5 files changed, 74 insertions, 11 deletions

diff --git a/src/or/circuitlist.c b/src/or/circuitlist.c
index 8716d10a5c..cf55b51dd2 100644
--- a/src/or/circuitlist.c
+++ b/src/or/circuitlist.c
@@ -32,6 +32,7 @@ static void circuit_free_cpath_node(crypt_path_t *victim);
 
 /********* END VARIABLES ************/
 
+/** DOCDOC This whole section */
 struct orconn_circid_circuit_map_t {
   SPLAY_ENTRY(orconn_circid_circuit_map_t) node;
   connection_t *or_conn;
@@ -298,8 +299,60 @@ circuit_t *circuit_get_by_circid_orconn(uint16_t circ_id, connection_t *conn) {
   found = SPLAY_FIND(orconn_circid_tree, &orconn_circid_circuit_map, &search);
   if (found && found->circuit && !found->circuit->marked_for_close)
     return found->circuit;
-  else
+
+  /* The rest of this can be replaced with
+     "return NULL;" once we believe the code works. */
+
+  {
+    circuit_t *circ;
+    for (circ=global_circuitlist;circ;circ = circ->next) {
+      if (circ->marked_for_close)
+        continue;
+
+      if (circ->p_conn == conn && circ->p_circ_id == circ_id) {
+        log_fn(LOG_WARN, "circuit matches p_conn, but not in tree (Bug!)");
+        return circ;
+      }
+      if (circ->n_conn == conn && circ->n_circ_id == circ_id) {
+        log_fn(LOG_WARN, "circuit matches n_conn, but not in tree (Bug!)");
+        return circ;
+      }
+    }
     return NULL;
+  }
+
+}
+
+/** DOCDOC */
+circuit_t *circuit_get_by_stream(connection_t *conn)
+{
+  circuit_t *circ;
+  connection_t *tmpconn;
+  tor_assert(CONN_IS_EDGE(conn));
+
+  if (! conn->on_circuit) {
+    /* return NULL; */
+    circ = circuit_get_by_conn(conn);
+    if (circ) {
+      log_fn(LOG_WARN, "BUG: conn->on_circuit==NULL, but there was in fact a circuit there. ");
+    }
+    return circ;
+  }
+
+  circ = conn->on_circuit;
+  /* All this stuff here is sanity-checking. */
+  tor_assert(circ->magic == CIRCUIT_MAGIC);
+  for (tmpconn = circ->p_streams; tmpconn; tmpconn=tmpconn->next_stream)
+    if (tmpconn == conn)
+      return circ;
+  for (tmpconn = circ->n_streams; tmpconn; tmpconn=tmpconn->next_stream)
+    if (tmpconn == conn)
+      return circ;
+  for (tmpconn = circ->resolving_streams; tmpconn; tmpconn=tmpconn->next_stream)
+    if (tmpconn == conn)
+      return circ;
+
+  tor_assert(0);
 }
 
 /** Return a circ such that circ is attached to <b>conn</b>, either as
@@ -505,6 +558,7 @@ void _circuit_mark_for_close(circuit_t *circ, int line, const char *file)
       conn->has_sent_end = 1; /* we're closing the circuit, nothing to send to */
       connection_mark_for_close(conn);
     }
+    conn->on_circuit = NULL;
   }
   if (circ->p_conn)
     connection_send_destroy(circ->p_circ_id, circ->p_conn);
diff --git a/src/or/circuituse.c b/src/or/circuituse.c
index 756baea85a..bfaafdbe82 100644
--- a/src/or/circuituse.c
+++ b/src/or/circuituse.c
@@ -417,6 +417,7 @@ void circuit_detach_stream(circuit_t *circ, connection_t *conn) {
   tor_assert(conn);
 
   conn->cpath_layer = NULL; /* make sure we don't keep a stale pointer */
+  conn->on_circuit = NULL;
 
   if (conn == circ->p_streams) {
     circ->p_streams = conn->next_stream;
@@ -923,6 +924,7 @@ static void link_apconn_to_circ(connection_t *apconn, circuit_t *circ) {
   log_fn(LOG_DEBUG,"attaching new conn to circ. n_circ_id %d.", circ->n_circ_id);
   apconn->timestamp_lastread = time(NULL); /* reset it, so we can measure circ timeouts */
   apconn->next_stream = circ->p_streams;
+  apconn->on_circuit = circ;
   /* assert_connection_ok(conn, time(NULL)); */
   circ->p_streams = apconn;
 
diff --git a/src/or/connection_edge.c b/src/or/connection_edge.c
index 1e72d6f7d3..f9273d2bc2 100644
--- a/src/or/connection_edge.c
+++ b/src/or/connection_edge.c
@@ -142,18 +142,19 @@ int connection_edge_process_inbuf(connection_t *conn, int package_partial) {
 int connection_edge_destroy(uint16_t circ_id, connection_t *conn) {
   tor_assert(CONN_IS_EDGE(conn));
 
-  if (conn->marked_for_close)
-    return 0; /* already marked; probably got an 'end' */
-  log_fn(LOG_INFO,"CircID %d: At an edge. Marking connection for close.",
-         circ_id);
-  if (conn->type == CONN_TYPE_AP) {
-    connection_mark_unattached_ap(conn, END_STREAM_REASON_DESTROY);
-  } else {
-    conn->has_sent_end = 1; /* we're closing the circuit, nothing to send to */
-    connection_mark_for_close(conn);
-    conn->hold_open_until_flushed = 1;
+  if (!conn->marked_for_close) {
+    log_fn(LOG_INFO,"CircID %d: At an edge. Marking connection for close.",
+           circ_id);
+    if (conn->type == CONN_TYPE_AP) {
+      connection_mark_unattached_ap(conn, END_STREAM_REASON_DESTROY);
+    } else {
+      conn->has_sent_end = 1; /* we're closing the circuit, nothing to send to */
+      connection_mark_for_close(conn);
+      conn->hold_open_until_flushed = 1;
+    }
   }
   conn->cpath_layer = NULL;
+  conn->on_circuit = NULL;
   return 0;
 }
 
@@ -1368,6 +1369,7 @@ int connection_exit_begin_conn(cell_t *cell, circuit_t *circ) {
 
     /* add it into the linked list of n_streams on this circuit */
     n_stream->next_stream = circ->n_streams;
+    n_stream->on_circuit = circ;
     circ->n_streams = n_stream;
     assert_circuit_ok(circ);
 
@@ -1392,6 +1394,7 @@ int connection_exit_begin_conn(cell_t *cell, circuit_t *circ) {
 
       /* add it into the linked list of n_streams on this circuit */
       n_stream->next_stream = circ->n_streams;
+      n_stream->on_circuit = circ;
       circ->n_streams = n_stream;
       assert_circuit_ok(circ);
 
@@ -1403,6 +1406,7 @@ int connection_exit_begin_conn(cell_t *cell, circuit_t *circ) {
     case 0: /* resolve added to pending list */
       /* add it into the linked list of resolving_streams on this circuit */
       n_stream->next_stream = circ->resolving_streams;
+      n_stream->on_circuit = circ;
       circ->resolving_streams = n_stream;
       assert_circuit_ok(circ);
       ;
@@ -1447,6 +1451,7 @@ int connection_exit_begin_resolve(cell_t *cell, circuit_t *circ) {
       return 0;
     case 0: /* resolve added to pending list */
       dummy_conn->next_stream = circ->resolving_streams;
+      dummy_conn->on_circuit = circ;
       circ->resolving_streams = dummy_conn;
       assert_circuit_ok(circ);
       break;
diff --git a/src/or/dns.c b/src/or/dns.c
index 02f44697e5..1a488920e2 100644
--- a/src/or/dns.c
+++ b/src/or/dns.c
@@ -571,6 +571,7 @@ static void dns_found_answer(char *address, uint32_t addr, char outcome) {
         circuit_detach_stream(circ, pend->conn);
         /* and link it to n_streams */
         pend->conn->next_stream = circ->n_streams;
+        pend->conn->on_circuit = circ;
         circ->n_streams = pend->conn;
 
         connection_exit_connect(pend->conn);
diff --git a/src/or/or.h b/src/or/or.h
index 1233ee721d..1a07ee0884 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -629,6 +629,7 @@ struct connection_t {
   int done_receiving; /**< For half-open connections; not used currently. */
   char has_sent_end; /**< For debugging: set once we've set the stream end,
                         and check in circuit_about_to_close_connection(). */
+  struct circuit_t *on_circuit; /**< DOCDOC */
 
   /* Used only by AP connections */
   socks_request_t *socks_request; /**< SOCKS structure describing request (AP