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283 lines
8.4 KiB
283 lines
8.4 KiB
/**
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* (C) 2007-20 - ntop.org and contributors
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not see see <http://www.gnu.org/licenses/>
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*
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*/
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#ifdef __linux__
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#include "n2n.h"
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static int setup_ifname (int fd, const char *ifname, const char *ipaddr,
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const char *netmask, uint8_t *mac, int mtu) {
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struct ifreq ifr;
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memset(&ifr, 0, sizeof(ifr));
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strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
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ifr.ifr_name[IFNAMSIZ-1] = '\0';
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ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;
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memcpy(ifr.ifr_hwaddr.sa_data, mac, 6);
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if(ioctl(fd, SIOCSIFHWADDR, &ifr) == -1) {
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traceEvent(TRACE_ERROR, "ioctl(SIOCSIFHWADDR) failed [%d]: %s", errno, strerror(errno));
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return -1;
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}
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ifr.ifr_addr.sa_family = AF_INET;
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// interface address
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inet_pton(AF_INET, ipaddr, &((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr);
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if(ioctl(fd, SIOCSIFADDR, &ifr) == -1) {
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traceEvent(TRACE_ERROR, "ioctl(SIOCSIFADDR) failed [%d]: %s", errno, strerror(errno));
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return -2;
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}
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// netmask
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if(netmask && (((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr.s_addr != 0)) {
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inet_pton(AF_INET, netmask, &((struct sockaddr_in*)&ifr.ifr_addr)->sin_addr);
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if(ioctl(fd, SIOCSIFNETMASK, &ifr) == -1) {
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traceEvent(TRACE_ERROR, "ioctl(SIOCSIFNETMASK, %s) failed [%d]: %s", netmask, errno, strerror(errno));
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return -3;
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}
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}
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// MTU
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ifr.ifr_mtu = mtu;
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if(ioctl(fd, SIOCSIFMTU, &ifr) == -1) {
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traceEvent(TRACE_ERROR, "ioctl(SIOCSIFMTU) failed [%d]: %s", errno, strerror(errno));
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return -4;
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}
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// set up and running
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if(ioctl(fd, SIOCGIFFLAGS, &ifr) == -1) {
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traceEvent(TRACE_ERROR, "ioctl(SIOCGIFFLAGS) failed [%d]: %s", errno, strerror(errno));
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return -5;
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}
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ifr.ifr_flags |= (IFF_UP | IFF_RUNNING);
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if(ioctl(fd, SIOCSIFFLAGS, &ifr) == -1) {
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traceEvent(TRACE_ERROR, "ioctl(SIOCSIFFLAGS) failed [%d]: %s", errno, strerror(errno));
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return -6;
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}
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return 0;
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}
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/** @brief Open and configure the TAP device for packet read/write.
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*
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* This routine creates the interface via the tuntap driver and then
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* configures it.
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*
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* @param device - [inout] a device info holder object
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* @param dev - user-defined name for the new iface,
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* if NULL system will assign a name
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* @param device_ip - address of iface
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* @param device_mask - netmask for device_ip
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* @param mtu - MTU for device_ip
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*
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* @return - negative value on error
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* - non-negative file-descriptor on success
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*/
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int tuntap_open (tuntap_dev *device,
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char *dev, /* user-definable interface name, eg. edge0 */
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const char *address_mode, /* static or dhcp */
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char *device_ip,
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char *device_mask,
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const char * device_mac,
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int mtu) {
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char *tuntap_device = "/dev/net/tun";
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int ioctl_fd;
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struct ifreq ifr;
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int rc;
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int nl_fd;
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char nl_buf[8192]; /* >= 8192 to avoid truncation, see "man 7 netlink" */
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struct iovec iov;
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struct sockaddr_nl sa;
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int up_and_running = 0;
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struct msghdr msg;
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device->fd = open(tuntap_device, O_RDWR);
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if(device->fd < 0) {
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traceEvent(TRACE_ERROR, "tuntap open() error: %s[%d]. Is the tun kernel module loaded?\n", strerror(errno), errno);
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return -1;
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}
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memset(&ifr, 0, sizeof(ifr));
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// want a TAP device for layer 2 frames
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ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
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strncpy(ifr.ifr_name, dev, IFNAMSIZ-1);
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ifr.ifr_name[IFNAMSIZ-1] = '\0';
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rc = ioctl(device->fd, TUNSETIFF, (void *)&ifr);
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if(rc < 0) {
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traceEvent(TRACE_ERROR, "tuntap ioctl(TUNSETIFF, IFF_TAP) error: %s[%d]\n", strerror(errno), rc);
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close(device->fd);
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return -1;
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}
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// store the device name for later reuse
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strncpy(device->dev_name, ifr.ifr_name, MIN(IFNAMSIZ, N2N_IFNAMSIZ));
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if(device_mac && device_mac[0]) {
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// use the user-provided MAC
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str2mac(device->mac_addr, device_mac);
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} else {
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// set an explicit random MAC to know the exact MAC in use, manually
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// reading the MAC address is not safe as it may change internally
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// also after the TAP interface UP status has been notified
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int i;
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for(i = 0; i < 6; i++)
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device->mac_addr[i] = n2n_rand();
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// clear multicast bit
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device->mac_addr[0] &= ~0x01;
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// set locally-assigned bit
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device->mac_addr[0] |= 0x02;
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}
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// initialize netlink socket
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if((nl_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) == -1) {
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traceEvent(TRACE_ERROR, "netlink socket creation failed [%d]: %s", errno, strerror(errno));
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return -1;
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}
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iov.iov_base = nl_buf;
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iov.iov_len = sizeof(nl_buf);
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memset(&sa, 0, sizeof(sa));
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sa.nl_family = PF_NETLINK;
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sa.nl_groups = RTMGRP_LINK;
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sa.nl_pid = getpid();
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memset(&msg, 0, sizeof(msg));
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msg.msg_name = &sa;
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msg.msg_namelen = sizeof(sa);
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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// subscribe to interface events
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if(bind(nl_fd, (struct sockaddr*)&sa, sizeof(sa)) == -1) {
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traceEvent(TRACE_ERROR, "netlink socket bind failed [%d]: %s", errno, strerror(errno));
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return -1;
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}
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if((ioctl_fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0) {
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traceEvent(TRACE_ERROR, "socket creation failed [%d]: %s", errno, strerror(errno));
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close(nl_fd);
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return -1;
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}
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if(setup_ifname(ioctl_fd, device->dev_name, device_ip, device_mask, device->mac_addr, mtu) < 0) {
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close(nl_fd);
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close(ioctl_fd);
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close(device->fd);
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return -1;
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}
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close(ioctl_fd);
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// wait for the up and running notification
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traceEvent(TRACE_INFO, "Waiting for TAP interface to be up and running...");
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while(!up_and_running) {
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ssize_t len = recvmsg(nl_fd, &msg, 0);
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struct nlmsghdr *nh;
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for(nh = (struct nlmsghdr *)nl_buf; NLMSG_OK(nh, len); nh = NLMSG_NEXT(nh, len)) {
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if(nh->nlmsg_type == NLMSG_ERROR) {
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traceEvent(TRACE_DEBUG, "nh->nlmsg_type == NLMSG_ERROR");
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break;
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}
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if(nh->nlmsg_type == NLMSG_DONE)
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break;
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if(nh->nlmsg_type == NETLINK_GENERIC) {
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struct ifinfomsg *ifi = NLMSG_DATA(nh);
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// NOTE: skipping interface name check, assuming it's our TAP
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if((ifi->ifi_flags & IFF_UP) && (ifi->ifi_flags & IFF_RUNNING)) {
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up_and_running = 1;
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traceEvent(TRACE_INFO, "Interface is up and running");
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break;
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}
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}
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}
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}
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close(nl_fd);
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device->ip_addr = inet_addr(device_ip);
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device->device_mask = inet_addr(device_mask);
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device->if_idx = if_nametoindex(dev);
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return device->fd;
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}
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int tuntap_read (struct tuntap_dev *tuntap, unsigned char *buf, int len) {
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return read(tuntap->fd, buf, len);
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}
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int tuntap_write (struct tuntap_dev *tuntap, unsigned char *buf, int len) {
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return write(tuntap->fd, buf, len);
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}
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void tuntap_close (struct tuntap_dev *tuntap) {
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close(tuntap->fd);
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}
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// fill out the ip_addr value from the interface, called to pick up dynamic address changes
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void tuntap_get_address (struct tuntap_dev *tuntap) {
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struct ifreq ifr;
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int fd;
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if((fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)) < 0) {
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traceEvent(TRACE_ERROR, "socket creation failed [%d]: %s", errno, strerror(errno));
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return;
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}
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ifr.ifr_addr.sa_family = AF_INET;
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strncpy(ifr.ifr_name, tuntap->dev_name, IFNAMSIZ);
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ifr.ifr_name[IFNAMSIZ-1] = '\0';
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if(ioctl(fd, SIOCGIFADDR, &ifr) != -1)
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tuntap->ip_addr = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr;
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close(fd);
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}
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#endif /* #ifdef __linux__ */
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