prop224: Link rendezvous circuit to edge connection

This commit refactors the handle_hs_exit_conn() function introduced at a prior
commit that connects the rendezvous circuit to the edge connection used to
connect to the service virtual port requested in a BEGIN cell.

The refactor adds the support for prop224 adding the
hs_service_set_conn_addr_port() function that has the same purpose has
rend_service_set_connection_addr_port() from the legacy code.

The rend_service_set_connection_addr_port() has also been a bit refactored so
the common code can be shared between the two HS subsystems (legacy and
prop224).

In terms of functionallity, nothing has changed, we still close the circuits
in case of failure for the same reasons as the legacy system currently does.

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

1 files changed, 106 insertions, 0 deletions

diff --git a/src/or/hs_common.c b/src/or/hs_common.c
index 4d5417afae..20b53bb91c 100644
--- a/src/or/hs_common.c
+++ b/src/or/hs_common.c
@@ -32,6 +32,60 @@ static const char *str_ed25519_basepoint =
   "463168356949264781694283940034751631413"
   "07993866256225615783033603165251855960)";
 
+#ifdef HAVE_SYS_UN_H
+
+/** Given <b>ports</b>, a smarlist containing rend_service_port_config_t,
+ * add the given <b>p</b>, a AF_UNIX port to the list. Return 0 on success
+ * else return -ENOSYS if AF_UNIX is not supported (see function in the
+ * #else statement below). */
+static int
+add_unix_port(smartlist_t *ports, rend_service_port_config_t *p)
+{
+  tor_assert(ports);
+  tor_assert(p);
+  tor_assert(p->is_unix_addr);
+
+  smartlist_add(ports, p);
+  return 0;
+}
+
+/** Given <b>conn</b> set it to use the given port <b>p</b> values. Return 0
+ * on success else return -ENOSYS if AF_UNIX is not supported (see function
+ * in the #else statement below). */
+static int
+set_unix_port(edge_connection_t *conn, rend_service_port_config_t *p)
+{
+  tor_assert(conn);
+  tor_assert(p);
+  tor_assert(p->is_unix_addr);
+
+  conn->base_.socket_family = AF_UNIX;
+  tor_addr_make_unspec(&conn->base_.addr);
+  conn->base_.port = 1;
+  conn->base_.address = tor_strdup(p->unix_addr);
+  return 0;
+}
+
+#else /* defined(HAVE_SYS_UN_H) */
+
+static int
+set_unix_port(edge_connection_t *conn, rend_service_port_config_t *p)
+{
+  (void) conn;
+  (void) p;
+  return -ENOSYS;
+}
+
+static int
+add_unix_port(smartlist_t *ports, rend_service_port_config_t *p)
+{
+  (void) ports;
+  (void) p;
+  return -ENOSYS;
+}
+
+#endif /* HAVE_SYS_UN_H */
+
 /* Helper function: The key is a digest that we compare to a node_t object
  * current hsdir_index. */
 static int
@@ -602,6 +656,58 @@ hs_get_subcredential(const ed25519_public_key_t *identity_pk,
   crypto_digest_free(digest);
 }
 
+/* From the given list of hidden service ports, find the matching one from the
+ * given edge connection conn and set the connection address from the service
+ * port object. Return 0 on success or -1 if none. */
+int
+hs_set_conn_addr_port(const smartlist_t *ports, edge_connection_t *conn)
+{
+  rend_service_port_config_t *chosen_port;
+  unsigned int warn_once = 0;
+  smartlist_t *matching_ports;
+
+  tor_assert(ports);
+  tor_assert(conn);
+
+  matching_ports = smartlist_new();
+  SMARTLIST_FOREACH_BEGIN(ports, rend_service_port_config_t *, p) {
+    if (TO_CONN(conn)->port != p->virtual_port) {
+      continue;
+    }
+    if (!(p->is_unix_addr)) {
+      smartlist_add(matching_ports, p);
+    } else {
+      if (add_unix_port(matching_ports, p)) {
+        if (!warn_once) {
+          /* Unix port not supported so warn only once. */
+          log_warn(LD_REND, "Saw AF_UNIX virtual port mapping for port %d "
+                            "which is unsupported on this platform. "
+                            "Ignoring it.",
+                   TO_CONN(conn)->port);
+        }
+        warn_once++;
+      }
+    }
+  } SMARTLIST_FOREACH_END(p);
+
+  chosen_port = smartlist_choose(matching_ports);
+  smartlist_free(matching_ports);
+  if (chosen_port) {
+    if (!(chosen_port->is_unix_addr)) {
+      /* Get a non-AF_UNIX connection ready for connection_exit_connect() */
+      tor_addr_copy(&TO_CONN(conn)->addr, &chosen_port->real_addr);
+      TO_CONN(conn)->port = chosen_port->real_port;
+    } else {
+      if (set_unix_port(conn, chosen_port)) {
+        /* Simply impossible to end up here else we were able to add a Unix
+         * port without AF_UNIX support... ? */
+        tor_assert(0);
+      }
+    }
+  }
+  return (chosen_port) ? 0 : -1;
+}
+
 /* Using a base32 representation of a service address, parse its content into
  * the key_out, checksum_out and version_out. Any out variable can be NULL in
  * case the caller would want only one field. checksum_out MUST at least be 2