relay: New file relay_resolve_addr.{c|h}

This commit moves router_pick_published_address() and the related helper
functions into the new file.

The log_addr_has_changed() function has been made public in router.h so we can
use it in relay_resolve_addr.c.

This is a refactoring as part of Sponsor 55. Only code movement at this
commit.

Part of #33789

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

5 files changed, 162 insertions, 121 deletions

diff --git a/src/feature/relay/include.am b/src/feature/relay/include.am
index 654432c34b..2aa2985607 100644
--- a/src/feature/relay/include.am
+++ b/src/feature/relay/include.am
@@ -2,6 +2,7 @@
 # Legacy shared relay code: migrate to the relay module over time
 LIBTOR_APP_A_SOURCES += 			\
 	src/feature/relay/onion_queue.c		\
+	src/feature/relay/relay_resolve_addr.c	\
 	src/feature/relay/router.c
 
 # The Relay module.
@@ -31,6 +32,7 @@ noinst_HEADERS +=					\
 	src/feature/relay/relay_handshake.h		\
 	src/feature/relay/relay_periodic.h		\
 	src/feature/relay/relay_sys.h			\
+	src/feature/relay/relay_resolve_addr.h		\
 	src/feature/relay/router.h			\
 	src/feature/relay/routerkeys.h			\
 	src/feature/relay/routermode.h			\
diff --git a/src/feature/relay/relay_resolve_addr.c b/src/feature/relay/relay_resolve_addr.c
new file mode 100644
index 0000000000..7d83d870c7
--- /dev/null
+++ b/src/feature/relay/relay_resolve_addr.c
@@ -0,0 +1,132 @@
+/* Copyright (c) 2001-2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file relay_resolve_addr.c
+ * \brief Implement relay resolving address mechanism.
+ **/
+
+#include "core/or/or.h"
+
+#include "app/config/config.h"
+
+#include "core/mainloop/mainloop.h"
+
+#include "feature/control/control_events.h"
+#include "feature/dircommon/dir_connection_st.h"
+#include "feature/relay/relay_resolve_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;
+}
diff --git a/src/feature/relay/relay_resolve_addr.h b/src/feature/relay/relay_resolve_addr.h
new file mode 100644
index 0000000000..1ead2baf7a
--- /dev/null
+++ b/src/feature/relay/relay_resolve_addr.h
@@ -0,0 +1,23 @@
+/* Copyright (c) 2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file relay_resolve_addr.h
+ * \brief Header file for relay_resolve_addr.c.
+ **/
+
+#ifndef TOR_RELAY_RESOLVE_ADDR_H
+#define TOR_RELAY_RESOLVE_ADDR_H
+
+MOCK_DECL(int, router_pick_published_address,
+          (const or_options_t *options, uint32_t *addr, int cache_only));
+
+void router_new_address_suggestion(const char *suggestion,
+                                   const dir_connection_t *d_conn);
+
+#ifdef RELAY_RESOLVE_ADDR_PRIVATE
+
+#endif /* RELAY_RESOLVE_ADDR_PRIVATE */
+
+#endif /* TOR_RELAY_RESOLVE_ADDR_H */
+
diff --git a/src/feature/relay/router.c b/src/feature/relay/router.c
index 2858371af5..cbb49ede15 100644
--- a/src/feature/relay/router.c
+++ b/src/feature/relay/router.c
@@ -36,6 +36,7 @@
 #include "feature/nodelist/torcert.h"
 #include "feature/relay/dns.h"
 #include "feature/relay/relay_config.h"
+#include "feature/relay/relay_resolve_addr.h"
 #include "feature/relay/router.h"
 #include "feature/relay/routerkeys.h"
 #include "feature/relay/routermode.h"
@@ -1763,41 +1764,6 @@ router_get_descriptor_gen_reason(void)
   return desc_gen_reason;
 }
 
-static int router_guess_address_from_dir_headers(uint32_t *guess);
-
-/** 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;
-}
-
 /* Like router_check_descriptor_address_consistency, but specifically for the
  * ORPort or DirPort.
  * listener_type is either CONN_TYPE_OR_LISTENER or CONN_TYPE_DIR_LISTENER. */
@@ -2523,7 +2489,7 @@ check_descriptor_bandwidth_changed(time_t now)
 
 /** Note at log level severity that our best guess of address has changed from
  * <b>prev</b> to <b>cur</b>. */
-static void
+void
 log_addr_has_changed(int severity,
                      const tor_addr_t *prev,
                      const tor_addr_t *cur,
@@ -2595,86 +2561,6 @@ check_descriptor_ipaddress_changed(time_t now)
   tor_free(hostname);
 }
 
-/** The most recently guessed value of our IP address, based on directory
- * headers. */
-static tor_addr_t last_guessed_ip = TOR_ADDR_NULL;
-
-/** 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 */
-  }
-}
-
-/** 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;
-}
-
 /** Set <b>platform</b> (max length <b>len</b>) to a NUL-terminated short
  * string describing the version of Tor and the operating system we're
  * currently running on.
diff --git a/src/feature/relay/router.h b/src/feature/relay/router.h
index 39c550dd25..50790a73dd 100644
--- a/src/feature/relay/router.h
+++ b/src/feature/relay/router.h
@@ -87,8 +87,6 @@ void mark_my_descriptor_dirty(const char *reason);
 void check_descriptor_bandwidth_changed(time_t now);
 void check_descriptor_ipaddress_changed(time_t now);
 int router_has_bandwidth_to_be_dirserver(const or_options_t *options);
-void router_new_address_suggestion(const char *suggestion,
-                                   const dir_connection_t *d_conn);
 int router_compare_to_my_exit_policy(const tor_addr_t *addr, uint16_t port);
 MOCK_DECL(int, router_my_exit_policy_is_reject_star,(void));
 MOCK_DECL(const routerinfo_t *, router_get_my_routerinfo, (void));
@@ -100,9 +98,6 @@ int router_digest_is_me(const char *digest);
 const uint8_t *router_get_my_id_digest(void);
 int router_extrainfo_digest_is_me(const char *digest);
 int router_is_me(const routerinfo_t *router);
-MOCK_DECL(int,router_pick_published_address,(const or_options_t *options,
-                                             uint32_t *addr,
-                                             int cache_only));
 int router_build_fresh_descriptor(routerinfo_t **r, extrainfo_t **e);
 int router_rebuild_descriptor(int force);
 char *router_dump_router_to_string(routerinfo_t *router,
@@ -120,6 +115,9 @@ int extrainfo_dump_to_string(char **s, extrainfo_t *extrainfo,
 const char *routerinfo_err_to_string(int err);
 int routerinfo_err_is_transient(int err);
 
+void log_addr_has_changed(int severity, const tor_addr_t *prev,
+                          const tor_addr_t *cur, const char *source);
+
 void router_reset_warnings(void);
 void router_free_all(void);