Fix #2255 and #2256

Author: yhirose

httplib.h

@@ -11306,21 +11306,22 @@ SSLClient::verify_host_with_subject_alt_name(X509 *server_cert) const {
 
     for (decltype(count) i = 0; i < count && !dsn_matched; i++) {
       auto val = sk_GENERAL_NAME_value(alt_names, i);
-      if (val->type == type) {
-        auto name =
-            reinterpret_cast<const char *>(ASN1_STRING_get0_data(val->d.ia5));
-        auto name_len = static_cast<size_t>(ASN1_STRING_length(val->d.ia5));
-
-        switch (type) {
-        case GEN_DNS: dsn_matched = check_host_name(name, name_len); break;
-
-        case GEN_IPADD:
-          if (!memcmp(&addr6, name, addr_len) ||
-              !memcmp(&addr, name, addr_len)) {
-            ip_matched = true;
-          }
-          break;
+      if (!val || val->type != type) { continue; }
+
+      auto name =
+          reinterpret_cast<const char *>(ASN1_STRING_get0_data(val->d.ia5));
+      if (name == nullptr) { continue; }
+
+      auto name_len = static_cast<size_t>(ASN1_STRING_length(val->d.ia5));
+
+      switch (type) {
+      case GEN_DNS: dsn_matched = check_host_name(name, name_len); break;
+
+      case GEN_IPADD:
+        if (!memcmp(&addr6, name, addr_len) || !memcmp(&addr, name, addr_len)) {
+          ip_matched = true;
         }
+        break;
       }
     }