freeswitch/libs/srtp/test/rtp_decoder.c

771 lines
25 KiB
C

/*
* rtp_decoder.c
*
* decoder structures and functions for SRTP pcap decoder
*
* Example:
* $ wget --no-check-certificate \
* https://raw.githubusercontent.com/gteissier/srtp-decrypt/master/marseillaise-srtp.pcap
* $ ./test/rtp_decoder -a -t 10 -e 128 -b \
* aSBrbm93IGFsbCB5b3VyIGxpdHRsZSBzZWNyZXRz \
* < ~/marseillaise-srtp.pcap \
* | text2pcap -t "%M:%S." -u 10000,10000 - - \
* > ./marseillaise-rtp.pcap
*
* There is also a different way of setting up key size and tag size
* based upon RFC 4568 crypto suite specification, i.e.:
*
* $ ./test/rtp_decoder -s AES_CM_128_HMAC_SHA1_80 -b \
* aSBrbm93IGFsbCB5b3VyIGxpdHRsZSBzZWNyZXRz ...
*
* Audio can be extracted using extractaudio utility from the RTPproxy
* package:
*
* $ extractaudio -A ./marseillaise-rtp.pcap ./marseillaise-out.wav
*
* Bernardo Torres <bernardo@torresautomacao.com.br>
*
* Some structure and code from https://github.com/gteissier/srtp-decrypt
*/
/*
*
* Copyright (c) 2001-2017 Cisco Systems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* Neither the name of the Cisco Systems, Inc. nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "getopt_s.h" /* for local getopt() */
#include <assert.h> /* for assert() */
#include <pcap.h>
#include "rtp_decoder.h"
#include "util.h"
#ifndef timersub
#define timersub(a, b, result) \
do { \
(result)->tv_sec = (a)->tv_sec - (b)->tv_sec; \
(result)->tv_usec = (a)->tv_usec - (b)->tv_usec; \
if ((result)->tv_usec < 0) { \
--(result)->tv_sec; \
(result)->tv_usec += 1000000; \
} \
} while (0)
#endif
#define MAX_KEY_LEN 96
#define MAX_FILTER 256
#define MAX_FILE 255
struct srtp_crypto_suite {
const char *can_name;
int gcm_on;
int key_size;
int tag_size;
};
static struct srtp_crypto_suite srtp_crypto_suites[] = {
#if 0
{.can_name = "F8_128_HMAC_SHA1_32", .gcm_on = 0, .key_size = 128, .tag_size = 4},
#endif
{.can_name = "AES_CM_128_HMAC_SHA1_32",
.gcm_on = 0,
.key_size = 128,
.tag_size = 4 },
{.can_name = "AES_CM_128_HMAC_SHA1_80",
.gcm_on = 0,
.key_size = 128,
.tag_size = 10 },
{.can_name = "AES_192_CM_HMAC_SHA1_32",
.gcm_on = 0,
.key_size = 192,
.tag_size = 4 },
{.can_name = "AES_192_CM_HMAC_SHA1_80",
.gcm_on = 0,
.key_size = 192,
.tag_size = 10 },
{.can_name = "AES_256_CM_HMAC_SHA1_32",
.gcm_on = 0,
.key_size = 256,
.tag_size = 4 },
{.can_name = "AES_256_CM_HMAC_SHA1_80",
.gcm_on = 0,
.key_size = 256,
.tag_size = 10 },
{.can_name = "AEAD_AES_128_GCM",
.gcm_on = 1,
.key_size = 128,
.tag_size = 16 },
{.can_name = "AEAD_AES_256_GCM",
.gcm_on = 1,
.key_size = 256,
.tag_size = 16 },
{.can_name = NULL }
};
void rtp_decoder_srtp_log_handler(srtp_log_level_t level,
const char *msg,
void *data)
{
char level_char = '?';
switch (level) {
case srtp_log_level_error:
level_char = 'e';
break;
case srtp_log_level_warning:
level_char = 'w';
break;
case srtp_log_level_info:
level_char = 'i';
break;
case srtp_log_level_debug:
level_char = 'd';
break;
}
fprintf(stderr, "SRTP-LOG [%c]: %s\n", level_char, msg);
}
int main(int argc, char *argv[])
{
char errbuf[PCAP_ERRBUF_SIZE];
bpf_u_int32 pcap_net = 0;
pcap_t *pcap_handle;
#if BEW
struct sockaddr_in local;
#endif
srtp_sec_serv_t sec_servs = sec_serv_none;
int c;
struct srtp_crypto_suite scs, *i_scsp;
scs.key_size = 128;
scs.tag_size = 0;
int gcm_on = 0;
char *input_key = NULL;
int b64_input = 0;
char key[MAX_KEY_LEN];
struct bpf_program fp;
char filter_exp[MAX_FILTER] = "";
char pcap_file[MAX_FILE] = "-";
int rtp_packet_offset = DEFAULT_RTP_OFFSET;
rtp_decoder_t dec;
srtp_policy_t policy = { { 0 } };
rtp_decoder_mode_t mode = mode_rtp;
srtp_err_status_t status;
int len;
int expected_len;
int do_list_mods = 0;
fprintf(stderr, "Using %s [0x%x]\n", srtp_get_version_string(),
srtp_get_version());
/* initialize srtp library */
status = srtp_init();
if (status) {
fprintf(stderr,
"error: srtp initialization failed with error code %d\n",
status);
exit(1);
}
status = srtp_install_log_handler(rtp_decoder_srtp_log_handler, NULL);
if (status) {
fprintf(stderr, "error: install log handler failed\n");
exit(1);
}
/* check args */
while (1) {
c = getopt_s(argc, argv, "b:k:gt:ae:ld:f:s:m:p:o:");
if (c == -1) {
break;
}
switch (c) {
case 'b':
b64_input = 1;
/* fall thru */
case 'k':
input_key = optarg_s;
break;
case 'e':
scs.key_size = atoi(optarg_s);
if (scs.key_size != 128 && scs.key_size != 192 &&
scs.key_size != 256) {
fprintf(
stderr,
"error: encryption key size must be 128, 192 or 256 (%d)\n",
scs.key_size);
exit(1);
}
input_key = malloc(scs.key_size);
sec_servs |= sec_serv_conf;
break;
case 't':
scs.tag_size = atoi(optarg_s);
break;
case 'a':
sec_servs |= sec_serv_auth;
break;
case 'g':
gcm_on = 1;
sec_servs |= sec_serv_auth;
break;
case 'd':
status = srtp_set_debug_module(optarg_s, 1);
if (status) {
fprintf(stderr, "error: set debug module (%s) failed\n",
optarg_s);
exit(1);
}
break;
case 'f':
if (strlen(optarg_s) > MAX_FILTER) {
fprintf(stderr, "error: filter bigger than %d characters\n",
MAX_FILTER);
exit(1);
}
fprintf(stderr, "Setting filter as %s\n", optarg_s);
strcpy(filter_exp, optarg_s);
break;
case 'l':
do_list_mods = 1;
break;
case 's':
for (i_scsp = &srtp_crypto_suites[0]; i_scsp->can_name != NULL;
i_scsp++) {
if (strcasecmp(i_scsp->can_name, optarg_s) == 0) {
break;
}
}
if (i_scsp->can_name == NULL) {
fprintf(stderr, "Unknown/unsupported crypto suite name %s\n",
optarg_s);
exit(1);
}
scs = *i_scsp;
input_key = malloc(scs.key_size);
sec_servs |= sec_serv_conf | sec_serv_auth;
gcm_on = scs.gcm_on;
break;
case 'm':
if (strcasecmp("rtp", optarg_s) == 0) {
mode = mode_rtp;
} else if (strcasecmp("rtcp", optarg_s) == 0) {
mode = mode_rtcp;
} else if (strcasecmp("rtcp-mux", optarg_s) == 0) {
mode = mode_rtcp_mux;
} else {
fprintf(stderr, "Unknown/unsupported mode %s\n", optarg_s);
exit(1);
}
break;
case 'p':
if (strlen(optarg_s) > MAX_FILE) {
fprintf(stderr,
"error: pcap file path bigger than %d characters\n",
MAX_FILE);
exit(1);
}
strcpy(pcap_file, optarg_s);
break;
case 'o':
rtp_packet_offset = atoi(optarg_s);
break;
default:
usage(argv[0]);
}
}
if (scs.tag_size == 0) {
if (gcm_on) {
scs.tag_size = 16;
} else {
scs.tag_size = 10;
}
}
if (gcm_on && scs.tag_size != 8 && scs.tag_size != 16) {
fprintf(stderr, "error: GCM tag size must be 8 or 16 (%d)\n",
scs.tag_size);
exit(1);
}
if (!gcm_on && scs.tag_size != 4 && scs.tag_size != 10) {
fprintf(stderr, "error: non GCM tag size must be 4 or 10 (%d)\n",
scs.tag_size);
exit(1);
}
if (do_list_mods) {
status = srtp_list_debug_modules();
if (status) {
fprintf(stderr, "error: list of debug modules failed\n");
exit(1);
}
return 0;
}
if ((sec_servs && !input_key) || (!sec_servs && input_key)) {
/*
* a key must be provided if and only if security services have
* been requested
*/
if (input_key == NULL) {
fprintf(stderr, "key not provided\n");
}
if (!sec_servs) {
fprintf(stderr, "no secservs\n");
}
fprintf(stderr, "provided\n");
usage(argv[0]);
}
/* report security services selected on the command line */
fprintf(stderr, "security services: ");
if (sec_servs & sec_serv_conf)
fprintf(stderr, "confidentiality ");
if (sec_servs & sec_serv_auth)
fprintf(stderr, "message authentication");
if (sec_servs == sec_serv_none)
fprintf(stderr, "none");
fprintf(stderr, "\n");
/* set up the srtp policy and master key */
if (sec_servs) {
/*
* create policy structure, using the default mechanisms but
* with only the security services requested on the command line,
* using the right SSRC value
*/
switch (sec_servs) {
case sec_serv_conf_and_auth:
if (gcm_on) {
#ifdef OPENSSL
switch (scs.key_size) {
case 128:
if (scs.tag_size == 16) {
srtp_crypto_policy_set_aes_gcm_128_16_auth(&policy.rtp);
srtp_crypto_policy_set_aes_gcm_128_16_auth(
&policy.rtcp);
} else {
srtp_crypto_policy_set_aes_gcm_128_8_auth(&policy.rtp);
srtp_crypto_policy_set_aes_gcm_128_8_auth(&policy.rtcp);
}
break;
case 256:
if (scs.tag_size == 16) {
srtp_crypto_policy_set_aes_gcm_256_16_auth(&policy.rtp);
srtp_crypto_policy_set_aes_gcm_256_16_auth(
&policy.rtcp);
} else {
srtp_crypto_policy_set_aes_gcm_256_8_auth(&policy.rtp);
srtp_crypto_policy_set_aes_gcm_256_8_auth(&policy.rtcp);
}
break;
}
#else
fprintf(stderr, "error: GCM mode only supported when using the "
"OpenSSL crypto engine.\n");
return 0;
#endif
} else {
switch (scs.key_size) {
case 128:
if (scs.tag_size == 4) {
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32(
&policy.rtp);
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(
&policy.rtcp);
} else {
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(
&policy.rtp);
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(
&policy.rtcp);
}
break;
case 192:
#ifdef OPENSSL
if (scs.tag_size == 4) {
srtp_crypto_policy_set_aes_cm_192_hmac_sha1_32(
&policy.rtp);
srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(
&policy.rtcp);
} else {
srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(
&policy.rtp);
srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(
&policy.rtcp);
}
#else
fprintf(stderr,
"error: AES 192 mode only supported when using the "
"OpenSSL crypto engine.\n");
return 0;
#endif
break;
case 256:
if (scs.tag_size == 4) {
srtp_crypto_policy_set_aes_cm_256_hmac_sha1_32(
&policy.rtp);
srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(
&policy.rtcp);
} else {
srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(
&policy.rtp);
srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(
&policy.rtcp);
}
break;
}
}
break;
case sec_serv_conf:
if (gcm_on) {
fprintf(
stderr,
"error: GCM mode must always be used with auth enabled\n");
return -1;
} else {
switch (scs.key_size) {
case 128:
srtp_crypto_policy_set_aes_cm_128_null_auth(&policy.rtp);
srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(
&policy.rtcp);
break;
case 192:
#ifdef OPENSSL
srtp_crypto_policy_set_aes_cm_192_null_auth(&policy.rtp);
srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(
&policy.rtcp);
#else
fprintf(stderr,
"error: AES 192 mode only supported when using the "
"OpenSSL crypto engine.\n");
return 0;
#endif
break;
case 256:
srtp_crypto_policy_set_aes_cm_256_null_auth(&policy.rtp);
srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(
&policy.rtcp);
break;
}
}
break;
case sec_serv_auth:
if (gcm_on) {
#ifdef OPENSSL
switch (scs.key_size) {
case 128:
srtp_crypto_policy_set_aes_gcm_128_8_only_auth(&policy.rtp);
srtp_crypto_policy_set_aes_gcm_128_8_only_auth(
&policy.rtcp);
break;
case 256:
srtp_crypto_policy_set_aes_gcm_256_8_only_auth(&policy.rtp);
srtp_crypto_policy_set_aes_gcm_256_8_only_auth(
&policy.rtcp);
break;
}
#else
printf("error: GCM mode only supported when using the OpenSSL "
"crypto engine.\n");
return 0;
#endif
} else {
srtp_crypto_policy_set_null_cipher_hmac_sha1_80(&policy.rtp);
srtp_crypto_policy_set_rtcp_default(&policy.rtcp);
}
break;
default:
fprintf(stderr, "error: unknown security service requested\n");
return -1;
}
policy.key = (uint8_t *)key;
policy.next = NULL;
policy.window_size = 128;
policy.allow_repeat_tx = 0;
policy.rtp.sec_serv = sec_servs;
policy.rtcp.sec_serv =
sec_servs; // sec_serv_none; /* we don't do RTCP anyway */
fprintf(stderr, "setting tag len %d\n", scs.tag_size);
policy.rtp.auth_tag_len = scs.tag_size;
if (gcm_on && scs.tag_size != 8) {
fprintf(stderr, "set tag len %d\n", scs.tag_size);
policy.rtp.auth_tag_len = scs.tag_size;
}
/*
* read key from hexadecimal or base64 on command line into an octet
* string
*/
if (b64_input) {
int pad;
expected_len = policy.rtp.cipher_key_len * 4 / 3;
len = base64_string_to_octet_string(key, &pad, input_key,
strlen(input_key));
} else {
expected_len = policy.rtp.cipher_key_len * 2;
len = hex_string_to_octet_string(key, input_key, expected_len);
}
/* check that hex string is the right length */
if (len < expected_len) {
fprintf(stderr, "error: too few digits in key/salt "
"(should be %d digits, found %d)\n",
expected_len, len);
exit(1);
}
if (strlen(input_key) > policy.rtp.cipher_key_len * 2) {
fprintf(stderr, "error: too many digits in key/salt "
"(should be %d hexadecimal digits, found %u)\n",
policy.rtp.cipher_key_len * 2, (unsigned)strlen(input_key));
exit(1);
}
int key_octets = (scs.key_size / 8);
int salt_octets = policy.rtp.cipher_key_len - key_octets;
fprintf(stderr, "set master key/salt to %s/",
octet_string_hex_string(key, key_octets));
fprintf(stderr, "%s\n",
octet_string_hex_string(key + key_octets, salt_octets));
} else {
fprintf(stderr,
"error: neither encryption or authentication were selected\n");
exit(1);
}
pcap_handle = pcap_open_offline(pcap_file, errbuf);
if (!pcap_handle) {
fprintf(stderr, "libpcap failed to open file '%s'\n", errbuf);
exit(1);
}
assert(pcap_handle != NULL);
if ((pcap_compile(pcap_handle, &fp, filter_exp, 1, pcap_net)) == -1) {
fprintf(stderr, "Couldn't parse filter %s: %s\n", filter_exp,
pcap_geterr(pcap_handle));
return (2);
}
if (pcap_setfilter(pcap_handle, &fp) == -1) {
fprintf(stderr, "couldn't install filter %s: %s\n", filter_exp,
pcap_geterr(pcap_handle));
return (2);
}
dec = rtp_decoder_alloc();
if (dec == NULL) {
fprintf(stderr, "error: malloc() failed\n");
exit(1);
}
fprintf(stderr, "Starting decoder\n");
if (rtp_decoder_init(dec, policy, mode, rtp_packet_offset)) {
fprintf(stderr, "error: init failed\n");
exit(1);
}
pcap_loop(pcap_handle, 0, rtp_decoder_handle_pkt, (u_char *)dec);
if (dec->mode == mode_rtp || dec->mode == mode_rtcp_mux) {
fprintf(stderr, "RTP packets decoded: %d\n", dec->rtp_cnt);
}
if (dec->mode == mode_rtcp || dec->mode == mode_rtcp_mux) {
fprintf(stderr, "RTCP packets decoded: %d\n", dec->rtcp_cnt);
}
fprintf(stderr, "Packet decode errors: %d\n", dec->error_cnt);
rtp_decoder_deinit(dec);
rtp_decoder_dealloc(dec);
status = srtp_shutdown();
if (status) {
fprintf(stderr, "error: srtp shutdown failed with error code %d\n",
status);
exit(1);
}
return 0;
}
void usage(char *string)
{
fprintf(
stderr,
"usage: %s [-d <debug>]* [[-k][-b] <key>] [-a][-t][-e] [-s "
"<srtp-crypto-suite>] [-m <mode>]\n"
"or %s -l\n"
"where -a use message authentication\n"
" -e <key size> use encryption (use 128 or 256 for key size)\n"
" -g Use AES-GCM mode (must be used with -e)\n"
" -t <tag size> Tag size to use (in GCM mode use 8 or 16)\n"
" -k <key> sets the srtp master key given in hexadecimal\n"
" -b <key> sets the srtp master key given in base64\n"
" -l list debug modules\n"
" -f \"<pcap filter>\" to filter only the desired SRTP packets\n"
" -d <debug> turn on debugging for module <debug>\n"
" -s \"<srtp-crypto-suite>\" to set both key and tag size based\n"
" on RFC4568-style crypto suite specification\n"
" -m <mode> set the mode to be one of [rtp]|rtcp|rtcp-mux\n"
" -p <pcap file> path to pcap file (defaults to stdin)\n"
" -o byte offset of RTP packet in capture (defaults to 42)\n",
string, string);
exit(1);
}
rtp_decoder_t rtp_decoder_alloc(void)
{
return (rtp_decoder_t)malloc(sizeof(rtp_decoder_ctx_t));
}
void rtp_decoder_dealloc(rtp_decoder_t rtp_ctx)
{
free(rtp_ctx);
}
int rtp_decoder_deinit(rtp_decoder_t decoder)
{
if (decoder->srtp_ctx) {
return srtp_dealloc(decoder->srtp_ctx);
}
return 0;
}
int rtp_decoder_init(rtp_decoder_t dcdr,
srtp_policy_t policy,
rtp_decoder_mode_t mode,
int rtp_packet_offset)
{
dcdr->rtp_offset = rtp_packet_offset;
dcdr->srtp_ctx = NULL;
dcdr->start_tv.tv_usec = 0;
dcdr->start_tv.tv_sec = 0;
dcdr->frame_nr = -1;
dcdr->error_cnt = 0;
dcdr->rtp_cnt = 0;
dcdr->rtcp_cnt = 0;
dcdr->mode = mode;
dcdr->policy = policy;
dcdr->policy.ssrc.type = ssrc_any_inbound;
if (srtp_create(&dcdr->srtp_ctx, &dcdr->policy)) {
return 1;
}
return 0;
}
/*
* decodes key as base64
*/
void hexdump(const void *ptr, size_t size)
{
int i, j;
const unsigned char *cptr = ptr;
for (i = 0; i < size; i += 16) {
fprintf(stdout, "%04x ", i);
for (j = 0; j < 16 && i + j < size; j++) {
fprintf(stdout, "%02x ", cptr[i + j]);
}
fprintf(stdout, "\n");
}
}
void rtp_decoder_handle_pkt(u_char *arg,
const struct pcap_pkthdr *hdr,
const u_char *bytes)
{
rtp_decoder_t dcdr = (rtp_decoder_t)arg;
rtp_msg_t message;
int rtp;
int pktsize;
struct timeval delta;
int octets_recvd;
srtp_err_status_t status;
dcdr->frame_nr++;
if ((dcdr->start_tv.tv_sec == 0) && (dcdr->start_tv.tv_usec == 0)) {
dcdr->start_tv = hdr->ts;
}
if (hdr->caplen < dcdr->rtp_offset) {
return;
}
const void *rtp_packet = bytes + dcdr->rtp_offset;
memcpy((void *)&message, rtp_packet, hdr->caplen - dcdr->rtp_offset);
pktsize = hdr->caplen - dcdr->rtp_offset;
octets_recvd = pktsize;
if (octets_recvd == -1) {
return;
}
if (dcdr->mode == mode_rtp) {
rtp = 1;
} else if (dcdr->mode == mode_rtcp) {
rtp = 0;
} else {
rtp = 1;
if (octets_recvd >= 2) {
/* rfc5761 */
u_char payload_type = *(bytes + dcdr->rtp_offset + 1) & 0x7f;
rtp = payload_type < 64 || payload_type > 95;
}
}
if (rtp) {
/* verify rtp header */
if (message.header.version != 2) {
return;
}
status = srtp_unprotect(dcdr->srtp_ctx, &message, &octets_recvd);
if (status) {
dcdr->error_cnt++;
return;
}
dcdr->rtp_cnt++;
} else {
status = srtp_unprotect_rtcp(dcdr->srtp_ctx, &message, &octets_recvd);
if (status) {
dcdr->error_cnt++;
return;
}
dcdr->rtcp_cnt++;
}
timersub(&hdr->ts, &dcdr->start_tv, &delta);
fprintf(stdout, "%02ld:%02ld.%06ld\n", delta.tv_sec / 60, delta.tv_sec % 60,
(long)delta.tv_usec);
hexdump(&message, octets_recvd);
}