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feat(checksum): --checksum-choice/--cc and --checksum-seed for whole-file digest

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Adds real algorithm selection (xxh64 default, plus md5 via OpenSSL EVP) and a
64-bit seed for the per-file whole-file digest used by the --incremental/
--checksum handshake and basis-dir content verification. The seed also feeds
the delta path's per-block xxHash32 strong checksum (low 32 bits) so an
explicit seed deterministically changes those digests too. Sender and receiver
hash identically: the algorithm id and seed cross the config wire frame and the
STATUS_CHECK handshake now carries a length-prefixed, bounded digest instead of
a fixed 64-bit value. Unsupported algorithm names are rejected at parse time
(never a silent no-op). PROTOCOL_VERSION bumped 2.9.0 -> 2.10.0; defaults
(xxh64, seed 0) preserve prior byte-for-byte behavior.
This commit is contained in:
TapTap
2026-09-07 17:42:47 +02:00
parent 6701c103cb
commit 0afda6b094
12 changed files with 316 additions and 43 deletions
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src/shared/config.c
+24 -3
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@@ -127,6 +127,8 @@ static void config_set_defaults(Config* config) {
config->daemon_config = NULL;
config->server_mode = false;
config->checksum = false;
config->checksum_algo = CHECKSUM_ALGO_XXH64;
config->checksum_seed = 0;
config->compress_choice = NULL;
config->chmod_spec = NULL;
config->skip_compress_suffixes = NULL;
@@ -172,7 +174,7 @@ static bool validate_received_config(const Config* config) {
!(config->delay_updates && delay_updates_staging_name_conflict(config->backup_dir)) &&
valid_wire_bool(config->partial) && valid_wire_bool(config->delete_before) &&
valid_wire_bool(config->checksum) && valid_wire_bool(config->eight_bit_output) &&
config_has_valid_delete_timing(config) &&
checksum_algo_valid(config->checksum_algo) && config_has_valid_delete_timing(config) &&
!(config->skip_compress_set && config->use_chunk_serialization) &&
(!config->use_compression ||
(config->compression_level >= 1 && config->compression_level <= 22)) &&
@@ -462,6 +464,15 @@ static bool send_fuzzy_option(int fd, const Config* c) {
return send_int(fd, c->fuzzy);
}
/* --checksum-choice/--cc + --checksum-seed. The algorithm id and seed travel
* with the config so the receiver hashes the on-disk old file with the same
* parameters the sender used for its digest (see checksum.h). Trailing fields
* on the config frame; protocol 2.10.0. */
static bool send_checksum_options(int fd, const Config* c) {
return send_int(fd, c->checksum_algo) &&
send_n_data(fd, &c->checksum_seed, sizeof(c->checksum_seed));
}
static bool receive_core_fields(int fd, Config* c) {
int value;
if (!receive_wire_bool(fd, &c->eight_bit_output))
@@ -637,13 +648,22 @@ static bool receive_fuzzy_option(int fd, Config* c) {
return receive_wire_bool(fd, &c->fuzzy);
}
static bool receive_checksum_options(int fd, Config* c) {
int algo;
if (!receive_int(fd, &algo) || !checksum_algo_valid(algo))
return false;
c->checksum_algo = algo;
return receive_n_data(fd, &c->checksum_seed, sizeof(c->checksum_seed));
}
bool config_send(int file_descriptor, const Config* config) {
protocol_session_set_max_alloc(NULL, config->max_alloc);
if (!send_core_fields(file_descriptor, config) || !send_delta_fields(file_descriptor, config) ||
!send_file_options(file_descriptor, config) ||
!send_selection_options(file_descriptor, config) ||
!send_resume_options(file_descriptor, config) ||
!send_basis_options(file_descriptor, config) || !send_fuzzy_option(file_descriptor, config))
!send_basis_options(file_descriptor, config) || !send_fuzzy_option(file_descriptor, config) ||
!send_checksum_options(file_descriptor, config))
return false;
Status status;
if (!receive_status(file_descriptor, &status))
@@ -677,7 +697,8 @@ Config* config_receive(int file_descriptor) {
!receive_selection_options(file_descriptor, config) ||
!receive_resume_options(file_descriptor, config) ||
!receive_basis_options(file_descriptor, config) ||
!receive_fuzzy_option(file_descriptor, config))
!receive_fuzzy_option(file_descriptor, config) ||
!receive_checksum_options(file_descriptor, config))
goto error;
if (config->compress_choice[0] != '\0' && strcmp(config->compress_choice, "zstd") != 0 &&
strcmp(config->compress_choice, "none") != 0) {