This is a topic that's been discussed occasionally, though not
(AFAIR) on this list.
A few weeks back, I implemented a patch to support interpolating
per-request environment variables in reverse proxying directives.
Note that this goes beyond what mod_rewrite already supports,
because it also interpolates response headers per
ProxyPassReverse and family.
Do we want this in /trunk/ ?
--
Nick Kew
Index: proxy_util.c
===================================================================
--- proxy_util.c (revision 421119)
+++ proxy_util.c (working copy)
@@ -1015,6 +1015,7 @@
PROXY_DECLARE(const char *) ap_proxy_location_reverse_map(request_rec *r,
proxy_dir_conf *conf, const char *url)
{
+ proxy_req_conf *rconf;
struct proxy_alias *ent;
int i, l1, l2;
char *u;
@@ -1023,9 +1024,18 @@
* XXX FIXME: Make sure this handled the ambiguous case of the :<PORT>
* after the hostname
*/
+ if (r->proxyreq != PROXYREQ_REVERSE) {
+ return url;
+ }
l1 = strlen(url);
- ent = (struct proxy_alias *)conf->raliases->elts;
+ if (conf->interpolate_env == 1) {
+ rconf = ap_get_module_config(r->request_config, &proxy_module);
+ ent = (struct proxy_alias *)rconf->raliases->elts;
+ }
+ else {
+ ent = (struct proxy_alias *)conf->raliases->elts;
+ }
for (i = 0; i < conf->raliases->nelts; i++) {
l2 = strlen(ent[i].real);
if (l1 >= l2 && strncasecmp(ent[i].real, url, l2) == 0) {
@@ -1047,6 +1057,8 @@
PROXY_DECLARE(const char *) ap_proxy_cookie_reverse_map(request_rec *r,
proxy_dir_conf *conf, const char *str)
{
+ proxy_req_conf *rconf = ap_get_module_config(r->request_config,
+ &proxy_module);
struct proxy_alias *ent;
size_t len = strlen(str);
const char *newpath = NULL;
@@ -1061,6 +1073,10 @@
int pdiff = 0;
char *ret;
+ if (r->proxyreq != PROXYREQ_REVERSE) {
+ return str;
+ }
+
/*
* Find the match and replacement, but save replacing until we've done
* both path and domain so we know the new strlen
@@ -1071,7 +1087,12 @@
pathe = ap_strchr_c(pathp, ';');
l1 = pathe ? (pathe - pathp) : strlen(pathp);
pathe = pathp + l1 ;
- ent = (struct proxy_alias *)conf->cookie_paths->elts;
+ if (conf->interpolate_env == 1) {
+ ent = (struct proxy_alias *)rconf->cookie_paths->elts;
+ }
+ else {
+ ent = (struct proxy_alias *)conf->cookie_paths->elts;
+ }
for (i = 0; i < conf->cookie_paths->nelts; i++) {
l2 = strlen(ent[i].fake);
if (l1 >= l2 && strncmp(ent[i].fake, pathp, l2) == 0) {
@@ -1088,7 +1109,12 @@
domaine = ap_strchr_c(domainp, ';');
l1 = domaine ? (domaine - domainp) : strlen(domainp);
domaine = domainp + l1;
- ent = (struct proxy_alias *)conf->cookie_domains->elts;
+ if (conf->interpolate_env == 1) {
+ ent = (struct proxy_alias *)rconf->cookie_domains->elts;
+ }
+ else {
+ ent = (struct proxy_alias *)conf->cookie_domains->elts;
+ }
for (i = 0; i < conf->cookie_domains->nelts; i++) {
l2 = strlen(ent[i].fake);
if (l1 >= l2 && strncasecmp(ent[i].fake, domainp, l2) == 0) {
Index: mod_proxy.c
===================================================================
--- mod_proxy.c (revision 421119)
+++ mod_proxy.c (working copy)
@@ -410,6 +410,57 @@
return DECLINED;
}
+static const char *proxy_interpolate(request_rec *r, const char *str)
+{
+ /* Interpolate an env str in a configuration string
+ * Syntax ${var} --> value_of(var)
+ * Method: replace one var, and recurse on remainder of string
+ * Nothing clever here, and crap like nested vars may do silly things
+ * but we'll at least avoid sending the unwary into a loop
+ */
+ const char *start;
+ const char *end;
+ const char *var;
+ const char *val;
+ const char *firstpart;
+
+ start = ap_strstr(str, "${");
+ if (start == NULL) {
+ return str;
+ }
+ end = ap_strchr(start+2, '}');
+ if (end == NULL) {
+ return str;
+ }
+ /* OK, this is syntax we want to interpolate. Is there such a var ? */
+ var = apr_pstrndup(r->pool, start+2, end-(start+2));
+ val = apr_table_get(r->subprocess_env, var);
+ firstpart = apr_pstrndup(r->pool, str, (start-str));
+
+ if (val == NULL) {
+ return apr_pstrcat(r->pool, firstpart,
+ proxy_interpolate(r, end+1), NULL);
+ }
+ else {
+ return apr_pstrcat(r->pool, firstpart, val,
+ proxy_interpolate(r, end+1), NULL);
+ }
+}
+static apr_array_header_t *proxy_vars(request_rec *r,
+ apr_array_header_t *hdr)
+{
+ int i;
+ apr_array_header_t *ret = apr_array_make(r->pool, hdr->nelts,
+ sizeof (struct proxy_alias));
+ struct proxy_alias *old = (struct proxy_alias *) hdr->elts;
+
+ for (i = 0; i < hdr->nelts; ++i) {
+ struct proxy_alias *newcopy = apr_array_push(ret);
+ newcopy->fake = proxy_interpolate(r, old[i].fake);
+ newcopy->real = proxy_interpolate(r, old[i].real);
+ }
+ return ret;
+}
static int proxy_trans(request_rec *r)
{
void *sconf = r->server->module_config;
@@ -417,6 +468,10 @@
(proxy_server_conf *) ap_get_module_config(sconf, &proxy_module);
int i, len;
struct proxy_alias *ent = (struct proxy_alias *) conf->aliases->elts;
+ proxy_dir_conf *dconf = ap_get_module_config(r->per_dir_config,
+ &proxy_module);
+ const char *fake;
+ const char *real;
if (r->proxyreq) {
/* someone has already set up the proxy, it was possibly ourselves
@@ -431,14 +486,22 @@
*/
for (i = 0; i < conf->aliases->nelts; i++) {
- len = alias_match(r->uri, ent[i].fake);
+ if (dconf->interpolate_env == 1) {
+ fake = proxy_interpolate(r, ent[i].fake);
+ real = proxy_interpolate(r, ent[i].real);
+ }
+ else {
+ fake = ent[i].fake;
+ real = ent[i].real;
+ }
+ len = alias_match(r->uri, fake);
if (len > 0) {
- if ((ent[i].real[0] == '!') && (ent[i].real[1] == 0)) {
+ if ((real[0] == '!') && (real[1] == 0)) {
return DECLINED;
}
- r->filename = apr_pstrcat(r->pool, "proxy:", ent[i].real,
+ r->filename = apr_pstrcat(r->pool, "proxy:", real,
r->uri + len, NULL);
r->handler = "proxy-server";
r->proxyreq = PROXYREQ_REVERSE;
@@ -506,6 +569,7 @@
return OK;
}
+
/* -------------------------------------------------------------- */
/* Fixup the filename */
@@ -516,6 +580,8 @@
{
char *url, *p;
int access_status;
+ proxy_dir_conf *dconf = ap_get_module_config(r->per_dir_config,
+ &proxy_module);
if (!r->proxyreq || !r->filename || strncmp(r->filename, "proxy:", 6) != 0)
return DECLINED;
@@ -523,6 +589,17 @@
/* XXX: Shouldn't we try this before we run the proxy_walk? */
url = &r->filename[6];
+ if ((dconf->interpolate_env == 1) && (r->proxyreq == PROXYREQ_REVERSE)) {
+ /* create per-request copy of reverse proxy conf,
+ * and interpolate vars in it
+ */
+ proxy_req_conf *rconf = apr_palloc(r->pool, sizeof(proxy_req_conf));
+ ap_set_module_config(r->request_config, &proxy_module, rconf);
+ rconf->raliases = proxy_vars(r, dconf->raliases);
+ rconf->cookie_paths = proxy_vars(r, dconf->cookie_paths);
+ rconf->cookie_domains = proxy_vars(r, dconf->cookie_domains);
+ }
+
/* canonicalise each specific scheme */
if ((access_status = proxy_run_canon_handler(r, url))) {
return access_status;
@@ -905,6 +982,7 @@
new->cookie_domains = apr_array_make(p, 10, sizeof(struct proxy_alias));
new->cookie_path_str = apr_strmatch_precompile(p, "path=", 0);
new->cookie_domain_str = apr_strmatch_precompile(p, "domain=", 0);
+ new->interpolate_env = -1; /* unset */
return (void *) new;
}
@@ -927,6 +1005,8 @@
= apr_array_append(p, base->cookie_domains, add->cookie_domains);
new->cookie_path_str = base->cookie_path_str;
new->cookie_domain_str = base->cookie_domain_str;
+ new->interpolate_env = (add->interpolate_env == -1) ? base->interpolate_env
+ : add->interpolate_env;
return new;
}
@@ -1052,7 +1132,7 @@
arr = apr_table_elts(params);
elts = (const apr_table_entry_t *)arr->elts;
- /* Distinguish the balancer from woker */
+ /* Distinguish the balancer from worker */
if (strncasecmp(r, "balancer:", 9) == 0) {
proxy_balancer *balancer = ap_proxy_get_balancer(cmd->pool, conf, r);
if (!balancer) {
@@ -1666,6 +1746,9 @@
"a scheme, partial URL or '*' and a proxy server"),
AP_INIT_TAKE2("ProxyRemoteMatch", add_proxy_regex, NULL, RSRC_CONF,
"a regex pattern and a proxy server"),
+ AP_INIT_FLAG("ProxyPassInterpolateEnv", ap_set_flag_slot,
+ (void*)APR_OFFSETOF(proxy_dir_conf, interpolate_env),
+ RSRC_CONF|ACCESS_CONF, "Interpolate Env Vars in reverse Proxy") ,
AP_INIT_RAW_ARGS("ProxyPass", add_pass, NULL, RSRC_CONF|ACCESS_CONF,
"a virtual path and a URL"),
AP_INIT_TAKE12("ProxyPassReverse", add_pass_reverse, NULL, RSRC_CONF|ACCESS_CONF,
@@ -1907,7 +1990,6 @@
proxy_lb_workers = 0;
return OK;
}
-
static void register_hooks(apr_pool_t *p)
{
/* fixup before mod_rewrite, so that the proxied url will not
Index: mod_proxy.h
===================================================================
--- mod_proxy.h (revision 421119)
+++ mod_proxy.h (working copy)
@@ -206,9 +206,19 @@
apr_array_header_t* cookie_domains;
const apr_strmatch_pattern* cookie_path_str;
const apr_strmatch_pattern* cookie_domain_str;
+ int interpolate_env;
} proxy_dir_conf;
+/* if we interpolate env vars per-request, we'll need a per-request
+ * copy of the reverse proxy config
+ */
typedef struct {
+ apr_array_header_t *raliases;
+ apr_array_header_t* cookie_paths;
+ apr_array_header_t* cookie_domains;
+} proxy_req_conf;
+
+typedef struct {
conn_rec *connection;
const char *hostname;
apr_port_t port;
