commit 912b0641e9e9922ad2da50973579de38cb4be6ba Author: Nick Mathewson nickm@torproject.org Date: Wed May 3 14:29:06 2017 -0400

Generate X-Or-Diff-From-Consensus headers correctly. --- src/or/directory.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/src/or/directory.c b/src/or/directory.c index 9c007e3..76fc121 100644 --- a/src/or/directory.c +++ b/src/or/directory.c @@ -130,6 +130,7 @@ static void directory_request_set_guard_state(directory_request_t *req, #define ALLOW_DIRECTORY_TIME_SKEW (30*60)

#define X_ADDRESS_HEADER "X-Your-Address-Is: " +#define X_OR_DIFF_FROM_CONSENSUS_HEADER "X-Or-Diff-From-Consensus"

/** HTTP cache control: how long do we tell proxies they can cache each * kind of document we serve? */ @@ -480,15 +481,18 @@ directory_pick_generic_dirserver(dirinfo_type_t type, int pds_flags, /** * Set the extra fields in <b>req</b> that are used when requesting a * consensus of type <b>resource</b>. + * + * Right now, these fields are if-modified-since and x-or-diff-from-consensus. */ static void dir_consensus_request_set_additional_headers(directory_request_t *req, const char *resource) { time_t if_modified_since = 0; + uint8_t or_diff_from[DIGEST256_LEN]; + int or_diff_from_is_set = 0;

int flav = FLAV_NS; - networkstatus_t *v; if (resource) flav = networkstatus_parse_flavor_name(resource);

@@ -499,6 +503,7 @@ dir_consensus_request_set_additional_headers(directory_request_t *req, if (flav != -1) { /* IF we have a parsed consensus of this type, we can do an * if-modified-time based on it. */ + networkstatus_t *v; v = networkstatus_get_latest_consensus_by_flavor(flav); if (v) { /* In networks with particularly short V3AuthVotingIntervals, @@ -510,6 +515,8 @@ dir_consensus_request_set_additional_headers(directory_request_t *req, ims_delay = (v->fresh_until - v->valid_after)/2; } if_modified_since = v->valid_after + ims_delay; + memcpy(or_diff_from, v->digest_full_sha3, DIGEST256_LEN); + or_diff_from_is_set = 1; } } else { /* Otherwise it might be a consensus we don't parse, but which we @@ -517,11 +524,21 @@ dir_consensus_request_set_additional_headers(directory_request_t *req, cached_dir_t *cd = dirserv_get_consensus(resource); /* We have no method of determining the voting interval from an * unparsed consensus, so we use the default. */ - if (cd) + if (cd) { if_modified_since = cd->published + DEFAULT_IF_MODIFIED_SINCE_DELAY; + memcpy(or_diff_from, cd->digest_sha3_full, DIGEST256_LEN); + or_diff_from_is_set = 1; + } }

- directory_request_set_if_modified_since(req, if_modified_since); + if (if_modified_since > 0) + directory_request_set_if_modified_since(req, if_modified_since); + if (or_diff_from_is_set) { + char hex[HEX_DIGEST256_LEN + 1]; + base16_encode(hex, sizeof(hex), + (const char*)or_diff_from, sizeof(or_diff_from)); + directory_request_add_header(req, X_OR_DIFF_FROM_CONSENSUS_HEADER, hex); + } }

/** Start a connection to a random running directory server, using @@ -3537,7 +3554,7 @@ warn_consensus_is_too_old(networkstatus_t *v, const char *flavor, time_t now) static int parse_or_diff_from_header(smartlist_t **digests_out, const char *headers) { - char *hdr = http_get_header(headers, "X-Or-Diff-From-Consensus"); + char *hdr = http_get_header(headers, X_OR_DIFF_FROM_CONSENSUS_HEADER); if (hdr == NULL) { return -1; }