[MINOR] redirect: add support for the "drop-query" option

If "drop-query" is present on a "redirect" line using the "prefix" mode,
then the returned Location header will be the request URI without the
query-string. This may be used on some login/logout pages, or when it
must be decided to redirect the user to a non-secure server.

(cherry-picked from commit f2d361ccd73aa16538ce767c766362dd8f0a88fd)

doc/configuration.txt

@@ -2336,7 +2336,8 @@ no option transparent
             "transparent" option of the "bind" keyword.
 
 
-redirect {location | prefix} <to> [code <code>] {if | unless} <condition>
+redirect location <to> [code <code>] {if | unless} <condition>
+redirect prefix <to> [drop-query] [code <code>] {if | unless} <condition>
   Return an HTTP redirection if/unless a condition is matched
   May be used in sections :   defaults | frontend | listen | backend
                                  no    |    yes   |   yes  |   yes
@@ -2345,7 +2346,10 @@ redirect {location | prefix} <to> [code <code>] {if | unless} <condition>
   response. There are currently two types of redirections : "location" and
   "prefix". With "location", the exact value in <to> is placed into the HTTP
   "Location" header. With "prefix", the "Location" header is built from the
-  concatenation of <to> and the URI. It is particularly suited for global site
+  concatenation of <to> and the URI. If the optional "drop-query" keyword is
+  used in a prefix-based redirection, then the location will be set without any
+  possible query-string, which is useful for directing users to a non-secure
+  page for instance. The "prefix" mode is particularly suited for global site
   redirections.
 
   The code is optional. It indicates in <code> which type of HTTP redirection
@@ -2356,7 +2360,9 @@ redirect {location | prefix} <to> [code <code>] {if | unless} <condition>
         acl clear      dst_port  80
         acl secure     dst_port  8080
         acl login_page url_beg   /login
+        acl uid_given  url_reg   /login?userid=[^&]+
         redirect prefix   https://mysite.com           if login_page !secure
+        redirect prefix   http://mysite.com drop-query if login_page !uid_given
         redirect location http://mysite.com/           if !login_page secure
 
   See section 2.3 about ACL usage.

include/types/proto_http.h

@@ -165,7 +165,11 @@ enum {
 	DATA_ST_PX_FIN,
 };
 
-
+/* Redirect flags */
+enum {
+	REDIRECT_FLAG_NONE = 0,
+	REDIRECT_FLAG_DROP_QS = 1,	/* drop query string */
+};
 
 /* Redirect types (location, prefix, extended ) */
 enum {

include/types/proxy.h

@@ -266,6 +266,7 @@ struct redirect_rule {
 	int rdr_len;
 	char *rdr_str;
 	int code;
+	unsigned int flags;
 };
 
 extern struct proxy *proxy;

src/cfgparse.c

@@ -1118,6 +1118,7 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int inv)
 		int type = REDIRECT_TYPE_NONE;
 		int code = 302;
 		char *destination = NULL;
+		unsigned int flags = REDIRECT_FLAG_NONE;
 
 		cur_arg = 1;
 		while (*(args[cur_arg])) {
@@ -1157,6 +1158,9 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int inv)
 					return -1;
 				}
 			}
+			else if (!strcmp(args[cur_arg],"drop-query")) {
+				flags |= REDIRECT_FLAG_DROP_QS;
+			}
 			else if (!strcmp(args[cur_arg], "if")) {
 				pol = ACL_COND_IF;
 				cur_arg++;
@@ -1200,6 +1204,7 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int inv)
 		rule->rdr_len = strlen(destination);
 		rule->type = type;
 		rule->code = code;
+		rule->flags = flags;
 		LIST_INIT(&rule->list);
 		LIST_ADDQ(&curproxy->redirect_rules, &rule->list);
 	}

src/proto_http.c

@@ -1894,6 +1894,16 @@ int http_process_request(struct session *s, struct buffer *req)
 					/* build message using path */
 					if (path) {
 						pathlen = txn->req.sl.rq.u_l + (txn->req.sol+txn->req.sl.rq.u) - path;
+						if (rule->flags & REDIRECT_FLAG_DROP_QS) {
+							int qs = 0;
+							while (qs < pathlen) {
+								if (path[qs] == '?') {
+									pathlen = qs;
+									break;
+								}
+								qs++;
+							}
+						}
 					} else {
 						path = "/";
 						pathlen = 1;

tests/test-redirect.cfg

@@ -17,9 +17,10 @@ listen  sample1
 
 	acl        url_test1 url_reg test1
 	acl        url_test2 url_reg test2
+	acl        url_test3 url_reg test3
 	redirect   location /abs/test code 301 if url_test1
 	redirect   prefix   /pfx/test code 302 if url_test2
-	redirect   prefix   /pfx/test code 303 if url_test2
+	redirect   prefix   /pfx/test code 303 drop-query if url_test3
 
 	### unconditional redirection
 	#redirect   location https://example.com/ if TRUE