From 4cc25f26f94859bf4dbc2d036d9d23e5a5a7a2de Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Thu, 11 Jan 2024 12:06:49 +0100
Subject: [PATCH] MEDIUM: http: add the ability to redefine http-err-codes and
 http-fail-codes

The new global keywords "http-err-codes" and "http-fail-codes" allow to
redefine which HTTP status codes indicate a client-induced error or a
server error, as tracked by stick-table counters. This is only done
globally, though everything was done so that it could easily be extended
to a per-proxy mechanism if there was a real need for this (but it would
eat quite more RAM then).

A simple reg-test was added (http-err-fail.vtc).
---
 doc/configuration.txt                  | 34 +++++++++
 reg-tests/http-rules/http-err-fail.vtc | 84 ++++++++++++++++++++++
 src/http.c                             | 98 ++++++++++++++++++++++++++
 3 files changed, 216 insertions(+)
 create mode 100644 reg-tests/http-rules/http-err-fail.vtc

diff --git a/doc/configuration.txt b/doc/configuration.txt
index ece3919f0..18da6a52b 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -1919,6 +1919,40 @@ hard-stop-after <time>
 
   See also: grace
 
+http-err-codes [+-]<range>[,...] [...]
+  Replace, reduce or extend the list of status codes that define an error as
+  considered by the termination codes and the "http_err_cnt" counter in stick
+  tables. The default range for errors is 400 to 499, but in certain contexts
+  some users prefer to exclude specific codes, especially when tracking client
+  errors (e.g. 404 on systems with dynamically generated contents). See also
+  "http-fail-codes" and "http_err_cnt".
+
+  A range specified without '+' nor '-' redefines the existing range to the new
+  one. A range starting with '+' extends the existing range to also include the
+  specified one, which may or may not overlap with the existing one. A range
+  starting with '-' removes the specified range from the existing one. A range
+  consists in a number from 100 to 599, optionally followed by "-" followed by
+  another number greater than or equal to the first one to indicate the high
+  boundary of the range. Multiple ranges may be delimited by commas for a same
+  add/del/ replace operation.
+
+  Example:
+     http-err-codes 400,402-444,446-480,490   # sets exactly these codes
+     http-err-codes 400-499 -450 +500         # sets 400 to 500 except 450
+     http-err-codes -450-459                  # removes 450 to 459 from range
+     http-err-codes +501,505                  # adds 501 and 505 to range
+
+http-fail-codes [+-]<range>[,...] [...]
+  Replace, reduce or extend the list of status codes that define a failure as
+  considered by the termination codes and the "http_fail_cnt" counter in stick
+  tables. The default range for failures is 500 to 599 except 501 and 505 which
+  can be triggered by clients, and normally indicate a failure from the server
+  to process the request. Some users prefer to exclude certain codes in certain
+  contexts where it is known they're not relevant, such as 500 in certain SOAP
+  environments as it doesn't translate a server fault there. The syntax is
+  exactly the same as for http-err-codes above. See also "http-err-codes" and
+  "http_fail_cnt".
+
 httpclient.resolvers.disabled <on|off>
   Disable the DNS resolution of the httpclient. Prevent the creation of the
   "default" resolvers section.
diff --git a/reg-tests/http-rules/http-err-fail.vtc b/reg-tests/http-rules/http-err-fail.vtc
new file mode 100644
index 000000000..6d8f9ea3e
--- /dev/null
+++ b/reg-tests/http-rules/http-err-fail.vtc
@@ -0,0 +1,84 @@
+varnishtest "test for http-err-codes/http-fail-codes redefinitions"
+
+feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(3.0-dev1)'"
+feature ignore_unknown_macro
+
+server s2 {
+	rxreq
+	txresp -status 220
+} -start
+
+server s3 {
+	rxreq
+	txresp -status 300
+} -start
+
+server s4 {
+	rxreq
+	txresp -status 400
+} -start
+
+server s5 {
+	rxreq
+	txresp -status 555
+} -start
+
+
+haproxy h1 -conf {
+    global
+	http-err-codes  220 +300-499 -300-399  # only 220, 400-499 remain
+	http-fail-codes -550-580 +555,599,556-566
+
+    defaults
+	mode http
+	timeout connect "${HAPROXY_TEST_TIMEOUT-5s}"
+	timeout client  "${HAPROXY_TEST_TIMEOUT-5s}"
+	timeout server  "${HAPROXY_TEST_TIMEOUT-5s}"
+	option socket-stats
+
+    frontend fe
+	bind "fd@${fe}"
+	http-request track-sc0 path
+	http-after-response add-header x-table err=%[sc0_http_err_cnt],fail=%[sc0_http_fail_cnt]
+	stick-table type string size 100 store http_err_cnt,http_fail_cnt
+	default_backend be
+
+    backend be
+	use-server s2 if { path -m beg /2 }
+	use-server s3 if { path -m beg /3 }
+	use-server s4 if { path -m beg /4 }
+	use-server s5 if { path -m beg /5 }
+
+	server s2 ${s2_addr}:${s2_port}
+	server s3 ${s3_addr}:${s3_port}
+	server s4 ${s4_addr}:${s4_port}
+	server s5 ${s5_addr}:${s5_port}
+} -start
+
+client c2 -connect ${h1_fe_sock} {
+	txreq -url "/2"
+	rxresp
+	expect resp.status == 220
+	expect resp.http.x-table ~ "err=1,fail=0"
+} -run
+
+client c3 -connect ${h1_fe_sock} {
+	txreq -url "/3"
+	rxresp
+	expect resp.status == 300
+	expect resp.http.x-table ~ "err=0,fail=0"
+} -run
+
+client c4 -connect ${h1_fe_sock} {
+	txreq -url "/4"
+	rxresp
+	expect resp.status == 400
+	expect resp.http.x-table ~ "err=1,fail=0"
+} -run
+
+client c5 -connect ${h1_fe_sock} {
+	txreq -url "/5"
+	rxresp
+	expect resp.status == 555
+	expect resp.http.x-table ~ "err=0,fail=1"
+} -run
diff --git a/src/http.c b/src/http.c
index 82da7bb13..8c94dfb36 100644
--- a/src/http.c
+++ b/src/http.c
@@ -12,6 +12,7 @@
 
 #include <ctype.h>
 #include <haproxy/api.h>
+#include <haproxy/cfgparse.h>
 #include <haproxy/http.h>
 #include <haproxy/tools.h>
 
@@ -1483,3 +1484,100 @@ static void _http_init()
 	http_status_del_range(http_fail_status_codes, 505, 505);
 }
 INITCALL0(STG_INIT, _http_init);
+
+/*
+ * registered keywords below
+ */
+
+/* parses a global "http-err-codes" and "http-fail-codes" directive. */
+static int http_parse_http_err_fail_codes(char **args, int section_type, struct proxy *curpx,
+					  const struct proxy *defpx, const char *file, int line,
+					  char **err)
+{
+	const char *cmd = args[0];
+	const char *p, *b, *e;
+	int op, low, high;
+	long *bitfield;
+	int ret = -1;
+
+	if (strcmp(cmd, "http-err-codes") == 0)
+		bitfield = http_err_status_codes;
+	else if (strcmp(cmd, "http-fail-codes") == 0)
+		bitfield = http_fail_status_codes;
+	else
+		ABORT_NOW();
+
+	if (!*args[1]) {
+		memprintf(err, "Missing status codes range for '%s'.", cmd);
+		goto end;
+	}
+
+	/* operation: <0 = remove, 0 = replace, >0 = add. The operation is only
+	 * reset for each new arg so that we can do +200,300,400 without
+	 * changing the operation.
+	 */
+	for (; *(p = *(++args)); ) {
+		switch (*p) {
+		case '+': op =  1; p++; break;
+		case '-': op = -1; p++; break;
+		default:  op =  0; break;
+		}
+
+		if (!*p)
+			goto inval;
+
+		while (1) {
+			b = p;
+			e = p + strlen(p);
+			low = read_uint(&p, e);
+			if (b == e || p == b)
+				goto inval;
+
+			high = low;
+			if (*p == '-') {
+				p++;
+				b = p;
+				high = read_uint(&p, e);
+				if (b == e || p == b || (*p && *p != ','))
+					goto inval;
+			}
+			else if (*p && *p != ',')
+				goto inval;
+
+			if (high < low || low < 100 || high > 599) {
+				memprintf(err, "Invalid status codes range '%s' in '%s'.\n"
+					  " Codes must be between 100 and 599 and ranges in ascending order.",
+					  *args, cmd);
+				goto end;
+			}
+
+			if (!op)
+				memset(bitfield, 0, sizeof(http_err_status_codes));
+			if (op >= 0)
+				http_status_add_range(bitfield, low, high);
+			if (op < 0)
+				http_status_del_range(bitfield, low, high);
+
+			if (!*p)
+				break;
+			/* skip ',' */
+			p++;
+		}
+	}
+	ret = 0;
+ end:
+	return ret;
+ inval:
+	memprintf(err, "Invalid status codes range '%s' in '%s' at position %lu. Ranges must be in the form [+-]{low[-{high}]}[,...].",
+		  *args, cmd, (ulong)(p - *args));
+	goto end;
+
+}
+
+static struct cfg_kw_list cfg_kws = {{ },{
+	{ CFG_GLOBAL, "http-err-codes",      http_parse_http_err_fail_codes },
+	{ CFG_GLOBAL, "http-fail-codes",     http_parse_http_err_fail_codes },
+	{ /* END */ }
+}};
+
+INITCALL1(STG_REGISTER, cfg_register_keywords, &cfg_kws);