confd: relocate generation of mdns service records to C

Simplify and consolidate generation of mdns service records from an
external script to C. This reduces fork + exec and saves two seconds
of boot time on single core Cortex-A7 systems.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/confd/bin/Makefile.am

@@ -1,4 +1,4 @@
-pkglibexec_SCRIPTS = bootstrap error load gen-service gen-hostname \
+pkglibexec_SCRIPTS = bootstrap error load gen-hostname \
 		     gen-interfaces gen-motd gen-hardware gen-version \
 		     mstpd-wait-online wait-interface
 sbin_SCRIPTS       = dagger migrate firewall

src/confd/bin/gen-service

@@ -1,46 +0,0 @@
-#!/bin/sh
-# Very basic avahi .service generator, works for tcp (http) services
-. /etc/os-release
-
-cmd=$1
-host=$2
-name=$3
-type=$4
-port=$5
-desc=$6
-shift 6
-file="/etc/avahi/services/$name.service"
-
-case $cmd in
-    delete)
-	rm -f "$file"
-	exit 0
-	;;
-    update)
-	if [ ! -f "$file" ]; then
-	    exit 0
-	fi
-	;;
-    *)
-	;;
-esac
-
-cat <<EOF >"$file"
-<?xml version="1.0" standalone='no'?>
-<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
-<service-group>
-  <name replace-wildcards="yes">$desc</name>
-  <service>
-    <type>$type</type>
-    <port>$port</port>
-    <txt-record>vv=1</txt-record>
-    <txt-record>vendor=$(jq -r .vendor /run/system.json)</txt-record>
-    <txt-record>product=$(jq -r '."product-name"' /run/system.json)</txt-record>
-    <txt-record>serial=$(jq -r '."serial-number"' /run/system.json)</txt-record>
-    <txt-record>deviceid=$(jq -r '."mac-address"' /run/system.json)</txt-record>
-    <txt-record>vn=$VENDOR_NAME</txt-record>
-    <txt-record>on=$NAME</txt-record>
-    <txt-record>ov=$VERSION_ID</txt-record>$(for txt in "$@"; do printf "\n    <txt-record>%s</txt-record>" "$txt"; done)
-  </service>
-</service-group>
-EOF

src/confd/src/services.c

@@ -19,9 +19,13 @@
 #define GENERATE_ENUM(ENUM)      ENUM,
 #define GENERATE_STRING(STRING) #STRING,
 
+#define AVAHI_SVC_PATH "/etc/avahi/services"
+
 #define LLDP_CONFIG "/etc/lldpd.d/confd.conf"
 #define LLDP_CONFIG_NEXT LLDP_CONFIG"+"
 
+enum mdns_cmd { MDNS_ADD, MDNS_DELETE, MDNS_UPDATE };
+
 #define FOREACH_SVC(SVC)			\
         SVC(none)				\
         SVC(ssh)				\
@@ -68,6 +72,13 @@ struct mdns_svc {
 	{ ssh,      "ssh",      "_ssh._tcp",           22, "Secure shell command line interface (CLI)", NULL },
 };
 
+static const char *jgets(json_t *obj, const char *key)
+{
+	json_t *val = json_object_get(obj, key);
+
+	return val ? json_string_value(val) : NULL;
+}
+
 /*
  * On hostname changes we need to update the mDNS records, in particular
  * the ones advertising an adminurl (standarized by Apple), because they
@@ -77,27 +88,77 @@ struct mdns_svc {
  *      adminurl to include 'admin@%s.local' to pre-populate the default
  *      username in the login dialog.
  */
-static int mdns_records(const char *cmd, svc type)
+static int mdns_records(int cmd, svc type)
 {
 	char hostname[MAXHOSTNAMELEN + 1];
+	const char *vendor, *product, *serial, *mac;
+	const char *vn, *on, *ov;
 
 	if (gethostname(hostname, sizeof(hostname))) {
 		ERRNO("failed getting system hostname");
 		return SR_ERR_SYS;
 	}
 
+	vendor  = jgets(confd.root, "vendor");
+	product = jgets(confd.root, "product-name");
+	serial  = jgets(confd.root, "serial-number");
+	mac     = jgets(confd.root, "mac-address");
+
+	vn = fgetkey("/etc/os-release", "VENDOR_NAME");
+	on = fgetkey("/etc/os-release", "NAME");
+	ov = fgetkey("/etc/os-release", "VERSION_ID");
+
 	for (size_t i = 0; i < NELEMS(services); i++) {
 		struct mdns_svc *srv = &services[i];
-		char buf[256] = "";
+		FILE *fp;
 
 		if (type != all && srv->svc != type)
 			continue;
 
-		if (srv->text)
-			snprintf(buf, sizeof(buf), srv->text, hostname);
+		if (cmd == MDNS_DELETE) {
+			erasef(AVAHI_SVC_PATH "/%s.service", srv->name);
+			continue;
+		}
 
-		systemf("/usr/libexec/confd/gen-service %s %s %s %s %d \"%s\" %s", cmd,
-			hostname, srv->name, srv->type, srv->port, srv->desc, buf);
+		if (cmd == MDNS_UPDATE && !fexistf(AVAHI_SVC_PATH "/%s.service", srv->name))
+			continue;
+
+		fp = fopenf("w", AVAHI_SVC_PATH "/%s.service", srv->name);
+		if (!fp) {
+			ERRNO("failed creating %s.service", srv->name);
+			continue;
+		}
+
+		fprintf(fp,
+			"<?xml version=\"1.0\" standalone='no'?>\n"
+			"<!DOCTYPE service-group SYSTEM \"avahi-service.dtd\">\n"
+			"<service-group>\n"
+			"  <name replace-wildcards=\"yes\">%s</name>\n"
+			"  <service>\n"
+			"    <type>%s</type>\n"
+			"    <port>%d</port>\n"
+			"    <txt-record>vv=1</txt-record>\n"
+			"    <txt-record>vendor=%s</txt-record>\n"
+			"    <txt-record>product=%s</txt-record>\n"
+			"    <txt-record>serial=%s</txt-record>\n"
+			"    <txt-record>deviceid=%s</txt-record>\n"
+			"    <txt-record>vn=%s</txt-record>\n"
+			"    <txt-record>on=%s</txt-record>\n"
+			"    <txt-record>ov=%s</txt-record>\n",
+			srv->desc, srv->type, srv->port,
+			vendor  ?: "", product ?: "", serial ?: "", mac ?: "",
+			vn ?: "", on ?: "", ov ?: "");
+
+		if (srv->text) {
+			fprintf(fp, "    <txt-record>");
+			fprintf(fp, srv->text, hostname);
+			fprintf(fp, "</txt-record>\n");
+		}
+
+		fprintf(fp,
+			"  </service>\n"
+			"</service-group>\n");
+		fclose(fp);
 	}
 
 	return SR_ERR_OK;
@@ -182,7 +243,7 @@ static void svc_enadis(int ena, svc type, const char *svc)
 	}
 
 	if (type != none)
-		mdns_records(ena ? "add" : "delete", type);
+		mdns_records(ena ? MDNS_ADD : MDNS_DELETE, type);
 
 	systemf("initctl -nbq touch avahi");
 	systemf("initctl -nbq touch nginx");
@@ -291,7 +352,7 @@ static int mdns_change(sr_session_ctx_t *session, struct lyd_node *config, struc
 		mdns_conf(srv);
 
 		/* Generate/update basic mDNS service records */
-		mdns_records("update", all);
+		mdns_records(MDNS_UPDATE, all);
 	}
 
 	svc_enadis(ena, none, "avahi");