From cd441c5f29433a3bffeedd9d10e46eb3eeef7d63 Mon Sep 17 00:00:00 2001
From: David Scott <dave@recoil.org>
Date: Thu, 12 May 2016 15:38:33 +0100
Subject: [PATCH] tap-vsockd: add a function to open a TAP device

Signed-off-by: David Scott <dave@recoil.org>
---
 alpine/packages/tap-vsockd/Dockerfile   |  2 +-
 alpine/packages/tap-vsockd/tap-vsockd.c | 42 +++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/alpine/packages/tap-vsockd/Dockerfile b/alpine/packages/tap-vsockd/Dockerfile
index 7f08ede6e..74f5ce00d 100644
--- a/alpine/packages/tap-vsockd/Dockerfile
+++ b/alpine/packages/tap-vsockd/Dockerfile
@@ -1,6 +1,6 @@
 FROM alpine:3.3
 
-RUN apk update && apk upgrade && apk add alpine-sdk util-linux-dev
+RUN apk update && apk upgrade && apk add alpine-sdk util-linux-dev linux-headers
 
 RUN mkdir -p /tap-vsockd
 WORKDIR /tap-vsockd
diff --git a/alpine/packages/tap-vsockd/tap-vsockd.c b/alpine/packages/tap-vsockd/tap-vsockd.c
index c982f5d2a..449591ef3 100644
--- a/alpine/packages/tap-vsockd/tap-vsockd.c
+++ b/alpine/packages/tap-vsockd/tap-vsockd.c
@@ -6,10 +6,52 @@
 #include <string.h>
 #include <getopt.h>
 
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <err.h>
+#include <arpa/inet.h>
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <linux/if_tun.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <ifaddrs.h>
+
+
 #include "compat.h"
 
 int verbose_flag = 0;
 
+int alloc_tap(char *dev) {
+  int fd;
+  struct ifreq ifr;
+  const char *clonedev = "/dev/net/tun";
+  if ((fd = open(clonedev, O_RDWR)) == -1) {
+    perror("Failed to open /dev/net/tun");
+    exit(1);
+  }
+  memset(&ifr, 0, sizeof(ifr));
+  ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+  strncpy(ifr.ifr_name, dev, IFNAMSIZ);
+  if (ioctl(fd, TUNSETIFF, (void*) &ifr) < 0) {
+    perror("TUNSETIFF failed");
+    exit(1);
+  }
+  int persist = 1;
+  if (ioctl(fd, TUNSETPERSIST, persist) < 0) {
+    perror("TUNSETPERSIST failed");
+    exit(1);
+  }
+  fprintf(stderr, "successfully created TAP device %s\n", dev);
+  return fd;
+}
+
+
 #define SVR_BUF_LEN (3 * 4096)
 #define MAX_BUF_LEN (2 * 1024 * 1024)