136 lines
3.5 KiB
C++
136 lines
3.5 KiB
C++
#include <linux/if.h>
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#include <linux/if_tun.h>
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#include <sys/stat.h>
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#include <sys/ioctl.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include "TunDevice.hpp"
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static const size_t TUN_MTU = 1500; // TODO determine this cleanly
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TunDevice::TunDevice(const char* dev)
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{
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struct ifreq ifr;
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int fd;
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if( (fd = open("/dev/net/tun", O_RDWR)) < 0 ) {
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perror("Tun device: cannot open /dev/net/tun: ");
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exit(1);
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}
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memset(&ifr, 0, sizeof(ifr));
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/* Flags: IFF_TUN - TUN device (no Ethernet headers)
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* IFF_TAP - TAP device
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*
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* IFF_NO_PI - Do not provide packet information
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*/
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ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
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if(dev != nullptr) {
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if(strlen(dev) >= IFNAMSIZ - 2) {
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fprintf(stderr, "Tun device: device name is too long.\n");
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exit(1);
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}
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strncpy(ifr.ifr_name, dev, IFNAMSIZ-1);
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}
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if(ioctl(fd, TUNSETIFF, (void *) &ifr) < 0){
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close(fd);
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perror("Tun device: tunnel interface failed [TUNSETIFF]: ");
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exit(1);
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}
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_dev_name = ifr.ifr_name;
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_fd = fd;
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// Bring interface up
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kdebugf("Bringing interface up...\n");
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int sockfd = socket(AF_INET, SOCK_DGRAM, 0); // Any socket will do
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if(ioctl(sockfd, SIOCGIFFLAGS, (void*) &ifr) < 0) {
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close(fd);
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close(sockfd);
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perror("Tun device: could not get tunnel interface flags: ");
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exit(1);
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}
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ifr.ifr_flags |= IFF_UP | IFF_RUNNING;
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if(ioctl(sockfd, SIOCSIFFLAGS, (void*) &ifr) < 0) {
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close(fd);
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close(sockfd);
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perror("Tun device: could not bring tunnel interface up: ");
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exit(1);
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}
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close(sockfd);
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// The device is now fully set up
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_poll_fd.fd = _fd;
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_poll_fd.events = POLLIN;
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}
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TunDevice::~TunDevice() {
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close(_fd);
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}
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uint16_t TunDevice::get_mtu() const {
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int sockfd = socket(AF_INET, SOCK_DGRAM, 0); // Any socket will do
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struct ifreq ifr;
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ifr.ifr_addr.sa_family = AF_INET6;
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strncpy(ifr.ifr_name, _dev_name, sizeof(ifr.ifr_name)-1);
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if (ioctl(sockfd, SIOCGIFMTU, (caddr_t)&ifr) < 0)
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return 0;
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close(sockfd);
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return ifr.ifr_mtu;
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}
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bool TunDevice::set_mtu(uint16_t mtu) {
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int sockfd = socket(AF_INET, SOCK_DGRAM, 0); // Any socket will do
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struct ifreq ifr;
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ifr.ifr_addr.sa_family = AF_INET6;
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strncpy(ifr.ifr_name, _dev_name, sizeof(ifr.ifr_name)-1);
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ifr.ifr_mtu = mtu;
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if (ioctl(sockfd, SIOCSIFMTU, (caddr_t)&ifr) < 0)
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return false;
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close(sockfd);
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return true;
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}
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size_t TunDevice::poll_packet(char* read_buffer, size_t buf_size, int timeout) {
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int poll_rc = poll(&_poll_fd, 1, timeout);
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if(poll_rc < 0) {
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if(errno == EINTR) // Interrupt.
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return 0;
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perror("Tun device: error polling from interface: ");
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exit(1);
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}
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else if(poll_rc == 0 || (_poll_fd.revents & POLLIN) == 0) {
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// Nothing to read
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return 0;
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}
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return this->read(read_buffer, buf_size);
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}
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size_t TunDevice::read(char* read_buffer, size_t buf_size) {
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int nread = ::read(_fd, read_buffer, buf_size);
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if(nread < 0) {
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perror("Tun device: error reading from interface: ");
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exit(1);
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}
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_last_read_size = nread;
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return _last_read_size;
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}
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size_t TunDevice::write(const char* data, size_t len) {
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int nwritten = ::write(_fd, data, len);
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if(nwritten < 0) {
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perror("Tun device: error writing to interface: ");
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exit(1);
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}
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return nwritten;
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}
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