Reload unparseable descriptor dump FIFO state from on-disk dumped descriptors at startup

This commit is contained in:
Andrea Shepard 2016-06-30 04:36:23 +00:00
parent 38cced90ef
commit 421cf21b3c

View File

@ -588,6 +588,8 @@ static int check_signature_token(const char *digest,
/* Dump mechanism for unparseable descriptors */
static void dump_desc_populate_fifo_from_directory(const char *dirname);
/** List of dumped descriptors for FIFO cleanup purposes */
STATIC smartlist_t *descs_dumped = NULL;
/** Total size of dumped descriptors for FIFO cleanup */
@ -597,6 +599,7 @@ static int have_dump_desc_dir = 0;
static int problem_with_dump_desc_dir = 0;
#define DESC_DUMP_DATADIR_SUBDIR "unparseable-descs"
#define DESC_DUMP_BASE_FILENAME "unparseable-desc"
/*
* One entry in the list of dumped descriptors; filename dumped to, length
@ -607,6 +610,7 @@ typedef struct {
char *filename;
size_t len;
uint8_t digest_sha256[DIGEST256_LEN];
time_t when;
} dumped_desc_t;
/** Find the dump directory and check if we'll be able to create it */
@ -660,6 +664,10 @@ dump_desc_init(void)
problem_with_dump_desc_dir = 1;
}
if (have_dump_desc_dir && !problem_with_dump_desc_dir) {
dump_desc_populate_fifo_from_directory(dump_desc_dir);
}
tor_free(dump_desc_dir);
}
@ -718,6 +726,7 @@ dump_desc_fifo_add_and_clean(char *filename, const uint8_t *digest_sha256,
ent = tor_malloc_zero(sizeof(*ent));
ent->filename = filename;
ent->len = len;
ent->when = time(NULL);
memcpy(ent->digest_sha256, digest_sha256, DIGEST256_LEN);
/* Do we need to do some cleanup? */
@ -790,6 +799,8 @@ dump_desc_fifo_bump_hash(const uint8_t *digest_sha256)
} SMARTLIST_FOREACH_END(ent);
if (match) {
/* Update the timestamp */
match->when = time(NULL);
/* Add it back at the end of the list */
smartlist_add(descs_dumped, match);
@ -820,6 +831,225 @@ dump_desc_fifo_cleanup(void)
}
}
/** Handle one file for dump_desc_populate_fifo_from_directory(); make sure
* the filename is sensibly formed and matches the file content, and either
* return a dumped_desc_t for it or remove the file and return NULL.
*/
static dumped_desc_t *
dump_desc_populate_one_file(const char *dirname, const char *f)
{
dumped_desc_t *ent = NULL;
char *path = NULL, *desc = NULL;
const char *digest_str;
char digest[DIGEST256_LEN], content_digest[DIGEST256_LEN];
/* Expected prefix before digest in filenames */
const char *f_pfx = DESC_DUMP_BASE_FILENAME ".";
/*
* Stat while reading; this is important in case the file
* contains a NUL character.
*/
struct stat st;
/* Sanity-check args */
tor_assert(dirname != NULL);
tor_assert(f != NULL);
/* Form the full path */
tor_asprintf(&path, "%s" PATH_SEPARATOR "%s", dirname, f);
/* Check that f has the form DESC_DUMP_BASE_FILENAME.<digest256> */
if (!strcmpstart(f, f_pfx)) {
/* It matches the form, but is the digest parseable as such? */
digest_str = f + strlen(f_pfx);
if (base16_decode(digest, DIGEST256_LEN,
digest_str, strlen(digest_str)) != DIGEST256_LEN) {
/* We failed to decode it */
digest_str = NULL;
}
} else {
/* No match */
digest_str = NULL;
}
if (!digest_str) {
/* We couldn't get a sensible digest */
log_notice(LD_DIR,
"Removing unrecognized filename %s from unparseable "
"descriptors directory", f);
tor_unlink(path);
/* We're done */
goto done;
}
/*
* The filename has the form DESC_DUMP_BASE_FILENAME "." <digest256> and
* we've decoded the digest. Next, check that we can read it and the
* content matches this digest. We are relying on the fact that if the
* file contains a '\0', read_file_to_str() will allocate space for and
* read the entire file and return the correct size in st.
*/
desc = read_file_to_str(path, RFTS_IGNORE_MISSING, &st);
if (!desc) {
/* We couldn't read it */
log_notice(LD_DIR,
"Failed to read %s from unparseable descriptors directory; "
"attempting to remove it.", f);
tor_unlink(path);
/* We're done */
goto done;
}
/*
* We got one; now compute its digest and check that it matches the
* filename.
*/
if (crypto_digest256((char *)content_digest, desc, st.st_size,
DIGEST_SHA256) != 0) {
/* Weird, but okay */
log_info(LD_DIR,
"Unable to hash content of %s from unparseable descriptors "
"directory", f);
tor_unlink(path);
/* We're done */
goto done;
}
/* Compare the digests */
if (memcmp(digest, content_digest, DIGEST256_LEN) != 0) {
/* No match */
log_info(LD_DIR,
"Hash of %s from unparseable descriptors directory didn't "
"match its filename; removing it", f);
tor_unlink(path);
/* We're done */
goto done;
}
/* Okay, it's a match, we should prepare ent */
ent = tor_malloc_zero(sizeof(dumped_desc_t));
ent->filename = path;
memcpy(ent->digest_sha256, digest, DIGEST256_LEN);
ent->len = st.st_size;
ent->when = st.st_mtime;
/* Null out path so we don't free it out from under ent */
path = NULL;
done:
/* Free allocations if we had them */
tor_free(desc);
tor_free(path);
return ent;
}
/** Sort helper for dump_desc_populate_fifo_from_directory(); compares
* the when field of dumped_desc_ts in a smartlist to put the FIFO in
* the correct order after reconstructing it from the directory.
*/
static int
dump_desc_compare_fifo_entries(const void **a_v, const void **b_v)
{
const dumped_desc_t **a = (const dumped_desc_t **)a_v;
const dumped_desc_t **b = (const dumped_desc_t **)b_v;
if ((a != NULL) && (*a != NULL)) {
if ((b != NULL) && (*b != NULL)) {
/* We have sensible dumped_desc_ts to compare */
if ((*a)->when < (*b)->when) {
return -1;
} else if ((*a)->when == (*b)->when) {
return 0;
} else {
return 1;
}
} else {
/*
* We shouldn't see this, but what the hell, NULLs precede everythin
* else
*/
return 1;
}
} else {
return -1;
}
}
/** Scan the contents of the directory, and update FIFO/counters; this will
* consistency-check descriptor dump filenames against hashes of descriptor
* dump file content, and remove any inconsistent/unreadable dumps, and then
* reconstruct the dump FIFO as closely as possible for the last time the
* tor process shut down. If a previous dump was repeated more than once and
* moved ahead in the FIFO, the mtime will not have been updated and the
* reconstructed order will be wrong, but will always be a permutation of
* the original.
*/
static void
dump_desc_populate_fifo_from_directory(const char *dirname)
{
smartlist_t *files = NULL;
dumped_desc_t *ent = NULL;
tor_assert(dirname != NULL);
/* Get a list of files */
files = tor_listdir(dirname);
if (!files) {
log_notice(LD_DIR,
"Unable to get contents of unparseable descriptor dump "
"directory %s",
dirname);
return;
}
/*
* Iterate through the list and decide which files should go in the
* FIFO and which should be purged.
*/
SMARTLIST_FOREACH_BEGIN(files, char *, f) {
/* Try to get a FIFO entry */
ent = dump_desc_populate_one_file(dirname, f);
if (ent) {
/*
* We got one; add it to the FIFO. No need for duplicate checking
* here since we just verified the name and digest match.
*/
/* Make sure we have a list to add it to */
if (!descs_dumped) {
descs_dumped = smartlist_new();
len_descs_dumped = 0;
}
/* Add it and adjust the counter */
smartlist_add(descs_dumped, ent);
len_descs_dumped += ent->len;
}
/*
* If we didn't, we will have unlinked the file if necessary and
* possible, and emitted a log message about it, so just go on to
* the next.
*/
} SMARTLIST_FOREACH_END(f);
/* Did we get anything? */
if (descs_dumped != NULL) {
/* Sort the FIFO in order of increasing timestamp */
smartlist_sort(descs_dumped, dump_desc_compare_fifo_entries);
/* Log some stats */
log_info(LD_DIR,
"Reloaded unparseable descriptor dump FIFO with %d dump(s) "
"totaling " U64_FORMAT " bytes",
smartlist_len(descs_dumped), U64_PRINTF_ARG(len_descs_dumped));
}
/* Free the original list */
SMARTLIST_FOREACH(files, char *, f, tor_free(f));
smartlist_free(files);
}
/** For debugging purposes, dump unparseable descriptor *<b>desc</b> of
* type *<b>type</b> to file $DATADIR/unparseable-desc. Do not write more
* than one descriptor to disk per minute. If there is already such a
@ -853,7 +1083,8 @@ dump_desc(const char *desc, const char *type)
* We mention type and hash in the main log; don't clutter up the files
* with anything but the exact dump.
*/
tor_asprintf(&debugfile_base, "unparseable-desc.%s", digest_sha256_hex);
tor_asprintf(&debugfile_base,
DESC_DUMP_BASE_FILENAME ".%s", digest_sha256_hex);
debugfile = get_datadir_fname2(DESC_DUMP_DATADIR_SUBDIR, debugfile_base);
if (!sandbox_is_active()) {