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Fix O(n^2) performance when parsing a big pile of extrainfos

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We were doing an O(n) strlen in router_get_extrainfo_hash() for
every one we tried to parse.  Instead, have
router_get_extrainfo_hash() take the length of the extrainfo as an
argument, so that when it's called from
extrainfo_parse_from_string(), it doesn't do a strlen() over the
whole pile of extrainfos.
This commit is contained in:
Nick Mathewson
2012-05-10 17:27:16 -04:00
committed by Roger Dingledine
parent 62f8e3926d
commit 02a650786b
4 changed files with 11 additions and 7 deletions
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src/or/routerparse.c
+5 -5
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@@ -682,12 +682,12 @@ router_get_networkstatus_v3_hash(const char *s, char *digest,
' ', alg);
}
/** Set <b>digest</b> to the SHA-1 digest of the hash of the extrainfo
* string in <b>s</b>. Return 0 on success, -1 on failure. */
/** Set <b>digest</b> to the SHA-1 digest of the hash of the <b>s_len</b>-byte
* extrainfo string at <b>s</b>. Return 0 on success, -1 on failure. */
int
router_get_extrainfo_hash(const char *s, char *digest)
router_get_extrainfo_hash(const char *s, size_t s_len, char *digest)
{
return router_get_hash_impl(s, strlen(s), digest, "extra-info",
return router_get_hash_impl(s, s_len, digest, "extra-info",
"\nrouter-signature",'\n', DIGEST_SHA1);
}
@@ -1643,7 +1643,7 @@ extrainfo_parse_entry_from_string(const char *s, const char *end,
while (end > s+2 && *(end-1) == '\n' && *(end-2) == '\n')
--end;
if (router_get_extrainfo_hash(s, digest) < 0) {
if (router_get_extrainfo_hash(s, end-s, digest) < 0) {
log_warn(LD_DIR, "Couldn't compute router hash.");
goto err;
}