From 08356b5c4bfde66a5cab9694ae945657e7df55f0 Mon Sep 17 00:00:00 2001
From: Matthew Newton <matthew-git@newtoncomputing.co.uk>
Date: Sun, 16 Feb 2020 23:56:47 +0000
Subject: [PATCH] lib/json: verify json format struct

---
 src/lib/json/base.h |  2 ++
 src/lib/json/json.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/src/lib/json/base.h b/src/lib/json/base.h
index a7270eaf02cd..0888ae3b70fa 100644
--- a/src/lib/json/base.h
+++ b/src/lib/json/base.h
@@ -255,4 +255,6 @@ void		fr_json_version_print(void);
 
 char		*fr_json_afrom_pair_list(TALLOC_CTX *ctx, VALUE_PAIR *vps,
 					 fr_json_format_t const *format);
+
+bool		fr_json_format_verify(fr_json_format_t const *format, bool verbose);
 #endif
diff --git a/src/lib/json/json.c b/src/lib/json/json.c
index 11d63dd6cc89..5b9c2a2331ea 100644
--- a/src/lib/json/json.c
+++ b/src/lib/json/json.c
@@ -430,6 +430,59 @@ static inline char const *attr_name_with_prefix(char *buf, size_t buf_len, const
 }
 
 
+/** Verify that the options in fr_json_format_t are valid
+ *
+ * Warnings are optional, will fatal error if the format is corrupt.
+ *
+ * @param[in] format	the format structure to check
+ * @param[in] verbose	print out warnings if set
+ * @return		true if format is good, otherwise false
+ */
+bool fr_json_format_verify(fr_json_format_t const *format, bool verbose)
+{
+	bool ret = true;
+
+	rad_assert(format);
+
+	switch (format->output_mode) {
+	case JSON_MODE_OBJECT:
+	case JSON_MODE_OBJECT_SIMPLE:
+	case JSON_MODE_ARRAY:
+		/* all options are valid */
+		return true;
+	case JSON_MODE_ARRAY_OF_VALUES:
+		if (format->attr.prefix) {
+			if (verbose) WARN("attribute name prefix not valid in output_mode 'array_of_values' and will be ignored");
+			ret = false;
+		}
+		if (format->value.value_as_array) {
+			if (verbose) WARN("'value_as_array' not valid in output_mode 'array_of_values' and will be ignored");
+			ret = false;
+		}
+		return ret;
+	case JSON_MODE_ARRAY_OF_NAMES:
+		if (format->value.value_as_array) {
+			if (verbose) WARN("'value_as_array' not valid in output_mode 'array_of_names' and will be ignored");
+			ret = false;
+		}
+		if (format->value.enum_as_int) {
+			if (verbose) WARN("'enum_as_int' not valid in output_mode 'array_of_names' and will be ignored");
+			ret = false;
+		}
+		if (format->value.always_string) {
+			if (verbose) WARN("'always_string' not valid in output_mode 'array_of_names' and will be ignored");
+			ret = false;
+		}
+		return ret;
+	default:
+		ERROR("JSON format output mode is invalid");
+	}
+
+	/* If we get here, something has gone wrong */
+	rad_assert(0);
+}
+
+
 /** Returns a JSON object representation of a list of value pairs
  *
  * The result is a struct json_object, which should be free'd with