[tor-commits] [tor/release-0.2.4] Refactor format_networkstatus_vote to avoid preallocating a buffer.
arma at torproject.org
arma at torproject.org
Sat May 25 03:58:40 UTC 2013
commit 9f044eac77ee2245de71283e71361346ee194f25
Author: Nick Mathewson <nickm at torproject.org>
Date: Wed Feb 20 00:36:59 2013 -0500
Refactor format_networkstatus_vote to avoid preallocating a buffer.
This saves a lot of "are we about to overrun the buffer?" checking,
and unmoots a bunch of "did we allocate enough" discussion.
---
src/or/dirvote.c | 138 +++++++++++++++++++-----------------------------------
1 file changed, 47 insertions(+), 91 deletions(-)
diff --git a/src/or/dirvote.c b/src/or/dirvote.c
index bcfe2b0..bd4e2f6 100644
--- a/src/or/dirvote.c
+++ b/src/or/dirvote.c
@@ -67,17 +67,15 @@ char *
format_networkstatus_vote(crypto_pk_t *private_signing_key,
networkstatus_t *v3_ns)
{
- size_t len;
- char *status = NULL;
+ smartlist_t *chunks;
const char *client_versions = NULL, *server_versions = NULL;
- char *outp, *endp;
char fingerprint[FINGERPRINT_LEN+1];
char digest[DIGEST_LEN];
uint32_t addr;
- routerlist_t *rl = router_get_routerlist();
- char *version_lines = NULL;
- int r;
+ char *client_versions_line = NULL, *server_versions_line = NULL;
networkstatus_voter_info_t *voter;
+ char *status = NULL;
+ size_t status_len;
tor_assert(private_signing_key);
tor_assert(v3_ns->type == NS_TYPE_VOTE || v3_ns->type == NS_TYPE_OPINION);
@@ -91,43 +89,20 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
client_versions = v3_ns->client_versions;
server_versions = v3_ns->server_versions;
- if (client_versions || server_versions) {
- size_t v_len = 64;
- char *cp;
- if (client_versions)
- v_len += strlen(client_versions);
- if (server_versions)
- v_len += strlen(server_versions);
- version_lines = tor_malloc(v_len);
- cp = version_lines;
- if (client_versions) {
- r = tor_snprintf(cp, v_len-(cp-version_lines),
- "client-versions %s\n", client_versions);
- if (r < 0) {
- log_err(LD_BUG, "Insufficient memory for client-versions line");
- tor_assert(0);
- }
- cp += strlen(cp);
- }
- if (server_versions) {
- r = tor_snprintf(cp, v_len-(cp-version_lines),
- "server-versions %s\n", server_versions);
- if (r < 0) {
- log_err(LD_BUG, "Insufficient memory for server-versions line");
- tor_assert(0);
- }
- }
+ if (client_versions) {
+ tor_asprintf(&client_versions_line, "client-versions %s\n",
+ client_versions);
} else {
- version_lines = tor_strdup("");
+ client_versions_line = tor_strdup("");
+ }
+ if (server_versions) {
+ tor_asprintf(&server_versions_line, "server-versions %s\n",
+ server_versions);
+ } else {
+ server_versions_line = tor_strdup("");
}
- len = 8192;
- len += strlen(version_lines);
- len += (RS_ENTRY_LEN+MICRODESC_LINE_LEN)*smartlist_len(rl->routers);
- len += strlen("\ndirectory-footer\n");
- len += v3_ns->cert->cache_info.signed_descriptor_len;
-
- status = tor_malloc(len);
+ chunks = smartlist_new();
{
char published[ISO_TIME_LEN+1];
char va[ISO_TIME_LEN+1];
@@ -151,7 +126,7 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
params = tor_strdup("");
tor_assert(cert);
- r = tor_snprintf(status, len,
+ smartlist_add_asprintf(chunks,
"network-status-version 3\n"
"vote-status %s\n"
"consensus-methods %s\n"
@@ -160,7 +135,7 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
"fresh-until %s\n"
"valid-until %s\n"
"voting-delay %d %d\n"
- "%s" /* versions */
+ "%s%s" /* versions */
"known-flags %s\n"
"flag-thresholds %s\n"
"params %s\n"
@@ -170,7 +145,8 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
methods,
published, va, fu, vu,
v3_ns->vote_seconds, v3_ns->dist_seconds,
- version_lines,
+ client_versions_line,
+ server_versions_line,
flags,
flag_thresholds,
params,
@@ -178,88 +154,63 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
fmt_addr32(addr), voter->dir_port, voter->or_port,
voter->contact);
- if (r < 0) {
- log_err(LD_BUG, "Insufficient memory for network status line");
- tor_assert(0);
- }
-
tor_free(params);
tor_free(flags);
tor_free(flag_thresholds);
tor_free(methods);
- outp = status + strlen(status);
- endp = status + len;
if (!tor_digest_is_zero(voter->legacy_id_digest)) {
char fpbuf[HEX_DIGEST_LEN+1];
base16_encode(fpbuf, sizeof(fpbuf), voter->legacy_id_digest, DIGEST_LEN);
- r = tor_snprintf(outp, endp-outp, "legacy-dir-key %s\n", fpbuf);
- if (r < 0) {
- log_err(LD_BUG, "Insufficient memory for legacy-dir-key line");
- tor_assert(0);
- }
- outp += strlen(outp);
+ smartlist_add_asprintf(chunks, "legacy-dir-key %s\n", fpbuf);
}
- tor_assert(outp + cert->cache_info.signed_descriptor_len < endp);
- memcpy(outp, cert->cache_info.signed_descriptor_body,
- cert->cache_info.signed_descriptor_len);
-
- outp += cert->cache_info.signed_descriptor_len;
+ smartlist_add(chunks, tor_strndup(cert->cache_info.signed_descriptor_body,
+ cert->cache_info.signed_descriptor_len));
}
SMARTLIST_FOREACH_BEGIN(v3_ns->routerstatus_list, vote_routerstatus_t *,
vrs) {
+#define MAX_VOTE_ROUTERSTATUS_LEN 8192
+ char rs_buf[MAX_VOTE_ROUTERSTATUS_LEN];
vote_microdesc_hash_t *h;
- if (routerstatus_format_entry(outp, endp-outp, &vrs->status,
+ if (routerstatus_format_entry(rs_buf, sizeof(rs_buf), &vrs->status,
vrs->version, NS_V3_VOTE, vrs) < 0) {
- log_warn(LD_BUG, "Unable to print router status.");
- goto err;
+ log_warn(LD_BUG, "Unable to print router status; skipping");
+ continue;
}
- outp += strlen(outp);
+ smartlist_add(chunks, tor_strdup(rs_buf));
for (h = vrs->microdesc; h; h = h->next) {
- size_t mlen = strlen(h->microdesc_hash_line);
- if (outp+mlen >= endp) {
- log_warn(LD_BUG, "Can't fit microdesc line in vote.");
- }
- memcpy(outp, h->microdesc_hash_line, mlen+1);
- outp += strlen(outp);
+ smartlist_add(chunks, tor_strdup(h->microdesc_hash_line));
}
} SMARTLIST_FOREACH_END(vrs);
- r = tor_snprintf(outp, endp-outp, "directory-footer\n");
- if (r < 0) {
- log_err(LD_BUG, "Insufficient memory for directory-footer line");
- tor_assert(0);
- }
- outp += strlen(outp);
+ smartlist_add(chunks, tor_strdup("directory-footer\n"));
{
char signing_key_fingerprint[FINGERPRINT_LEN+1];
- if (tor_snprintf(outp, endp-outp, "directory-signature ")<0) {
- log_warn(LD_BUG, "Unable to start signature line.");
- goto err;
- }
- outp += strlen(outp);
-
if (crypto_pk_get_fingerprint(private_signing_key,
signing_key_fingerprint, 0)<0) {
log_warn(LD_BUG, "Unable to get fingerprint for signing key");
goto err;
}
- if (tor_snprintf(outp, endp-outp, "%s %s\n", fingerprint,
- signing_key_fingerprint)<0) {
- log_warn(LD_BUG, "Unable to end signature line.");
- goto err;
- }
- outp += strlen(outp);
+
+ smartlist_add_asprintf(chunks, "directory-signature %s %s\n", fingerprint,
+ signing_key_fingerprint);
}
+ status = smartlist_join_strings(chunks, "", 0, NULL);
+#define MAX_VOTE_SIGNATURE_LEN 4096
+ status_len = strlen(status) + MAX_VOTE_SIGNATURE_LEN + 1;
+ status = tor_realloc(status, status_len);
+
if (router_get_networkstatus_v3_hash(status, digest, DIGEST_SHA1)<0)
goto err;
note_crypto_pk_op(SIGN_DIR);
- if (router_append_dirobj_signature(outp,endp-outp,digest, DIGEST_LEN,
+ if (router_append_dirobj_signature(status+strlen(status),
+ status_len,
+ digest, DIGEST_LEN,
private_signing_key)<0) {
log_warn(LD_BUG, "Unable to sign networkstatus vote.");
goto err;
@@ -282,7 +233,12 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
err:
tor_free(status);
done:
- tor_free(version_lines);
+ tor_free(client_versions_line);
+ tor_free(server_versions_line);
+ if (chunks) {
+ SMARTLIST_FOREACH(chunks, char *, cp, tor_free(cp));
+ smartlist_free(chunks);
+ }
return status;
}
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