diff options
| -rw-r--r-- | channels/chan_iax2.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c index b77b89da7..df72a5e4a 100644 --- a/channels/chan_iax2.c +++ b/channels/chan_iax2.c @@ -874,7 +874,7 @@ static void prune_users(void); static int decode_frame(aes_decrypt_ctx *dcx, struct ast_iax2_full_hdr *fh, struct ast_frame *f, int *datalen); static int encrypt_frame(aes_encrypt_ctx *ecx, struct ast_iax2_full_hdr *fh, unsigned char *poo, int *datalen); static void build_ecx_key(const unsigned char *digest, struct chan_iax2_pvt *pvt); - +static void build_rand_pad(unsigned char *buf, ssize_t len); static const struct ast_channel_tech iax2_tech = { .type = "IAX2", @@ -2274,6 +2274,9 @@ static int update_packet(struct iax_frame *f) /* Now re-encrypt the frame */ if (f->encmethods) { + /* since this is a retransmit frame, create a new random padding + * before re-encrypting. */ + build_rand_pad(f->semirand, sizeof(f->semirand)); encrypt_frame(&f->ecx, fh, f->semirand, &f->datalen); } return 0; @@ -4306,6 +4309,18 @@ static int iax2_trunk_queue(struct chan_iax2_pvt *pvt, struct iax_frame *fr) return 0; } +/* IAX2 encryption requires 16 to 32 bytes of random padding to be present + * before the encryption data. This function randomizes that data. */ +static void build_rand_pad(unsigned char *buf, ssize_t len) +{ + long tmp; + for (tmp = ast_random(); len > 0; tmp = ast_random()) { + memcpy(buf, (unsigned char *) &tmp, (len > sizeof(tmp)) ? sizeof(tmp) : len); + buf += sizeof(tmp); + len -= sizeof(tmp); + } +} + static void build_encryption_keys(const unsigned char *digest, struct chan_iax2_pvt *pvt) { build_ecx_key(digest, pvt); @@ -4317,6 +4332,7 @@ static void build_ecx_key(const unsigned char *digest, struct chan_iax2_pvt *pvt /* it is required to hold the corresponding decrypt key to our encrypt key * in the pvt struct because queued frames occasionally need to be decrypted and * re-encrypted when updated for a retransmission */ + build_rand_pad(pvt->semirand, sizeof(pvt->semirand)); aes_encrypt_key128(digest, &pvt->ecx); aes_decrypt_key128(digest, &pvt->mydcx); } @@ -4383,7 +4399,7 @@ static int decode_frame(aes_decrypt_ctx *dcx, struct ast_iax2_full_hdr *fh, stru /* Decrypt */ memcpy_decrypt(workspace, efh->encdata, *datalen - sizeof(struct ast_iax2_full_enc_hdr), dcx); - padding = 16 + (workspace[15] & 0xf); + padding = 16 + (workspace[15] & 0x0f); if (option_debug && iaxdebug) ast_log(LOG_DEBUG, "Decoding full frame with length %d (padding = %d) (15=%02x)\n", *datalen, padding, workspace[15]); if (*datalen < padding + sizeof(struct ast_iax2_full_hdr)) |