1 /* -*- c++ -*- */
2 /*
3 * Copyright 2013 Free Software Foundation, Inc.
4 *
5 * This file is part of GNU Radio
6 *
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3, or (at your option)
10 * any later version.
11 *
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
21 */
22
23 #ifdef HAVE_CONFIG_H
24 #include "config.h"
25 #endif
26
27 #include "tuntap_pdu_impl.h"
28 #include <gnuradio/blocks/pdu.h>
29 #include <gnuradio/io_signature.h>
30 #include <boost/format.hpp>
31
32 #include <fcntl.h>
33 #include <sys/stat.h>
34 #include <sys/types.h>
35
36 #if (defined(linux) || defined(__linux) || defined(__linux__))
37 #include <arpa/inet.h>
38 #include <linux/if.h>
39 #include <sys/ioctl.h>
40 #endif
41
42 namespace gr {
43 namespace blocks {
44
make(std::string dev,int MTU,bool istunflag)45 tuntap_pdu::sptr tuntap_pdu::make(std::string dev, int MTU, bool istunflag)
46 {
47 #if (defined(linux) || defined(__linux) || defined(__linux__))
48 return gnuradio::get_initial_sptr(new tuntap_pdu_impl(dev, MTU, istunflag));
49 #else
50 throw std::runtime_error("tuntap_pdu not implemented on this platform");
51 #endif
52 }
53
54 #if (defined(linux) || defined(__linux) || defined(__linux__))
tuntap_pdu_impl(std::string dev,int MTU,bool istunflag)55 tuntap_pdu_impl::tuntap_pdu_impl(std::string dev, int MTU, bool istunflag)
56 : block("tuntap_pdu", io_signature::make(0, 0, 0), io_signature::make(0, 0, 0)),
57 stream_pdu_base(istunflag ? MTU : MTU + 14),
58 d_dev(dev),
59 d_istunflag(istunflag)
60 {
61 // make the tuntap
62 char dev_cstr[1024];
63 memset(dev_cstr, 0x00, 1024);
64 strncpy(dev_cstr, dev.c_str(), std::min(sizeof(dev_cstr), dev.size()));
65
66 bool istun = d_istunflag;
67 if (istun) {
68 d_fd = tun_alloc(dev_cstr, (IFF_TUN | IFF_NO_PI));
69 } else {
70 d_fd = tun_alloc(dev_cstr, (IFF_TAP | IFF_NO_PI));
71 }
72
73 if (d_fd <= 0)
74 throw std::runtime_error(
75 "gr::tuntap_pdu::make: tun_alloc failed (are you running as root?)");
76
77 int err = set_mtu(dev_cstr, MTU);
78 if (err < 0)
79 std::cerr << boost::format("gr::tuntap_pdu: failed to set MTU to %d.\n"
80 "You should use ifconfig to set the MTU. E.g.,\n"
81 " $ sudo ifconfig %s mtu %d\n") %
82 MTU % dev % MTU
83 << std::endl;
84
85 std::cout << boost::format("Allocated virtual ethernet interface: %s\n"
86 "You must now use ifconfig to set its IP address. E.g.,\n"
87 " $ sudo ifconfig %s 192.168.200.1\n"
88 "Be sure to use a different address in the same subnet "
89 "for each machine.\n") %
90 dev % dev
91 << std::endl;
92
93 // set up output message port
94 message_port_register_out(pdu::pdu_port_id());
95 start_rxthread(this, pdu::pdu_port_id());
96
97 // set up input message port
98 message_port_register_in(pdu::pdu_port_id());
99 set_msg_handler(pdu::pdu_port_id(), [this](pmt::pmt_t msg) { this->send(msg); });
100 }
101
tun_alloc(char * dev,int flags)102 int tuntap_pdu_impl::tun_alloc(char* dev, int flags)
103 {
104 struct ifreq ifr;
105 int fd, err;
106 const char* clonedev = "/dev/net/tun";
107
108 /* Arguments taken by the function:
109 *
110 * char *dev: the name of an interface (or '\0'). MUST have enough
111 * space to hold the interface name if '\0' is passed
112 * int flags: interface flags (eg, IFF_TUN etc.)
113 */
114
115 /* open the clone device */
116 if ((fd = open(clonedev, O_RDWR)) < 0)
117 return fd;
118
119 /* preparation of the struct ifr, of type "struct ifreq" */
120 memset(&ifr, 0, sizeof(ifr));
121
122 ifr.ifr_flags = flags; /* IFF_TUN or IFF_TAP, plus maybe IFF_NO_PI */
123
124 /* if a device name was specified, put it in the structure; otherwise,
125 * the kernel will try to allocate the "next" device of the
126 * specified type
127 */
128 if (*dev)
129 strncpy(ifr.ifr_name, dev, IFNAMSIZ - 1);
130
131 /* try to create the device */
132 if ((err = ioctl(fd, TUNSETIFF, (void*)&ifr)) < 0) {
133 close(fd);
134 return err;
135 }
136
137 /* if the operation was successful, write back the name of the
138 * interface to the variable "dev", so the caller can know
139 * it. Note that the caller MUST reserve space in *dev (see calling
140 * code below)
141 */
142 strcpy(dev, ifr.ifr_name);
143
144 /* this is the special file descriptor that the caller will use to talk
145 * with the virtual interface
146 */
147 return fd;
148 }
149
set_mtu(const char * dev,int MTU)150 int tuntap_pdu_impl::set_mtu(const char* dev, int MTU)
151 {
152 struct ifreq ifr;
153 int sfd, err;
154
155 /* MTU must be set by passing a socket fd to ioctl;
156 * create an arbitrary socket for this purpose
157 */
158 if ((sfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
159 return sfd;
160
161 /* preparation of the struct ifr, of type "struct ifreq" */
162 memset(&ifr, 0, sizeof(ifr));
163 strncpy(ifr.ifr_name, dev, IFNAMSIZ);
164 ifr.ifr_addr.sa_family = AF_INET; /* address family */
165 ifr.ifr_mtu = MTU;
166
167 /* try to set MTU */
168 if ((err = ioctl(sfd, SIOCSIFMTU, (void*)&ifr)) < 0) {
169 close(sfd);
170 return err;
171 }
172
173 close(sfd);
174 return MTU;
175 }
176 #endif
177
178 } /* namespace blocks */
179 } /* namespace gr */
180