tlv #

A small C23 library for serializing and deserializing typed values over sockets using the Type-Length-Value wire format.

• https://wikipedia.org/wiki/Type%E2%80%93length%E2%80%93value

Each message looks like this:

packet
title TLV Message
+1: "Type"
+4: "Length"
+8: "Value (could be more than 8 bytes)"

Multiple frames can be concatenated into a single stream and sent in one write().

Supported types#

Usage#

Sending#

Steps:

1. serialize values
2. concatenate them into a stream
3. write to socket

#include "tlv.h"

Buffer stream = serialize((uint32_t)file_size);
stream = buf_append(stream, serialize_cstr(filename));
stream = buf_append(stream, serialize_bin(file_data));

write(fd, stream.bytes, stream.len);
free(stream.bytes);

Receiving#

Steps:

1. read from socket
2. deserialize
3. access by type

Buffer incoming = { .bytes = recv_buf, .len = n };
Message *msgs = deserialize(incoming);

uint32_t size     = message_u32(msgs[0]);
char    *filename = message_cstr(msgs[1]);   // heap-allocated, call free()
Buffer   data     = message_bin(msgs[2]);

// do your thing

free(filename);
for (size_t i = 0; i < da_length(msgs); i++)
	message_free(&msgs[i]);
da_free(msgs);

Build#

Bootstrap once:

cc nob.c -o nob

Then:

./nob            # build .build/libtlv.a and .build/libtlv.so
./nob test       # compile and run tests (ASan + UBSan enabled)
./nob static     # static library only
./nob dynamic    # dynamic library only
./nob docs       # generate HTML docs in .build/docs/html/index.html
./nob valgrind   # run tests under Valgrind
./nob clean      # remove .build/

The nob binary recompiles itself automatically when nob.c changes.

Ownership rules#

Remember this !!!

• serialize*() and buf_append() return an owned Buffer
  • call free(buf.bytes) when done.
• deserialize() returns an owned Message* array
  • call message_free() on each element, then da_free().
• message_cstr() returns a heap-allocated char*
  • call free() when done.