Add httpd API to extract URL fields

lib/isc/httpd.c

@@ -1118,3 +1118,20 @@ const isc_time_t *
 isc_httpd_if_modified_since(const isc_httpd_t *httpd) {
 	return (const isc_time_t *)&httpd->if_modified_since;
 }
+
+isc_result_t
+isc_httpd_geturlfield(const isc_httpd_t *httpd, isc_url_field_t field,
+		      char const **base, uint16_t *len) {
+	REQUIRE(httpd != NULL);
+	REQUIRE(base != NULL);
+	REQUIRE(len != NULL);
+
+	if (httpd->up.field_set & (1 << field))  {
+		*base = httpd->path + httpd->up.field_data[field].off;
+		*len = httpd->up.field_data[field].len;
+
+		return ISC_R_SUCCESS;
+	}
+
+	return ISC_R_NOTFOUND;
+}

lib/isc/include/isc/httpd.h

@@ -47,6 +47,10 @@ isc_result_t
 isc_httpdmgr_addurl(isc_httpdmgr_t *httpdmgr, const char *url, bool isstatic,
 		    isc_httpdaction_t *func, void *arg);
 
+isc_result_t
+isc_httpd_geturlfield(const isc_httpd_t *httpd, isc_url_field_t field,
+		      const char **base, uint16_t *len);
+
 void
 isc_httpd_setfinishhook(void (*fn)(void));