diff options
Diffstat (limited to 'netwerk/srtp/src/test/rtp_decoder.c')
| -rw-r--r-- | netwerk/srtp/src/test/rtp_decoder.c | 574 |
1 files changed, 574 insertions, 0 deletions
diff --git a/netwerk/srtp/src/test/rtp_decoder.c b/netwerk/srtp/src/test/rtp_decoder.c new file mode 100644 index 0000000000..d718a2b3ad --- /dev/null +++ b/netwerk/srtp/src/test/rtp_decoder.c @@ -0,0 +1,574 @@ +/* + * 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 + +struct srtp_crypto_suite { + const char *can_name; + int key_size; + int tag_size; +}; + +static struct srtp_crypto_suite srtp_crypto_suites[] = { + {.can_name = "AES_CM_128_HMAC_SHA1_32", .key_size = 128, .tag_size = 4 }, +#if 0 + {.can_name = "F8_128_HMAC_SHA1_32", .key_size = 128, .tag_size = 4}, +#endif + {.can_name = "AES_CM_128_HMAC_SHA1_32", .key_size = 128, .tag_size = 4 }, + {.can_name = "AES_CM_128_HMAC_SHA1_80", .key_size = 128, .tag_size = 10 }, + {.can_name = NULL } +}; + +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 = 8; + 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] = ""; + rtp_decoder_t dec; + srtp_policy_t policy; + 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); + } + + /* check args */ + while (1) { + c = getopt_s(argc, argv, "b:k:gt:ae:ld:f:s:"); + 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 != 256) { + fprintf(stderr, + "error: encryption key size must be 128 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_crypto_kernel_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; + break; + default: + usage(argv[0]); + } + } + + 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 (do_list_mods) { + status = srtp_crypto_kernel_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: + 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: + 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: + srtp_crypto_policy_set_rtp_default(&policy.rtp); + srtp_crypto_policy_set_rtcp_default(&policy.rtcp); + break; + case 256: + srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(&policy.rtp); + srtp_crypto_policy_set_rtcp_default(&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_rtcp_default(&policy.rtcp); + break; + case 256: + srtp_crypto_policy_set_aes_cm_256_null_auth(&policy.rtp); + srtp_crypto_policy_set_rtcp_default(&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.ekt = NULL; + 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, "setted 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, + expected_len); + if (pad != 0) { + fprintf(stderr, "error: padding in base64 unexpected\n"); + exit(1); + } + } 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); + } + + fprintf(stderr, "set master key/salt to %s/", + octet_string_hex_string(key, 16)); + fprintf(stderr, "%s\n", octet_string_hex_string(key + 16, 14)); + + } else { + fprintf(stderr, + "error: neither encryption or authentication were selected"); + exit(1); + } + + pcap_handle = pcap_open_offline("-", 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"); + rtp_decoder_init(dec, policy); + + pcap_loop(pcap_handle, 0, rtp_decoder_handle_pkt, (u_char *)dec); + + rtp_decoder_deinit_srtp(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][-e]]\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", + 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); +} + +srtp_err_status_t rtp_decoder_init_srtp(rtp_decoder_t decoder, + unsigned int ssrc) +{ + decoder->policy.ssrc.value = htonl(ssrc); + return srtp_create(&decoder->srtp_ctx, &decoder->policy); +} + +int rtp_decoder_deinit_srtp(rtp_decoder_t decoder) +{ + return srtp_dealloc(decoder->srtp_ctx); +} + +int rtp_decoder_init(rtp_decoder_t dcdr, srtp_policy_t policy) +{ + dcdr->rtp_offset = DEFAULT_RTP_OFFSET; + dcdr->srtp_ctx = NULL; + dcdr->start_tv.tv_usec = 0; + dcdr->start_tv.tv_sec = 0; + dcdr->frame_nr = -1; + dcdr->policy = policy; + dcdr->policy.ssrc.type = ssrc_specific; + 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; + 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 *)&dcdr->message, rtp_packet, hdr->caplen - dcdr->rtp_offset); + pktsize = hdr->caplen - dcdr->rtp_offset; + octets_recvd = pktsize; + + if (octets_recvd == -1) { + return; + } + + /* verify rtp header */ + if (dcdr->message.header.version != 2) { + return; + } + if (dcdr->srtp_ctx == NULL) { + status = rtp_decoder_init_srtp(dcdr, dcdr->message.header.ssrc); + if (status) { + exit(1); + } + } + status = srtp_unprotect(dcdr->srtp_ctx, &dcdr->message, &octets_recvd); + if (status) { + return; + } + 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(&dcdr->message, octets_recvd); +} + +void rtp_print_error(srtp_err_status_t status, char *message) +{ + // clang-format off + fprintf(stderr, + "error: %s %d%s\n", message, status, + status == srtp_err_status_replay_fail ? " (replay check failed)" : + status == srtp_err_status_bad_param ? " (bad param)" : + status == srtp_err_status_no_ctx ? " (no context)" : + status == srtp_err_status_cipher_fail ? " (cipher failed)" : + status == srtp_err_status_key_expired ? " (key expired)" : + status == srtp_err_status_auth_fail ? " (auth check failed)" : ""); + // clang-format on +} |