Add TTLs to RESOLVED, CONNECTED, and END_REASON_EXITPOLICY cells. Also, add a...

Add TTLs to RESOLVED, CONNECTED, and END_REASON_EXITPOLICY cells.  Also, add a missing ntohl in connection_ap_handshake_socks_resolved.


svn:r4894

doc/tor-spec.txt

@@ -469,8 +469,16 @@ TODO: (very soon)
    address cannot be resolved, or a connection can't be established, the
    exit node replies with a RELAY_END cell.  (See 5.4 below.)
    Otherwise, the exit node replies with a RELAY_CONNECTED cell, whose
-   payload is the 4-byte IPv4 address or the 16-byte IPv6 address to which
-   the connection was made.
+   payload is in one of the following formats:
+       The IPv4 address to which the connection was made [4 octets]
+       A number of seconds (TTL) for which the address may be cached [4 octets]
+    or
+       Four zero-valued octets [4 octets]
+       An address type (6)     [1 octet]
+       The IPv6 address to which the connection was made [16 octets]
+       A number of seconds (TTL) for which the address may be cached [4 octets]
+   [XXXX Versions of Tor before 0.1.1.6 ignore and do not generate the TTL
+   field.  No version of Tor currently generates the IPv6 format.]
 
    The OP waits for a RELAY_CONNECTED cell before sending any data.
    Once a connection has been established, the OP and exit node
@@ -511,7 +519,8 @@ TODO: (very soon)
                                    Tor protocol violations.)
 
    (With REASON_EXITPOLICY, the 4-byte IPv4 address or 16-byte IPv6 address
-   forms the optional data; no other reason currently has extra data.)
+   forms the optional data; no other reason currently has extra data.
+   As of 0.1.1.6, the body also contains a 4-byte TTL.)
 
    OPs and ORs MUST accept reasons not on the above list, since future
    versions of Tor may provide more fine-grained reasons.
@@ -558,6 +567,7 @@ TODO: (very soon)
        Type   (1 octet)
        Length (1 octet)
        Value  (variable-width)
+       TTL    (4 octets)
    "Length" is the length of the Value field.
    "Type" is one of:
       0x00 -- Hostname

src/or/connection_edge.c

@@ -48,7 +48,7 @@ _connection_mark_unattached_ap(connection_t *conn, int endreason,
     if (conn->socks_request->command == SOCKS_COMMAND_CONNECT)
       connection_ap_handshake_socks_reply(conn, NULL, 0, socksreason);
     else
-      connection_ap_handshake_socks_resolved(conn,RESOLVED_TYPE_ERROR,0,NULL);
+      connection_ap_handshake_socks_resolved(conn,RESOLVED_TYPE_ERROR,0,NULL,-1);
   }
 
   _connection_mark_for_close(conn, line, file);
@@ -194,7 +194,8 @@ connection_edge_end(connection_t *conn, char reason, crypt_path_t *cpath_layer)
     /* this is safe even for rend circs, because they never fail
      * because of exitpolicy */
     set_uint32(payload+1, htonl(conn->addr));
-    payload_len += 4;
+    set_uint32(payload+5, htonl(MAX_DNS_ENTRY_AGE)); /* XXXXfill with a real TTL*/
+    payload_len += 8;
   }
 
   circ = circuit_get_by_edge_conn(conn);
@@ -266,7 +267,6 @@ connection_edge_finished_flushing(connection_t *conn)
 int
 connection_edge_finished_connecting(connection_t *conn)
 {
-  char connected_payload[4];
   char valbuf[INET_NTOA_BUF_LEN];
   struct in_addr in;
 
@@ -289,9 +289,12 @@ connection_edge_finished_connecting(connection_t *conn)
                                      RELAY_COMMAND_CONNECTED, NULL, 0, conn->cpath_layer) < 0)
       return 0; /* circuit is closed, don't continue */
   } else {
-    *(uint32_t*)connected_payload = htonl(conn->addr);
+    char connected_payload[8];
+    set_uint32(connected_payload, htonl(htonl(conn->addr)));
+    set_uint32(connected_payload+4,
+               htonl(MAX_DNS_ENTRY_AGE)); /* XXXX fill with a real TTL */
     if (connection_edge_send_command(conn, circuit_get_by_edge_conn(conn),
-        RELAY_COMMAND_CONNECTED, connected_payload, 4, conn->cpath_layer) < 0)
+        RELAY_COMMAND_CONNECTED, connected_payload, 8, conn->cpath_layer) < 0)
       return 0; /* circuit is closed, don't continue */
   }
   tor_assert(conn->package_window > 0);
@@ -683,9 +686,13 @@ client_dns_clear_failures(const char *address)
  *
  * If <b>exitname</b> is defined, then append the addresses with
  * ".exitname.exit" before registering the mapping.
+ *
+ * If <b>ttl</b> is nonnegative, the mapping will be valid for
+ * <b>ttl</b>seconds.
  */
 void
-client_dns_set_addressmap(const char *address, uint32_t val, const char *exitname)
+client_dns_set_addressmap(const char *address, uint32_t val, const char *exitname,
+                          int ttl)
 {
   struct in_addr in;
   char extendedaddress[MAX_SOCKS_ADDR_LEN+MAX_HEX_NICKNAME_LEN+10];
@@ -694,6 +701,9 @@ client_dns_set_addressmap(const char *address, uint32_t val, const char *exitnam
 
   tor_assert(address); tor_assert(val);
 
+  if (ttl<0 || ttl>MAX_DNS_ENTRY_AGE)
+    ttl = MAX_DNS_ENTRY_AGE;
+
   if (tor_inet_aton(address, &in))
     return; /* If address was an IP address already, don't add a mapping. */
   in.s_addr = htonl(val);
@@ -709,8 +719,7 @@ client_dns_set_addressmap(const char *address, uint32_t val, const char *exitnam
     tor_snprintf(extendedval, sizeof(extendedval),
                  "%s", valbuf);
   }
-  addressmap_register(extendedaddress, tor_strdup(extendedval),
-                      time(NULL) + MAX_DNS_ENTRY_AGE);
+  addressmap_register(extendedaddress, tor_strdup(extendedval), time(NULL) + ttl);
 }
 
 /* Currently, we hand out 127.192.0.1 through 127.254.254.254.
@@ -1019,14 +1028,14 @@ connection_ap_handshake_process_socks(connection_t *conn)
       /* Reply to resolves immediately if we can. */
       if (strlen(socks->address) > RELAY_PAYLOAD_SIZE) {
         log_fn(LOG_WARN,"Address to be resolved is too large. Failing.");
-        connection_ap_handshake_socks_resolved(conn,RESOLVED_TYPE_ERROR,0,NULL);
+        connection_ap_handshake_socks_resolved(conn,RESOLVED_TYPE_ERROR,0,NULL,-1);
         connection_mark_unattached_ap(conn, END_STREAM_REASON_ALREADY_SOCKS_REPLIED);
         return -1;
       }
       if (tor_inet_aton(socks->address, &in)) { /* see if it's an IP already */
         answer = in.s_addr; /* leave it in network order */
         connection_ap_handshake_socks_resolved(conn,RESOLVED_TYPE_IPV4,4,
-                                               (char*)&answer);
+                                               (char*)&answer,-1);
         connection_mark_unattached_ap(conn, END_STREAM_REASON_ALREADY_SOCKS_REPLIED);
         return 0;
       }
@@ -1075,7 +1084,7 @@ connection_ap_handshake_process_socks(connection_t *conn)
       /* if it's a resolve request, fail it right now, rather than
        * building all the circuits and then realizing it won't work. */
       log_fn(LOG_WARN,"Resolve requests to hidden services not allowed. Failing.");
-      connection_ap_handshake_socks_resolved(conn,RESOLVED_TYPE_ERROR,0,NULL);
+      connection_ap_handshake_socks_resolved(conn,RESOLVED_TYPE_ERROR,0,NULL,-1);
       connection_mark_unattached_ap(conn, END_STREAM_REASON_ALREADY_SOCKS_REPLIED);
       return -1;
     }
@@ -1299,16 +1308,17 @@ void
 connection_ap_handshake_socks_resolved(connection_t *conn,
                                        int answer_type,
                                        size_t answer_len,
-                                       const char *answer)
+                                       const char *answer,
+                                       int ttl)
 {
   char buf[256];
   size_t replylen;
 
   if (answer_type == RESOLVED_TYPE_IPV4) {
-    uint32_t a = get_uint32(answer);
+    uint32_t a = ntohl(get_uint32(answer));
     if (a)
       client_dns_set_addressmap(conn->socks_request->address, ntohl(a),
-                                conn->chosen_exit_name);
+                                conn->chosen_exit_name, ttl);
   }
 
   if (conn->socks_request->socks_version == 4) {
@@ -1581,7 +1591,6 @@ connection_exit_begin_resolve(cell_t *cell, circuit_t *circ)
 void
 connection_exit_connect(connection_t *conn)
 {
-  char connected_payload[4];
   uint32_t addr;
   uint16_t port;
 
@@ -1649,10 +1658,13 @@ connection_exit_connect(connection_t *conn)
                                  NULL, 0, conn->cpath_layer);
   } else { /* normal stream */
     /* This must be the original address, not the redirected address. */
-    *(uint32_t*)connected_payload = htonl(conn->addr);
+    char connected_payload[8];
+    set_uint32(connected_payload, htonl(htonl(conn->addr)));
+    set_uint32(connected_payload+4,
+               htonl(MAX_DNS_ENTRY_AGE)); /* XXXX fill with a real TTL */
     connection_edge_send_command(conn, circuit_get_by_edge_conn(conn),
                                  RELAY_COMMAND_CONNECTED,
-                                 connected_payload, 4, conn->cpath_layer);
+                                 connected_payload, 8, conn->cpath_layer);
   }
 }
 

src/or/dns.c

@@ -192,14 +192,21 @@ send_resolved_cell(connection_t *conn, uint8_t answer_type)
     case RESOLVED_TYPE_IPV4:
       buf[1] = 4;
       set_uint32(buf+2, htonl(conn->addr));
-      buflen = 6;
+      set_uint32(buf+6, htonl(MAX_DNS_ENTRY_AGE)); /*XXXX send a real TTL*/
+      buflen = 10;
       break;
     case RESOLVED_TYPE_ERROR_TRANSIENT:
     case RESOLVED_TYPE_ERROR:
-      buf[1] = 24; /* length of "error resolving hostname" */
-      strlcpy(buf+2, "error resolving hostname", sizeof(buf)-2);
-      buflen = 26;
+      {
+        const char *errmsg = "Error resolving hostname";
+        int msglen = strlen(errmsg);
+        int ttl = (answer_type == RESOLVED_TYPE_ERROR ? MAX_DNS_ENTRY_AGE : 0);
+        buf[1] = msglen;
+        strlcpy(buf+2, errmsg, sizeof(buf)-2);
+        set_uint32(buf+2+msglen, htonl((uint32_t)ttl));
+        buflen = 6+msglen;
         break;
+      }
     default:
       tor_assert(0);
     }

src/or/relay.c

@@ -640,14 +640,19 @@ connection_edge_process_end_not_open(
       case END_STREAM_REASON_EXITPOLICY:
         if (rh->length >= 5) {
           uint32_t addr = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+1));
+          int ttl;
           if (!addr) {
             log_fn(LOG_INFO,"Address '%s' resolved to 0.0.0.0. Closing,",
                    safe_str(conn->socks_request->address));
             connection_mark_unattached_ap(conn, END_STREAM_REASON_TORPROTOCOL);
             return 0;
           }
+          if (rh->length >= 9)
+            ttl = (int)ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+5));
+          else
+            ttl = -1;
           client_dns_set_addressmap(conn->socks_request->address, addr,
-                                    conn->chosen_exit_name);
+                                    conn->chosen_exit_name, ttl);
         }
         /* check if he *ought* to have allowed it */
         if (exitrouter &&
@@ -735,14 +740,19 @@ connection_edge_process_relay_cell_not_open(
            (int)(time(NULL) - conn->timestamp_lastread));
     if (rh->length >= 4) {
       uint32_t addr = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE));
+      int ttl;
       if (!addr) {
         log_fn(LOG_INFO,"...but it claims the IP address was 0.0.0.0. Closing.");
         connection_edge_end(conn, END_STREAM_REASON_TORPROTOCOL, conn->cpath_layer);
         connection_mark_unattached_ap(conn, END_STREAM_REASON_TORPROTOCOL);
         return 0;
       }
+      if (rh->length >= 8)
+        ttl = (int)ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+8));
+      else
+        ttl = -1;
       client_dns_set_addressmap(conn->socks_request->address, addr,
-                                conn->chosen_exit_name);
+                                conn->chosen_exit_name, ttl);
     }
     circuit_log_path(LOG_INFO,circ);
     connection_ap_handshake_socks_reply(conn, NULL, 0, SOCKS5_SUCCEEDED);
@@ -755,20 +765,28 @@ connection_edge_process_relay_cell_not_open(
     return 0;
   }
   if (conn->type == CONN_TYPE_AP && rh->command == RELAY_COMMAND_RESOLVED) {
+    int ttl;
+    int answer_len;
     if (conn->state != AP_CONN_STATE_RESOLVE_WAIT) {
       log_fn(LOG_WARN,"Got a 'resolved' cell while not in state resolve_wait. Dropping.");
       return 0;
     }
     tor_assert(conn->socks_request->command == SOCKS_COMMAND_RESOLVE);
-    if (rh->length < 2 || cell->payload[RELAY_HEADER_SIZE+1]+2>rh->length) {
+    answer_len = cell->payload[RELAY_HEADER_SIZE+1];
+    if (rh->length < 2 || answer_len+2>rh->length) {
       log_fn(LOG_WARN, "Dropping malformed 'resolved' cell");
       connection_mark_unattached_ap(conn, END_STREAM_REASON_TORPROTOCOL);
       return 0;
     }
+    if (rh->length >= answer_len+6)
+      ttl = (int)ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+6));
+    else
+      ttl = -1;
     connection_ap_handshake_socks_resolved(conn,
                    cell->payload[RELAY_HEADER_SIZE], /*answer_type*/
                    cell->payload[RELAY_HEADER_SIZE+1], /*answer_len*/
-                   cell->payload+RELAY_HEADER_SIZE+2); /* answer */
+                   cell->payload+RELAY_HEADER_SIZE+2,
+                   ttl); /* answer */
     connection_mark_unattached_ap(conn, END_STREAM_REASON_ALREADY_SOCKS_REPLIED);
     return 0;
   }