MINOR: http-rules: Add a flag on redirect rules to know the rule direction

HTTP redirect rules can be evaluated on the request or the response path. So
when a redirect rule is evaluated, it is important to have this information
because some specific processing may be performed depending on the direction. So
the REDIRECT_FLAG_FROM_REQ flag has been added. It is set when applicable on the
redirect rule during the parsing.

This patch is mandatory to fix a bug on redirect rule. It must be backported to
all stable versions.

include/types/http_ana.h

@@ -99,6 +99,7 @@ enum {
 	REDIRECT_FLAG_NONE = 0,
 	REDIRECT_FLAG_DROP_QS = 1,	/* drop query string */
 	REDIRECT_FLAG_APPEND_SLASH = 2,	/* append a slash if missing at the end */
+	REDIRECT_FLAG_FROM_REQ = 3,     /* redirect rule on the request path */
 };
 
 /* Redirect types (location, prefix, extended ) */

src/http_rules.c

@@ -206,7 +206,7 @@ struct redirect_rule *http_parse_redirect_rule(const char *file, int linenum, st
 	const char *destination = NULL;
 	const char *cookie = NULL;
 	int cookie_set = 0;
-	unsigned int flags = REDIRECT_FLAG_NONE;
+	unsigned int flags = (!dir ? REDIRECT_FLAG_FROM_REQ : REDIRECT_FLAG_NONE);
 	struct acl_cond *cond = NULL;
 
 	cur_arg = 0;