1 files changed, 38 insertions, 19 deletions

diff --git a/tools/libskrewt.c b/tools/libskrewt.c
index c8f2ccd..5e06dea 100644
--- a/tools/libskrewt.c
+++ b/tools/libskrewt.c
@@ -236,6 +236,24 @@ void check_spf(name_tester& fqdn, const string ip) {
    }
 }
 
+bool operator==(const struct addrinfo& aaa,
+                const struct addrinfo& bbb) {
+  if (aaa.ai_family != bbb.ai_family) return 0;
+  if (memcmp(aaa.ai_addr, bbb.ai_addr, aaa.ai_addrlen) != 0) return 0;
+  return 1;
+}
+
+// loop over all IP addresses in linked list, checking for a match
+bool matchany(const struct addrinfo& aaa,
+                const struct addrinfo* blist){
+  for (const struct addrinfo *bbb = blist; bbb != NULL; bbb = bbb->ai_next){
+    if (aaa == *bbb) {
+      return 1;         // match
+    }
+  }
+  return 0;
+}
+
 void check_map2ip(name_tester& fqdn, const string ipstr) {
   if (ipstr.length() == 0) {
     cerr << progid << " check_map2ip: no addr specified." << endl;
@@ -243,10 +261,13 @@ void check_map2ip(name_tester& fqdn, const string ipstr) {
     return;
   }
 
-// convert address-as-string to address-as-bits.
-// also get information about family
-  struct addrinfo *ipresult;
-  struct addrinfo *result;
+// Convert address-as-string to address-as-bits.
+// Also get information about family.
+// The trick is, we will get address info about an /address/.
+// (This is in contrast to a normal fwd dns lookup,
+// which gets address info about a name.)
+
+  struct addrinfo *ip_bits;
   addrinfo hints;
   int error;
 
@@ -254,7 +275,7 @@ void check_map2ip(name_tester& fqdn, const string ipstr) {
   // restrict to TCP only; otherwise we get N records per address
   hints.ai_protocol = IPPROTO_TCP;
 
-  error = getaddrinfo(ipstr.c_str(), NULL, &hints, &ipresult);
+  error = getaddrinfo(ipstr.c_str(), NULL, &hints, &ip_bits);
   // EAI_NONAME covers the case of malformed IP address
   // e.g. 1.2.3.4.5
   if (error == EAI_NONAME) {
@@ -269,14 +290,17 @@ void check_map2ip(name_tester& fqdn, const string ipstr) {
     fqdn.map2ip = fail;
     return;
   }
-  if (!ipresult) {
+  if (!ip_bits) {
     cerr << progid
          <<" ??? should never happen (ipstr with no ipbits?)" << endl;
     fqdn.map2ip = fail;
     return;
   }
 
-  error = getaddrinfo(fqdn.name.c_str(), NULL, &hints, &result);
+// do the forward dns lookup
+// result is a list of ip addresses
+  struct addrinfo *fwd_rslt;
+  error = getaddrinfo(fqdn.name.c_str(), NULL, &hints, &fwd_rslt);
   if (error == EAI_NONAME) {
     // malformed name, or no address for name
     fqdn.map2ip = fail;
@@ -291,19 +315,14 @@ void check_map2ip(name_tester& fqdn, const string ipstr) {
     return;
   }
 
-// loop over all returned results and check for a match.
-  for (struct addrinfo *res = result; res != NULL; res = res->ai_next){
-    if (memcmp(res->ai_addr, ipresult->ai_addr, res->ai_addrlen) == 0) {
-      // match!
-      goto done;
-    }
+  if (!matchany(*ip_bits, fwd_rslt)) {
+    fqdn.map2ip = fail;
+    return;
   }
-  // here if no match
-  fqdn.map2ip = fail;
-  return;
-done:
-  fqdn.map2ip = pass;
-  return;
+
+// here if all checks have been passed
+    fqdn.map2ip = pass;
+    return;
 }
 
 void check_name_ip(name_tester& fqdn, const string ip) {