Libraryize test.cc

.gitignore

@@ -1 +1,2 @@
 bazel-*
+*.swp

BUILD

@@ -1,6 +0,0 @@
-cc_binary(
-  name = "test",
-  srcs = [
-    "test.cc",
-  ],
-)

build/CROSSTOOL

@@ -55,6 +55,7 @@ toolchain {
   compiler_flag: "-fPIE"
   linker_flag: "-Wl,-z,relro,-z,now"
   linker_flag: "-pie"
+  linker_flag: "-lstdc++"
 
   compilation_mode_flags {
     mode: OPT

format.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+exec find $(dirname $0) \
+  -name '*.cc' -o -name '*.h' \
+  -exec clang-format-3.8 -i --style=google '{}' ';'

lib/BUILD

@@ -1,3 +1,5 @@
+package(default_visibility = ["//visibility:public"])
+
 cc_library(
   name = "tun_tap_device_lib",
   hdrs = [

lib/tun_tap_device.cc

@@ -1 +1,41 @@
 #include "lib/tun_tap_device.h"
+
+#include <sys/socket.h>
+#include <linux/if.h>
+#include <glog/logging.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+namespace funstraw {
+
+namespace {
+const std::string kCloneDevice = "/dev/net/tun";
+}
+
+TunTapDevice::TunTapDevice(const std::string& name, uint64_t if_flags, uint64_t fd_flags) {
+  auto fd_ = open(kCloneDevice.c_str(), fd_flags);
+  CHECK_NE(fd_, -1) << strerror(errno);
+
+  struct ifreq ifr = {0};
+  ifr.ifr_flags = if_flags;
+  if (!name.empty()) {
+    CHECK_LT(name.length(), IFNAMSIZ);
+    strcpy(ifr.ifr_name, name.c_str());
+  }
+
+  CHECK_EQ(ioctl(fd_, TUNSETIFF, &ifr), 0) << strerror(errno);
+
+  name_ = ifr.ifr_name;
+}
+
+TunTapDevice::~TunTapDevice() {
+  CHECK_EQ(close(fd_), 0);
+}
+
+size_t TunTapDevice::Read(char* buf) {
+  auto bytes = read(fd_, buf, 2048);
+  CHECK_NE(bytes, -1) << strerror(errno);
+  return bytes;
+}
+
+}  // namespace funstraw

lib/tun_tap_device.h

@@ -1,21 +1,33 @@
 #include <string>
 
+#include <fcntl.h>
 #include <linux/if_tun.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 
-class TapTunDevice {
+namespace funstraw {
+
+class TunTapDevice {
  public:
-  static const auto kTunFormat = IFF_TUN;
+  static const auto kIfFormatTun = IFF_TUN;
-  static const auto kTapFormat = IFF_TAP;
+  static const auto kIfFormatTap = IFF_TAP;
-  static const auto kNoPacketInfo = IFF_NO_PI;
+  static const auto kIfNoPacketInfo = IFF_NO_PI;
 
-	TapTunDevice(const std::string& name, uint64_t flags);
+  static const auto kFdReadOnly = O_RDONLY;
-	TapTunDevice(uint64_t flags);
+  static const auto kFdWriteOnly = O_WRONLY;
+  static const auto kFdReadWrite = O_RDWR;
 
-  const std::string& Name() {
+  TunTapDevice(const std::string& name, uint64_t if_flags, uint64_t fd_flags);
-    return name_;
+  ~TunTapDevice();
-  }
+
+  const std::string& Name() { return name_; }
+
+  // TODO: real buffer object
+  size_t Read(char* buf);
 
  private:
+  int fd_;
   std::string name_;
 };
 
+}  // namespace funstraw

test.cc

@@ -1,87 +0,0 @@
-#include <sys/socket.h>
-#include <fcntl.h>
-#include <linux/if.h>
-#include <linux/if_tun.h>
-#include <string.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/ioctl.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <unistd.h>
-
-int tun_alloc(char *dev, int flags) {
-
-  struct ifreq ifr;
-  int fd, err;
-  const char *clonedev = "/dev/net/tun";
-
-  /* Arguments taken by the function:
-   *
-   * char *dev: the name of an interface (or '\0'). MUST have enough
-   *   space to hold the interface name if '\0' is passed
-   * int flags: interface flags (eg, IFF_TUN etc.)
-   */
-
-   /* open the clone device */
-   if( (fd = open(clonedev, O_RDWR)) < 0 ) {
-     return fd;
-   }
-
-   /* preparation of the struct ifr, of type "struct ifreq" */
-   memset(&ifr, 0, sizeof(ifr));
-
-   ifr.ifr_flags = flags;   /* IFF_TUN or IFF_TAP, plus maybe IFF_NO_PI */
-
-   if (*dev) {
-     /* if a device name was specified, put it in the structure; otherwise,
-      * the kernel will try to allocate the "next" device of the
-      * specified type */
-     strncpy(ifr.ifr_name, dev, IFNAMSIZ);
-   }
-
-   /* try to create the device */
-   if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ) {
-     close(fd);
-     return err;
-   }
-
-  /* if the operation was successful, write back the name of the
-   * interface to the variable "dev", so the caller can know
-   * it. Note that the caller MUST reserve space in *dev (see calling
-   * code below) */
-  strcpy(dev, ifr.ifr_name);
-
-  /* this is the special file descriptor that the caller will use to talk
-   * with the virtual interface */
-  return fd;
-}
-
-int main(int argc, char *argv[]) {
-  char tun_name[IFNAMSIZ];
-  
-  /* Connect to the device */
-  strcpy(tun_name, "tun77");
-  int tun_fd = tun_alloc(tun_name, IFF_TUN);  /* tun interface */
-
-  if(tun_fd < 0){
-    perror("Allocating interface");
-    exit(1);
-  }
-
-	char buffer[2048];
-  /* Now read data coming from the kernel */
-  while(1) {
-    /* Note that "buffer" should be at least the MTU size of the interface, eg 1500 bytes */
-    int nread = read(tun_fd,buffer,sizeof(buffer));
-    if(nread < 0) {
-      perror("Reading from interface");
-      close(tun_fd);
-      exit(1);
-    }
-
-    /* Do whatever with the data */
-    printf("Read %d bytes from device %s\n", nread, tun_name);
-  }
-  return 0;
-}

tools/BUILD

@@ -0,0 +1,12 @@
+cc_binary(
+  name = "dump_tun",
+  srcs = [
+    "dump_tun.cc",
+  ],
+  deps = [
+    "//lib:tun_tap_device_lib",
+  ],
+  linkopts = [
+    "-lglog",
+  ],
+)

tools/dump_tun.cc

@@ -0,0 +1,18 @@
+#include "lib/tun_tap_device.h"
+
+#include "glog/logging.h"
+
+using funstraw::TunTapDevice;
+
+int main(int argc, char* argv[]) {
+  google::InitGoogleLogging(argv[0]);
+
+  TunTapDevice dev("", TunTapDevice::kIfFormatTun | TunTapDevice::kIfNoPacketInfo, TunTapDevice::kFdReadOnly);
+
+  LOG(INFO) << "Device: " << dev.Name();
+  while (true) {
+    char buf[2048];
+    auto bytes = dev.Read(buf);
+    LOG(INFO) << bytes << " byte packet";
+  }
+}