[tor-commits] [tor/master] Split consensus-request parsing into a separate function
nickm at torproject.org
nickm at torproject.org
Mon May 15 22:18:15 UTC 2017
commit 4531fdbbff4ac5127d3de421903ccf2fe2171097
Author: Nick Mathewson <nickm at torproject.org>
Date: Thu May 4 11:13:44 2017 -0400
Split consensus-request parsing into a separate function
This ought to make the control flow a tiny bit more readable.
---
src/or/directory.c | 131 +++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 96 insertions(+), 35 deletions(-)
diff --git a/src/or/directory.c b/src/or/directory.c
index 71ae274..4537d79 100644
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -3822,43 +3822,75 @@ find_best_compression_method(unsigned compression_methods, int stream)
return NO_METHOD;
}
-/** Helper function for GET /tor/status-vote/current/consensus
+/** Encodes the results of parsing a consensus request to figure out what
+ * consensus, and possibly what diffs, the user asked for. */
+typedef struct {
+ /** name of the flavor to retrieve. */
+ char *flavor;
+ /** flavor to retrive, as enum. */
+ consensus_flavor_t flav;
+ /** plus-separated list of authority fingerprints; see
+ * client_likes_consensus(). Aliases the URL in the request passed to
+ * parse_consensus_request(). */
+ const char *want_fps;
+ /** Optionally, a smartlist of sha3 digests-as-signed of the consensuses
+ * to return a diff from. */
+ smartlist_t *diff_from_digests;
+ /** If true, never send a full consensus. If there is no diff, send
+ * a 404 instead. */
+ int diff_only;
+} parsed_consensus_request_t;
+
+/** Remove all data held in <b>req</b>. Do not free <b>req</b> itself, since
+ * it is stack-allocated. */
+static void
+parsed_consensus_request_clear(parsed_consensus_request_t *req)
+{
+ if (!req)
+ return;
+ tor_free(req->flavor);
+ if (req->diff_from_digests) {
+ SMARTLIST_FOREACH(req->diff_from_digests, uint8_t *, d, tor_free(d));
+ smartlist_free(req->diff_from_digests);
+ }
+ memset(req, 0, sizeof(parsed_consensus_request_t));
+}
+
+/**
+ * Parse the URL and relevant headers of <b>args</b> for a current-consensus
+ * request to learn what flavor of consensus we want, what keys it must be
+ * signed with, and what diffs we would accept (or demand) instead. Return 0
+ * on success and -1 on failure.
*/
static int
-handle_get_current_consensus(dir_connection_t *conn,
- const get_handler_args_t *args)
+parse_consensus_request(parsed_consensus_request_t *out,
+ const get_handler_args_t *args)
{
const char *url = args->url;
- const compress_method_t compress_method =
- find_best_compression_method(args->compression_supported, 0);
- const time_t if_modified_since = args->if_modified_since;
- int clear_spool = 0;
-
- /* v3 network status fetch. */
- long lifetime = NETWORKSTATUS_CACHE_LIFETIME;
+ memset(out, 0, sizeof(parsed_consensus_request_t));
+ out->flav = FLAV_NS;
- time_t now = time(NULL);
- const char *want_fps = NULL, *after_flavor = NULL;
- char *flavor = NULL;
- int flav = FLAV_NS;
const char CONSENSUS_URL_PREFIX[] = "/tor/status-vote/current/consensus/";
const char CONSENSUS_FLAVORED_PREFIX[] =
"/tor/status-vote/current/consensus-";
/* figure out the flavor if any, and who we wanted to sign the thing */
+ const char *after_flavor = NULL;
+
if (!strcmpstart(url, CONSENSUS_FLAVORED_PREFIX)) {
const char *f, *cp;
f = url + strlen(CONSENSUS_FLAVORED_PREFIX);
cp = strchr(f, '/');
if (cp) {
after_flavor = cp+1;
- flavor = tor_strndup(f, cp-f);
+ out->flavor = tor_strndup(f, cp-f);
} else {
- flavor = tor_strdup(f);
+ out->flavor = tor_strdup(f);
}
- flav = networkstatus_parse_flavor_name(flavor);
+ int flav = networkstatus_parse_flavor_name(out->flavor);
if (flav < 0)
flav = FLAV_NS;
+ out->flav = flav;
} else {
if (!strcmpstart(url, CONSENSUS_URL_PREFIX))
after_flavor = url+strlen(CONSENSUS_URL_PREFIX);
@@ -3874,44 +3906,74 @@ handle_get_current_consensus(dir_connection_t *conn,
const char *cp = strchr(after_flavor, '/');
if (cp) {
diff_hash_in_url = tor_strndup(after_flavor, cp-after_flavor);
- want_fps = cp+1;
+ out->want_fps = cp+1;
} else {
diff_hash_in_url = tor_strdup(after_flavor);
- want_fps = NULL;
+ out->want_fps = NULL;
}
} else {
- want_fps = after_flavor;
+ out->want_fps = after_flavor;
}
- struct consensus_cache_entry_t *cached_consensus = NULL;
- smartlist_t *diff_from_digests = NULL;
- compress_method_t compression_used = NO_METHOD;
if (diff_hash_in_url) {
uint8_t diff_from[DIGEST256_LEN];
- diff_from_digests = smartlist_new();
+ out->diff_from_digests = smartlist_new();
+ out->diff_only = 1;
if (!parse_one_diff_hash(diff_from, diff_hash_in_url, "URL",
"rejecting")) {
- smartlist_add(diff_from_digests, tor_memdup(diff_from, DIGEST256_LEN));
+ smartlist_add(out->diff_from_digests,
+ tor_memdup(diff_from, DIGEST256_LEN));
+ } else {
+ return -1;
}
- } else if (!parse_or_diff_from_header(&diff_from_digests, args->headers)) {
- tor_assert(diff_from_digests);
+ } else {
+ parse_or_diff_from_header(&out->diff_from_digests, args->headers);
}
- if (diff_from_digests) {
- cached_consensus = find_best_diff(diff_from_digests, flav,
+ return 0;
+}
+
+/** Helper function for GET /tor/status-vote/current/consensus
+ */
+static int
+handle_get_current_consensus(dir_connection_t *conn,
+ const get_handler_args_t *args)
+{
+ const compress_method_t compress_method =
+ find_best_compression_method(args->compression_supported, 0);
+ const time_t if_modified_since = args->if_modified_since;
+ int clear_spool = 0;
+
+ /* v3 network status fetch. */
+ long lifetime = NETWORKSTATUS_CACHE_LIFETIME;
+
+ time_t now = time(NULL);
+ const char *want_fps = NULL;
+ parsed_consensus_request_t req;
+
+ if (parse_consensus_request(&req, args) < 0) {
+ write_http_status_line(conn, 404, "Couldn't parse request");
+ goto done;
+ }
+
+ struct consensus_cache_entry_t *cached_consensus = NULL;
+
+ compress_method_t compression_used = NO_METHOD;
+ if (req.diff_from_digests) {
+ cached_consensus = find_best_diff(req.diff_from_digests, req.flav,
args->compression_supported,
&compression_used);
}
- if (diff_hash_in_url && !cached_consensus) {
+ if (req.diff_only && !cached_consensus) {
write_http_status_line(conn, 404, "No such diff available");
- // XXXX warn_consensus_is_too_old(v, flavor, now);
+ // XXXX warn_consensus_is_too_old(v, req.flavor, now);
geoip_note_ns_response(GEOIP_REJECT_NOT_FOUND);
goto done;
}
if (! cached_consensus) {
- cached_consensus = find_best_consensus(flav,
+ cached_consensus = find_best_consensus(req.flav,
args->compression_supported,
&compression_used);
}
@@ -3928,7 +3990,7 @@ handle_get_current_consensus(dir_connection_t *conn,
if (cached_consensus && have_valid_until &&
!networkstatus_valid_until_is_reasonably_live(valid_until, now)) {
write_http_status_line(conn, 404, "Consensus is too old");
- warn_consensus_is_too_old(cached_consensus, flavor, now);
+ warn_consensus_is_too_old(cached_consensus, req.flavor, now);
geoip_note_ns_response(GEOIP_REJECT_NOT_FOUND);
goto done;
}
@@ -4014,8 +4076,7 @@ handle_get_current_consensus(dir_connection_t *conn,
goto done;
done:
- tor_free(flavor);
- tor_free(diff_hash_in_url);
+ parsed_consensus_request_clear(&req);
if (clear_spool) {
dir_conn_clear_spool(conn);
}
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