From 395bb5c76422c8e8423730b2d17498aa330ce85d Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Wed, 19 Aug 2026 23:45:45 -0500
Subject: [PATCH] dns configuration

---
 client.cpp | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/client.cpp b/client.cpp
index 18ca6ff..608280a 100644
--- a/client.cpp
+++ b/client.cpp
@@ -5,6 +5,7 @@
 #include <stddef.h>
 #include <time.h>
 
+#include <fcntl.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>
 #include <sys/ioctl.h>
@@ -288,10 +289,35 @@ int main()
                        p.dhcp4->yiaddr,
                        options.router);
 
+  //////////////////////////////////////////////////////////////////////
+  // dns configure
+  //////////////////////////////////////////////////////////////////////
+
+  int dfd = open("/etc/resolv.conf", O_CREAT | O_WRONLY | O_TRUNC);
+  if (dfd < 0) {
+    perror("open");
+    exit(EXIT_FAILURE);
+  }
+
+  char dbuf[1024];
+  int dbuflen = snprintf(dbuf, (sizeof (dbuf)), "nameserver %s\n",
+                         ip4::tostr(options.domain_name_server));
+  if (dbuflen < 0) {
+    perror("snprintf");
+    exit(EXIT_FAILURE);
+  }
+
+  ssize_t dret = write(dfd, dbuf, dbuflen);
+  if (dret < 0) {
+    perror("write");
+    exit(EXIT_FAILURE);
+  }
+
   //////////////////////////////////////////////////////////////////////
   // exit
   //////////////////////////////////////////////////////////////////////
 
+  close(dfd);
   close(s);
   close(sf);
   exit(EXIT_SUCCESS);