From c14b4e41526e08f921243aad0906550d7cd2cbc5 Mon Sep 17 00:00:00 2001
From: Joachim Wiberg <troglobit@gmail.com>
Date: Fri, 8 Dec 2023 08:29:33 +0100
Subject: [PATCH] confd: initial enhancements to DHCP client

 - Add support for option 12, provide current hostname to server for
   registering the lease with -- this allows registering in local DNS
   for some DHCP servers.
 - Add support for option 50, request any previously cached IP address
 - Override option 60, vendor class identifier, with Infix vYY.MM
 - Adjust timers and retry options to be more persistant
 - Include initial metric as environment variable to client
 - Disable all default options, set a hard-coded subset, which will be
   replaced in a later commit by a generated list.
 - Ensure udhcpc creates a pid file, in case we may need to start any
   other service/task in sync with the DHCP client

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
---
 src/confd/src/infix-dhcp.c | 74 +++++++++++++++++++++++++++++++++++---
 1 file changed, 70 insertions(+), 4 deletions(-)

diff --git a/src/confd/src/infix-dhcp.c b/src/confd/src/infix-dhcp.c
index cdc76b6e..58591703 100644
--- a/src/confd/src/infix-dhcp.c
+++ b/src/confd/src/infix-dhcp.c
@@ -21,8 +21,10 @@ static const struct srx_module_requirement infix_dhcp_reqs[] = {
 
 static void add(const char *ifname, const char *client_id)
 {
-	char *args = NULL;
-	FILE *fp;
+	const char *opts = "-O subnet -O router -O dns -O domain -O ntpsrv -O 121";
+	char *args = NULL, *ipcache = NULL;
+	char buf[256], vendor[128] = { 0 };
+	FILE *fp, *xp;
 
 	fp = fopenf("w", "/etc/finit.d/available/dhcp-%s.conf", ifname);
 	if (!fp) {
@@ -31,13 +33,77 @@ static void add(const char *ifname, const char *client_id)
 		return;
 	}
 
+	if (fexistf("/var/lib/misc/%s.cache", ifname)) {
+		struct in_addr ina;
+
+		xp = fopenf("r", "/var/lib/misc/%s.cache", ifname);
+		if (!xp)
+			goto nocache;
+
+		if (!fgets(buf, sizeof(buf), xp)) {
+			fclose(xp);
+			goto nocache;
+		}
+		fclose(xp);
+		chomp(buf);
+
+		if (!inet_aton(buf, &ina)) {
+			erasef("/var/lib/misc/%s.cache", ifname);
+			goto nocache;
+		}
+
+		ipcache = alloca(20);
+		if (ipcache)
+			snprintf(ipcache, 20, "-r %.15s", buf);
+	nocache:
+	}
+
+	xp = fopen("/etc/os-relase", "r");
+	if (xp) {
+		while (fgets(buf, sizeof(buf), xp)) {
+			if (!strncmp(buf, "NAME=", 5))
+				snprintf(vendor, sizeof(vendor), "-V '%.32s ", &buf[5]);
+			if (!strncmp(buf, "VERSION=", 8)) {
+				strlcat(vendor, &buf[8], sizeof(vendor));
+				strlcat(vendor, "'", sizeof(vendor));
+				break;
+			}
+		}
+		fclose(xp);
+	}
+
+	xp = fopen("/etc/hostname", "r");
+	if (xp) {
+		int pos;
+
+		pos = snprintf(buf, sizeof(buf), "-x hostname:");
+		if (!fgets(&buf[pos], sizeof(buf) - pos, xp))
+			buf[0] = 0;
+		fclose(xp);
+		chomp(buf);
+	}
+
 	if (client_id && client_id[0]) {
 		args = alloca(strlen(client_id) + 12);
 		if (args)
 			sprintf(args, "-C -x 61:'\"%s\"'", client_id);
 	}
-	fprintf(fp, "service name:dhcp :%s udhcpc -f -S -R -i %s %s -- DHCP client @%s\n",
-	        ifname, ifname, args ?: "", ifname);
+
+	/*
+	 * XXX: hard-coded metric for now.  Should be 100 + ifmetric,
+	 * which in turn should be based on the iftype.  E.g., a WiFi
+	 * interface should have a base metric of 500 while a plain
+	 * Ethernet interface has a base metric of 0.  These are the
+	 * defaults, a user should be able to override this all by a
+	 * dhcp routing metric.
+	 */
+	fprintf(fp, "# Generated by Infix confd\n");
+	fprintf(fp, "metric=100\n");
+	fprintf(fp, "service <!> name:dhcp :%s\\\n"
+		"	[2345] udhcpc -f -p /run/dhcp-%s.pid -t 10 -T 3 -A 10\\\n"
+		"		-S -R %s -o %s -i %s %s %s %s\\\n"
+		"		-- DHCP client @%s\n", ifname, ifname,
+		buf, opts, ifname, args ?: "", ipcache ?: "", vendor, ifname);
 	fclose(fp);
 
 	if (systemf("initctl -bfq enable dhcp-%s", ifname))