MEDIUM: checks: capture groups in expect regexes
Parse back-references in comments of tcp-check expect rules. If references are
made, capture groups in the match and replace references to it within the
comment when logging the error. Both text and binary regex can caputre groups
and reference them in the expect rule comment.
[Cf: I slightly updated the patch. exp_replace() function is used instead of a
custom one. And if the trash buffer is too small to contain the comment during
the substitution, the comment is ignored.]
diff --git a/src/cfgparse-listen.c b/src/cfgparse-listen.c
index 13ce19c..06ed3e4 100644
--- a/src/cfgparse-listen.c
+++ b/src/cfgparse-listen.c
@@ -162,6 +162,55 @@
warnif_misplaced_tcp_sess(proxy, file, line, arg);
}
+/* Parse a comment string for an expect check rule to find a potential
+ * regex backreference. If so, check that it is valid.
+ * returns:
+ * 0 if none found.
+ * 1 if at least one found and all are valid.
+ * -1 if at least one found and at least one is invalid.
+ */
+static int find_and_check_backreferences(const char *str, char **err)
+{
+ static char *errors[] = {
+ "invalid backreference value",
+ "backreference is not within range [1, 9]",
+ };
+ char *backslash;
+ unsigned long int ref;
+ int found = 0;
+
+ while ((backslash = strchr(str, '\\'))) {
+ char *next, *end;
+
+ next = backslash + 1;
+ if (!isdigit(*next)) {
+ str = next;
+ continue;
+ }
+
+ errno = 0;
+ ref = strtoul(next, &end, 10);
+ if (errno == EINVAL) {
+ *err = errors[0];
+ return -1;
+ }
+ else if (errno == ERANGE) {
+ *err = errors[1];
+ return -1;
+ }
+
+ if (ref == 0 || ref > 9) {
+ *err = errors[1];
+ return -1;
+ }
+
+ found = 1;
+ str = end;
+ }
+
+ return found;
+}
+
int cfg_parse_listen(const char *file, int linenum, char **args, int kwm)
{
static struct proxy *curproxy = NULL;
@@ -3318,6 +3367,22 @@
goto out;
}
tcpcheck->comment = strdup(args[cur_arg + 1]);
+ rc = find_and_check_backreferences(tcpcheck->comment, &error);
+ if (rc > 0) {
+ if (!inverse) {
+ ha_warning("parsing [%s:%d] : "
+ "using backreference in a positive expect comment is useless.\n",
+ file, linenum);
+ err_code |= ERR_WARN;
+ }
+ expect->with_capture = 1;
+ }
+ else if (rc < 0) {
+ ha_alert("parsing [%s:%d] : %s.\n",
+ file, linenum, error);
+ err_code |= ERR_ALERT | ERR_FATAL;
+ goto out;
+ }
}
/* All tcp-check expect points back to the first inverse expect rule