[tor-commits] [tor/master] Request (and try to use) consensus diffs.
nickm at torproject.org
nickm at torproject.org
Thu May 4 12:58:39 UTC 2017
commit c12d2cb2dcfe52aadf528a70433b468327472eaf
Author: Nick Mathewson <nickm at torproject.org>
Date: Wed May 3 15:08:59 2017 -0400
Request (and try to use) consensus diffs.
---
src/or/consdiff.c | 9 +++++++
src/or/consdiff.h | 2 ++
src/or/directory.c | 58 +++++++++++++++++++++++++++++++++++++----
src/or/networkstatus.c | 71 ++++++++++++++++++++++++++++++++------------------
src/or/networkstatus.h | 1 +
5 files changed, 111 insertions(+), 30 deletions(-)
diff --git a/src/or/consdiff.c b/src/or/consdiff.c
index 3c2140b..1baa118 100644
--- a/src/or/consdiff.c
+++ b/src/or/consdiff.c
@@ -1401,3 +1401,12 @@ consensus_diff_apply(const char *consensus,
return result;
}
+/** Return true iff, based on its header, <b>document</b> is likely
+ * to be a consensus diff. */
+int
+looks_like_a_consensus_diff(const char *document, size_t len)
+{
+ return (len >= strlen(ns_diff_version) &&
+ fast_memeq(document, ns_diff_version, strlen(ns_diff_version)));
+}
+
diff --git a/src/or/consdiff.h b/src/or/consdiff.h
index 284a576..d05df74 100644
--- a/src/or/consdiff.h
+++ b/src/or/consdiff.h
@@ -12,6 +12,8 @@ char *consensus_diff_generate(const char *cons1,
char *consensus_diff_apply(const char *consensus,
const char *diff);
+int looks_like_a_consensus_diff(const char *document, size_t len);
+
#ifdef CONSDIFF_PRIVATE
struct memarea_t;
diff --git a/src/or/directory.c b/src/or/directory.c
index 76fc121..bf963f1 100644
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -13,6 +13,7 @@
#include "config.h"
#include "connection.h"
#include "connection_edge.h"
+#include "consdiff.h"
#include "consdiffmgr.h"
#include "control.h"
#include "compat.h"
@@ -2417,6 +2418,10 @@ handle_response_fetch_consensus(dir_connection_t *conn,
const char *reason = args->reason;
const time_t now = approx_time();
+ const char *consensus;
+ char *new_consensus = NULL;
+ const char *sourcename;
+
int r;
const char *flavname = conn->requested_resource;
if (status_code != 200) {
@@ -2429,15 +2434,57 @@ handle_response_fetch_consensus(dir_connection_t *conn,
networkstatus_consensus_download_failed(status_code, flavname);
return -1;
}
- log_info(LD_DIR,"Received consensus directory (body size %d) from server "
- "'%s:%d'", (int)body_len, conn->base_.address, conn->base_.port);
- if ((r=networkstatus_set_current_consensus(body, flavname, 0,
+
+ if (looks_like_a_consensus_diff(body, body_len)) {
+ /* First find our previous consensus. Maybe it's in ram, maybe not. */
+ cached_dir_t *cd = dirserv_get_consensus(flavname);
+ const char *consensus_body;
+ char *owned_consensus = NULL;
+ if (cd) {
+ consensus_body = cd->dir;
+ } else {
+ owned_consensus = networkstatus_read_cached_consensus(flavname);
+ consensus_body = owned_consensus;
+ }
+ if (!consensus_body) {
+ log_warn(LD_DIR, "Received a consensus diff, but we can't find "
+ "any %s-flavored consensus in our current cache.",flavname);
+ networkstatus_consensus_download_failed(0, flavname);
+ // XXXX if this happens too much, see below
+ return -1;
+ }
+
+ new_consensus = consensus_diff_apply(consensus_body, body);
+ tor_free(owned_consensus);
+ if (new_consensus == NULL) {
+ log_warn(LD_DIR, "Could not apply consensus diff received from server "
+ "'%s:%d'", conn->base_.address, conn->base_.port);
+ // XXXX If this happens too many times, we should maybe not use
+ // XXXX this directory for diffs any more?
+ networkstatus_consensus_download_failed(0, flavname);
+ return -1;
+ }
+ log_info(LD_DIR, "Applied consensus diff (body size %d) from server "
+ "'%s:%d' resulted in a new consensus document (size %d).",
+ (int)body_len, conn->base_.address, conn->base_.port,
+ (int)strlen(new_consensus));
+ consensus = new_consensus;
+ sourcename = "generated based on a diff";
+ } else {
+ log_info(LD_DIR,"Received consensus directory (body size %d) from server "
+ "'%s:%d'", (int)body_len, conn->base_.address, conn->base_.port);
+ consensus = body;
+ sourcename = "downloaded";
+ }
+
+ if ((r=networkstatus_set_current_consensus(consensus, flavname, 0,
conn->identity_digest))<0) {
log_fn(r<-1?LOG_WARN:LOG_INFO, LD_DIR,
- "Unable to load %s consensus directory downloaded from "
+ "Unable to load %s consensus directory %s from "
"server '%s:%d'. I'll try again soon.",
- flavname, conn->base_.address, conn->base_.port);
+ flavname, sourcename, conn->base_.address, conn->base_.port);
networkstatus_consensus_download_failed(0, flavname);
+ tor_free(new_consensus);
return -1;
}
@@ -2455,6 +2502,7 @@ handle_response_fetch_consensus(dir_connection_t *conn,
}
log_info(LD_DIR, "Successfully loaded consensus.");
+ tor_free(new_consensus);
return 0;
}
diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c
index 8a5cdaf..18537a3 100644
--- a/src/or/networkstatus.c
+++ b/src/or/networkstatus.c
@@ -179,53 +179,74 @@ networkstatus_reset_download_failures(void)
download_status_reset(&consensus_bootstrap_dl_status[i]);
}
+/**
+ * Read and and return the cached consensus of type <b>flavorname</b>. If
+ * <b>unverified</b> is false, get the one we haven't verified. Return NULL if
+ * the file isn't there. */
+static char *
+networkstatus_read_cached_consensus_impl(int flav,
+ const char *flavorname,
+ int unverified_consensus)
+{
+ char buf[128];
+ const char *prefix;
+ if (unverified_consensus) {
+ prefix = "unverified";
+ } else {
+ prefix = "cached";
+ }
+ if (flav == FLAV_NS) {
+ tor_snprintf(buf, sizeof(buf), "%s-consensus", prefix);
+ } else {
+ tor_snprintf(buf, sizeof(buf), "%s-%s-consensus", prefix, flavorname);
+ }
+
+ char *filename = get_datadir_fname(buf);
+ char *result = read_file_to_str(filename, RFTS_IGNORE_MISSING, NULL);
+ tor_free(filename);
+ return result;
+}
+
+/** Return a new string containing the current cached consensus of flavor
+ * <b>flavorname</b>. */
+char *
+networkstatus_read_cached_consensus(const char *flavorname)
+ {
+ int flav = networkstatus_parse_flavor_name(flavorname);
+ if (flav < 0)
+ return NULL;
+ return networkstatus_read_cached_consensus_impl(flav, flavorname, 0);
+}
+
/** Read every cached v3 consensus networkstatus from the disk. */
int
router_reload_consensus_networkstatus(void)
{
- char *filename;
- char *s;
const unsigned int flags = NSSET_FROM_CACHE | NSSET_DONT_DOWNLOAD_CERTS;
int flav;
/* FFFF Suppress warnings if cached consensus is bad? */
for (flav = 0; flav < N_CONSENSUS_FLAVORS; ++flav) {
- char buf[128];
const char *flavor = networkstatus_get_flavor_name(flav);
- if (flav == FLAV_NS) {
- filename = get_datadir_fname("cached-consensus");
- } else {
- tor_snprintf(buf, sizeof(buf), "cached-%s-consensus", flavor);
- filename = get_datadir_fname(buf);
- }
- s = read_file_to_str(filename, RFTS_IGNORE_MISSING, NULL);
+ char *s = networkstatus_read_cached_consensus_impl(flav, flavor, 0);
if (s) {
if (networkstatus_set_current_consensus(s, flavor, flags, NULL) < -1) {
- log_warn(LD_FS, "Couldn't load consensus %s networkstatus from \"%s\"",
- flavor, filename);
+ log_warn(LD_FS, "Couldn't load consensus %s networkstatus from cache",
+ flavor);
}
tor_free(s);
}
- tor_free(filename);
- if (flav == FLAV_NS) {
- filename = get_datadir_fname("unverified-consensus");
- } else {
- tor_snprintf(buf, sizeof(buf), "unverified-%s-consensus", flavor);
- filename = get_datadir_fname(buf);
- }
-
- s = read_file_to_str(filename, RFTS_IGNORE_MISSING, NULL);
+ s = networkstatus_read_cached_consensus_impl(flav, flavor, 1);
if (s) {
if (networkstatus_set_current_consensus(s, flavor,
flags|NSSET_WAS_WAITING_FOR_CERTS,
NULL)) {
- log_info(LD_FS, "Couldn't load consensus %s networkstatus from \"%s\"",
- flavor, filename);
- }
+ log_info(LD_FS, "Couldn't load unverified consensus %s networkstatus "
+ "from cache", flavor);
+ }
tor_free(s);
}
- tor_free(filename);
}
if (!networkstatus_get_latest_consensus()) {
diff --git a/src/or/networkstatus.h b/src/or/networkstatus.h
index 8a9f5f0..6a90d70 100644
--- a/src/or/networkstatus.h
+++ b/src/or/networkstatus.h
@@ -16,6 +16,7 @@
void networkstatus_reset_warnings(void);
void networkstatus_reset_download_failures(void);
+char *networkstatus_read_cached_consensus(const char *flavorname);
int router_reload_consensus_networkstatus(void);
void routerstatus_free(routerstatus_t *rs);
void networkstatus_vote_free(networkstatus_t *ns);
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