1 files changed, 133 insertions, 0 deletions
diff --git a/src/feature/relay/relay_find_addr.c b/src/feature/relay/relay_find_addr.c
new file mode 100644
index 0000000000..86cd799d42
--- /dev/null
+++ b/src/feature/relay/relay_find_addr.c
@@ -0,0 +1,133 @@
+/* Copyright (c) 2001-2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file relay_find_addr.c
+ * \brief Implement mechanism for a relay to find its address.
+ **/
+
+#include "core/or/or.h"
+
+#include "app/config/config.h"
+#include "app/config/resolve_addr.h"
+
+#include "core/mainloop/mainloop.h"
+
+#include "feature/control/control_events.h"
+#include "feature/dircommon/dir_connection_st.h"
+#include "feature/relay/relay_find_addr.h"
+#include "feature/relay/router.h"
+#include "feature/relay/routermode.h"
+
+/** The most recently guessed value of our IP address, based on directory
+ * headers. */
+static tor_addr_t last_guessed_ip = TOR_ADDR_NULL;
+
+/** We failed to resolve our address locally, but we'd like to build
+ * a descriptor and publish / test reachability. If we have a guess
+ * about our address based on directory headers, answer it and return
+ * 0; else return -1. */
+static int
+router_guess_address_from_dir_headers(uint32_t *guess)
+{
+  if (!tor_addr_is_null(&last_guessed_ip)) {
+    *guess = tor_addr_to_ipv4h(&last_guessed_ip);
+    return 0;
+  }
+  return -1;
+}
+
+/** A directory server <b>d_conn</b> told us our IP address is
+ * <b>suggestion</b>.
+ * If this address is different from the one we think we are now, and
+ * if our computer doesn't actually know its IP address, then switch. */
+void
+router_new_address_suggestion(const char *suggestion,
+                              const dir_connection_t *d_conn)
+{
+  tor_addr_t addr;
+  uint32_t cur = 0;             /* Current IPv4 address.  */
+  const or_options_t *options = get_options();
+
+  /* first, learn what the IP address actually is */
+  if (tor_addr_parse(&addr, suggestion) == -1) {
+    log_debug(LD_DIR, "Malformed X-Your-Address-Is header %s. Ignoring.",
+              escaped(suggestion));
+    return;
+  }
+
+  log_debug(LD_DIR, "Got X-Your-Address-Is: %s.", suggestion);
+
+  if (!server_mode(options)) {
+    tor_addr_copy(&last_guessed_ip, &addr);
+    return;
+  }
+
+  /* XXXX ipv6 */
+  cur = get_last_resolved_addr();
+  if (cur ||
+      resolve_my_address(LOG_INFO, options, &cur, NULL, NULL) >= 0) {
+    /* We're all set -- we already know our address. Great. */
+    tor_addr_from_ipv4h(&last_guessed_ip, cur); /* store it in case we
+                                                   need it later */
+    return;
+  }
+  if (tor_addr_is_internal(&addr, 0)) {
+    /* Don't believe anybody who says our IP is, say, 127.0.0.1. */
+    return;
+  }
+  if (tor_addr_eq(&d_conn->base_.addr, &addr)) {
+    /* Don't believe anybody who says our IP is their IP. */
+    log_debug(LD_DIR, "A directory server told us our IP address is %s, "
+              "but they are just reporting their own IP address. Ignoring.",
+              suggestion);
+    return;
+  }
+
+  /* Okay.  We can't resolve our own address, and X-Your-Address-Is is giving
+   * us an answer different from what we had the last time we managed to
+   * resolve it. */
+  if (!tor_addr_eq(&last_guessed_ip, &addr)) {
+    control_event_server_status(LOG_NOTICE,
+                                "EXTERNAL_ADDRESS ADDRESS=%s METHOD=DIRSERV",
+                                suggestion);
+    log_addr_has_changed(LOG_NOTICE, &last_guessed_ip, &addr,
+                         d_conn->base_.address);
+    ip_address_changed(0);
+    tor_addr_copy(&last_guessed_ip, &addr); /* router_rebuild_descriptor()
+                                               will fetch it */
+  }
+}
+
+/** Make a current best guess at our address, either because
+ * it's configured in torrc, or because we've learned it from
+ * dirserver headers. Place the answer in *<b>addr</b> and return
+ * 0 on success, else return -1 if we have no guess.
+ *
+ * If <b>cache_only</b> is true, just return any cached answers, and
+ * don't try to get any new answers.
+ */
+MOCK_IMPL(int,
+router_pick_published_address, (const or_options_t *options, uint32_t *addr,
+                                int cache_only))
+{
+  /* First, check the cached output from resolve_my_address(). */
+  *addr = get_last_resolved_addr();
+  if (*addr)
+    return 0;
+
+  /* Second, consider doing a resolve attempt right here. */
+  if (!cache_only) {
+    if (resolve_my_address(LOG_INFO, options, addr, NULL, NULL) >= 0) {
+      log_info(LD_CONFIG,"Success: chose address '%s'.", fmt_addr32(*addr));
+      return 0;
+    }
+  }
+
+  /* Third, check the cached output from router_new_address_suggestion(). */
+  if (router_guess_address_from_dir_headers(addr) >= 0)
+    return 0;
+
+  /* We have no useful cached answers. Return failure. */
+  return -1;
+}