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Refactor format_networkstatus_vote to avoid preallocating a buffer.

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This saves a lot of "are we about to overrun the buffer?" checking,
and unmoots a bunch of "did we allocate enough" discussion.
This commit is contained in:
Nick Mathewson 2013-02-20 00:36:59 -05:00
parent 337e32f5b8
commit 9f044eac77
1 changed files with 47 additions and 91 deletions
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138
src/or/dirvote.c
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@ -67,17 +67,15 @@ char *
format_networkstatus_vote(crypto_pk_t *private_signing_key, format_networkstatus_vote(crypto_pk_t *private_signing_key,
networkstatus_t *v3_ns) networkstatus_t *v3_ns)
{ {
size_t len; smartlist_t *chunks;
char *status = NULL;
const char *client_versions = NULL, *server_versions = NULL; const char *client_versions = NULL, *server_versions = NULL;
char *outp, *endp;
char fingerprint[FINGERPRINT_LEN+1]; char fingerprint[FINGERPRINT_LEN+1];
char digest[DIGEST_LEN]; char digest[DIGEST_LEN];
uint32_t addr; uint32_t addr;
routerlist_t *rl = router_get_routerlist(); char *client_versions_line = NULL, *server_versions_line = NULL;
char *version_lines = NULL;
int r;
networkstatus_voter_info_t *voter; networkstatus_voter_info_t *voter;
char *status = NULL;
size_t status_len;
tor_assert(private_signing_key); tor_assert(private_signing_key);
tor_assert(v3_ns->type == NS_TYPE_VOTE || v3_ns->type == NS_TYPE_OPINION); 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; client_versions = v3_ns->client_versions;
server_versions = v3_ns->server_versions; server_versions = v3_ns->server_versions;
if (client_versions || server_versions) { if (client_versions) {
size_t v_len = 64; tor_asprintf(&client_versions_line, "client-versions %s\n",
char *cp; client_versions);
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);
}
}
} else { } 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; chunks = smartlist_new();
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);
{ {
char published[ISO_TIME_LEN+1]; char published[ISO_TIME_LEN+1];
char va[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(""); params = tor_strdup("");
tor_assert(cert); tor_assert(cert);
r = tor_snprintf(status, len, smartlist_add_asprintf(chunks,
"network-status-version 3\n" "network-status-version 3\n"
"vote-status %s\n" "vote-status %s\n"
"consensus-methods %s\n" "consensus-methods %s\n"
@ -160,7 +135,7 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
"fresh-until %s\n" "fresh-until %s\n"
"valid-until %s\n" "valid-until %s\n"
"voting-delay %d %d\n" "voting-delay %d %d\n"
"%s" /* versions */ "%s%s" /* versions */
"known-flags %s\n" "known-flags %s\n"
"flag-thresholds %s\n" "flag-thresholds %s\n"
"params %s\n" "params %s\n"
@ -170,7 +145,8 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
methods, methods,
published, va, fu, vu, published, va, fu, vu,
v3_ns->vote_seconds, v3_ns->dist_seconds, v3_ns->vote_seconds, v3_ns->dist_seconds,
version_lines, client_versions_line,
server_versions_line,
flags, flags,
flag_thresholds, flag_thresholds,
params, params,
@ -178,88 +154,63 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
fmt_addr32(addr), voter->dir_port, voter->or_port, fmt_addr32(addr), voter->dir_port, voter->or_port,
voter->contact); voter->contact);
if (r < 0) {
log_err(LD_BUG, "Insufficient memory for network status line");
tor_assert(0);
}
tor_free(params); tor_free(params);
tor_free(flags); tor_free(flags);
tor_free(flag_thresholds); tor_free(flag_thresholds);
tor_free(methods); tor_free(methods);
outp = status + strlen(status);
endp = status + len;
if (!tor_digest_is_zero(voter->legacy_id_digest)) { if (!tor_digest_is_zero(voter->legacy_id_digest)) {
char fpbuf[HEX_DIGEST_LEN+1]; char fpbuf[HEX_DIGEST_LEN+1];
base16_encode(fpbuf, sizeof(fpbuf), voter->legacy_id_digest, DIGEST_LEN); base16_encode(fpbuf, sizeof(fpbuf), voter->legacy_id_digest, DIGEST_LEN);
r = tor_snprintf(outp, endp-outp, "legacy-dir-key %s\n", fpbuf); smartlist_add_asprintf(chunks, "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);
} }
tor_assert(outp + cert->cache_info.signed_descriptor_len < endp); smartlist_add(chunks, tor_strndup(cert->cache_info.signed_descriptor_body,
memcpy(outp, cert->cache_info.signed_descriptor_body, cert->cache_info.signed_descriptor_len));
cert->cache_info.signed_descriptor_len);
outp += cert->cache_info.signed_descriptor_len;
} }
SMARTLIST_FOREACH_BEGIN(v3_ns->routerstatus_list, vote_routerstatus_t *, SMARTLIST_FOREACH_BEGIN(v3_ns->routerstatus_list, vote_routerstatus_t *,
vrs) { vrs) {
#define MAX_VOTE_ROUTERSTATUS_LEN 8192
char rs_buf[MAX_VOTE_ROUTERSTATUS_LEN];
vote_microdesc_hash_t *h; 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) { vrs->version, NS_V3_VOTE, vrs) < 0) {
log_warn(LD_BUG, "Unable to print router status."); log_warn(LD_BUG, "Unable to print router status; skipping");
goto err; continue;
} }
outp += strlen(outp); smartlist_add(chunks, tor_strdup(rs_buf));
for (h = vrs->microdesc; h; h = h->next) { for (h = vrs->microdesc; h; h = h->next) {
size_t mlen = strlen(h->microdesc_hash_line); smartlist_add(chunks, tor_strdup(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_FOREACH_END(vrs); } SMARTLIST_FOREACH_END(vrs);
r = tor_snprintf(outp, endp-outp, "directory-footer\n"); smartlist_add(chunks, tor_strdup("directory-footer\n"));
if (r < 0) {
log_err(LD_BUG, "Insufficient memory for directory-footer line");
tor_assert(0);
}
outp += strlen(outp);
{ {
char signing_key_fingerprint[FINGERPRINT_LEN+1]; 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, if (crypto_pk_get_fingerprint(private_signing_key,
signing_key_fingerprint, 0)<0) { signing_key_fingerprint, 0)<0) {
log_warn(LD_BUG, "Unable to get fingerprint for signing key"); log_warn(LD_BUG, "Unable to get fingerprint for signing key");
goto err; goto err;
} }
if (tor_snprintf(outp, endp-outp, "%s %s\n", fingerprint,
signing_key_fingerprint)<0) { smartlist_add_asprintf(chunks, "directory-signature %s %s\n", fingerprint,
log_warn(LD_BUG, "Unable to end signature line."); signing_key_fingerprint);
goto err;
}
outp += strlen(outp);
} }
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) if (router_get_networkstatus_v3_hash(status, digest, DIGEST_SHA1)<0)
goto err; goto err;
note_crypto_pk_op(SIGN_DIR); 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) { private_signing_key)<0) {
log_warn(LD_BUG, "Unable to sign networkstatus vote."); log_warn(LD_BUG, "Unable to sign networkstatus vote.");
goto err; goto err;
@ -282,7 +233,12 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
err: err:
tor_free(status); tor_free(status);
done: 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; return status;
} }