mirror of
https://github.com/ElementsProject/lightning.git
synced 2026-08-13 12:32:55 +02:00
4ca60ba6e0
dev_override_randbytes() hashes argv0 into the CLN_DEV_ENTROPY_SEED stream, so every plugin and subdaemon gets a distinct seed. But lightningd execs them with absolute paths, so the "deterministic" stream silently depended on where the source tree was checked out: canned blocks generated in one directory would not replay in another (funding tx output order and nlocktime fuzz diverge, so txids change). This is why check-doc-examples passed locally but failed in CI. Hash only the basename: binaries still get distinct seeds, but the stream no longer depends on the checkout path.
71 lines
1.8 KiB
C
71 lines
1.8 KiB
C
#include "config.h"
|
|
#include <assert.h>
|
|
#include <ccan/crypto/siphash24/siphash24.h>
|
|
#include <ccan/endian/endian.h>
|
|
#include <ccan/tal/tal.h>
|
|
#include <common/memleak.h>
|
|
#include <common/pseudorand.h>
|
|
#include <common/randbytes.h>
|
|
#include <common/utils.h>
|
|
#include <sodium/randombytes.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
|
|
static bool used = false;
|
|
static u64 dev_seed = 0;
|
|
|
|
bool randbytes_overridden(void)
|
|
{
|
|
return dev_seed != 0;
|
|
}
|
|
|
|
void randbytes_(void *bytes, size_t num_bytes, u64 *offset)
|
|
{
|
|
static u64 offset_init;
|
|
be64 pattern;
|
|
|
|
used = true;
|
|
if (!randbytes_overridden()) {
|
|
randombytes_buf(bytes, num_bytes); /* discouraged: use randbytes() */
|
|
return;
|
|
}
|
|
|
|
/* First time, start callers at different offsets */
|
|
if (*offset == 0) {
|
|
*offset = offset_init;
|
|
offset_init += 1000;
|
|
}
|
|
|
|
/* Somewhat recognizable pattern */
|
|
pattern = cpu_to_be64(dev_seed + (*offset)++);
|
|
for (size_t i = 0; i < num_bytes; i += sizeof(pattern)) {
|
|
size_t copy = num_bytes - i;
|
|
if (copy > sizeof(pattern))
|
|
copy = sizeof(pattern);
|
|
|
|
memcpy((u8 *)bytes + i, &pattern, copy);
|
|
}
|
|
}
|
|
|
|
/* We want different seeds for each plugin (hence argv0), and for each
|
|
* lightningd instance, (hence seed from environment) */
|
|
void dev_override_randbytes(const char *argv0, long int seed)
|
|
{
|
|
struct siphash_seed hashseed;
|
|
const char *base;
|
|
assert(!used);
|
|
|
|
/* Hash only the basename: binaries still get distinct seeds, but
|
|
* the stream no longer depends on the checkout path. Plugins and
|
|
* subdaemons are exec'd with absolute paths: hash only the basename,
|
|
* so the stream doesn't depend on where the source tree lives */
|
|
base = strrchr(argv0, '/');
|
|
base = base ? base + 1 : argv0;
|
|
|
|
hashseed.u.u64[0] = seed;
|
|
hashseed.u.u64[1] = 0;
|
|
|
|
dev_seed = siphash24(&hashseed, base, strlen(base));
|
|
assert(randbytes_overridden());
|
|
}
|