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[dns-client] use DecompressRecordData() for broader record type support (#11412)

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This commit updates the DNS client to use `DecompressRecordData()`
helper method when processing `QueryRecord()` responses for
arbitrary record types.

This enables decompression of embedded DNS names within the received
record data for a wider range of record types. In particular, name
decompression is now supported for PTR, CNAME, DNAME, NS, SRV, SOA,
MX, RP, AFSDB, RT, PX, KX, and NSEC records.
This commit is contained in:
Abtin Keshavarzian
2025-04-23 16:40:56 -07:00
committed by GitHub
parent b0176443cc
commit 3e7528e4e9
3 changed files with 15 additions and 47 deletions
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12
include/openthread/dns_client.h
View File

@ -760,11 +760,11 @@ otError otDnsRecordResponseGetQueryName(const otDnsRecordResponse *aResponse,
* - The data is copied into `mDataBuffer` (if not `NULL`) up to its capacity specified by `mDataBufferSize`.
* - `mDataBufferSize` is then updated to reflect the number of bytes actually written into `mDataBuffer`.
*
* If the retrieved record type is PTR (12), CNAME (5), DNAME (39), NS (2), or SRV (33), the record data in the
* received response contains a DNS name which may use DNS name compression. For these specific record types, the
* record data is first decompressed such that it contains the full uncompressed DNS name. This decompressed data is
* then provided in `mDataBuffer`, and `mRecordDataLength` will indicate the length of this decompressed data. For all
* other record types, the record data is read and provided as it appears in the received response message.
* If the retrieved record type is NS, CNAME, SOA, PTR, MX, RP, AFSDB, RT, PX, SRV, KX, DNAME, or NSEC, the record
* data in the received response contains a DNS name which may use DNS name compression. For these specific record
* types, the record data is first decompressed such that it contains the full uncompressed DNS name. This decompressed
* data is then provided in `mDataBuffer`, and `mRecordDataLength` will indicate the length of this decompressed data.
* For all other record types, the record data is read and provided as it appears in the received response message.
*
* @param[in] aResponse A pointer to the response.
* @param[in] aIndex The record index to retrieve.
@ -774,7 +774,7 @@ otError otDnsRecordResponseGetQueryName(const otDnsRecordResponse *aResponse,
* @retval OT_ERROR_NOT_FOUND No record in @p aResponse at @p aIndex.
* @retval OT_ERROR_PARSE Could not parse the records in the @p aResponse.
* @retval OT_ERROR_NO_BUFS The record name does not fit in the provided `mNameBufferSize` in @p aRecordInfo, or
* failed to allocate buffer to decompress a compressed DNS name (PTR, SRV, CNAME).
* failed to allocate buffer to decompress a compressed DNS name.
*/
otError otDnsRecordResponseGetRecordInfo(const otDnsRecordResponse *aResponse,
uint16_t aIndex,

2
include/openthread/instance.h
View File

@ -52,7 +52,7 @@ extern "C" {
*
* @note This number versions both OpenThread platform and user APIs.
*/
#define OPENTHREAD_API_VERSION (501)
#define OPENTHREAD_API_VERSION (502)
/**
* @addtogroup api-instance

48
src/core/net/dns_client.cpp
View File

@ -378,10 +378,10 @@ exit:
Error Client::Response::ReadRecordInfo(uint16_t aIndex, RecordInfo &aRecordInfo) const
{
Error error;
uint16_t offset;
ResourceRecord record;
Message *decompressedData = nullptr;
Error error;
uint16_t offset;
ResourceRecord record;
OwnedPtr<Message> decompressedData;
if (aIndex < mAnswerRecordCount)
{
@ -406,43 +406,12 @@ Error Client::Response::ReadRecordInfo(uint16_t aIndex, RecordInfo &aRecordInfo)
SuccessOrExit(error = Name::ReadName(*mMessage, offset, aRecordInfo.mNameBuffer, aRecordInfo.mNameBufferSize));
SuccessOrExit(error = mMessage->Read(offset, record));
VerifyOrExit(offset + record.GetSize() <= mMessage->GetLength(), error = kErrorParse);
offset += sizeof(record);
aRecordInfo.mRecordType = record.GetType();
aRecordInfo.mTtl = record.GetTtl();
// We may need to translate the record data for PTR, CNAME, DNAME, NS
// and SRV record since the data format contains a DNS name which
// may use compression.
switch (record.GetType())
{
case ResourceRecord::kTypePtr:
case ResourceRecord::kTypeCname:
case ResourceRecord::kTypeDname:
case ResourceRecord::kTypeNs:
case ResourceRecord::kTypeSrv:
decompressedData = mMessage->Get<MessagePool>().Allocate(Message::kTypeOther);
VerifyOrExit(decompressedData != nullptr, error = kErrorNoBufs);
if (record.GetType() == ResourceRecord::kTypeSrv)
{
uint16_t srvMinLength = sizeof(SrvRecord) - sizeof(ResourceRecord);
VerifyOrExit(record.GetLength() > srvMinLength, error = kErrorParse);
SuccessOrExit(error = decompressedData->AppendBytesFromMessage(*mMessage, offset, srvMinLength));
offset += srvMinLength;
}
SuccessOrExit(error = Name(*mMessage, offset).AppendTo(*decompressedData));
break;
default:
break;
}
SuccessOrExit(error = ResourceRecord::DecompressRecordData(*mMessage, offset, decompressedData));
aRecordInfo.mRecordType = record.GetType();
aRecordInfo.mRecordLength = (decompressedData != nullptr) ? decompressedData->GetLength() : record.GetLength();
aRecordInfo.mTtl = record.GetTtl();
if (aRecordInfo.mDataBuffer == nullptr)
{
@ -458,11 +427,10 @@ Error Client::Response::ReadRecordInfo(uint16_t aIndex, RecordInfo &aRecordInfo)
}
else
{
mMessage->ReadBytes(offset, aRecordInfo.mDataBuffer, aRecordInfo.mDataBufferSize);
mMessage->ReadBytes(offset + sizeof(ResourceRecord), aRecordInfo.mDataBuffer, aRecordInfo.mDataBufferSize);
}
exit:
FreeMessage(decompressedData);
return error;
}