From 9a66cc102074b33f1c01b27a725447cc7e82c1b3 Mon Sep 17 00:00:00 2001
From: "Alan T. DeKok" <aland@freeradius.org>
Date: Tue, 3 Dec 2024 20:08:39 -0500
Subject: [PATCH] add FR_CONF_OFFSET_REF()

which allows you to reference another conf_parser_t, without
requiring an intermediary CONF_SECTION
---
 src/lib/server/cf_parse.c | 48 +++++++++++++++++++++++++++++++++++++--
 src/lib/server/cf_parse.h | 14 ++++++++++++
 2 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/src/lib/server/cf_parse.c b/src/lib/server/cf_parse.c
index 29a8647c1c161..1ead95765ea37 100644
--- a/src/lib/server/cf_parse.c
+++ b/src/lib/server/cf_parse.c
@@ -723,6 +723,9 @@ static int cf_section_parse_init(CONF_SECTION *cs, void *base, conf_parser_t con
 {
 	CONF_PAIR *cp;
 
+	/*
+	 *	This rule refers to a named subsection
+	 */
 	if ((rule->flags & CONF_FLAG_SUBSECTION)) {
 		char const	*name2 = NULL;
 		CONF_SECTION	*subcs;
@@ -785,6 +788,14 @@ static int cf_section_parse_init(CONF_SECTION *cs, void *base, conf_parser_t con
 		return 0;
 	}
 
+	/*
+	 *	This rule refers to another conf_parse_t which is included in-line in
+	 *	this section.
+	 */
+	if ((rule->flags & CONF_FLAG_REF) != 0) {
+		return 0;
+	}
+
 	/*
 	 *	Don't re-initialize data which was already parsed.
 	 */
@@ -971,7 +982,7 @@ static int cf_subsection_parse(TALLOC_CTX *ctx, void *out, void *base, CONF_SECT
 	return 0;
 }
 
-static int cf_section_parse_rule(TALLOC_CTX *ctx, void *base, CONF_SECTION *cs, conf_parser_t *rule)
+static int cf_section_parse_rule(TALLOC_CTX *ctx, void *base, CONF_SECTION *cs, conf_parser_t const *rule)
 {
 	int		ret;
 	bool		*is_set = NULL;
@@ -999,7 +1010,40 @@ static int cf_section_parse_rule(TALLOC_CTX *ctx, void *base, CONF_SECTION *cs,
 	 */
 	if (rule->flags & CONF_FLAG_SUBSECTION) {
 		return cf_subsection_parse(ctx, data, base, cs, rule);
-	} /* else it's a CONF_PAIR */
+	}
+
+	/*
+	 *	Ignore this rule if it's a reference, as the
+	 *	rules it points to have been pushed by the
+	 *	above function.
+	 */
+	if ((rule->flags & CONF_FLAG_REF) != 0) {
+		conf_parser_t const *rule_p;
+		uint8_t *sub_base = base;
+
+		fr_assert(rule->subcs != NULL);
+
+		sub_base += rule->offset;
+
+		for (rule_p = rule->subcs; rule_p->name1; rule_p++) {
+			if (rule_p->flags & CONF_FLAG_DEPRECATED) continue;	/* Skip deprecated */
+
+			ret = cf_section_parse_rule(ctx, sub_base, cs, rule_p);
+			if (ret < 0) return ret;
+		}
+
+		/*
+		 *	Ensure we have a proper terminator, type so we catch
+		 *	missing terminators reliably
+		 */
+		fr_cond_assert(rule_p->type == conf_term.type);
+
+		return 0;
+	}
+
+	/*
+	 *	Else it's a CONF_PAIR
+	 */
 
 	/*
 	 *	Pair either needs an output destination or
diff --git a/src/lib/server/cf_parse.h b/src/lib/server/cf_parse.h
index f1dbdd9bebbe3..e175d50639f9d 100644
--- a/src/lib/server/cf_parse.h
+++ b/src/lib/server/cf_parse.h
@@ -300,6 +300,19 @@ _Generic(&(_ct), \
 	.offset = offsetof(_struct, _field), \
 	.subcs = _subcs
 
+/** conf_parser_t which populates a sub-struct using a CONF_SECTION
+ *
+ * @param[in] _name		of the CONF_SECTION to search for.
+ * @param[in] _struct		containing the sub-struct to populate.
+ * @param[in] _field		containing the sub-struct to populate.
+ * @param[in] _subcs		conf_parser_t to include in-line in this section
+ */
+#  define FR_CONF_OFFSET_REF(__struct, _field, _subcs) \
+	.name1 = CF_IDENT_NONE, \
+	.flags = CONF_FLAG_REF, \
+	.offset = offsetof(_struct, _field), \
+	.subcs = _subcs
+
 /** conf_parser_t which parses a single CONF_PAIR producing a single global result
  *
  * @param[in] _name		of the CONF_PAIR to search for.
@@ -427,6 +440,7 @@ typedef enum CC_HINT(flag_enum) {
 	CONF_FLAG_OK_MISSING     	= (1 << 22), 			//!< OK if it's missing
 	CONF_FLAG_HIDDEN		= (1 << 23),			//!< Used by scripts to omit items from the
 									///< generated documentation.
+	CONF_FLAG_REF			= (1 << 24),			//!< reference another conf_parser_t inline in this one
 } conf_parser_flags_t;
 DIAG_ON(attributes)