fix: the bug where iobuf should be enlarged during the replication (#…

…1744)

If an empty buffer is passed to the socket Recv function - it returns error 103.
Even if we returned success, this would lead to the endless loop since the parser
requires more data to parse the load.
Fixes #1680

Signed-off-by: Roman Gershman <[email protected]>

src/server/protocol_client.cc

@@ -315,6 +315,7 @@ io::Result<ProtocolClient::ReadRespRes> ProtocolClient::ReadRespReply(base::IoBu
   while (!ec) {
     uint32_t consumed;
     if (buffer->InputLen() == 0 || result == RedisParser::INPUT_PENDING) {
+      DCHECK_GT(buffer->AppendLen(), 0u);
       io::MutableBytes buf = buffer->AppendBuffer();
       io::Result<size_t> size_res = sock_->Recv(buf);
       if (!size_res) {
@@ -344,6 +345,11 @@ io::Result<ProtocolClient::ReadRespRes> ProtocolClient::ReadRespReply(base::IoBu
       LOG(ERROR) << "Invalid parser status " << result << " for response " << last_resp_;
       return nonstd::make_unexpected(std::make_error_code(std::errc::bad_message));
     }
+
+    // We need to read more data. Check that we have enough space.
+    if (buffer->AppendLen() < 64u) {
+      buffer->EnsureCapacity(buffer->Capacity() * 2);
+    }
   }
 
   return nonstd::make_unexpected(ec);