prop224: Client callback when descriptor has arrived

When a descriptor fetch has completed and it has been successfully stored in
the client cache, this callback will take appropriate actions to attach
streams and/or launch neede circuits to connect to the service.

Signed-off-by: David Goulet <dgoulet@torproject.org>

src/or/directory.c

@@ -3103,6 +3103,7 @@ handle_response_fetch_hsdesc_v3(dir_connection_t *conn,
     } else {
       log_info(LD_REND, "Stored hidden service descriptor successfully.");
       TO_CONN(conn)->purpose = DIR_PURPOSE_HAS_FETCHED_HSDESC;
+      hs_client_desc_has_arrived(conn->hs_ident);
     }
     break;
   case 404:

src/or/hs_client.c

@@ -24,6 +24,7 @@
 #include "circuituse.h"
 #include "connection.h"
 #include "circpathbias.h"
+#include "connection.h"
 
 /* Get all connections that are waiting on a circuit and flag them back to
  * waiting for a hidden service descriptor for the given service key
@@ -580,3 +581,65 @@ hs_client_receive_rendezvous_acked(origin_circuit_t *circ,
   return -1;
 }
 
+/* This is called when a descriptor has arrived following a fetch request and
+ * has been stored in the client cache. Every entry connection that matches
+ * the service identity key in the ident will get attached to the hidden
+ * service circuit. */
+void
+hs_client_desc_has_arrived(const hs_ident_dir_conn_t *ident)
+{
+  time_t now = time(NULL);
+  smartlist_t *conns = NULL;
+
+  tor_assert(ident);
+
+  conns = connection_list_by_type_state(CONN_TYPE_AP,
+                                        AP_CONN_STATE_RENDDESC_WAIT);
+  SMARTLIST_FOREACH_BEGIN(conns, connection_t *, base_conn) {
+    const hs_descriptor_t *desc;
+    entry_connection_t *entry_conn = TO_ENTRY_CONN(base_conn);
+    const edge_connection_t *edge_conn = ENTRY_TO_EDGE_CONN(entry_conn);
+
+    /* Only consider the entry connections that matches the service for which
+     * we just fetched its descriptor. */
+    if (!edge_conn->hs_ident ||
+        !ed25519_pubkey_eq(&ident->identity_pk,
+                           &edge_conn->hs_ident->identity_pk)) {
+      continue;
+    }
+    assert_connection_ok(base_conn, now);
+
+    /* We were just called because we stored the descriptor for this service
+     * so not finding a descriptor means we have a bigger problem. */
+    desc = hs_cache_lookup_as_client(&ident->identity_pk);
+    if (BUG(desc == NULL)) {
+      goto end;
+    }
+
+    if (!hs_client_any_intro_points_usable(desc)) {
+      log_info(LD_REND, "Hidden service descriptor is unusable. "
+                        "Closing streams.");
+      connection_mark_unattached_ap(entry_conn,
+                                    END_STREAM_REASON_RESOLVEFAILED);
+      /* XXX: Note the connection attempt. */
+      goto end;
+    }
+
+    log_info(LD_REND, "Descriptor has arrived. Launching circuits.");
+
+    /* Restart their timeout values, so they get a fair shake at connecting to
+     * the hidden service. XXX: Improve comment on why this is needed. */
+    base_conn->timestamp_created = now;
+    base_conn->timestamp_lastread = now;
+    base_conn->timestamp_lastwritten = now;
+    /* Change connection's state into waiting for a circuit. */
+    base_conn->state = AP_CONN_STATE_CIRCUIT_WAIT;
+
+    connection_ap_mark_as_pending_circuit(entry_conn);
+  } SMARTLIST_FOREACH_END(base_conn);
+
+ end:
+  /* We don't have ownership of the objects in this list. */
+  smartlist_free(conns);
+}
+

src/or/hs_client.h

@@ -11,6 +11,7 @@
 
 #include "crypto_ed25519.h"
 #include "hs_descriptor.h"
+#include "hs_ident.h"
 
 void hs_client_note_connection_attempt_succeeded(
                                        const edge_connection_t *conn);
@@ -31,5 +32,7 @@ int hs_client_receive_rendezvous_acked(origin_circuit_t *circ,
                                        const uint8_t *payload,
                                        size_t payload_len);
 
+void hs_client_desc_has_arrived(const hs_ident_dir_conn_t *ident);
+
 #endif /* TOR_HS_CLIENT_H */