqno) : false;
+ } 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;
}
+ }
- s->buflen += toread;
- len -= toread;
- data += toread;
-
- // Exit early if we don't have the full length.
- if(s->buflen < 6)
- return true;
-
- // If we have the length bytes, ensure our buffer can hold the whole request.
- uint16_t reclen;
- memcpy(&reclen, s->inbuf + 4, 2);
- reclen = htons(reclen);
- s->inbuf = realloc(s->inbuf, reclen + 23UL);
- if(!s->inbuf)
- return error(s, errno, strerror(errno));
-
- // Add sequence number.
- uint32_t seqno = htonl(s->inseqno++);
- memcpy(s->inbuf, &seqno, 4);
-
- // Exit early if we have no more data to process.
- if(!len)
- return true;
+ 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 void *data, size_t len) {
+ if(!s->instate || len < 21)
+ return error(s, EIO, "Received short packet");
+
+ uint32_t seqno;
+ memcpy(&seqno, data, 4);
+ seqno = ntohl(seqno);
+ if (!sptps_check_seqno(s, seqno, false))
+ return false;
+
+ 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) {
+ if(len < (s->instate ? 21 : 5))
+ return error(s, EIO, "Received short packet");
+
+ uint32_t seqno;
+ memcpy(&seqno, data, 4);
+ seqno = ntohl(seqno);
+ data += 4; len -= 4;
+
+ if(!s->instate) {
+ if(seqno != s->inseqno)
+ return error(s, EIO, "Invalid packet seqno: %d != %d", seqno, s->inseqno);
+
+ s->inseqno = seqno + 1;
+
+ uint8_t type = *(data++); len--;
+
+ if(type != SPTPS_HANDSHAKE)
+ return error(s, EIO, "Application record received before handshake finished");
+
+ return receive_handshake(s, data, len);
+ }
+
+ // Decrypt
+
+ char buffer[len];
+ size_t outlen;
+ if(!chacha_poly1305_decrypt(s->incipher, seqno, data, len, buffer, &outlen))
+ return error(s, EIO, "Failed to decrypt and verify packet");
+
+ if(!sptps_check_seqno(s, seqno, true))
+ return false;
+
+ // Append a NULL byte for safety.
+ buffer[outlen] = 0;
+
+ data = buffer;
+ len = outlen;
+
+ uint8_t type = *(data++); len--;
- // Read up to the end of the record.
- uint16_t reclen;
- memcpy(&reclen, s->inbuf + 4, 2);
- reclen = htons(reclen);
- size_t toread = reclen + (s->state ? 23UL : 7UL) - s->buflen;
+ if(type < SPTPS_HANDSHAKE) {
+ if(!s->instate)
+ return error(s, EIO, "Application record received before handshake finished");
+ if(!s->receive_record(s->handle, type, data, len))
+ return false;
+ } else if(type == SPTPS_HANDSHAKE) {
+ if(!receive_handshake(s, data, len))
+ return false;
+ } 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.
+size_t sptps_receive_data(sptps_t *s, const void *data, size_t len) {
+ size_t total_read = 0;
+
+ if(!s->state)
+ return error(s, EIO, "Invalid session state zero");
+
+ if(s->datagram)
+ return sptps_receive_data_datagram(s, data, len) ? len : false;
+
+ // First read the 2 length bytes.
+ if(s->buflen < 2) {
+ size_t toread = 2 - s->buflen;
if(toread > len)
toread = len;
- if(s->state) {
- if(!cipher_decrypt(&s->incipher, data, toread, s->inbuf + s->buflen, NULL, false))
- return false;
- } else {
- memcpy(s->inbuf + s->buflen, data, toread);
- }
+ memcpy(s->inbuf + s->buflen, data, toread);
+ total_read += toread;
s->buflen += toread;
len -= toread;
data += toread;
- // If we don't have a whole record, exit.
- if(s->buflen < reclen + (s->state ? 23UL : 7UL))
- return true;
+ // Exit early if we don't have the full length.
+ if(s->buflen < 2)
+ return total_read;
- // Check HMAC.
- if(s->state)
- if(!digest_verify(&s->indigest, s->inbuf, reclen + 7UL, s->inbuf + reclen + 7UL))
- error(s, EIO, "Invalid HMAC");
+ // Get the length bytes
- uint8_t type = s->inbuf[6];
+ memcpy(&s->reclen, s->inbuf, 2);
+ s->reclen = ntohs(s->reclen);
- // Handle record.
- if(type < 128) {
- if(!s->receive_record(s->handle, type, s->inbuf + 7, reclen))
- return false;
- } else if(type == 128) {
- if(!receive_handshake(s, s->inbuf + 7, reclen))
- return false;
- } else {
- return error(s, EIO, "Invalid record type");
- }
+ // If we have the length bytes, ensure our buffer can hold the whole request.
+ s->inbuf = realloc(s->inbuf, s->reclen + 19UL);
+ if(!s->inbuf)
+ return error(s, errno, strerror(errno));
- s->buflen = 4;
+ // Exit early if we have no more data to process.
+ if(!len)
+ return total_read;
}
- return true;
+ // Read up to the end of the record.
+ size_t toread = s->reclen + (s->instate ? 19UL : 3UL) - s->buflen;
+ if(toread > len)
+ toread = len;
+
+ memcpy(s->inbuf + s->buflen, data, toread);
+ total_read += toread;
+ s->buflen += toread;
+ len -= toread;
+ data += toread;
+
+ // If we don't have a whole record, exit.
+ if(s->buflen < s->reclen + (s->instate ? 19UL : 3UL))
+ return total_read;
+
+ // Update sequence number.
+
+ uint32_t seqno = s->inseqno++;
+
+ // Check HMAC and decrypt.
+ if(s->instate) {
+ if(!chacha_poly1305_decrypt(s->incipher, seqno, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL))
+ return error(s, EINVAL, "Failed to decrypt and verify record");
+ }
+
+ // Append a NULL byte for safety.
+ s->inbuf[s->reclen + 3UL] = 0;
+
+ uint8_t type = s->inbuf[2];
+
+ if(type < SPTPS_HANDSHAKE) {
+ if(!s->instate)
+ return error(s, EIO, "Application record received before handshake finished");
+ if(!s->receive_record(s->handle, type, s->inbuf + 3, s->reclen))
+ return false;
+ } else if(type == SPTPS_HANDSHAKE) {
+ if(!receive_handshake(s, s->inbuf + 3, s->reclen))
+ return false;
+ } else {
+ return error(s, EIO, "Invalid record type %d", type);
+ }
+
+ s->buflen = 0;
+
+ return total_read;
}
-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) {
+// Start a SPTPS session.
+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);
s->handle = handle;
s->initiator = initiator;
+ s->datagram = datagram;
s->mykey = mykey;
s->hiskey = hiskey;
+ s->replaywin = sptps_replaywin;
+ if(s->replaywin) {
+ s->late = malloc(s->replaywin);
+ if(!s->late)
+ return error(s, errno, strerror(errno));
+ memset(s->late, 0, s->replaywin);
+ }
s->label = malloc(labellen);
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 = 0;
+ }
memcpy(s->label, label, labellen);
s->labellen = labellen;
s->receive_record = receive_record;
// Do first KEX immediately
+ s->state = SPTPS_KEX;
return send_kex(s);
}
-bool stop_sptps(sptps_t *s) {
+// Stop a SPTPS session.
+bool sptps_stop(sptps_t *s) {
// Clean up any resources.
- ecdh_free(&s->ecdh);
+ chacha_poly1305_exit(s->incipher);
+ chacha_poly1305_exit(s->outcipher);
+ ecdh_free(s->ecdh);
free(s->inbuf);
- free(s->myrandom);
+ free(s->mykex);
+ free(s->hiskex);
free(s->key);
free(s->label);
+ free(s->late);
+ memset(s, 0, sizeof *s);
return true;
}
projects / tinc / blobdiff