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r9277@Kushana: nickm | 2006-10-19 19:03:05 -0400

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Add pragma:no-cache and expires headers so that directory lookups can work better in the presence of caching HTTP proxies. (I would have used Cache-Control, but that is an HTTP/1.1 thing.)  All timeouts are currently wild-assed guesses.


svn:r8765
This commit is contained in:
Nick Mathewson 2006-10-19 23:05:34 +00:00
parent f47c49228d
commit 974bdee183
4 changed files with 89 additions and 30 deletions
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3
ChangeLog
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@ -8,6 +8,9 @@ Changes in version 0.1.2.3-alpha - 2006-10-??
recommended by no authorities, or until we get a better one for the
same router. Make caches consider retaining old recommended
routers for even longer.
- Directory servers now provide 'Pragma: no-cache' and 'Expires'
headers for content, so that we can work better in the presence of
caching HTTP proxies.
o Minor features, controller:
- Add a REASON field to CIRC events; for backward compatibility, this

18
doc/TODO
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@ -159,16 +159,16 @@ N - split "router is down" from "dirport shouldn't be tried for a while"?
when they feel like it.
- update dir-spec with what we decided for each of these
N - provide no-cache no-index headers from the dirport?
- Specify
- cacheing
- Single network-statuses, single descriptors, "all", "authority",
o provide no-cache no-index headers from the dirport?
o Specify
o cacheing
o Single network-statuses, single descriptors, "all", "authority",
and v1 directory stuff are all cacheable for a short time.
- Multiple network-statuses or descriptors are not cacheable.
- Be sure to be correct wrt HTTP/1.0
- indexing
- robots.txt
- Implement
o Multiple network-statuses or descriptors are not cacheable.
o Be sure to be correct wrt HTTP/1.0
o indexing
o robots.txt (oh, it was already there.)
o Implement
- Windows server usability
- Solve the ENOBUFS problem.

22
doc/dir-spec.txt
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@ -565,7 +565,6 @@ $Id$
For debugging, directories SHOULD expose non-compressed objects at URLs like
the above, but without the final ".z".
Clients MUST handle compressed concatenated information in two forms:
- A concatenated list of zlib-compressed objects.
- A zlib-compressed concatenated list of objects.
@ -801,7 +800,24 @@ $Id$
...
7.0 Error and return codes in the directory protocol
7. Standards compliance
We should write down what return codes dirservers send in what situations.
All clients and servers MUST support HTTP 1.0.
7.1. HTTP headers
Servers MAY set the Content-Length header. Servers SHOULD set
Content-Encoding to "deflate" or "identity".
Servers MAY include an X-Your-Address-Is: header, whose value is the
apparent IP address of the client connecting to them (as a dotted quad).
Servers SHOULD disable caching of multiple network statuses or multiple
router descriptors. Servers MAY enable caching of single descriptors,
single network statuses, the list of all router descriptors, a v1
directory, or a v1 running routers document. XXX mention times.
7.2. HTTP status codes
XXX We should write down what return codes dirservers send in what situations.

76
src/or/directory.c
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@ -61,6 +61,13 @@ static void note_request(const char *key, size_t bytes);
#define X_ADDRESS_HEADER "X-Your-Address-Is: "
/* HTTP cache control: how long do we tell proxies they can cache things? */
#define FULL_DIR_CACHE_LIFETIME (60*60)
#define RUNNINGROUTERS_CACHE_LIFETIME (20*60)
#define NETWORKSTATUS_CACHE_LIFETIME (5*60)
#define ROUTERDESC_CACHE_LIFETIME (30*60)
#define ROBOTS_CACHE_LIFETIME (24*60*60)
/********* END VARIABLES ************/
/** Return true iff the directory purpose 'purpose' must use an
@ -1297,19 +1304,27 @@ write_http_status_line(dir_connection_t *conn, int status,
connection_write_to_buf(buf, strlen(buf), TO_CONN(conn));
}
/** DOCDOC */
/** Write the header for an HTTP/1.0 response onto <b>conn</b>->outbuf,
* with <b>type</b> as the Content-Type.
*
* If <b>length</b> is nonnegative, it is the Content-Length.
* If <b>encoding</b> is provided, it is the Content-Encoding.
* If <b>cache_lifetime</b> is greater than 0, the content may be cached for
* up to cache_lifetime seconds. Otherwise, the content may not be cached. */
static void
write_http_response_header(dir_connection_t *conn, ssize_t length,
const char *type, const char *encoding)
const char *type, const char *encoding,
int cache_lifetime)
{
char date[RFC1123_TIME_LEN+1];
char tmp[1024];
char *cp;
time_t now = time(NULL);
tor_assert(conn);
tor_assert(type);
format_rfc1123_time(date, time(NULL));
format_rfc1123_time(date, now);
cp = tmp;
tor_snprintf(cp, sizeof(tmp),
"HTTP/1.0 200 OK\r\nDate: %s\r\nContent-Type: %s\r\n"
@ -1326,6 +1341,20 @@ write_http_response_header(dir_connection_t *conn, ssize_t length,
"Content-Length: %ld\r\n", (long)length);
cp += strlen(cp);
}
if (cache_lifetime > 0) {
char expbuf[RFC1123_TIME_LEN+1];
format_rfc1123_time(expbuf, now + cache_lifetime);
/* We could say 'Cache-control: max-age=%d' here if we start doing
* http/1.1 */
tor_snprintf(cp, sizeof(tmp)-(cp-tmp),
"Expires: %s\r\n", expbuf);
cp += strlen(cp);
} else {
/* We could say 'Cache-control: no-cache' here if we start doing
* http/1.1 */
strlcpy(cp, "Pragma: no-cache\r\n", sizeof(tmp)-(cp-tmp));
cp += strlen(cp);
}
if (sizeof(tmp)-(cp-tmp) > 3)
memcpy(cp, "\r\n", 3);
else
@ -1484,7 +1513,8 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
deflated?"deflated ":"");
write_http_response_header(conn, dlen,
deflated?"application/octet-stream":"text/plain",
deflated?"deflate":"identity");
deflated?"deflate":"identity",
FULL_DIR_CACHE_LIFETIME);
conn->cached_dir = d;
conn->cached_dir_offset = 0;
if (! deflated)
@ -1513,7 +1543,8 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
write_http_response_header(conn, dlen,
deflated?"application/octet-stream":"text/plain",
deflated?"deflate":"identity");
deflated?"deflate":"identity",
RUNNINGROUTERS_CACHE_LIFETIME);
connection_write_to_buf(cp, strlen(cp), TO_CONN(conn));
return 0;
}
@ -1545,9 +1576,9 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
}
// note_request(request_type,dlen);
write_http_response_header(conn, -1,
deflated?"application/octet_stream":"text/plain",
deflated?"deflate":NULL);
deflated?"application/octet_stream":"text/plain",
deflated?"deflate":NULL,
smartlist_len(dir_fps) == 1 ? NETWORKSTATUS_CACHE_LIFETIME:0);
conn->fingerprint_stack = dir_fps;
if (! deflated)
conn->zlib_state = tor_zlib_new(0, ZLIB_METHOD);
@ -1565,23 +1596,31 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
int res;
const char *msg;
const char *request_type = NULL;
int cache_lifetime = 0;
if (deflated)
url[url_len-2] = '\0';
conn->fingerprint_stack = smartlist_create();
res = dirserv_get_routerdesc_fingerprints(conn->fingerprint_stack, url,
&msg);
if (!strcmpstart(url, "/tor/server/fp/"))
if (!strcmpstart(url, "/tor/server/fp/")) {
request_type = deflated?"/tor/server/fp.z":"/tor/server/fp";
else if (!strcmpstart(url, "/tor/server/authority"))
if (smartlist_len(conn->fingerprint_stack) == 1)
cache_lifetime = ROUTERDESC_CACHE_LIFETIME;
} else if (!strcmpstart(url, "/tor/server/authority")) {
request_type = deflated?"/tor/server/authority.z":
"/tor/server/authority";
else if (!strcmpstart(url, "/tor/server/all"))
cache_lifetime = ROUTERDESC_CACHE_LIFETIME;
} else if (!strcmpstart(url, "/tor/server/all")) {
request_type = deflated?"/tor/server/all.z":"/tor/server/all";
else if (!strcmpstart(url, "/tor/server/d/"))
cache_lifetime = FULL_DIR_CACHE_LIFETIME;
} else if (!strcmpstart(url, "/tor/server/d/")) {
request_type = deflated?"/tor/server/d.z":"/tor/server/d";
else
if (smartlist_len(conn->fingerprint_stack) == 1)
cache_lifetime = ROUTERDESC_CACHE_LIFETIME;
} else {
request_type = "/tor/server/?";
}
if (!strcmpstart(url, "/tor/server/d/"))
conn->dir_spool_src = DIR_SPOOL_SERVER_BY_DIGEST;
else
@ -1592,7 +1631,7 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
else {
write_http_response_header(conn, -1,
deflated?"application/octet_stream":"text/plain",
deflated?"deflate":NULL);
deflated?"deflate":NULL, cache_lifetime);
if (deflated)
conn->zlib_state = tor_zlib_new(1, ZLIB_METHOD);
/* Prime the connection with some data. */
@ -1613,7 +1652,7 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
switch (rend_cache_lookup_desc(query, versioned?-1:0, &descp, &desc_len)) {
case 1: /* valid */
write_http_response_header(conn, desc_len, "application/octet-stream",
NULL);
NULL, 0);
note_request("/tor/rendezvous?/", desc_len);
/* need to send descp separately, because it may include nuls */
connection_write_to_buf(descp, desc_len, TO_CONN(conn));
@ -1632,7 +1671,7 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
if (!strcmpstart(url,"/tor/bytes.txt")) {
char *bytes = directory_dump_request_log();
size_t len = strlen(bytes);
write_http_response_header(conn, len, "text/plain", NULL);
write_http_response_header(conn, len, "text/plain", NULL, 0);
connection_write_to_buf(bytes, len, TO_CONN(conn));
tor_free(bytes);
tor_free(url);
@ -1643,7 +1682,8 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
rewritten to /tor/robots.txt */
char robots[] = "User-agent: *\r\nDisallow: /\r\n";
size_t len = strlen(robots);
write_http_response_header(conn, len, "text/plain", NULL);
write_http_response_header(conn, len, "text/plain", NULL,
ROBOTS_CACHE_LIFETIME);
connection_write_to_buf(robots, len, TO_CONN(conn));
tor_free(url);
return 0;
@ -1665,7 +1705,7 @@ directory_handle_command_get(dir_connection_t *conn, char *headers,
dlen = strlen(new_directory);
write_http_response_header(conn, dlen, "text/plain", "identity");
write_http_response_header(conn, dlen, "text/plain", "identity", 0);
connection_write_to_buf(new_directory, dlen, TO_CONN(conn));
tor_free(new_directory);