Address nickm's comments at https://trac.torproject.org/projects/tor/ticket/933#comment:4

1. Implement the following mapping rules:

   MapAddress a.b.c d.e.f # This is what we have now
   MapAddress .a.b.c d.e.f # Replaces any address ending with .a.b.c with d.e.f
   MapAddress .a.b.c .d.e.f # Replaces the .a.b.c at the end of any addr with .d.e.f

   (Note that 'a.b.c .d.e.f' is invalid, and will be rejected.)

2. Add tests for the new rules.

3. Allow proper wildcard annotation, i.e. '*.d.e' '.d.e' will still work.

4. Update addressmap_entry_t with an is_wildcard member.

2 files changed, 28 insertions, 10 deletions

diff --git a/src/or/config.c b/src/or/config.c
index afcea1f4c..1744b84c4 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -4464,7 +4464,18 @@ config_register_addressmaps(const or_options_t *options)
     if (smartlist_len(elts) >= 2) {
       from = smartlist_get(elts,0);
       to = smartlist_get(elts,1);
-      if (address_is_invalid_destination(to, 1)) {
+
+      /* Remove leading asterisk in expressions of type: '*.example.com' */
+      if (from[0] == '*' && strlen(from) > 1)
+        from++;
+      if (to[0] == '*' && strlen(to) > 1)
+        to++;
+      if (to[0] == '.' && from[0] != '.') {
+        log_warn(LD_CONFIG,
+                 "Skipping invalid argument '%s' to MapAddress: "
+                 "can only use wildcard (i.e. '.' or '*.') if 'from' address "
+                 "uses wildcard also", to);
+      } else if (address_is_invalid_destination(to, 1)) {
         log_warn(LD_CONFIG,
                  "Skipping invalid argument '%s' to MapAddress", to);
       } else {
diff --git a/src/or/connection_edge.c b/src/or/connection_edge.c
index 4bb49c831..2c8c9da25 100644
--- a/src/or/connection_edge.c
+++ b/src/or/connection_edge.c
@@ -794,6 +794,7 @@ typedef struct {
   char *new_address;
   time_t expires;
   addressmap_entry_source_t source:3;
+  int is_wildcard:1;
   short num_resolve_failures;
 } addressmap_entry_t;
 
@@ -1037,8 +1038,12 @@ addressmap_free_all(void)
   virtaddress_reversemap = NULL;
 }
 
-/** Try to find a match for AddressMap directives that use
- *  domain notation such as '.torproject.org .exitnode.exit'.
+/** Try to find a match for AddressMap expressions that use
+ *  wildcard notation such as '*.c.d *.e.f' (so 'a.c.d' will map to 'a.e.f') or
+ *  '*.c.d a.b.c' (so 'a.c.d' will map to a.b.c).
+ *  Returns the matching entry in AddressMap or 0 if no match is found.
+ *  For expressions such as '*.c.d *.e.f' the <b>address</b> 'a.c.d' will
+ *  get truncated to 'a' before we return the matching AddressMap entry.
  */
 static addressmap_entry_t *
 addressmap_match_superdomains(char *address)
@@ -1047,13 +1052,18 @@ addressmap_match_superdomains(char *address)
   const char *key;
   void *_val;
   addressmap_entry_t *val;
+  char *matched_domains = 0;
 
   for (iter = strmap_iter_init(addressmap); !strmap_iter_done(iter); ) {
     strmap_iter_get(iter, &key, &_val);
     val = _val;
-    if (key[0] == '.') { /* match end */
-      if (!strcasecmpend(address, key) || !strcasecmp(address, &key[1]))
+    if (key[0] == '.') {
+      if (!strcasecmpend(address, key) || !strcasecmp(address, &key[1])) {
+        matched_domains = strstr(address, key);
+        if (val->is_wildcard && matched_domains)
+            *matched_domains = '\0';
         return val;
+      }
     }
     iter = strmap_iter_next(addressmap,iter);
   }
@@ -1073,7 +1083,6 @@ addressmap_rewrite(char *address, size_t maxlen, time_t *expires_out)
   addressmap_entry_t *ent;
   int rewrites;
   char *cp;
-  char *s;
   time_t expires = TIME_MAX;
 
   for (rewrites = 0; rewrites < 16; rewrites++) {
@@ -1089,10 +1098,7 @@ addressmap_rewrite(char *address, size_t maxlen, time_t *expires_out)
     }
 
     cp = tor_strdup(escaped_safe_str_client(address));
-    /* If the address to rewrite to is in the form '.exitnode.exit'
-       then append it to the given address */
-    s = strrchr(ent->new_address,'.');
-    if (ent->new_address[0] == '.' && !strcmp(s+1,"exit"))
+    if (ent->is_wildcard)
       strlcpy(address + strlen(address), ent->new_address,
               (maxlen - strlen(address)));
     else
@@ -1211,6 +1217,7 @@ addressmap_register(const char *address, char *new_address, time_t expires,
   ent->expires = expires==2 ? 1 : expires;
   ent->num_resolve_failures = 0;
   ent->source = source;
+  ent->is_wildcard = (new_address[0] == '.') ? 1 : 0;
 
   log_info(LD_CONFIG, "Addressmap: (re)mapped '%s' to '%s'",
            safe_str_client(address),