1 files changed, 225 insertions, 20 deletions

diff --git a/src/ssl/d1_srtp.c b/src/ssl/d1_srtp.c
index 2fcc1ea..5928fc8 100644
--- a/src/ssl/d1_srtp.c
+++ b/src/ssl/d1_srtp.c
@@ -114,8 +114,6 @@
   Copyright (C) 2011, RTFM, Inc.
 */
 
-#include <openssl/ssl.h>
-
 #include <stdio.h>
 #include <string.h>
 
@@ -124,14 +122,15 @@
 #include <openssl/obj.h>
 
 #include "internal.h"
+#include <openssl/srtp.h>
 
 
-const SRTP_PROTECTION_PROFILE kSRTPProfiles[] = {
+static const SRTP_PROTECTION_PROFILE srtp_known_profiles[] = {
     {
-        "SRTP_AES128_CM_SHA1_80", SRTP_AES128_CM_SHA1_80,
+     "SRTP_AES128_CM_SHA1_80", SRTP_AES128_CM_SHA1_80,
     },
     {
-        "SRTP_AES128_CM_SHA1_32", SRTP_AES128_CM_SHA1_32,
+     "SRTP_AES128_CM_SHA1_32", SRTP_AES128_CM_SHA1_32,
     },
     {0},
 };
@@ -141,7 +140,7 @@ static int find_profile_by_name(const char *profile_name,
                                 size_t len) {
   const SRTP_PROTECTION_PROFILE *p;
 
-  p = kSRTPProfiles;
+  p = srtp_known_profiles;
   while (p->name) {
     if (len == strlen(p->name) && !strncmp(p->name, profile_name, len)) {
       *pptr = p;
@@ -154,6 +153,22 @@ static int find_profile_by_name(const char *profile_name,
   return 0;
 }
 
+static int find_profile_by_num(unsigned profile_num,
+                               const SRTP_PROTECTION_PROFILE **pptr) {
+  const SRTP_PROTECTION_PROFILE *p;
+
+  p = srtp_known_profiles;
+  while (p->name) {
+    if (p->id == profile_num) {
+      *pptr = p;
+      return 1;
+    }
+    p++;
+  }
+
+  return 0;
+}
+
 static int ssl_ctx_make_profiles(const char *profiles_string,
                                  STACK_OF(SRTP_PROTECTION_PROFILE) **out) {
   STACK_OF(SRTP_PROTECTION_PROFILE) *profiles;
@@ -163,7 +178,8 @@ static int ssl_ctx_make_profiles(const char *profiles_string,
 
   profiles = sk_SRTP_PROTECTION_PROFILE_new_null();
   if (profiles == NULL) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_SRTP_COULD_NOT_ALLOCATE_PROFILES);
+    OPENSSL_PUT_ERROR(SSL, ssl_ctx_make_profiles,
+                      SSL_R_SRTP_COULD_NOT_ALLOCATE_PROFILES);
     return 0;
   }
 
@@ -174,7 +190,8 @@ static int ssl_ctx_make_profiles(const char *profiles_string,
     if (find_profile_by_name(ptr, &p, col ? col - ptr : strlen(ptr))) {
       sk_SRTP_PROTECTION_PROFILE_push(profiles, p);
     } else {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_SRTP_UNKNOWN_PROTECTION_PROFILE);
+      OPENSSL_PUT_ERROR(SSL, ssl_ctx_make_profiles,
+                        SSL_R_SRTP_UNKNOWN_PROTECTION_PROFILE);
       return 0;
     }
 
@@ -192,28 +209,28 @@ int SSL_CTX_set_srtp_profiles(SSL_CTX *ctx, const char *profiles) {
   return ssl_ctx_make_profiles(profiles, &ctx->srtp_profiles);
 }
 
-int SSL_set_srtp_profiles(SSL *ssl, const char *profiles) {
-  return ssl_ctx_make_profiles(profiles, &ssl->srtp_profiles);
+int SSL_set_srtp_profiles(SSL *s, const char *profiles) {
+  return ssl_ctx_make_profiles(profiles, &s->srtp_profiles);
 }
 
-STACK_OF(SRTP_PROTECTION_PROFILE) *SSL_get_srtp_profiles(SSL *ssl) {
-  if (ssl == NULL) {
+STACK_OF(SRTP_PROTECTION_PROFILE) *SSL_get_srtp_profiles(SSL *s) {
+  if (s == NULL) {
     return NULL;
   }
 
-  if (ssl->srtp_profiles != NULL) {
-    return ssl->srtp_profiles;
+  if (s->srtp_profiles != NULL) {
+    return s->srtp_profiles;
   }
 
-  if (ssl->ctx != NULL && ssl->ctx->srtp_profiles != NULL) {
-    return ssl->ctx->srtp_profiles;
+  if (s->ctx != NULL && s->ctx->srtp_profiles != NULL) {
+    return s->ctx->srtp_profiles;
   }
 
   return NULL;
 }
 
-const SRTP_PROTECTION_PROFILE *SSL_get_selected_srtp_profile(SSL *ssl) {
-  return ssl->srtp_profile;
+const SRTP_PROTECTION_PROFILE *SSL_get_selected_srtp_profile(SSL *s) {
+  return s->srtp_profile;
 }
 
 int SSL_CTX_set_tlsext_use_srtp(SSL_CTX *ctx, const char *profiles) {
@@ -221,7 +238,195 @@ int SSL_CTX_set_tlsext_use_srtp(SSL_CTX *ctx, const char *profiles) {
   return !SSL_CTX_set_srtp_profiles(ctx, profiles);
 }
 
-int SSL_set_tlsext_use_srtp(SSL *ssl, const char *profiles) {
+int SSL_set_tlsext_use_srtp(SSL *s, const char *profiles) {
   /* This API inverts its return value. */
-  return !SSL_set_srtp_profiles(ssl, profiles);
+  return !SSL_set_srtp_profiles(s, profiles);
+}
+
+/* Note: this function returns 0 length if there are no profiles specified */
+int ssl_add_clienthello_use_srtp_ext(SSL *s, uint8_t *p, int *len, int maxlen) {
+  int ct = 0;
+  int i;
+  STACK_OF(SRTP_PROTECTION_PROFILE) *clnt = 0;
+  const SRTP_PROTECTION_PROFILE *prof;
+
+  clnt = SSL_get_srtp_profiles(s);
+  ct = sk_SRTP_PROTECTION_PROFILE_num(clnt); /* -1 if clnt == 0 */
+
+  if (p) {
+    if (ct == 0) {
+      OPENSSL_PUT_ERROR(SSL, ssl_add_clienthello_use_srtp_ext,
+                        SSL_R_EMPTY_SRTP_PROTECTION_PROFILE_LIST);
+      return 0;
+    }
+
+    if (2 + ct * 2 + 1 > maxlen) {
+      OPENSSL_PUT_ERROR(SSL, ssl_add_clienthello_use_srtp_ext,
+                        SSL_R_SRTP_PROTECTION_PROFILE_LIST_TOO_LONG);
+      return 0;
+    }
+
+    /* Add the length */
+    s2n(ct * 2, p);
+    for (i = 0; i < ct; i++) {
+      prof = sk_SRTP_PROTECTION_PROFILE_value(clnt, i);
+      s2n(prof->id, p);
+    }
+
+    /* Add an empty use_mki value */
+    *p++ = 0;
+  }
+
+  *len = 2 + ct * 2 + 1;
+
+  return 1;
+}
+
+int ssl_parse_clienthello_use_srtp_ext(SSL *s, CBS *cbs, int *out_alert) {
+  CBS profile_ids, srtp_mki;
+  const SRTP_PROTECTION_PROFILE *cprof, *sprof;
+  STACK_OF(SRTP_PROTECTION_PROFILE) *client_profiles = 0, *server_profiles;
+  size_t i, j;
+  int ret = 0;
+
+  if (!CBS_get_u16_length_prefixed(cbs, &profile_ids) ||
+      CBS_len(&profile_ids) < 2 ||
+      !CBS_get_u8_length_prefixed(cbs, &srtp_mki) ||
+      CBS_len(cbs) != 0) {
+    OPENSSL_PUT_ERROR(SSL, ssl_parse_clienthello_use_srtp_ext,
+                      SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
+    *out_alert = SSL_AD_DECODE_ERROR;
+    goto done;
+  }
+
+  client_profiles = sk_SRTP_PROTECTION_PROFILE_new_null();
+  if (client_profiles == NULL) {
+    OPENSSL_PUT_ERROR(SSL, ssl_parse_clienthello_use_srtp_ext,
+                      ERR_R_MALLOC_FAILURE);
+    *out_alert = SSL_AD_INTERNAL_ERROR;
+    goto done;
+  }
+
+  while (CBS_len(&profile_ids) > 0) {
+    uint16_t profile_id;
+
+    if (!CBS_get_u16(&profile_ids, &profile_id)) {
+      *out_alert = SSL_AD_DECODE_ERROR;
+      goto done;
+    }
+
+    if (find_profile_by_num(profile_id, &cprof)) {
+      sk_SRTP_PROTECTION_PROFILE_push(client_profiles, cprof);
+    }
+  }
+
+  /* Discard the MKI value for now. */
+
+  server_profiles = SSL_get_srtp_profiles(s);
+
+  /* Pick the server's most preferred profile. */
+  for (i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(server_profiles); i++) {
+    sprof = sk_SRTP_PROTECTION_PROFILE_value(server_profiles, i);
+
+    for (j = 0; j < sk_SRTP_PROTECTION_PROFILE_num(client_profiles); j++) {
+      cprof = sk_SRTP_PROTECTION_PROFILE_value(client_profiles, j);
+
+      if (cprof->id == sprof->id) {
+        s->srtp_profile = sprof;
+        ret = 1;
+        goto done;
+      }
+    }
+  }
+
+  ret = 1;
+
+done:
+  if (client_profiles) {
+    sk_SRTP_PROTECTION_PROFILE_free(client_profiles);
+  }
+
+  return ret;
+}
+
+int ssl_add_serverhello_use_srtp_ext(SSL *s, unsigned char *p, int *len,
+                                     int maxlen) {
+  if (p) {
+    if (maxlen < 5) {
+      OPENSSL_PUT_ERROR(SSL, ssl_add_serverhello_use_srtp_ext,
+                        SSL_R_SRTP_PROTECTION_PROFILE_LIST_TOO_LONG);
+      return 0;
+    }
+
+    if (s->srtp_profile == 0) {
+      OPENSSL_PUT_ERROR(SSL, ssl_add_serverhello_use_srtp_ext,
+                        SSL_R_USE_SRTP_NOT_NEGOTIATED);
+      return 0;
+    }
+
+    s2n(2, p);
+    s2n(s->srtp_profile->id, p);
+    *p++ = 0;
+  }
+
+  *len = 5;
+
+  return 1;
+}
+
+int ssl_parse_serverhello_use_srtp_ext(SSL *s, CBS *cbs, int *out_alert) {
+  CBS profile_ids, srtp_mki;
+  uint16_t profile_id;
+  size_t i;
+
+  STACK_OF(SRTP_PROTECTION_PROFILE) *client_profiles;
+  const SRTP_PROTECTION_PROFILE *prof;
+
+  /* The extension consists of a u16-prefixed profile ID list containing a
+   * single uint16_t profile ID, then followed by a u8-prefixed srtp_mki field.
+   *
+   * See https://tools.ietf.org/html/rfc5764#section-4.1.1 */
+  if (!CBS_get_u16_length_prefixed(cbs, &profile_ids) ||
+      !CBS_get_u16(&profile_ids, &profile_id) || CBS_len(&profile_ids) != 0 ||
+      !CBS_get_u8_length_prefixed(cbs, &srtp_mki) || CBS_len(cbs) != 0) {
+    OPENSSL_PUT_ERROR(SSL, ssl_parse_serverhello_use_srtp_ext,
+                      SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
+    *out_alert = SSL_AD_DECODE_ERROR;
+    return 0;
+  }
+
+  if (CBS_len(&srtp_mki) != 0) {
+    /* Must be no MKI, since we never offer one. */
+    OPENSSL_PUT_ERROR(SSL, ssl_parse_serverhello_use_srtp_ext,
+                      SSL_R_BAD_SRTP_MKI_VALUE);
+    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+    return 0;
+  }
+
+  client_profiles = SSL_get_srtp_profiles(s);
+
+  /* Throw an error if the server gave us an unsolicited extension */
+  if (client_profiles == NULL) {
+    OPENSSL_PUT_ERROR(SSL, ssl_parse_serverhello_use_srtp_ext,
+                      SSL_R_NO_SRTP_PROFILES);
+    *out_alert = SSL_AD_DECODE_ERROR;
+    return 0;
+  }
+
+  /* Check to see if the server gave us something we support
+     (and presumably offered). */
+  for (i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(client_profiles); i++) {
+    prof = sk_SRTP_PROTECTION_PROFILE_value(client_profiles, i);
+
+    if (prof->id == profile_id) {
+      s->srtp_profile = prof;
+      *out_alert = 0;
+      return 1;
+    }
+  }
+
+  OPENSSL_PUT_ERROR(SSL, ssl_parse_serverhello_use_srtp_ext,
+                    SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
+  *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+  return 0;
 }