Various maxmind_acl fixes (#8181)

* Various maxmind_acl fixes

 - Add a check for non-nullptr client addr
 - Add null termination for iso_codes. They are stored unterminated in the database so to properly
   lookup in the map we need to terminate ourselves

* Review fixes

Author: ezelkow1

plugins/experimental/maxmind_acl/mmdb.cc

@@ -406,7 +406,16 @@ Acl::eval(TSRemapRequestInfo *rri, TSHttpTxn txnp)
 {
   bool ret = default_allow;
   int mmdb_error;
-  MMDB_lookup_result_s result = MMDB_lookup_sockaddr(&_mmdb, TSHttpTxnClientAddrGet(txnp), &mmdb_error);
+
+  auto sockaddr = TSHttpTxnClientAddrGet(txnp);
+
+  if (sockaddr == nullptr) {
+    TSDebug(PLUGIN_NAME, "Err during TsHttpClientAddrGet, nullptr returned");
+    ret = false;
+    return ret;
+  }
+
+  MMDB_lookup_result_s result = MMDB_lookup_sockaddr(&_mmdb, sockaddr, &mmdb_error);
 
   if (MMDB_SUCCESS != mmdb_error) {
     TSDebug(PLUGIN_NAME, "Error during sockaddr lookup: %s", MMDB_strerror(mmdb_error));
@@ -498,8 +507,11 @@ Acl::eval_country(MMDB_entry_data_s *entry_data, const char *path, int path_len)
   bool ret     = false;
   bool allow   = default_allow;
   char *output = nullptr;
-  output       = static_cast<char *>(malloc((sizeof(char) * entry_data->data_size)));
+
+  // We need to null terminate the iso_code ourselves, they are unterminated in the DBs
+  output = static_cast<char *>(malloc((sizeof(char) * (entry_data->data_size + 1))));
   strncpy(output, entry_data->utf8_string, entry_data->data_size);
+  output[entry_data->data_size] = '\0';
   TSDebug(PLUGIN_NAME, "This IP Country Code: %s", output);
   auto exists = allow_country.count(output);