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Generate X-Or-Diff-From-Consensus headers correctly.

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This commit is contained in:
Nick Mathewson 2017-05-03 14:29:06 -04:00
parent 94ae99067f
commit 912b0641e9
1 changed files with 21 additions and 4 deletions
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25
src/or/directory.c
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@ -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;
}