dns configuration

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);