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srtp_driver.c
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/*
* srtp_driver.c
*
* a test driver for libSRTP
*
* David A. McGrew
* Cisco Systems, Inc.
*/
/*
*
* Copyright (c) 2001-2006, 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 <string.h> /* for memcpy() */
#include <time.h> /* for clock() */
#include <stdlib.h> /* for malloc(), free() */
#include <stdio.h> /* for print(), fflush() */
#include "getopt_s.h" /* for local getopt() */
#include "srtp_priv.h"
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#elif defined HAVE_WINSOCK2_H
# include <winsock2.h>
#endif
#define PRINT_REFERENCE_PACKET 1
err_status_t
srtp_validate(void);
err_status_t
srtp_validate_aes_256(void);
err_status_t
srtp_create_big_policy(srtp_policy_t **list);
err_status_t
srtp_dealloc_big_policy(srtp_policy_t *list);
err_status_t
srtp_test_remove_stream(void);
double
srtp_bits_per_second(int msg_len_octets, const srtp_policy_t *policy);
double
srtp_rejections_per_second(int msg_len_octets, const srtp_policy_t *policy);
void
srtp_do_timing(const srtp_policy_t *policy);
void
srtp_do_rejection_timing(const srtp_policy_t *policy);
err_status_t
srtp_test(const srtp_policy_t *policy);
err_status_t
srtcp_test(const srtp_policy_t *policy);
err_status_t
srtp_session_print_policy(srtp_t srtp);
err_status_t
srtp_print_policy(const srtp_policy_t *policy);
char *
srtp_packet_to_string(srtp_hdr_t *hdr, int packet_len);
double
mips_estimate(int num_trials, int *ignore);
extern uint8_t test_key[46];
void
usage(char *prog_name) {
printf("usage: %s [ -t ][ -c ][ -v ][-d <debug_module> ]* [ -l ]\n"
" -t run timing test\n"
" -r run rejection timing test\n"
" -c run codec timing test\n"
" -v run validation tests\n"
" -d <mod> turn on debugging module <mod>\n"
" -l list debugging modules\n", prog_name);
exit(1);
}
/*
* The policy_array is a null-terminated array of policy structs. it
* is declared at the end of this file
*/
extern const srtp_policy_t *policy_array[];
/* the wildcard_policy is declared below; it has a wildcard ssrc */
extern const srtp_policy_t wildcard_policy;
/*
* mod_driver debug module - debugging module for this test driver
*
* we use the crypto_kernel debugging system in this driver, which
* makes the interface uniform and increases portability
*/
debug_module_t mod_driver = {
0, /* debugging is off by default */
"driver" /* printable name for module */
};
int
main (int argc, char *argv[]) {
int q;
unsigned do_timing_test = 0;
unsigned do_rejection_test = 0;
unsigned do_codec_timing = 0;
unsigned do_validation = 0;
unsigned do_list_mods = 0;
err_status_t status;
/*
* verify that the compiler has interpreted the header data
* structure srtp_hdr_t correctly
*/
if (sizeof(srtp_hdr_t) != 12) {
printf("error: srtp_hdr_t has incorrect size"
"(size is %ld bytes, expected 12)\n",
(long)sizeof(srtp_hdr_t));
exit(1);
}
/* initialize srtp library */
status = srtp_init();
if (status) {
printf("error: srtp init failed with error code %d\n", status);
exit(1);
}
/* load srtp_driver debug module */
status = crypto_kernel_load_debug_module(&mod_driver);
if (status) {
printf("error: load of srtp_driver debug module failed "
"with error code %d\n", status);
exit(1);
}
/* process input arguments */
while (1) {
q = getopt_s(argc, argv, "trcvld:");
if (q == -1)
break;
switch (q) {
case 't':
do_timing_test = 1;
break;
case 'r':
do_rejection_test = 1;
break;
case 'c':
do_codec_timing = 1;
break;
case 'v':
do_validation = 1;
break;
case 'l':
do_list_mods = 1;
break;
case 'd':
status = crypto_kernel_set_debug_module(optarg_s, 1);
if (status) {
printf("error: set debug module (%s) failed\n", optarg_s);
exit(1);
}
break;
default:
usage(argv[0]);
}
}
if (!do_validation && !do_timing_test && !do_codec_timing
&& !do_list_mods && !do_rejection_test)
usage(argv[0]);
if (do_list_mods) {
status = crypto_kernel_list_debug_modules();
if (status) {
printf("error: list of debug modules failed\n");
exit(1);
}
}
if (do_validation) {
const srtp_policy_t **policy = policy_array;
srtp_policy_t *big_policy;
/* loop over policy array, testing srtp and srtcp for each policy */
while (*policy != NULL) {
printf("testing srtp_protect and srtp_unprotect\n");
if (srtp_test(*policy) == err_status_ok)
printf("passed\n\n");
else {
printf("failed\n");
exit(1);
}
printf("testing srtp_protect_rtcp and srtp_unprotect_rtcp\n");
if (srtcp_test(*policy) == err_status_ok)
printf("passed\n\n");
else {
printf("failed\n");
exit(1);
}
policy++;
}
/* create a big policy list and run tests on it */
status = srtp_create_big_policy(&big_policy);
if (status) {
printf("unexpected failure with error code %d\n", status);
exit(1);
}
printf("testing srtp_protect and srtp_unprotect with big policy\n");
if (srtp_test(big_policy) == err_status_ok)
printf("passed\n\n");
else {
printf("failed\n");
exit(1);
}
status = srtp_dealloc_big_policy(big_policy);
if (status) {
printf("unexpected failure with error code %d\n", status);
exit(1);
}
/* run test on wildcard policy */
printf("testing srtp_protect and srtp_unprotect on "
"wildcard ssrc policy\n");
if (srtp_test(&wildcard_policy) == err_status_ok)
printf("passed\n\n");
else {
printf("failed\n");
exit(1);
}
/*
* run validation test against the reference packets - note
* that this test only covers the default policy
*/
printf("testing srtp_protect and srtp_unprotect against "
"reference packets\n");
if (srtp_validate() == err_status_ok)
printf("passed\n\n");
else {
printf("failed\n");
exit(1);
}
//FIXME: need to get this working with the OpenSSL AES module
#ifndef OPENSSL
/*
* run validation test against the reference packets for
* AES-256
*/
printf("testing srtp_protect and srtp_unprotect against "
"reference packets (AES-256)\n");
if (srtp_validate_aes_256() == err_status_ok)
printf("passed\n\n");
else {
printf("failed\n");
exit(1);
}
#endif
/*
* test the function srtp_remove_stream()
*/
printf("testing srtp_remove_stream()...");
if (srtp_test_remove_stream() == err_status_ok)
printf("passed\n");
else {
printf("failed\n");
exit(1);
}
}
if (do_timing_test) {
const srtp_policy_t **policy = policy_array;
/* loop over policies, run timing test for each */
while (*policy != NULL) {
srtp_print_policy(*policy);
srtp_do_timing(*policy);
policy++;
}
}
if (do_rejection_test) {
const srtp_policy_t **policy = policy_array;
/* loop over policies, run rejection timing test for each */
while (*policy != NULL) {
srtp_print_policy(*policy);
srtp_do_rejection_timing(*policy);
policy++;
}
}
if (do_codec_timing) {
srtp_policy_t policy;
int ignore;
double mips = mips_estimate(1000000000, &ignore);
crypto_policy_set_rtp_default(&policy.rtp);
crypto_policy_set_rtcp_default(&policy.rtcp);
policy.ssrc.type = ssrc_specific;
policy.ssrc.value = 0xdecafbad;
policy.key = test_key;
policy.ekt = NULL;
policy.window_size = 128;
policy.allow_repeat_tx = 0;
policy.next = NULL;
printf("mips estimate: %e\n", mips);
printf("testing srtp processing time for voice codecs:\n");
printf("codec\t\tlength (octets)\t\tsrtp instructions/second\n");
printf("G.711\t\t%d\t\t\t%e\n", 80,
(double) mips * (80 * 8) /
srtp_bits_per_second(80, &policy) / .01 );
printf("G.711\t\t%d\t\t\t%e\n", 160,
(double) mips * (160 * 8) /
srtp_bits_per_second(160, &policy) / .02);
printf("G.726-32\t%d\t\t\t%e\n", 40,
(double) mips * (40 * 8) /
srtp_bits_per_second(40, &policy) / .01 );
printf("G.726-32\t%d\t\t\t%e\n", 80,
(double) mips * (80 * 8) /
srtp_bits_per_second(80, &policy) / .02);
printf("G.729\t\t%d\t\t\t%e\n", 10,
(double) mips * (10 * 8) /
srtp_bits_per_second(10, &policy) / .01 );
printf("G.729\t\t%d\t\t\t%e\n", 20,
(double) mips * (20 * 8) /
srtp_bits_per_second(20, &policy) / .02 );
printf("Wideband\t%d\t\t\t%e\n", 320,
(double) mips * (320 * 8) /
srtp_bits_per_second(320, &policy) / .01 );
printf("Wideband\t%d\t\t\t%e\n", 640,
(double) mips * (640 * 8) /
srtp_bits_per_second(640, &policy) / .02 );
}
status = srtp_shutdown();
if (status) {
printf("error: srtp shutdown failed with error code %d\n", status);
exit(1);
}
return 0;
}
/*
* srtp_create_test_packet(len, ssrc) returns a pointer to a
* (malloced) example RTP packet whose data field has the length given
* by pkt_octet_len and the SSRC value ssrc. The total length of the
* packet is twelve octets longer, since the header is at the
* beginning. There is room at the end of the packet for a trailer,
* and the four octets following the packet are filled with 0xff
* values to enable testing for overwrites.
*
* note that the location of the test packet can (and should) be
* deallocated with the free() call once it is no longer needed.
*/
srtp_hdr_t *
srtp_create_test_packet(int pkt_octet_len, uint32_t ssrc) {
int i;
uint8_t *buffer;
srtp_hdr_t *hdr;
int bytes_in_hdr = 12;
/* allocate memory for test packet */
hdr = (srtp_hdr_t*) malloc(pkt_octet_len + bytes_in_hdr
+ SRTP_MAX_TRAILER_LEN + 4);
if (!hdr)
return NULL;
hdr->version = 2; /* RTP version two */
hdr->p = 0; /* no padding needed */
hdr->x = 0; /* no header extension */
hdr->cc = 0; /* no CSRCs */
hdr->m = 0; /* marker bit */
hdr->pt = 0xf; /* payload type */
hdr->seq = htons(0x1234); /* sequence number */
hdr->ts = htonl(0xdecafbad); /* timestamp */
hdr->ssrc = htonl(ssrc); /* synch. source */
buffer = (uint8_t *)hdr;
buffer += bytes_in_hdr;
/* set RTP data to 0xab */
for (i=0; i < pkt_octet_len; i++)
*buffer++ = 0xab;
/* set post-data value to 0xffff to enable overrun checking */
for (i=0; i < SRTP_MAX_TRAILER_LEN+4; i++)
*buffer++ = 0xff;
return hdr;
}
void
srtp_do_timing(const srtp_policy_t *policy) {
int len;
/*
* note: the output of this function is formatted so that it
* can be used in gnuplot. '#' indicates a comment, and "\r\n"
* terminates a record
*/
printf("# testing srtp throughput:\r\n");
printf("# mesg length (octets)\tthroughput (megabits per second)\r\n");
for (len=16; len <= 2048; len *= 2)
printf("%d\t\t\t%f\r\n", len,
srtp_bits_per_second(len, policy) / 1.0E6);
/* these extra linefeeds let gnuplot know that a dataset is done */
printf("\r\n\r\n");
}
void
srtp_do_rejection_timing(const srtp_policy_t *policy) {
int len;
/*
* note: the output of this function is formatted so that it
* can be used in gnuplot. '#' indicates a comment, and "\r\n"
* terminates a record
*/
printf("# testing srtp rejection throughput:\r\n");
printf("# mesg length (octets)\trejections per second\r\n");
for (len=8; len <= 2048; len *= 2)
printf("%d\t\t\t%e\r\n", len, srtp_rejections_per_second(len, policy));
/* these extra linefeeds let gnuplot know that a dataset is done */
printf("\r\n\r\n");
}
#define MAX_MSG_LEN 1024
double
srtp_bits_per_second(int msg_len_octets, const srtp_policy_t *policy) {
srtp_t srtp;
srtp_hdr_t *mesg;
int i;
clock_t timer;
int num_trials = 100000;
int len;
uint32_t ssrc;
err_status_t status;
/*
* allocate and initialize an srtp session
*/
status = srtp_create(&srtp, policy);
if (status) {
printf("error: srtp_create() failed with error code %d\n", status);
exit(1);
}
/*
* if the ssrc is unspecified, use a predetermined one
*/
if (policy->ssrc.type != ssrc_specific) {
ssrc = 0xdeadbeef;
} else {
ssrc = policy->ssrc.value;
}
/*
* create a test packet
*/
mesg = srtp_create_test_packet(msg_len_octets, ssrc);
if (mesg == NULL)
return 0.0; /* indicate failure by returning zero */
timer = clock();
for (i=0; i < num_trials; i++) {
len = msg_len_octets + 12; /* add in rtp header length */
/* srtp protect message */
status = srtp_protect(srtp, mesg, &len);
if (status) {
printf("error: srtp_protect() failed with error code %d\n", status);
exit(1);
}
/* increment message number */
{
/* hack sequence to avoid problems with macros for htons/ntohs on some systems */
short new_seq = ntohs(mesg->seq) + 1;
mesg->seq = htons(new_seq);
}
}
timer = clock() - timer;
free(mesg);
status = srtp_dealloc(srtp);
if (status) {
printf("error: srtp_dealloc() failed with error code %d\n", status);
exit(1);
}
return (double) (msg_len_octets) * 8 *
num_trials * CLOCKS_PER_SEC / timer;
}
double
srtp_rejections_per_second(int msg_len_octets, const srtp_policy_t *policy) {
srtp_ctx_t *srtp;
srtp_hdr_t *mesg;
int i;
int len;
clock_t timer;
int num_trials = 1000000;
uint32_t ssrc = policy->ssrc.value;
err_status_t status;
/*
* allocate and initialize an srtp session
*/
status = srtp_create(&srtp, policy);
if (status) {
printf("error: srtp_create() failed with error code %d\n", status);
exit(1);
}
mesg = srtp_create_test_packet(msg_len_octets, ssrc);
if (mesg == NULL)
return 0.0; /* indicate failure by returning zero */
len = msg_len_octets;
srtp_protect(srtp, (srtp_hdr_t *)mesg, &len);
timer = clock();
for (i=0; i < num_trials; i++) {
len = msg_len_octets;
srtp_unprotect(srtp, (srtp_hdr_t *)mesg, &len);
}
timer = clock() - timer;
free(mesg);
status = srtp_dealloc(srtp);
if (status) {
printf("error: srtp_dealloc() failed with error code %d\n", status);
exit(1);
}
return (double) num_trials * CLOCKS_PER_SEC / timer;
}
void
err_check(err_status_t s) {
if (s == err_status_ok)
return;
else
fprintf(stderr, "error: unexpected srtp failure (code %d)\n", s);
exit (1);
}
err_status_t
srtp_test(const srtp_policy_t *policy) {
int i;
srtp_t srtp_sender;
srtp_t srtp_rcvr;
err_status_t status = err_status_ok;
srtp_hdr_t *hdr, *hdr2;
uint8_t hdr_enc[64];
uint8_t *pkt_end;
int msg_len_octets, msg_len_enc;
int len;
int tag_length = policy->rtp.auth_tag_len;
uint32_t ssrc;
srtp_policy_t *rcvr_policy;
err_check(srtp_create(&srtp_sender, policy));
/* print out policy */
err_check(srtp_session_print_policy(srtp_sender));
/*
* initialize data buffer, using the ssrc in the policy unless that
* value is a wildcard, in which case we'll just use an arbitrary
* one
*/
if (policy->ssrc.type != ssrc_specific)
ssrc = 0xdecafbad;
else
ssrc = policy->ssrc.value;
msg_len_octets = 28;
hdr = srtp_create_test_packet(msg_len_octets, ssrc);
if (hdr == NULL)
return err_status_alloc_fail;
hdr2 = srtp_create_test_packet(msg_len_octets, ssrc);
if (hdr2 == NULL) {
free(hdr);
return err_status_alloc_fail;
}
/* set message length */
len = msg_len_octets;
debug_print(mod_driver, "before protection:\n%s",
srtp_packet_to_string(hdr, len));
#if PRINT_REFERENCE_PACKET
debug_print(mod_driver, "reference packet before protection:\n%s",
octet_string_hex_string((uint8_t *)hdr, len));
#endif
err_check(srtp_protect(srtp_sender, hdr, &len));
debug_print(mod_driver, "after protection:\n%s",
srtp_packet_to_string(hdr, len));
#if PRINT_REFERENCE_PACKET
debug_print(mod_driver, "after protection:\n%s",
octet_string_hex_string((uint8_t *)hdr, len));
#endif
/* save protected message and length */
memcpy(hdr_enc, hdr, len);
msg_len_enc = len;
/*
* check for overrun of the srtp_protect() function
*
* The packet is followed by a value of 0xfffff; if the value of the
* data following the packet is different, then we know that the
* protect function is overwriting the end of the packet.
*/
pkt_end = (uint8_t *)hdr + sizeof(srtp_hdr_t)
+ msg_len_octets + tag_length;
for (i = 0; i < 4; i++)
if (pkt_end[i] != 0xff) {
fprintf(stdout, "overwrite in srtp_protect() function "
"(expected %x, found %x in trailing octet %d)\n",
0xff, ((uint8_t *)hdr)[i], i);
free(hdr);
free(hdr2);
return err_status_algo_fail;
}
/*
* if the policy includes confidentiality, check that ciphertext is
* different than plaintext
*
* Note that this check will give false negatives, with some small
* probability, especially if the packets are short. For that
* reason, we skip this check if the plaintext is less than four
* octets long.
*/
if ((policy->rtp.sec_serv & sec_serv_conf) && (msg_len_octets >= 4)) {
printf("testing that ciphertext is distinct from plaintext...");
status = err_status_algo_fail;
for (i=12; i < msg_len_octets+12; i++)
if (((uint8_t *)hdr)[i] != ((uint8_t *)hdr2)[i]) {
status = err_status_ok;
}
if (status) {
printf("failed\n");
free(hdr);
free(hdr2);
return status;
}
printf("passed\n");
}
/*
* if the policy uses a 'wildcard' ssrc, then we need to make a copy
* of the policy that changes the direction to inbound
*
* we always copy the policy into the rcvr_policy, since otherwise
* the compiler would fret about the constness of the policy
*/
rcvr_policy = (srtp_policy_t*) malloc(sizeof(srtp_policy_t));
if (rcvr_policy == NULL) {
free(hdr);
free(hdr2);
return err_status_alloc_fail;
}
memcpy(rcvr_policy, policy, sizeof(srtp_policy_t));
if (policy->ssrc.type == ssrc_any_outbound) {
rcvr_policy->ssrc.type = ssrc_any_inbound;
}
err_check(srtp_create(&srtp_rcvr, rcvr_policy));
err_check(srtp_unprotect(srtp_rcvr, hdr, &len));
debug_print(mod_driver, "after unprotection:\n%s",
srtp_packet_to_string(hdr, len));
/* verify that the unprotected packet matches the origial one */
for (i=0; i < msg_len_octets; i++)
if (((uint8_t *)hdr)[i] != ((uint8_t *)hdr2)[i]) {
fprintf(stdout, "mismatch at octet %d\n", i);
status = err_status_algo_fail;
}
if (status) {
free(hdr);
free(hdr2);
free(rcvr_policy);
return status;
}
/*
* if the policy includes authentication, then test for false positives
*/
if (policy->rtp.sec_serv & sec_serv_auth) {
char *data = ((char *)hdr) + 12;
printf("testing for false positives in replay check...");
/* set message length */
len = msg_len_enc;
/* unprotect a second time - should fail with a replay error */
status = srtp_unprotect(srtp_rcvr, hdr_enc, &len);
if (status != err_status_replay_fail) {
printf("failed with error code %d\n", status);
free(hdr);
free(hdr2);
free(rcvr_policy);
return status;
} else {
printf("passed\n");
}
printf("testing for false positives in auth check...");
/* increment sequence number in header */
hdr->seq++;
/* set message length */
len = msg_len_octets;
/* apply protection */
err_check(srtp_protect(srtp_sender, hdr, &len));
/* flip bits in packet */
data[0] ^= 0xff;
/* unprotect, and check for authentication failure */
status = srtp_unprotect(srtp_rcvr, hdr, &len);
if (status != err_status_auth_fail) {
printf("failed\n");
free(hdr);
free(hdr2);
free(rcvr_policy);
return status;
} else {
printf("passed\n");
}
}
err_check(srtp_dealloc(srtp_sender));
err_check(srtp_dealloc(srtp_rcvr));
free(hdr);
free(hdr2);
free(rcvr_policy);
return err_status_ok;
}
err_status_t
srtcp_test(const srtp_policy_t *policy) {
int i;
srtp_t srtcp_sender;
srtp_t srtcp_rcvr;
err_status_t status = err_status_ok;
srtp_hdr_t *hdr, *hdr2;
uint8_t hdr_enc[64];
uint8_t *pkt_end;
int msg_len_octets, msg_len_enc;
int len;
int tag_length = policy->rtp.auth_tag_len;
uint32_t ssrc;
srtp_policy_t *rcvr_policy;
err_check(srtp_create(&srtcp_sender, policy));
/* print out policy */
err_check(srtp_session_print_policy(srtcp_sender));
/*
* initialize data buffer, using the ssrc in the policy unless that
* value is a wildcard, in which case we'll just use an arbitrary
* one
*/
if (policy->ssrc.type != ssrc_specific)
ssrc = 0xdecafbad;
else
ssrc = policy->ssrc.value;
msg_len_octets = 28;
hdr = srtp_create_test_packet(msg_len_octets, ssrc);
if (hdr == NULL)
return err_status_alloc_fail;
hdr2 = srtp_create_test_packet(msg_len_octets, ssrc);
if (hdr2 == NULL) {
free(hdr);
return err_status_alloc_fail;
}
/* set message length */
len = msg_len_octets;
debug_print(mod_driver, "before protection:\n%s",
srtp_packet_to_string(hdr, len));
#if PRINT_REFERENCE_PACKET
debug_print(mod_driver, "reference packet before protection:\n%s",
octet_string_hex_string((uint8_t *)hdr, len));
#endif
err_check(srtp_protect_rtcp(srtcp_sender, hdr, &len));
debug_print(mod_driver, "after protection:\n%s",
srtp_packet_to_string(hdr, len));
#if PRINT_REFERENCE_PACKET
debug_print(mod_driver, "after protection:\n%s",
octet_string_hex_string((uint8_t *)hdr, len));
#endif
/* save protected message and length */
memcpy(hdr_enc, hdr, len);
msg_len_enc = len;
/*
* check for overrun of the srtp_protect() function
*
* The packet is followed by a value of 0xfffff; if the value of the
* data following the packet is different, then we know that the
* protect function is overwriting the end of the packet.
*/
pkt_end = (uint8_t *)hdr + sizeof(srtp_hdr_t)
+ msg_len_octets + tag_length;
for (i = 0; i < 4; i++)
if (pkt_end[i] != 0xff) {
fprintf(stdout, "overwrite in srtp_protect_rtcp() function "
"(expected %x, found %x in trailing octet %d)\n",
0xff, ((uint8_t *)hdr)[i], i);
free(hdr);
free(hdr2);
return err_status_algo_fail;
}
/*
* if the policy includes confidentiality, check that ciphertext is
* different than plaintext
*
* Note that this check will give false negatives, with some small
* probability, especially if the packets are short. For that
* reason, we skip this check if the plaintext is less than four
* octets long.
*/
if ((policy->rtp.sec_serv & sec_serv_conf) && (msg_len_octets >= 4)) {
printf("testing that ciphertext is distinct from plaintext...");
status = err_status_algo_fail;
for (i=12; i < msg_len_octets+12; i++)
if (((uint8_t *)hdr)[i] != ((uint8_t *)hdr2)[i]) {
status = err_status_ok;
}
if (status) {
printf("failed\n");
free(hdr);
free(hdr2);
return status;
}
printf("passed\n");
}
/*
* if the policy uses a 'wildcard' ssrc, then we need to make a copy
* of the policy that changes the direction to inbound
*
* we always copy the policy into the rcvr_policy, since otherwise
* the compiler would fret about the constness of the policy
*/
rcvr_policy = (srtp_policy_t*) malloc(sizeof(srtp_policy_t));
if (rcvr_policy == NULL)
return err_status_alloc_fail;
memcpy(rcvr_policy, policy, sizeof(srtp_policy_t));
if (policy->ssrc.type == ssrc_any_outbound) {
rcvr_policy->ssrc.type = ssrc_any_inbound;
}
err_check(srtp_create(&srtcp_rcvr, rcvr_policy));
err_check(srtp_unprotect_rtcp(srtcp_rcvr, hdr, &len));
debug_print(mod_driver, "after unprotection:\n%s",
srtp_packet_to_string(hdr, len));
/* verify that the unprotected packet matches the origial one */
for (i=0; i < msg_len_octets; i++)
if (((uint8_t *)hdr)[i] != ((uint8_t *)hdr2)[i]) {
fprintf(stdout, "mismatch at octet %d\n", i);
status = err_status_algo_fail;
}
if (status) {
free(hdr);
free(hdr2);
free(rcvr_policy);
return status;
}
/*
* if the policy includes authentication, then test for false positives
*/
if (policy->rtp.sec_serv & sec_serv_auth) {
char *data = ((char *)hdr) + 12;
printf("testing for false positives in replay check...");
/* set message length */
len = msg_len_enc;
/* unprotect a second time - should fail with a replay error */
status = srtp_unprotect_rtcp(srtcp_rcvr, hdr_enc, &len);
if (status != err_status_replay_fail) {
printf("failed with error code %d\n", status);
free(hdr);
free(hdr2);
free(rcvr_policy);
return status;
} else {
printf("passed\n");
}
printf("testing for false positives in auth check...");
/* increment sequence number in header */
hdr->seq++;
/* set message length */
len = msg_len_octets;
/* apply protection */
err_check(srtp_protect_rtcp(srtcp_sender, hdr, &len));
/* flip bits in packet */
data[0] ^= 0xff;