Migrating from BPF Compiler Collection (BCC) to Aya

[davegreeko2023]

Hi there,
I use the Kernel Connection Multiplexor (KCM) which requires an fd of a BPF program. This BPF program simply looks at the TCP payload and extracts the 4 bytes integer. I got the sample Hello program in Aya to compile and worked as expected. But I could not manage to figure it out in Aya.
Any help on acheiving the below in Aya instead of bcc/libbpf is very much appreciated.

const char *bpf_prog_string = "                \
ssize_t bpf_prog1(struct __sk_buff *skb)	\
{                                                               \
	// ssize_t s: logic to extract 4 byes from tcp payload \
         return s;           \
}						                  \
";

int bpf_get_fd(void)
{
	int fd, map_fd;
	void *mod;
	int key;
	long long value = 0;

	mod = bpf_module_create_c_from_string(bpf_prog_string, 0, NULL, 0);
	fd = bpf_prog_load(
		BPF_PROG_TYPE_SOCKET_FILTER,
		bpf_function_start(mod, "bpf_prog1"),
		bpf_function_size(mod, "bpf_prog1"),
		bpf_module_license(mod),
		bpf_module_kern_version(mod),
		NULL, 0);

	if (fd == -1)
		exit(1);
	return fd;	
}