MINOR: sample: Added support for Arrays in sample_conv_json_query in sample.c

Method now returns the content of Json Arrays, if it is specified in
Json Path as String. The start and end character is a square bracket. Any
complex object in the array is returned as Json, so that you might get Arrays
of Array or objects. Only recommended for Arrays of simple types (e.g.,
String or int) which will be returned as CSV String. Also updated
documentation and fixed issue with parenthesis and other changes from
comments.

This patch was discussed in issue #2281.

Signed-off-by: William Lallemand <wlallemand@haproxy.com>

doc/configuration.txt

@@ -18423,10 +18423,18 @@ json([<input-code>])
      {"ip":"127.0.0.1","user-agent":"Very \"Ugly\" UA 1\/2"}
 
 json_query(<json_path>,[<output_type>])
-  The json_query converter supports the JSON types string, boolean and
-  number. Floating point numbers will be returned as a string. By
+  The json_query converter supports the JSON types string, boolean, number
+  and array. Floating point numbers will be returned as a string. By
   specifying the output_type 'int' the value will be converted to an
-  Integer. If conversion is not possible the json_query converter fails.
+  Integer. Arrays will be returned as string, starting and ending with a
+  square brackets. The content is a CSV. Depending on the data type, the
+  array values might be quoted. If the array values are complex types,
+  the string contains the complete json representation of each value
+  separated by a comma. Example result for a roles query to a JWT:
+
+     ["manage-account","manage-account-links","view-profile"]
+
+  If conversion is not possible the json_query converter fails.
 
   <json_path> must be a valid JSON Path string as defined in
   https://datatracker.ietf.org/doc/draft-ietf-jsonpath-base/

reg-tests/converter/json_query.vtc

@@ -98,4 +98,10 @@ client c1 -connect ${h1_fe_sock} {
 	rxresp
 	expect resp.status == 200
 	expect resp.http.x-var_body_mykey ~ "myvalue"
-} -run
+
+	txreq -url "/" \
+	 -body "{\"my.key\":[\"val1\",\"val2\",\"val3\"],\"key2\":\"val4\"}"
+	expect resp.status == 200
+	expect resp.http.x-var_body_mykey ~ "[\"val1\",\"val2\",\"val3\"]"
+
+} -run

src/sample.c

@@ -4212,8 +4212,15 @@ static int sample_conv_json_query(const struct arg *args, struct sample *smp, vo
 
 			return 1;
 		}
+               case MJSON_TOK_ARRAY: {
+                       // We copy the complete array, including square brackets into the return buffer
+                       // result looks like: ["manage-account","manage-account-links","view-profile"]
+                       trash->data = b_putblk(trash, token, token_size);
+                       smp->data.u.str = *trash;
+                       smp->data.type = SMP_T_STR;
+                       return 1;
+               }
 		case MJSON_TOK_NULL:
-		case MJSON_TOK_ARRAY:
 		case MJSON_TOK_OBJECT:
 			/* We cannot handle these. */
 			return 0;