[dns-client] allow empty question section in response with error code (#7438)
This commit updates `Dns::Client` such that when parsing a query
response we allow and accept a message with empty question section if
the response code in header indicates an error. This ensures that the
`Dns::Client` can work with DNS name resolvers that may not echo back
the question section in case of an error response.
diff --git a/src/core/net/dns_client.cpp b/src/core/net/dns_client.cpp
index 29bc85e..136ae11 100644
--- a/src/core/net/dns_client.cpp
+++ b/src/core/net/dns_client.cpp
@@ -978,12 +978,18 @@
// Check the Question Section
- VerifyOrExit(header.GetQuestionCount() == kQuestionCount[aType], error = kErrorParse);
-
- for (uint8_t num = 0; num < kQuestionCount[aType]; num++)
+ if (header.GetQuestionCount() == kQuestionCount[aType])
{
- SuccessOrExit(error = Name::CompareName(message, offset, queryName));
- offset += sizeof(Question);
+ for (uint8_t num = 0; num < kQuestionCount[aType]; num++)
+ {
+ SuccessOrExit(error = Name::CompareName(message, offset, queryName));
+ offset += sizeof(Question);
+ }
+ }
+ else
+ {
+ VerifyOrExit((header.GetResponseCode() != Header::kResponseSuccess) && (header.GetQuestionCount() == 0),
+ error = kErrorParse);
}
// Check the answer, authority and additional record sections
