update avahi txt data conversion

src/mdns/mdns_avahi.cpp

@@ -798,48 +798,40 @@ otbrError PublisherAvahi::TxtDataToAvahiStringList(const TxtData &aTxtData,
  size_t used = 0;
  AvahiStringList *last = nullptr;
  AvahiStringList *curr = aBuffer;
- TxtList txtList;
-
- // TODO: Change this and simplify this...
- SuccessOrExit(error = DecodeTxtData(txtList, aTxtData.data(), aTxtData.size()));
+ const uint8_t *next;
+ const uint8_t *data = aTxtData.data();
+ const uint8_t *dataEnd = aTxtData.data() + aTxtData.size();
 
  aHead = nullptr;
- for (const auto &txtEntry : txtList)
+
+ while (data < dataEnd)
  {
- const char *key = txtEntry.mKey.c_str();
- size_t keyLength = txtEntry.mKey.length();
- const uint8_t *value = txtEntry.mValue.data();
- size_t valueLength = txtEntry.mValue.size();
- size_t needed = sizeof(AvahiStringList) - sizeof(AvahiStringList::text) + keyLength;
- const uint8_t *next;
-
- if (!txtEntry.mIsBooleanAttribute)
+ uint8_t entryLength = *data++;
+ size_t needed = sizeof(AvahiStringList) - sizeof(AvahiStringList::text) + entryLength;
+
+ if (entryLength == 0)
  {
- needed += valueLength + 1; // +1 is for `=` character.
+ continue;
  }
 
+ VerifyOrExit(data + entryLength <= dataEnd, error = OTBR_ERROR_PARSE);
+
  VerifyOrExit(used + needed <= aBufferSize, error = OTBR_ERROR_INVALID_ARGS);
  curr->next = last;
  last = curr;
- memcpy(curr->text, key, keyLength);
 
- if (!txtEntry.mIsBooleanAttribute)
- {
- curr->text[keyLength] = '=';
- memcpy(curr->text + keyLength + 1, value, valueLength);
- curr->size = keyLength + valueLength + 1;
- }
- else
- {
- curr->size = keyLength;
- }
+ memcpy(curr->text, data, entryLength);
+ curr->size = entryLength;
+
+ data += entryLength;
 
  next = curr->text + curr->size;
  curr = OTBR_ALIGNED(next, AvahiStringList *);
  used = static_cast<size_t>(reinterpret_cast<uint8_t *>(curr) - reinterpret_cast<uint8_t *>(aBuffer));
  }
- SuccessOrExit(error);
+
  aHead = last;
+
 exit:
  return error;
 }