fuzz-tests: Add a test for codex32 operations

tests/fuzz/Makefile

@@ -29,6 +29,7 @@ FUZZ_COMMON_OBJS := \
 	common/close_tx.o				\
 	common/configdir.o				\
 	common/configvar.o				\
+	common/codex32.o				\
 	common/channel_id.o				\
 	common/channel_type.o				\
 	common/cryptomsg.o				\

tests/fuzz/corpora/fuzz-codex32/0f6e115d13c3538a23f90ebf97d6ffcf39afbef1

@@ -0,0 +1 @@
+MS100c8vsm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06g42qu7vsz9wgr0jz

tests/fuzz/corpora/fuzz-codex32/2071fb7b8dbf38edee36f1caa1620ebd9fb3d420

@@ -0,0 +1 @@
+ms140c8vsm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06gnqu6zlx79ts4hcj

tests/fuzz/corpora/fuzz-codex32/20c397c481f3f8d3ecc1624db1326645323e96dc

@@ -0,0 +1 @@
+MS12NAMEA320ZYXWVUTSRQPNMLKJHGFEDCAXRPP870HKKQRM

tests/fuzz/corpora/fuzz-codex32/2292461473f18e7b5ed68854e12a48d0b55796f6

@@ -0,0 +1 @@
+ms180c8vsm32zxfguhpchtlupzry9x8gf2fkhxvfcmqcxxwqe6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjkl9y7srstuvwxy06g58dthswcy66xph0

tests/fuzz/corpora/fuzz-codex32/22c9d22149a88a53ca9f2be8bbb43f4d570ad807

@@ -0,0 +1 @@
+ms10testsxxxxxxxxxxxxxxxxxxxxxxxxxx4nzvca9cmczlw

tests/fuzz/corpora/fuzz-codex32/290bde6b9018bc4a9edae698a92696755ed42ec8

@@ -0,0 +1 @@
+MS17nameslllllllllllllz57lkjhgfedcuzh80a2znz6n9q

tests/fuzz/corpora/fuzz-codex32/39a55dd99efd4d701d7de9ff37f674e2aac70076

@@ -0,0 +1 @@
+ms12names320zyxwvutsrqpnmlkjhgfedcugxxlcvjgvqe3e

tests/fuzz/corpora/fuzz-codex32/4e6763c8c9c9276346e2704711ebc4a13c40e266

@@ -0,0 +1 @@
+ms10names320zyxwvutsrqpnmlkjhgfedcuup9w8ra3hptrg

tests/fuzz/corpora/fuzz-codex32/63fcae92694d895f4df7ca3783596b24bb18d505

@@ -0,0 +1 @@
+ms180c8vsm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06g0u59rdx3k4l2rjg

tests/fuzz/corpora/fuzz-codex32/78893b9e252cc455f3a146e46d64103946d82d0c

@@ -0,0 +1 @@
+MS10names320zyxwvutsrqpnmlkjhgfedcuuh8d459hdwn5e

tests/fuzz/corpora/fuzz-codex32/7b6adc5b7c2497cac64229fe91305744e1c071a5

@@ -0,0 +1 @@
+ms13cashsm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06g38ts4eqpa3r0kku

tests/fuzz/corpora/fuzz-codex32/7cc962060637c99db4e7f6aa892493e61c90b5ea

@@ -0,0 +1 @@
+ms10leetsllhdmn9m42vcsamx24zrxgs3qqjzqud4m0d6nlnve25gvezzyqqtum9pgv99ycma

tests/fuzz/corpora/fuzz-codex32/853bd4bb09ee7346226d1e145d8175af3597441b

@@ -0,0 +1 @@
+ms140c8vsm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce9lua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06gxm0cest56r8njq7

tests/fuzz/corpora/fuzz-codex32/930f7a3424bab036fedf263615886e8694b082fc

@@ -0,0 +1 @@
+ms10testsxxxxxxxxxxxxxxxxxxxxxxxxxywvfucx7rv8mk8

tests/fuzz/corpora/fuzz-codex32/b088c1c023479100b2c91a6d3f40e95857ec5b50

@@ -0,0 +1 @@
+MS180c8vsxxxxxxxxxxxxxxxxxxxxxxxxxy5a952cj7r8drc

tests/fuzz/corpora/fuzz-codex32/c7aefcf6a974689a8b3a2919a6e910f0d277c56f

@@ -0,0 +1 @@
+MS12namesm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06gt24sk25hk88n76n

tests/fuzz/corpora/fuzz-codex32/cf374613312e12f1898499ef8e94162812a1aebd

@@ -0,0 +1 @@
+ms180c8vsm32zxfguhpchtlupzry9x8gf2fkhxvfcmqcxxwqe6mua7lqpzygsfjd6anl74rxvcemlh8wu3tk925acdefghjkl9y7srstuvwxy06g87v7krj7ym8wd7c

tests/fuzz/corpora/fuzz-codex32/d5db34994bff7942eb0a1d8e01e54e88c26058ed

@@ -0,0 +1 @@
+ms14namesm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06gtxceduz052m230h

tests/fuzz/corpora/fuzz-codex32/d808433cd03005fd94ae8ac0dbc16d8d71731da9

@@ -0,0 +1 @@
+ms100c8vsm32zxfguhpcj8lupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06g2fgv8hruujfcuhf

tests/fuzz/corpora/fuzz-codex32/e3219b38a3d111855dc53eb854841f5b63ee12d1

@@ -0,0 +1 @@
+MS130c8vsllhdmn9m42vcsamx24zrxgs3qq5w70grz2ju7e7

tests/fuzz/corpora/fuzz-codex32/e7c0556d7a732825f98cece13f3a5c6dae849bcd

@@ -0,0 +1 @@
+MS19testsm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06gwmgfy2umstn3ypz

tests/fuzz/corpora/fuzz-codex32/f021be98ca9f9cbaa83068e741434a1460f64aa1

@@ -0,0 +1 @@
+ms19testsm32zxfguhpchtlupzry9x8gf2tvdw0s3jn54khce6mua7lqpzygsfjd6an074rxvcemlh8wu3tk925acdefghjklmnpqrstuvwxy06gr6agur2jwd7q72p

tests/fuzz/corpora/fuzz-codex32/fc27381877bc42626c85d82828bf67df075c6091

@@ -0,0 +1 @@
+ms12names320zyxwvutkwqvqxlkjhgfedcuz46tyk28vaq6y

tests/fuzz/fuzz-codex32.c

@@ -0,0 +1,174 @@
+#include "config.h"
+#include <assert.h>
+#include <ccan/ccan/array_size/array_size.h>
+#include <common/setup.h>
+#include <common/utils.h>
+#include <common/codex32.h>
+#include <tests/fuzz/libfuzz.h>
+
+/* Default mutator defined by libFuzzer */
+size_t LLVMFuzzerMutate(uint8_t *data, size_t size, size_t max_size);
+size_t LLVMFuzzerCustomMutator(uint8_t *fuzz_data, size_t size, size_t max_size,
+				unsigned int seed);
+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);
+
+/* Initial valid Codex32 strings for seeding */
+static const char *valid_vectors[] = {
+	"ms10testsxxxxxxxxxxxxxxxxxxxxxxxxxx4nzvca9cmczlw",
+	"MS12NAMEA320ZYXWVUTSRQPNMLKJHGFEDCAXRPP870HKKQRM",
+	"ms13cashsllhdmn9m42vcsamx24zrxgs3qqjzqud4m0d6nln",
+	"ms10leetsllhdmn9m42vcsamx24zrxgs3qqjzqud4m0d6nlnve25gvezzyqqtum9pgv99ycma",
+	"MS100C8VSM32ZXFGUHPCHTLUPZRY9X8GF2TVDW0S3JN54KHCE6MUA7LQPZYGSFJD6AN074RXV"
+	"CEMLH8WU3TK925ACDEFGHJKLMNPQRSTUVWXY06FHPV80UNDVARHRAK"
+};
+
+/* Generate valid initial input */
+static size_t initial_input(uint8_t *fuzz_data, size_t max_size)
+{
+	size_t idx = rand() % ARRAY_SIZE(valid_vectors);
+	const char *vec = valid_vectors[idx];
+	size_t len = strlen(vec);
+
+	if (len > max_size)
+		len = max_size;
+
+	memcpy(fuzz_data, vec, len);
+	return len;
+}
+
+void init(int *argc, char ***argv)
+{
+	common_setup("fuzzer");
+}
+
+/* Custom mutator preserving Codex32 structure */
+size_t LLVMFuzzerCustomMutator(uint8_t *fuzz_data, size_t size,
+				size_t max_size, unsigned int seed)
+{
+	srand(seed);
+	char *str = to_string(tmpctx, fuzz_data, size);
+	char *fail;
+	struct codex32 *parts = codex32_decode(tmpctx, NULL, str, &fail);
+
+	/* If invalid, return valid vector */
+	if (!parts)
+		return initial_input(fuzz_data, max_size);
+
+	/* Mutate a random component */
+	switch(rand() % 5) {
+		case 0: /* Mutate HRP */
+			if (streq(parts->hrp, "ms"))
+				parts->hrp = "MS";
+			else
+				parts->hrp = "ms";
+			break;
+		case 1: /* Mutate threshold (0-9) */
+			parts->threshold = rand() % 10;
+			break;
+		case 2: /* Mutate ID (4 characters) */
+			for (int i = 0; i < 4; i++)
+				parts->id[i] = 'A' + (rand() % 26);
+			parts->id[4] = '\0';
+			break;
+		case 3: /* Mutate share index (valid char) */
+			parts->share_idx = "abcdefghijklmnopqrstuvwxyzABCDEF"[rand() % 32];
+			break;
+		case 4: /* Mutate payload */
+			if (tal_bytelen(parts->payload) > 0) {
+			size_t mutate_len = 1 + rand() % tal_bytelen(parts->payload);
+			LLVMFuzzerMutate((u8 *) parts->payload, mutate_len,
+					tal_bytelen(parts->payload));
+			}
+			break;
+	}
+
+	/* Re-encode mutated parts */
+	char *reencoded;
+	const char *err = codex32_secret_encode(tmpctx, parts->hrp, parts->id, parts->threshold,
+				parts->payload, tal_bytelen(parts->payload), &reencoded);
+
+	if (err)
+		return initial_input(fuzz_data, max_size);
+
+	size_t len = strlen(reencoded);
+	if (len > max_size)
+		return initial_input(fuzz_data, max_size);
+
+	memcpy(fuzz_data, reencoded, len);
+	return len;
+}
+
+/* Custom crossover for Codex32 strings */
+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 either invalid, use initial input */
+	if (!p1 || !p2)
+		return initial_input(out, max_out_size);
+
+	/* Choose component to crossover */
+	struct codex32 *child = p1;
+	switch(rand() % 5) {
+		case 0:
+			child->hrp = p2->hrp;
+			break;
+		case 1:
+			child->threshold = p2->threshold;
+			break;
+		case 2:
+			memcpy(child->id, p2->id, 5);
+			break;
+		case 3:
+			child->share_idx = p2->share_idx;
+			break;
+		case 4: /* Payload crossover */
+			child->payload = tal_arr(child, u8, tal_bytelen(p2->payload));
+			memcpy((u8 *) child->payload, p2->payload, tal_bytelen(p2->payload));
+			break;
+	}
+
+	/* Re-encode child */
+	char *reencoded;
+	const char *err = codex32_secret_encode(tmpctx, child->hrp, child->id, child->threshold,
+				child->payload, tal_bytelen(child->payload), &reencoded);
+
+	if (err)
+		return initial_input(out, max_out_size);
+
+	size_t len = strlen(reencoded);
+	if (len > max_out_size)
+		return initial_input(out, max_out_size);
+
+	memcpy(out, reencoded, len);
+	clean_tmpctx();
+	return len;
+}
+
+void run(const uint8_t *data, size_t size)
+{
+	struct codex32 *c32;
+	char *str, *fail, *bip93;
+
+	str = to_string(tmpctx, data, size);
+
+	c32 = codex32_decode(tmpctx, NULL, str, &fail);
+	if (c32) {
+		const char *ret = codex32_secret_encode(tmpctx, c32->hrp, c32->id, c32->threshold,
+				c32->payload, tal_bytelen(c32->payload), &bip93);
+		assert(!ret && bip93);
+	} else
+		assert(fail);
+
+	clean_tmpctx();
+}