From: Aurelien DARRAGON <adarragon@haproxy.com>
Date: Fri, 6 Jan 2023 14:06:49 +0000 (+0100)
Subject: MINOR: http_ext/7239: warn the user when fetch is not available
X-Git-Tag: v2.8-dev3~63
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d745a3f117783fb4aa4bcdf62a0a18e589520574;p=thirdparty%2Fhaproxy.git

MINOR: http_ext/7239: warn the user when fetch is not available

http option forwarded (rfc7239) supports sample expressions when
configuring 'host', 'for' and 'by' parameters.

However, since we are in a http-backend-only context, right after http
header is processed, we have a limited resolution scope for the sample
expression provided by the user.

To prevent any confusion, a warning is emitted when parsing the option
if the user relies on a sample expression (more precisely a fetch) which
would yield unexpected results at runtime when processing the option.
---

diff --git a/src/http_ext.c b/src/http_ext.c
index 4a9a0b091a..f2e3781c59 100644
--- a/src/http_ext.c
+++ b/src/http_ext.c
@@ -1143,6 +1143,19 @@ int proxy_http_compile_7239(struct proxy *curproxy)
 			ha_free(&err);
 			cfgerr++;
 		}
+		else if (!(cur_expr->fetch->val & SMP_VAL_BE_HRQ_HDR)) {
+			/* fetch not available in this context: sample expr is resolved
+			 * within backend right after headers are processed.
+			 * (in http_process_request())
+			 * -> we simply warn the user about the misuse
+			 */
+			ha_warning("%s '%s' [%s:%d]: in 'option forwarded' sample expression '%s' : "
+				   "some args extract information from '%s', "
+				   "none of which is available here.\n",
+				   proxy_type_str(curproxy), curproxy->id,
+				   curproxy->http.fwd.c_file, curproxy->http.fwd.c_line,
+				   *expr_str, sample_ckp_names(cur_expr->fetch->use));
+		}
 		/* post parsing individual expr cleanup */
 		ha_free(expr_str);