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[tor-commits] [tor/master] Prop140, continued: accept "diff/<HASH>" in URLs, per proposal.
commit eb3c8d376dc240642f784830a9aec3fa95200764
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date: Thu May 4 10:53:22 2017 -0400
Prop140, continued: accept "diff/<HASH>" in URLs, per proposal.
---
src/or/directory.c | 86 +++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 69 insertions(+), 17 deletions(-)
diff --git a/src/or/directory.c b/src/or/directory.c
index a5121eb..71ae274 100644
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -3661,6 +3661,27 @@ warn_consensus_is_too_old(const struct consensus_cache_entry_t *consensus,
}
}
+/**
+ * Parse a single hex-encoded sha3-256 digest from <b>hex</b> into
+ * <b>digest</b>. Return 0 on success. On failure, report that the hash came
+ * from <b>location</b>, report that we are taking <b>action</b> with it, and
+ * return -1.
+ */
+static int
+parse_one_diff_hash(uint8_t *digest, const char *hex, const char *location,
+ const char *action)
+{
+ if (base16_decode((char*)digest, DIGEST256_LEN, hex, strlen(hex)) ==
+ DIGEST256_LEN) {
+ return 0;
+ } else {
+ log_fn(LOG_PROTOCOL_WARN, LD_DIR,
+ "%s contained bogus digest %s; %s.",
+ location, escaped(hex), action);
+ return -1;
+ }
+}
+
/** If there is an X-Or-Diff-From-Consensus header included in <b>headers</b>,
* set <b>digest_out<b> to a new smartlist containing every 256-bit
* hex-encoded digest listed in that header and return 0. Otherwise return
@@ -3678,13 +3699,9 @@ parse_or_diff_from_header(smartlist_t **digests_out, const char *headers)
SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
SMARTLIST_FOREACH_BEGIN(hex_digests, const char *, hex) {
uint8_t digest[DIGEST256_LEN];
- if (base16_decode((char*)digest, sizeof(digest), hex, strlen(hex)) ==
- DIGEST256_LEN) {
+ if (!parse_one_diff_hash(digest, hex, "X-Or-Diff-From-Consensus header",
+ "ignoring")) {
smartlist_add(*digests_out, tor_memdup(digest, sizeof(digest)));
- } else {
- log_fn(LOG_PROTOCOL_WARN, LD_DIR,
- "X-Or-Diff-From-Consensus header contained bogus digest %s; "
- "ignoring.", escaped(hex));
}
} SMARTLIST_FOREACH_END(hex);
SMARTLIST_FOREACH(hex_digests, char *, cp, tor_free(cp));
@@ -3821,18 +3838,20 @@ handle_get_current_consensus(dir_connection_t *conn,
long lifetime = NETWORKSTATUS_CACHE_LIFETIME;
time_t now = time(NULL);
- const char *want_fps = NULL;
+ const char *want_fps = NULL, *after_flavor = NULL;
char *flavor = NULL;
int flav = FLAV_NS;
-#define CONSENSUS_URL_PREFIX "/tor/status-vote/current/consensus/"
-#define CONSENSUS_FLAVORED_PREFIX "/tor/status-vote/current/consensus-"
+ 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 */
if (!strcmpstart(url, CONSENSUS_FLAVORED_PREFIX)) {
const char *f, *cp;
f = url + strlen(CONSENSUS_FLAVORED_PREFIX);
cp = strchr(f, '/');
if (cp) {
- want_fps = cp+1;
+ after_flavor = cp+1;
flavor = tor_strndup(f, cp-f);
} else {
flavor = tor_strdup(f);
@@ -3842,19 +3861,53 @@ handle_get_current_consensus(dir_connection_t *conn,
flav = FLAV_NS;
} else {
if (!strcmpstart(url, CONSENSUS_URL_PREFIX))
- want_fps = url+strlen(CONSENSUS_URL_PREFIX);
+ after_flavor = url+strlen(CONSENSUS_URL_PREFIX);
+ }
+
+ /* see whether we've been asked explicitly for a diff from an older
+ * consensus. (The user might also have said that a diff would be okay,
+ * via X-Or-Diff-From-Consensus */
+ const char DIFF_COMPONENT[] = "diff/";
+ char *diff_hash_in_url = NULL;
+ if (after_flavor && !strcmpstart(after_flavor, DIFF_COMPONENT)) {
+ after_flavor += strlen(DIFF_COMPONENT);
+ const char *cp = strchr(after_flavor, '/');
+ if (cp) {
+ diff_hash_in_url = tor_strndup(after_flavor, cp-after_flavor);
+ want_fps = cp+1;
+ } else {
+ diff_hash_in_url = tor_strdup(after_flavor);
+ want_fps = NULL;
+ }
+ } else {
+ 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 (!parse_or_diff_from_header(&diff_from_digests, args->headers)) {
+ if (diff_hash_in_url) {
+ uint8_t diff_from[DIGEST256_LEN];
+ diff_from_digests = smartlist_new();
+ if (!parse_one_diff_hash(diff_from, diff_hash_in_url, "URL",
+ "rejecting")) {
+ smartlist_add(diff_from_digests, tor_memdup(diff_from, DIGEST256_LEN));
+ }
+ } else if (!parse_or_diff_from_header(&diff_from_digests, args->headers)) {
tor_assert(diff_from_digests);
+ }
+
+ if (diff_from_digests) {
cached_consensus = find_best_diff(diff_from_digests, flav,
args->compression_supported,
&compression_used);
- SMARTLIST_FOREACH(diff_from_digests, uint8_t *, d, tor_free(d));
- smartlist_free(diff_from_digests);
+ }
+
+ if (diff_hash_in_url && !cached_consensus) {
+ write_http_status_line(conn, 404, "No such diff available");
+ // XXXX warn_consensus_is_too_old(v, flavor, now);
+ geoip_note_ns_response(GEOIP_REJECT_NOT_FOUND);
+ goto done;
}
if (! cached_consensus) {
@@ -3877,7 +3930,6 @@ handle_get_current_consensus(dir_connection_t *conn,
write_http_status_line(conn, 404, "Consensus is too old");
warn_consensus_is_too_old(cached_consensus, flavor, now);
geoip_note_ns_response(GEOIP_REJECT_NOT_FOUND);
- tor_free(flavor);
goto done;
}
@@ -3886,7 +3938,6 @@ handle_get_current_consensus(dir_connection_t *conn,
write_http_status_line(conn, 404, "Consensus not signed by sufficient "
"number of requested authorities");
geoip_note_ns_response(GEOIP_REJECT_NOT_ENOUGH_SIGS);
- tor_free(flavor);
goto done;
}
@@ -3898,7 +3949,6 @@ handle_get_current_consensus(dir_connection_t *conn,
spooled = spooled_resource_new_from_cache_entry(cached_consensus);
smartlist_add(conn->spool, spooled);
}
- tor_free(flavor);
}
lifetime = (have_fresh_until && fresh_until > now) ? fresh_until - now : 0;
@@ -3964,6 +4014,8 @@ handle_get_current_consensus(dir_connection_t *conn,
goto done;
done:
+ tor_free(flavor);
+ tor_free(diff_hash_in_url);
if (clear_spool) {
dir_conn_clear_spool(conn);
}
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