Mon Oct 8 12:39:29 2012

Asterisk developer's documentation


sdp_crypto.c File Reference

SDP Security descriptions. More...

#include "asterisk.h"
#include "asterisk/options.h"
#include "asterisk/utils.h"
#include "include/sdp_crypto.h"

Go to the source code of this file.

Data Structures

struct  sdp_crypto

Defines

#define SRTP_MASTER_LEN   30
#define SRTP_MASTER_LEN64   (((SRTP_MASTER_LEN) * 8 + 5) / 6 + 1)
#define SRTP_MASTERKEY_LEN   16
#define SRTP_MASTERSALT_LEN   ((SRTP_MASTER_LEN) - (SRTP_MASTERKEY_LEN))

Functions

static int sdp_crypto_activate (struct sdp_crypto *p, int suite_val, unsigned char *remote_key, struct ast_rtp_instance *rtp)
static struct sdp_cryptosdp_crypto_alloc (void)
const char * sdp_crypto_attrib (struct sdp_crypto *p)
void sdp_crypto_destroy (struct sdp_crypto *crypto)
int sdp_crypto_offer (struct sdp_crypto *p)
int sdp_crypto_process (struct sdp_crypto *p, const char *attr, struct ast_rtp_instance *rtp)
sdp_cryptosdp_crypto_setup (void)
static int set_crypto_policy (struct ast_srtp_policy *policy, int suite_val, const unsigned char *master_key, unsigned long ssrc, int inbound)

Variables

ast_srtp_resres_srtp
ast_srtp_policy_resres_srtp_policy


Detailed Description

SDP Security descriptions.

Specified in RFC 4568

Author:
Mikael Magnusson <mikma@users.sourceforge.net>

Definition in file sdp_crypto.c.


Define Documentation

#define SRTP_MASTER_LEN   30

Definition at line 40 of file sdp_crypto.c.

Referenced by sdp_crypto_process(), and sdp_crypto_setup().

#define SRTP_MASTER_LEN64   (((SRTP_MASTER_LEN) * 8 + 5) / 6 + 1)

Definition at line 43 of file sdp_crypto.c.

#define SRTP_MASTERKEY_LEN   16

Definition at line 41 of file sdp_crypto.c.

Referenced by set_crypto_policy().

#define SRTP_MASTERSALT_LEN   ((SRTP_MASTER_LEN) - (SRTP_MASTERKEY_LEN))

Definition at line 42 of file sdp_crypto.c.

Referenced by set_crypto_policy().


Function Documentation

static int sdp_crypto_activate ( struct sdp_crypto p,
int  suite_val,
unsigned char *  remote_key,
struct ast_rtp_instance rtp 
) [static]

Definition at line 133 of file sdp_crypto.c.

References ast_srtp_policy_res::alloc, ast_debug, ast_log(), ast_rtp_engine_srtp_is_registered(), ast_rtp_instance_add_srtp_policy(), ast_rtp_instance_get_stats(), AST_RTP_INSTANCE_STAT_LOCAL_SSRC, ast_srtp_policy_res::destroy, sdp_crypto::local_key, ast_rtp_instance_stats::local_ssrc, LOG_WARNING, res_srtp_policy, and set_crypto_policy().

Referenced by sdp_crypto_process().

00134 {
00135    struct ast_srtp_policy *local_policy = NULL;
00136    struct ast_srtp_policy *remote_policy = NULL;
00137    struct ast_rtp_instance_stats stats = {0,};
00138    int res = -1;
00139 
00140    if (!ast_rtp_engine_srtp_is_registered()) {
00141       return -1;
00142    }
00143 
00144    if (!p) {
00145       return -1;
00146    }
00147 
00148    if (!(local_policy = res_srtp_policy->alloc())) {
00149       return -1;
00150    }
00151 
00152    if (!(remote_policy = res_srtp_policy->alloc())) {
00153       goto err;
00154    }
00155 
00156    if (ast_rtp_instance_get_stats(rtp, &stats, AST_RTP_INSTANCE_STAT_LOCAL_SSRC)) {
00157       goto err;
00158    }
00159 
00160    if (set_crypto_policy(local_policy, suite_val, p->local_key, stats.local_ssrc, 0) < 0) {
00161       goto err;
00162    }
00163 
00164    if (set_crypto_policy(remote_policy, suite_val, remote_key, 0, 1) < 0) {
00165       goto err;
00166    }
00167 
00168    /* Add the SRTP policies */
00169    if (ast_rtp_instance_add_srtp_policy(rtp, remote_policy, local_policy)) {
00170       ast_log(LOG_WARNING, "Could not set SRTP policies\n");
00171       goto err;
00172    }
00173 
00174    ast_debug(1 , "SRTP policy activated\n");
00175    res = 0;
00176 
00177 err:
00178    if (local_policy) {
00179       res_srtp_policy->destroy(local_policy);
00180    }
00181 
00182    if (remote_policy) {
00183       res_srtp_policy->destroy(remote_policy);
00184    }
00185 
00186    return res;
00187 }

static struct sdp_crypto* sdp_crypto_alloc ( void   )  [static]

Definition at line 58 of file sdp_crypto.c.

References ast_calloc.

Referenced by sdp_crypto_setup().

00059 {
00060    return ast_calloc(1, sizeof(struct sdp_crypto));
00061 }

const char* sdp_crypto_attrib ( struct sdp_crypto p  ) 

Definition at line 314 of file sdp_crypto.c.

References sdp_crypto::a_crypto.

Referenced by get_crypto_attrib().

00315 {
00316    return p->a_crypto;
00317 }

void sdp_crypto_destroy ( struct sdp_crypto crypto  ) 

Definition at line 63 of file sdp_crypto.c.

References sdp_crypto::a_crypto, and ast_free.

Referenced by sdp_crypto_setup(), and sip_srtp_destroy().

00064 {
00065    ast_free(crypto->a_crypto);
00066    crypto->a_crypto = NULL;
00067    ast_free(crypto);
00068 }

int sdp_crypto_offer ( struct sdp_crypto p  ) 

Definition at line 290 of file sdp_crypto.c.

References sdp_crypto::a_crypto, ast_free, ast_strdup, ast_strlen_zero(), sdp_crypto::local_key64, and sdp_crypto::suite.

Referenced by get_crypto_attrib().

00291 {
00292    char crypto_buf[128];
00293 
00294    if (ast_strlen_zero(p->suite)) {
00295       /* Default crypto offer */
00296       strcpy(p->suite, "AES_CM_128_HMAC_SHA1_80");
00297    }
00298 
00299    if (p->a_crypto) {
00300       ast_free(p->a_crypto);
00301    }
00302 
00303    if (snprintf(crypto_buf, sizeof(crypto_buf), "a=crypto:1 %s inline:%s\r\n",  p->suite, p->local_key64) < 1) {
00304       return -1;
00305    }
00306 
00307    if (!(p->a_crypto = ast_strdup(crypto_buf))) {
00308       return -1;
00309    }
00310 
00311    return 0;
00312 }

int sdp_crypto_process ( struct sdp_crypto p,
const char *  attr,
struct ast_rtp_instance rtp 
)

Definition at line 189 of file sdp_crypto.c.

References sdp_crypto::a_crypto, AST_AES_CM_128_HMAC_SHA1_32, AST_AES_CM_128_HMAC_SHA1_80, ast_base64decode(), ast_calloc, ast_copy_string(), ast_debug, ast_log(), ast_rtp_engine_srtp_is_registered(), ast_strdupa, sdp_crypto::local_key64, LOG_ERROR, LOG_NOTICE, LOG_WARNING, sdp_crypto::remote_key, sdp_crypto_activate(), SRTP_MASTER_LEN, str, strsep(), and sdp_crypto::suite.

Referenced by process_crypto().

00190 {
00191    char *str = NULL;
00192    char *tag = NULL;
00193    char *suite = NULL;
00194    char *key_params = NULL;
00195    char *key_param = NULL;
00196    char *session_params = NULL;
00197    char *key_salt = NULL;
00198    char *lifetime = NULL;
00199    int found = 0;
00200    int attr_len = strlen(attr);
00201    int key_len = 0;
00202    int suite_val = 0;
00203    unsigned char remote_key[SRTP_MASTER_LEN];
00204 
00205    if (!ast_rtp_engine_srtp_is_registered()) {
00206       return -1;
00207    }
00208 
00209    str = ast_strdupa(attr);
00210 
00211    strsep(&str, ":");
00212    tag = strsep(&str, " ");
00213    suite = strsep(&str, " ");
00214    key_params = strsep(&str, " ");
00215    session_params = strsep(&str, " ");
00216 
00217    if (!tag || !suite) {
00218       ast_log(LOG_WARNING, "Unrecognized a=%s", attr);
00219       return -1;
00220    }
00221 
00222    if (session_params) {
00223       ast_log(LOG_WARNING, "Unsupported crypto parameters: %s", session_params);
00224       return -1;
00225    }
00226 
00227    if (!strcmp(suite, "AES_CM_128_HMAC_SHA1_80")) {
00228       suite_val = AST_AES_CM_128_HMAC_SHA1_80;
00229    } else if (!strcmp(suite, "AES_CM_128_HMAC_SHA1_32")) {
00230       suite_val = AST_AES_CM_128_HMAC_SHA1_32;
00231    } else {
00232       ast_log(LOG_WARNING, "Unsupported crypto suite: %s\n", suite);
00233       return -1;
00234    }
00235 
00236    while ((key_param = strsep(&key_params, ";"))) {
00237       char *method = NULL;
00238       char *info = NULL;
00239 
00240       method = strsep(&key_param, ":");
00241       info = strsep(&key_param, ";");
00242 
00243       if (!strcmp(method, "inline")) {
00244          key_salt = strsep(&info, "|");
00245          lifetime = strsep(&info, "|");
00246 
00247          if (lifetime) {
00248             ast_log(LOG_NOTICE, "Crypto life time unsupported: %s\n", attr);
00249             continue;
00250          }
00251 
00252          found = 1;
00253          break;
00254       }
00255    }
00256 
00257    if (!found) {
00258       ast_log(LOG_NOTICE, "SRTP crypto offer not acceptable\n");
00259       return -1;
00260    }
00261 
00262    if ((key_len = ast_base64decode(remote_key, key_salt, sizeof(remote_key))) != SRTP_MASTER_LEN) {
00263       ast_log(LOG_WARNING, "SRTP descriptions key %d != %d\n", key_len, SRTP_MASTER_LEN);
00264       return -1;
00265    }
00266 
00267    if (!memcmp(p->remote_key, remote_key, sizeof(p->remote_key))) {
00268       ast_debug(1, "SRTP remote key unchanged; maintaining current policy\n");
00269       return 0;
00270    }
00271 
00272    /* Set the accepted policy and remote key */
00273    ast_copy_string(p->suite, suite, sizeof(p->suite));
00274    memcpy(p->remote_key, remote_key, sizeof(p->remote_key));
00275 
00276    if (sdp_crypto_activate(p, suite_val, remote_key, rtp) < 0) {
00277       return -1;
00278    }
00279 
00280    if (!p->a_crypto) {
00281       if (!(p->a_crypto = ast_calloc(1, attr_len + 11))) {
00282          ast_log(LOG_ERROR, "Could not allocate memory for a_crypto\n");
00283          return -1;
00284       }
00285       snprintf(p->a_crypto, attr_len + 10, "a=crypto:%s %s inline:%s\r\n", tag, suite, p->local_key64);
00286    }
00287    return 0;
00288 }

struct sdp_crypto* sdp_crypto_setup ( void   ) 

Definition at line 70 of file sdp_crypto.c.

References ast_base64decode(), ast_base64encode(), ast_debug, ast_free, ast_log(), ast_rtp_engine_srtp_is_registered(), ast_srtp_res::get_random, sdp_crypto::local_key, sdp_crypto::local_key64, LOG_ERROR, sdp_crypto::remote_key, res_srtp, sdp_crypto_alloc(), sdp_crypto_destroy(), and SRTP_MASTER_LEN.

Referenced by get_crypto_attrib(), and process_crypto().

00071 {
00072    struct sdp_crypto *p;
00073    int key_len;
00074    unsigned char remote_key[SRTP_MASTER_LEN];
00075 
00076    if (!ast_rtp_engine_srtp_is_registered()) {
00077       return NULL;
00078    }
00079 
00080    if (!(p = sdp_crypto_alloc())) {
00081       return NULL;
00082    }
00083 
00084    if (res_srtp->get_random(p->local_key, sizeof(p->local_key)) < 0) {
00085       sdp_crypto_destroy(p);
00086       return NULL;
00087    }
00088 
00089    ast_base64encode(p->local_key64, p->local_key, SRTP_MASTER_LEN, sizeof(p->local_key64));
00090 
00091    key_len = ast_base64decode(remote_key, p->local_key64, sizeof(remote_key));
00092 
00093    if (key_len != SRTP_MASTER_LEN) {
00094       ast_log(LOG_ERROR, "base64 encode/decode bad len %d != %d\n", key_len, SRTP_MASTER_LEN);
00095       ast_free(p);
00096       return NULL;
00097    }
00098 
00099    if (memcmp(remote_key, p->local_key, SRTP_MASTER_LEN)) {
00100       ast_log(LOG_ERROR, "base64 encode/decode bad key\n");
00101       ast_free(p);
00102       return NULL;
00103    }
00104 
00105    ast_debug(1 , "local_key64 %s len %zu\n", p->local_key64, strlen(p->local_key64));
00106 
00107    return p;
00108 }

static int set_crypto_policy ( struct ast_srtp_policy policy,
int  suite_val,
const unsigned char *  master_key,
unsigned long  ssrc,
int  inbound 
) [static]

Definition at line 110 of file sdp_crypto.c.

References ast_log(), ast_rtp_engine_srtp_is_registered(), LOG_WARNING, res_srtp_policy, ast_srtp_policy_res::set_master_key, ast_srtp_policy_res::set_ssrc, ast_srtp_policy_res::set_suite, SRTP_MASTERKEY_LEN, and SRTP_MASTERSALT_LEN.

Referenced by sdp_crypto_activate().

00111 {
00112    const unsigned char *master_salt = NULL;
00113 
00114    if (!ast_rtp_engine_srtp_is_registered()) {
00115       return -1;
00116    }
00117 
00118    master_salt = master_key + SRTP_MASTERKEY_LEN;
00119    if (res_srtp_policy->set_master_key(policy, master_key, SRTP_MASTERKEY_LEN, master_salt, SRTP_MASTERSALT_LEN) < 0) {
00120       return -1;
00121    }
00122 
00123    if (res_srtp_policy->set_suite(policy, suite_val)) {
00124       ast_log(LOG_WARNING, "Could not set remote SRTP suite\n");
00125       return -1;
00126    }
00127 
00128    res_srtp_policy->set_ssrc(policy, ssrc, inbound);
00129 
00130    return 0;
00131 }


Variable Documentation

struct ast_srtp_res* res_srtp

Definition at line 48 of file rtp_engine.c.

Referenced by __rtp_recvfrom(), __rtp_sendto(), ast_rtp_change_source(), ast_rtp_engine_register_srtp(), ast_rtp_engine_srtp_is_registered(), ast_rtp_engine_unregister_srtp(), ast_rtp_instance_add_srtp_policy(), instance_destructor(), and sdp_crypto_setup().

struct ast_srtp_policy_res* res_srtp_policy

Definition at line 49 of file rtp_engine.c.

Referenced by ast_rtp_engine_register_srtp(), ast_rtp_engine_srtp_is_registered(), ast_rtp_engine_unregister_srtp(), sdp_crypto_activate(), and set_crypto_policy().


Generated on Mon Oct 8 12:39:29 2012 for Asterisk - The Open Source Telephony Project by  doxygen 1.4.7