Handle subscription of messages in the webapp.
Messages larger than a threshold are split and reassembled due to the
size limit in webrtc. Threshold may have to be adjusted somewhere between
64KiB and 256KiB.
This also includes a basic handler for a ping message and a more
advanced image handler.
Change-Id: If66acfb1bb84e9d3ff686994a94b1480cb70b2aa
diff --git a/aos/network/web_proxy_utils.cc b/aos/network/web_proxy_utils.cc
new file mode 100644
index 0000000..dbcc2e6
--- /dev/null
+++ b/aos/network/web_proxy_utils.cc
@@ -0,0 +1,43 @@
+#include "aos/network/web_proxy_utils.h"
+
+namespace aos {
+namespace web_proxy {
+
+// Recommended max size is 64KiB for compatibility reasons. 256KiB theoretically
+// works on chrome but seemed to have some consistency issues. Picked a size in
+// the middle which seems to work.
+constexpr size_t kPacketSize = 125000;
+
+int GetPacketCount(const Context &context) {
+ return context.size / kPacketSize + 1;
+}
+
+flatbuffers::Offset<MessageHeader> PackMessage(
+ flatbuffers::FlatBufferBuilder *fbb, const Context &context,
+ int channel_index, int packet_index) {
+ int packet_count = GetPacketCount(context);
+ flatbuffers::Offset<flatbuffers::Vector<uint8_t>> data_offset;
+ if (kPacketSize * (packet_index + 1) < context.size) {
+ data_offset = fbb->CreateVector(
+ static_cast<uint8_t *>(context.data) + kPacketSize * packet_index,
+ kPacketSize);
+ } else {
+ int prefix_size = kPacketSize * packet_index;
+ data_offset =
+ fbb->CreateVector(static_cast<uint8_t *>(context.data) + prefix_size,
+ context.size - prefix_size);
+ }
+
+ MessageHeader::Builder message_header_builder(*fbb);
+ message_header_builder.add_channel_index(channel_index);
+ message_header_builder.add_queue_index(context.queue_index);
+ message_header_builder.add_packet_count(packet_count);
+ message_header_builder.add_packet_index(packet_index);
+ message_header_builder.add_data(data_offset);
+ message_header_builder.add_length(context.size);
+
+ return message_header_builder.Finish();
+}
+
+} // namespace web_proxy
+} // namespace aos