Function LLVMFuzzerCustomCrossOver

tests/fuzz/fuzz-codex32.c:102–169

Custom crossover with structure-aware recombination */

/* Custom crossover with structure-aware recombination */
size_t LLVMFuzzerCustomCrossOver(const u8 *in1, size_t in1_size, const u8 *in2, size_t in2_size,
				u8 *out, size_t max_out_size, unsigned seed)
{
	srand(seed);
	char *str1 = to_string(tmpctx, in1, in1_size);
	char *str2 = to_string(tmpctx, in2, in2_size);
	char *fail;

	/* Decode both inputs */
	struct codex32 *p1 = codex32_decode(tmpctx, NULL, str1, &fail);
	struct codex32 *p2 = codex32_decode(tmpctx, NULL, str2, &fail);

	/* If both valid, try structure-aware crossover */
	if (p1 && p2) {
		/* Create child by combining parts */
		struct codex32 *child = codex32_dup(tmpctx, p1);

		/* Choose crossover method */
		switch(rand() % 3) {
		case 0: /* Crossover threshold */
			child->threshold = p2->threshold;
			break;

		case 1: /* Crossover ID */
			{
				size_t id_len = sizeof(p1->id) - 1;
				cross_over((const u8 *)p1->id, id_len, (const u8 *)p2->id, id_len,
					   (u8 *)child->id, id_len, rand());
				child->id[id_len] = '\0';
			}
			break;

		case 2: /* Crossover payload */
			{
				size_t p1_len = tal_bytelen(p1->payload);
				size_t p2_len = tal_bytelen(p2->payload);
				tal_resize(&child->payload, max_out_size);
				size_t new_payload_len = cross_over(p1->payload, p1_len,
								p2->payload, p2_len,
								(u8 *)child->payload, max_out_size, rand());
				tal_resize(&child->payload, new_payload_len);
			}
			break;
		}

		/* Always crossover the HRP to ensure it's valid for encoding. */
		char *new_hrp = tal_arr(child, char, 3);
		new_hrp[0] = valid_hrp_chars[rand() % strlen(valid_hrp_chars)];
		new_hrp[1] = valid_hrp_chars[rand() % strlen(valid_hrp_chars)];
		new_hrp[2] = '\0';
		child->hrp = new_hrp;

		char *reencoded;
		const char *err = codex32_secret_encode(tmpctx, child->hrp, child->id,
							child->threshold, child->payload,
							tal_bytelen(child->payload), &reencoded);
		if (!err) {
			size_t len = strlen(reencoded);