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Implement the server part of the consensus-by-authority-fpr proposal

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svn:r14445
This commit is contained in:
Peter Palfrader 2008-04-24 15:38:54 +00:00
parent d5be900986
commit 006b5762d3
1 changed files with 62 additions and 1 deletions
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63
src/or/directory.c
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@ -57,6 +57,7 @@ static void dir_routerdesc_download_failed(smartlist_t *failed,
int was_extrainfo,
int was_descriptor_digests);
static void note_request(const char *key, size_t bytes);
static int client_likes_consensus(networkstatus_t *v, const char *want_url);
/********* START VARIABLES **********/
@ -2164,6 +2165,57 @@ directory_dump_request_log(void)
}
#endif
/** Decide whether a client would accept the consensus we have
*
* Clients can say they only want a consensus if it's signed by more
* than half the authorities in <list>. They pass this list in
* the url as ..consensus/<fpr>+<fpr>+<fpr>
* <fpr> may be an abbreviated fingerprint, i.e. only a left substring
* of the full authority identity digest. (Only strings of even length,
* i.e. encodings of full bytes, are handled correctly. In the case
* of an odd number of hex digits the last one is silently ignored.)
*
* Returns 1 if more than half of the requested authorities signed the
* consensus, 0 otherwise.
*/
int
client_likes_consensus(networkstatus_t *v, const char *want_url)
{
smartlist_t *want_authorities = smartlist_create();
int need_at_least;
int have = 0;
dir_split_resource_into_fingerprints(want_url, want_authorities, NULL, 0, 0);
need_at_least = smartlist_len(want_authorities)/2+1;
SMARTLIST_FOREACH(want_authorities, const char *, d, {
char want_digest[DIGEST_LEN];
int want_len = strlen(d)/2;
if (want_len > DIGEST_LEN)
want_len = DIGEST_LEN;
if (base16_decode(want_digest, DIGEST_LEN, d, want_len*2) < 0) {
log_warn(LD_DIR,"Failed to decode requested authority digest %s.", d);
continue;
};
SMARTLIST_FOREACH(v->voters, networkstatus_voter_info_t *, vi, {
if (vi->signature &&
!memcmp(vi->identity_digest, want_digest, want_len)) {
have++;
break;
};
});
/* early exit, if we already have enough */
if (have >= need_at_least)
break;
});
SMARTLIST_FOREACH(want_authorities, char *, d, tor_free(d));
smartlist_free(want_authorities);
return (have >= need_at_least);
}
/** Helper function: called when a dirserver gets a complete HTTP GET
* request. Look for a request for a directory or for a rendezvous
* service descriptor. On finding one, write a response into
@ -2291,7 +2343,7 @@ directory_handle_command_get(dir_connection_t *conn, const char *headers,
}
if (!strcmpstart(url,"/tor/status/")
|| !strcmp(url, "/tor/status-vote/current/consensus")) {
|| !strcmpstart(url, "/tor/status-vote/current/consensus")) {
/* v2 or v3 network status fetch. */
smartlist_t *dir_fps = smartlist_create();
int is_v3 = !strcmpstart(url, "/tor/status-vote");
@ -2312,6 +2364,15 @@ directory_handle_command_get(dir_connection_t *conn, const char *headers,
} else {
networkstatus_t *v = networkstatus_get_latest_consensus();
time_t now = time(NULL);
#define CONSENSUS_URL_PREFIX "/tor/status-vote/current/consensus/"
if (!strcmpstart(url, CONSENSUS_URL_PREFIX) &&
!client_likes_consensus(v, url + strlen(CONSENSUS_URL_PREFIX))) {
write_http_status_line(conn, 404, "Consensus not signed by sufficient "
"number of requested authorities");
smartlist_free(dir_fps);
goto done;
}
smartlist_add(dir_fps, tor_memdup("\0\0\0\0\0\0\0\0\0\0"
"\0\0\0\0\0\0\0\0\0\0", 20));
request_type = compressed?"v3.z":"v3";