Function decompress

devtools/onion.c:275–314

}

static void decompress(char *hexprivkey, char *hexonion)
{
	struct privkey rendezvous_key;
	size_t onionlen = hex_data_size(strlen(hexonion));
	u8 *compressed;
	struct pubkey ephkey;
	struct secret shared_secret;
	struct onionpacket *onion;
	struct sphinx_compressed_onion *tinyonion;

	if (!hex_decode(hexprivkey, strlen(hexprivkey), &rendezvous_key, sizeof(rendezvous_key)))
		errx(1, "Invalid private key hex '%s'", hexprivkey);

	compressed = tal_arr(NULL, u8, onionlen);
	if (!hex_decode(hexonion, strlen(hexonion), compressed, onionlen))
		errx(1, "Invalid onion hex '%s'", hexonion);

	if (onionlen < HMAC_SIZE + 1 + PUBKEY_SIZE)
		errx(1, "Onion is too short to contain the version, ephemeral key and HMAC");

	pubkey_from_der(compressed + 1, PUBKEY_SIZE, &ephkey);

	tinyonion = sphinx_compressed_onion_deserialize(NULL, compressed);
	if (tinyonion == NULL)
		errx(1, "Could not deserialize compressed onion");

	if (!sphinx_create_shared_secret(&shared_secret,
					 &tinyonion->ephemeralkey,
					 &rendezvous_key.secret))
		errx(1,
		     "Could not generate shared secret from ephemeral key %s "
		     "and private key %s",
		     pubkey_to_hexstr(NULL, &ephkey), hexprivkey);

	onion = sphinx_decompress(NULL, tinyonion, &shared_secret);
	if (onion == NULL)
		errx(1, "Could not decompress compressed onion");

	printf("Decompressed Onion: %s\n", tal_hex(NULL, serialize_onionpacket(NULL, onion)));
}

/* Tal wrappers for opt. */
static void *opt_allocfn(size_t size)