Our new v2 hidden service descriptor format allows descriptors

that have no introduction points. But Tor crashed when we tried
to build a descriptor with no intro points (and it would have
crashed if we had tried to parse one). Bugfix on 0.2.0.x; patch
by Karsten Loesing.


svn:r12579

ChangeLog

@@ -13,6 +13,11 @@ Changes in version 0.2.0.13-alpha - 2007-11-??
     - Don't crash if we get an unexpected value for the
       PublishServerDescriptor config option. Reported by Matt Edman;
       bugfix on 0.2.0.9-alpha.
+    - Our new v2 hidden service descriptor format allows descriptors
+      that have no introduction points. But Tor crashed when we tried
+      to build a descriptor with no intro points (and it would have
+      crashed if we had tried to parse one). Bugfix on 0.2.0.x; patch
+      by Karsten Loesing.
 
 
 Changes in version 0.2.0.12-alpha - 2007-11-16

src/or/rendcommon.c

@@ -354,7 +354,8 @@ rend_encode_v2_descriptors(smartlist_t *desc_strs_out,
   seconds_valid = period * REND_TIME_PERIOD_V2_DESC_VALIDITY +
                   get_seconds_valid(now, service_id);
   /* Assemble, possibly encrypt, and encode introduction points. */
-  if (rend_encode_v2_intro_points(&ipos_base64, desc, descriptor_cookie) < 0) {
+  if (desc->n_intro_points > 0 &&
+      rend_encode_v2_intro_points(&ipos_base64, desc, descriptor_cookie) < 0) {
     log_warn(LD_REND, "Encoding of introduction points did not succeed.");
     tor_free(ipos_base64);
     return -1;
@@ -418,16 +419,12 @@ rend_encode_v2_descriptors(smartlist_t *desc_strs_out,
              "permanent-key\n%s"
              "secret-id-part %s\n"
              "publication-time %s\n"
-             "protocol-versions %s\n"
-             "introduction-points\n"
-             "-----BEGIN MESSAGE-----\n%s"
-             "-----END MESSAGE-----\n",
+             "protocol-versions %s\n",
         desc_id_base32,
         permanent_key,
         secret_id_part_base32,
         published,
-        protocol_versions_string,
-        ipos_base64);
+        protocol_versions_string);
     tor_free(permanent_key);
     if (result < 0) {
       log_warn(LD_BUG, "Descriptor ran out of room.");
@@ -435,6 +432,20 @@ rend_encode_v2_descriptors(smartlist_t *desc_strs_out,
       goto err;
     }
     written = result;
+    /* Add introduction points. */
+    if (ipos_base64) {
+      result = tor_snprintf(desc_str + written, desc_len - written,
+                            "introduction-points\n"
+                            "-----BEGIN MESSAGE-----\n%s"
+                            "-----END MESSAGE-----\n",
+                            ipos_base64);
+      if (result < 0) {
+        log_warn(LD_BUG, "could not write introduction points.");
+        tor_free(desc_str);
+        goto err;
+      }
+      written += result;
+    }
     /* Add signature. */
     strlcpy(desc_str + written, "signature\n", desc_len - written);
     written += strlen(desc_str + written);
@@ -1075,12 +1086,15 @@ rend_cache_store_v2_desc_as_client(const char *desc,
     return -1;
   }
   /* Decode/decrypt introduction points. */
-  if (rend_decrypt_introduction_points(parsed, descriptor_cookie,
+  if (intro_content &&
+      rend_decrypt_introduction_points(parsed, descriptor_cookie,
                                        intro_content, intro_size) < 0) {
     log_warn(LD_PROTOCOL,"Couldn't decode/decrypt introduction points.");
     rend_service_descriptor_free(parsed);
     tor_free(intro_content);
     return -1;
+  } else {
+    parsed->n_intro_points = 0;
   }
   /* We don't need the encoded/encrypted introduction points any longer. */
   tor_free(intro_content);

src/or/routerparse.c

@@ -324,7 +324,7 @@ static token_rule_t desc_token_table[] = {
   T1("secret-id-part", R_SECRET_ID_PART, EQ(1), NO_OBJ),
   T1("publication-time", R_PUBLICATION_TIME, CONCAT_ARGS, NO_OBJ),
   T1("protocol-versions", R_PROTOCOL_VERSIONS, EQ(1), NO_OBJ),
-  T1("introduction-points", R_INTRODUCTION_POINTS, NO_ARGS, NEED_OBJ),
+  T01("introduction-points", R_INTRODUCTION_POINTS, NO_ARGS, NEED_OBJ),
   T1_END("signature", R_SIGNATURE, NO_ARGS, NEED_OBJ),
   END_OF_TABLE
 };
@@ -3232,7 +3232,7 @@ rend_parse_v2_service_descriptor(rend_service_descriptor_t **parsed_out,
   /* Set length of encoded descriptor. */
   *encoded_size_out = eos - desc;
   /* Check min allowed length of token list. */
-  if (smartlist_len(tokens) < 8) {
+  if (smartlist_len(tokens) < 7) {
     log_warn(LD_REND, "Impossibly short descriptor.");
     goto err;
   }
@@ -3318,15 +3318,19 @@ rend_parse_v2_service_descriptor(rend_service_descriptor_t **parsed_out,
   smartlist_free(versions);
   /* Parse encrypted introduction points. Don't verify. */
   tok = find_first_by_keyword(tokens, R_INTRODUCTION_POINTS);
-  tor_assert(tok);
-  if (strcmp(tok->object_type, "MESSAGE")) {
-    log_warn(LD_DIR, "Bad object type: introduction points should be of "
-             "type MESSAGE");
-    goto err;
+  if (tok) {
+    if (strcmp(tok->object_type, "MESSAGE")) {
+      log_warn(LD_DIR, "Bad object type: introduction points should be of "
+               "type MESSAGE");
+      goto err;
+    }
+    *intro_points_encrypted_out = tok->object_body;
+    *intro_points_encrypted_size_out = tok->object_size;
+    tok->object_body = NULL; /* Prevent free. */
+  } else {
+    *intro_points_encrypted_out = NULL;
+    *intro_points_encrypted_size_out = 0;
   }
-  *intro_points_encrypted_out = tok->object_body;
-  *intro_points_encrypted_size_out = tok->object_size;
-  tok->object_body = NULL; /* Prevent free. */
   /* Parse and verify signature. */
   tok = find_first_by_keyword(tokens, R_SIGNATURE);
   tor_assert(tok);