addr: New function relay_address_new_suggestion()

This behaves like router_new_address_suggestion() but differs in couple of
ways:

  1. It takes a tor_addr_t instead of an address string and supports both
     AF_INET and AF_INET6.
  2. It does _not_ use the last_guessed_ip local cache and instead only relies
     on the last resolved address cache in resolve_addr.c

It is not used at this commit. This function is made to process a suggested
address found in a NETINFO cell exactly like router_new_address_suggestion()
does with the address a directory suggests us.

Related to #40022

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

1 files changed, 29 insertions, 0 deletions

diff --git a/src/app/config/resolve_addr.c b/src/app/config/resolve_addr.c
index 2a11ba3c00..75b5eb75b1 100644
--- a/src/app/config/resolve_addr.c
+++ b/src/app/config/resolve_addr.c
@@ -44,6 +44,12 @@ typedef enum {
 /** Last resolved addresses. */
 static tor_addr_t last_resolved_addrs[IDX_SIZE];
 
+/** Last suggested addresses.
+ *
+ * These addresses come from a NETINFO cell from a trusted relay (currently
+ * only authorities). We only use those in last resort. */
+static tor_addr_t last_suggested_addrs[IDX_SIZE];
+
 static inline int
 af_to_idx(const int family)
 {
@@ -60,6 +66,29 @@ af_to_idx(const int family)
   }
 }
 
+/** Copy the last suggested address of family into addr_out.
+ *
+ * If no last suggested address exists, the addr_out is a null address (use
+ * tor_addr_is_null() to confirm). */
+void
+resolved_addr_get_suggested(int family, tor_addr_t *addr_out)
+{
+  tor_addr_copy(addr_out, &last_suggested_addrs[af_to_idx(family)]);
+}
+
+/** Set the last suggested address into our cache. This is called when we get
+ * a new NETINFO cell from a trusted source. */
+void
+resolved_addr_set_suggested(const tor_addr_t *addr)
+{
+  if (BUG(tor_addr_family(addr) != AF_INET ||
+          tor_addr_family(addr) != AF_INET6)) {
+    return;
+  }
+  tor_addr_copy(&last_suggested_addrs[af_to_idx(tor_addr_family(addr))],
+                addr);
+}
+
 /** Copy the last resolved address of family into addr_out.
  *
  * If not last resolved address existed, the addr_out is a null address (use