put in the support for 'router twins'

basically, a twin is a router which is different except it shares
the same keypair. so in cases where we want to find a "next router"
and all we really care is that it can decrypt the next onion layer,
then a twin is just as good.

we still need to decide how to mark twins in the routerinfo_t and in
the routers config file.


svn:r30

src/or/circuit.c

@@ -98,7 +98,7 @@ aci_t get_unique_aci_by_addr_port(uint32_t addr, uint16_t port, int aci_type) {
   if(test_aci == 0)
     return get_unique_aci_by_addr_port(addr, port, aci_type); /* try again */ 
 
-  conn = connection_get_by_addr_port(addr,port);  
+  conn = connection_exact_get_by_addr_port(addr,port);
   if(!conn) /* there can't be a conflict -- no connection of that sort yet */
     return test_aci;
 

src/or/command.c

@@ -91,7 +91,7 @@ void command_process_create_cell(cell_t *cell, connection_t *conn) {
   }
 
   if(circ->n_addr && circ->n_port) { /* must send create cells to the next router */
-    n_conn = connection_get_by_addr_port(circ->n_addr,circ->n_port);
+    n_conn = connection_twin_get_by_addr_port(circ->n_addr,circ->n_port);
     if(!n_conn || n_conn->type != CONN_TYPE_OR) {
       /* i've disabled making connections through OPs, but it's definitely
        * possible here. I'm not sure if it would be a bug or a feature. -RD

src/or/connection.c

@@ -205,7 +205,7 @@ int retry_all_connections(int role, routerinfo_t **router_array, int rarray_len,
   if(role & ROLE_OR_CONNECT_ALL) {
     for (i=0;i<rarray_len;i++) {
       router = router_array[i];
-      if(!connection_get_by_addr_port(router->addr,router->or_port)) { /* not in the list */
+      if(!connection_exact_get_by_addr_port(router->addr,router->or_port)) { /* not in the list */
         log(LOG_DEBUG,"retry_all_connections(): connecting to OR %s:%u.",router->address,ntohs(router->or_port));
         connection_or_connect_as_or(router, prkey, &local);
       }

src/or/connection_ap.c

@@ -202,7 +202,7 @@ int ap_handshake_establish_circuit(connection_t *conn, unsigned int *route, int
 
   log(LOG_DEBUG,"ap_handshake_establish_circuit(): Looking for firsthop '%s:%u'",
       firsthop->address,ntohs(firsthop->or_port));
-  n_conn = connection_get_by_addr_port(firsthop->addr,firsthop->or_port);
+  n_conn = connection_twin_get_by_addr_port(firsthop->addr,firsthop->or_port);
   if(!n_conn) { /* not currently connected */
     if(global_role & ROLE_OR_CONNECT_ALL) { /* we would be connected if he were up. but he's not. */
       log(LOG_DEBUG,"ap_handshake_establish_circuit(): Route's firsthop isn't connected.");

src/or/connection_or.c

@@ -583,7 +583,7 @@ int or_handshake_server_process_auth(connection_t *conn) {
   log(LOG_DEBUG,"or_handshake_server_process_auth() : Router identified as %s:%u.",
       router->address,ntohs(router->or_port));
 
-  if(connection_get_by_addr_port(addr,port)) {
+  if(connection_exact_get_by_addr_port(addr,port)) {
     log(LOG_DEBUG,"or_handshake_server_process_auth(): That router is already connected. Dropping.");
     return -1;
   }

src/or/main.c

@@ -111,7 +111,25 @@ int connection_remove(connection_t *conn) {
   return 0;  
 }
 
-connection_t *connection_get_by_addr_port(uint32_t addr, uint16_t port) {
+connection_t *connection_twin_get_by_addr_port(uint32_t addr, uint16_t port) {
+  int i;
+  connection_t *conn;
+
+  /* first check if it's there exactly */
+  conn = connection_exact_get_by_addr_port(addr,port);
+  if(conn)
+    return conn;
+
+  /* now check if any of the other open connections are a twin for this one */
+
+  /* XXX */
+
+  /* guess not */
+  return NULL;
+
+}
+
+connection_t *connection_exact_get_by_addr_port(uint32_t addr, uint16_t port) {
   int i;
   connection_t *conn;
 

src/or/or.h

@@ -486,7 +486,8 @@ int connection_add(connection_t *conn);
 int connection_remove(connection_t *conn);
 void connection_set_poll_socket(connection_t *conn);
 
-connection_t *connection_get_by_addr_port(uint32_t addr, uint16_t port);
+connection_t *connection_twin_get_by_addr_port(uint32_t addr, uint16_t port);
+connection_t *connection_exact_get_by_addr_port(uint32_t addr, uint16_t port);
 
 connection_t *connection_get_by_type(int type);