cache_util.c revision e8f95a682820a599fe41b22977010636be5c2717
/* Copyright 2001-2005 The Apache Software Foundation or its licensors, as
* applicable.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define CORE_PRIVATE
#include "mod_cache.h"
#include <ap_provider.h>
/* -------------------------------------------------------------- */
extern module AP_MODULE_DECLARE_DATA cache_module;
/* Determine if "url" matches the hostname, scheme and port and path
* in "filter". All but the path comparisons are case-insensitive.
*/
static int uri_meets_conditions(apr_uri_t filter, int pathlen, apr_uri_t url)
{
/* Compare the hostnames */
if(filter.hostname) {
if (!url.hostname) {
return 0;
}
else if (strcasecmp(filter.hostname, url.hostname)) {
return 0;
}
}
/* Compare the schemes */
if(filter.scheme) {
if (!url.scheme) {
return 0;
}
else if (strcasecmp(filter.scheme, url.scheme)) {
return 0;
}
}
/* Compare the ports */
if(filter.port_str) {
if (url.port_str && filter.port != url.port) {
return 0;
}
/* NOTE: ap_port_of_scheme will return 0 if given NULL input */
else if (filter.port != apr_uri_port_of_scheme(url.scheme)) {
return 0;
}
}
else if(url.port_str && filter.scheme) {
if (apr_uri_port_of_scheme(filter.scheme) == url.port) {
return 0;
}
}
/* Url has met all of the filter conditions so far, determine
* if the paths match.
*/
return !strncmp(filter.path, url.path, pathlen);
}
CACHE_DECLARE(cache_provider_list *)ap_cache_get_providers(request_rec *r,
cache_server_conf *conf,
apr_uri_t uri)
{
cache_provider_list *providers = NULL;
int i;
/* loop through all the cacheenable entries */
for (i = 0; i < conf->cacheenable->nelts; i++) {
struct cache_enable *ent =
(struct cache_enable *)conf->cacheenable->elts;
if (uri_meets_conditions(ent[i].url, ent[i].pathlen, uri)) {
/* Fetch from global config and add to the list. */
cache_provider *provider;
provider = ap_lookup_provider(CACHE_PROVIDER_GROUP, ent[i].type,
"0");
if (!provider) {
/* Log an error! */
}
else {
cache_provider_list *newp;
newp = apr_pcalloc(r->pool, sizeof(cache_provider_list));
newp->provider_name = ent[i].type;
newp->provider = provider;
if (!providers) {
providers = newp;
}
else {
cache_provider_list *last = providers;
while (last->next) {
last = last->next;
}
last->next = newp;
}
}
}
}
/* then loop through all the cachedisable entries
* Looking for urls that contain the full cachedisable url and possibly
* more.
* This means we are disabling cachedisable url and below...
*/
for (i = 0; i < conf->cachedisable->nelts; i++) {
struct cache_disable *ent =
(struct cache_disable *)conf->cachedisable->elts;
if (uri_meets_conditions(ent[i].url, ent[i].pathlen, uri)) {
/* Stop searching now. */
return NULL;
}
}
return providers;
}
/* do a HTTP/1.1 age calculation */
CACHE_DECLARE(apr_int64_t) ap_cache_current_age(cache_info *info,
const apr_time_t age_value,
apr_time_t now)
{
apr_time_t apparent_age, corrected_received_age, response_delay,
corrected_initial_age, resident_time, current_age,
age_value_usec;
age_value_usec = apr_time_from_sec(age_value);
/* Perform an HTTP/1.1 age calculation. (RFC2616 13.2.3) */
apparent_age = MAX(0, info->response_time - info->date);
corrected_received_age = MAX(apparent_age, age_value_usec);
response_delay = info->response_time - info->request_time;
corrected_initial_age = corrected_received_age + response_delay;
resident_time = now - info->response_time;
current_age = corrected_initial_age + resident_time;
return apr_time_sec(current_age);
}
CACHE_DECLARE(int) ap_cache_check_freshness(cache_handle_t *h,
request_rec *r)
{
apr_int64_t age, maxage_req, maxage_cresp, maxage, smaxage, maxstale;
apr_int64_t minfresh;
const char *cc_cresp, *cc_req;
const char *pragma;
const char *agestr = NULL;
const char *expstr = NULL;
char *val;
apr_time_t age_c = 0;
cache_info *info = &(h->cache_obj->info);
cache_server_conf *conf =
(cache_server_conf *)ap_get_module_config(r->server->module_config,
&cache_module);
/*
* We now want to check if our cached data is still fresh. This depends
* on a few things, in this order:
*
* - RFC2616 14.9.4 End to end reload, Cache-Control: no-cache. no-cache in
* either the request or the cached response means that we must
* revalidate the request unconditionally, overriding any expiration
* mechanism. It's equivalent to max-age=0,must-revalidate.
*
* - RFC2616 14.32 Pragma: no-cache This is treated the same as
* Cache-Control: no-cache.
*
* - RFC2616 14.9.3 Cache-Control: max-stale, must-revalidate,
* proxy-revalidate if the max-stale request header exists, modify the
* stale calculations below so that an object can be at most <max-stale>
* seconds stale before we request a revalidation, _UNLESS_ a
* must-revalidate or proxy-revalidate cached response header exists to
* stop us doing this.
*
* - RFC2616 14.9.3 Cache-Control: s-maxage the origin server specifies the
* maximum age an object can be before it is considered stale. This
* directive has the effect of proxy|must revalidate, which in turn means
* simple ignore any max-stale setting.
*
* - RFC2616 14.9.4 Cache-Control: max-age this header can appear in both
* requests and responses. If both are specified, the smaller of the two
* takes priority.
*
* - RFC2616 14.21 Expires: if this request header exists in the cached
* entity, and it's value is in the past, it has expired.
*
*/
/* This value comes from the client's initial request. */
cc_req = apr_table_get(r->headers_in, "Cache-Control");
pragma = apr_table_get(r->headers_in, "Pragma");
if (ap_cache_liststr(NULL, pragma, "no-cache", NULL)
|| ap_cache_liststr(NULL, cc_req, "no-cache", NULL)) {
if (!conf->ignorecachecontrol) {
/* Treat as stale, causing revalidation */
return 0;
}
ap_log_error(APLOG_MARK, APLOG_INFO, 0, r->server,
"Incoming request is asking for a uncached version of "
"%s, but we know better and are ignoring it",
r->unparsed_uri);
}
/* These come from the cached entity. */
cc_cresp = apr_table_get(h->resp_hdrs, "Cache-Control");
expstr = apr_table_get(h->resp_hdrs, "Expires");
if ((agestr = apr_table_get(h->resp_hdrs, "Age"))) {
age_c = apr_atoi64(agestr);
}
/* calculate age of object */
age = ap_cache_current_age(info, age_c, r->request_time);
/* extract s-maxage */
if (cc_cresp && ap_cache_liststr(r->pool, cc_cresp, "s-maxage", &val)) {
smaxage = apr_atoi64(val);
}
else {
smaxage = -1;
}
/* extract max-age from request */
if (!conf->ignorecachecontrol
&& cc_req && ap_cache_liststr(r->pool, cc_req, "max-age", &val)) {
maxage_req = apr_atoi64(val);
}
else {
maxage_req = -1;
}
/* extract max-age from response */
if (cc_cresp && ap_cache_liststr(r->pool, cc_cresp, "max-age", &val)) {
maxage_cresp = apr_atoi64(val);
}
else {
maxage_cresp = -1;
}
/*
* if both maxage request and response, the smaller one takes priority
*/
if (maxage_req == -1) {
maxage = maxage_cresp;
}
else if (maxage_cresp == -1) {
maxage = maxage_req;
}
else {
maxage = MIN(maxage_req, maxage_cresp);
}
/* extract max-stale */
if (cc_req && ap_cache_liststr(r->pool, cc_req, "max-stale", &val)) {
maxstale = apr_atoi64(val);
}
else {
maxstale = 0;
}
/* extract min-fresh */
if (!conf->ignorecachecontrol
&& cc_req && ap_cache_liststr(r->pool, cc_req, "min-fresh", &val)) {
minfresh = apr_atoi64(val);
}
else {
minfresh = 0;
}
/* override maxstale if must-revalidate or proxy-revalidate */
if (maxstale && ((cc_cresp &&
ap_cache_liststr(NULL, cc_cresp,
"must-revalidate", NULL)) ||
(cc_cresp &&
ap_cache_liststr(NULL, cc_cresp,
"proxy-revalidate", NULL)))) {
maxstale = 0;
}
/* handle expiration */
if (((smaxage != -1) && (age < (smaxage - minfresh))) ||
((maxage != -1) && (age < (maxage + maxstale - minfresh))) ||
((smaxage == -1) && (maxage == -1) &&
(info->expire != APR_DATE_BAD) &&
(age < (apr_time_sec(info->expire - info->date) + maxstale - minfresh)))) {
const char *warn_head;
warn_head = apr_table_get(h->resp_hdrs, "Warning");
/* it's fresh darlings... */
/* set age header on response */
apr_table_set(h->resp_hdrs, "Age",
apr_psprintf(r->pool, "%lu", (unsigned long)age));
/* add warning if maxstale overrode freshness calculation */
if (!(((smaxage != -1) && age < smaxage) ||
((maxage != -1) && age < maxage) ||
(info->expire != APR_DATE_BAD &&
(info->expire - info->date) > age))) {
/* make sure we don't stomp on a previous warning */
if ((warn_head == NULL) ||
((warn_head != NULL) && (ap_strstr_c(warn_head, "110") == NULL))) {
apr_table_merge(h->resp_hdrs, "Warning",
"110 Response is stale");
}
}
/*
* If none of Expires, Cache-Control: max-age, or Cache-Control:
* s-maxage appears in the response, and the respose header age
* calculated is more than 24 hours add the warning 113
*/
if ((maxage_cresp == -1) && (smaxage == -1) &&
(expstr == NULL) && (age > 86400)) {
/* Make sure we don't stomp on a previous warning, and don't dup
* a 113 marning that is already present. Also, make sure to add
* the new warning to the correct *headers_out location.
*/
if ((warn_head == NULL) ||
((warn_head != NULL) && (ap_strstr_c(warn_head, "113") == NULL))) {
apr_table_merge(h->resp_hdrs, "Warning",
"113 Heuristic expiration");
}
}
return 1; /* Cache object is fresh (enough) */
}
return 0; /* Cache object is stale */
}
/*
* list is a comma-separated list of case-insensitive tokens, with
* optional whitespace around the tokens.
* The return returns 1 if the token val is found in the list, or 0
* otherwise.
*/
CACHE_DECLARE(int) ap_cache_liststr(apr_pool_t *p, const char *list,
const char *key, char **val)
{
apr_size_t key_len;
const char *next;
if (!list) {
return 0;
}
key_len = strlen(key);
next = list;
for (;;) {
/* skip whitespace and commas to find the start of the next key */
while (*next && (apr_isspace(*next) || (*next == ','))) {
next++;
}
if (!*next) {
return 0;
}
if (!strncasecmp(next, key, key_len)) {
/* this field matches the key (though it might just be
* a prefix match, so make sure the match is followed
* by either a space or an equals sign)
*/
next += key_len;
if (!*next || (*next == '=') || apr_isspace(*next) ||
(*next == ',')) {
/* valid match */
if (val) {
while (*next && (*next != '=') && (*next != ',')) {
next++;
}
if (*next == '=') {
next++;
while (*next && apr_isspace(*next )) {
next++;
}
if (!*next) {
*val = NULL;
}
else {
const char *val_start = next;
while (*next && !apr_isspace(*next) &&
(*next != ',')) {
next++;
}
*val = apr_pstrmemdup(p, val_start,
next - val_start);
}
}
}
return 1;
}
}
/* skip to the next field */
do {
next++;
if (!*next) {
return 0;
}
} while (*next != ',');
}
}
/* return each comma separated token, one at a time */
CACHE_DECLARE(const char *)ap_cache_tokstr(apr_pool_t *p, const char *list,
const char **str)
{
apr_size_t i;
const char *s;
s = ap_strchr_c(list, ',');
if (s != NULL) {
i = s - list;
do
s++;
while (apr_isspace(*s))
; /* noop */
}
else
i = strlen(list);
while (i > 0 && apr_isspace(list[i - 1]))
i--;
*str = s;
if (i)
return apr_pstrndup(p, list, i);
else
return NULL;
}
/*
* Converts apr_time_t expressed as hex digits to
* a true apr_time_t.
*/
CACHE_DECLARE(apr_time_t) ap_cache_hex2usec(const char *x)
{
int i, ch;
apr_time_t j;
for (i = 0, j = 0; i < sizeof(j) * 2; i++) {
ch = x[i];
j <<= 4;
if (apr_isdigit(ch))
j |= ch - '0';
else if (apr_isupper(ch))
j |= ch - ('A' - 10);
else
j |= ch - ('a' - 10);
}
return j;
}
/*
* Converts apr_time_t to apr_time_t expressed as hex digits.
*/
CACHE_DECLARE(void) ap_cache_usec2hex(apr_time_t j, char *y)
{
int i, ch;
for (i = (sizeof(j) * 2)-1; i >= 0; i--) {
ch = (int)(j & 0xF);
j >>= 4;
if (ch >= 10)
y[i] = ch + ('A' - 10);
else
y[i] = ch + '0';
}
y[sizeof(j) * 2] = '\0';
}
static void cache_hash(const char *it, char *val, int ndepth, int nlength)
{
apr_md5_ctx_t context;
unsigned char digest[16];
char tmp[22];
int i, k, d;
unsigned int x;
static const char enc_table[64] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_@";
apr_md5_init(&context);
apr_md5_update(&context, (const unsigned char *) it, strlen(it));
apr_md5_final(digest, &context);
/* encode 128 bits as 22 characters, using a modified uuencoding
* the encoding is 3 bytes -> 4 characters* i.e. 128 bits is
* 5 x 3 bytes + 1 byte -> 5 * 4 characters + 2 characters
*/
for (i = 0, k = 0; i < 15; i += 3) {
x = (digest[i] << 16) | (digest[i + 1] << 8) | digest[i + 2];
tmp[k++] = enc_table[x >> 18];
tmp[k++] = enc_table[(x >> 12) & 0x3f];
tmp[k++] = enc_table[(x >> 6) & 0x3f];
tmp[k++] = enc_table[x & 0x3f];
}
/* one byte left */
x = digest[15];
tmp[k++] = enc_table[x >> 2]; /* use up 6 bits */
tmp[k++] = enc_table[(x << 4) & 0x3f];
/* now split into directory levels */
for (i = k = d = 0; d < ndepth; ++d) {
memcpy(&val[i], &tmp[k], nlength);
k += nlength;
val[i + nlength] = '/';
i += nlength + 1;
}
memcpy(&val[i], &tmp[k], 22 - k);
val[i + 22 - k] = '\0';
}
CACHE_DECLARE(char *)ap_cache_generate_name(apr_pool_t *p, int dirlevels,
int dirlength, const char *name)
{
char hashfile[66];
cache_hash(name, hashfile, dirlevels, dirlength);
return apr_pstrdup(p, hashfile);
}
/* Create a new table consisting of those elements from an input
* headers table that are allowed to be stored in a cache.
*/
CACHE_DECLARE(apr_table_t *)ap_cache_cacheable_hdrs_out(apr_pool_t *pool,
apr_table_t *t,
server_rec *s)
{
cache_server_conf *conf;
char **header;
int i;
/* Make a copy of the headers, and remove from
* the copy any hop-by-hop headers, as defined in Section
* 13.5.1 of RFC 2616
*/
apr_table_t *headers_out;
headers_out = apr_table_copy(pool, t);
apr_table_unset(headers_out, "Connection");
apr_table_unset(headers_out, "Keep-Alive");
apr_table_unset(headers_out, "Proxy-Authenticate");
apr_table_unset(headers_out, "Proxy-Authorization");
apr_table_unset(headers_out, "TE");
apr_table_unset(headers_out, "Trailers");
apr_table_unset(headers_out, "Transfer-Encoding");
apr_table_unset(headers_out, "Upgrade");
conf = (cache_server_conf *)ap_get_module_config(s->module_config,
&cache_module);
/* Remove the user defined headers set with CacheIgnoreHeaders.
* This may break RFC 2616 compliance on behalf of the administrator.
*/
header = (char **)conf->ignore_headers->elts;
for (i = 0; i < conf->ignore_headers->nelts; i++) {
apr_table_unset(headers_out, header[i]);
}
return headers_out;
}