mirror of
https://github.com/cesanta/mongoose
synced 2026-08-25 22:26:06 -04:00
109 lines
3.5 KiB
C
109 lines
3.5 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/poll.h>
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#include <signal.h>
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#ifndef __OpenBSD__
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#include <linux/if.h>
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#include <linux/if_tun.h>
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#else
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#include <net/if.h>
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#include <net/if_tun.h>
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#include <net/if_types.h>
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#endif
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static volatile sig_atomic_t s_signo;
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void signal_handler(int signo) {
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s_signo = signo;
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}
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int main(void) {
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// Setup interface
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const char *iface = "tap0"; // Network iface
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const uint16_t port = 0x55AA; // UDP port
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#ifndef __OpenBSD__
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const char *tuntap_device = "/dev/net/tun";
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#else
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const char *tuntap_device = "/dev/tap0";
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#endif
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int fd = open(tuntap_device, O_RDWR);
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struct ifreq ifr;
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memset(&ifr, 0, sizeof(ifr));
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strncpy(ifr.ifr_name, iface, IFNAMSIZ);
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#ifndef __OpenBSD__
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ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
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if (ioctl(fd, TUNSETIFF, (void *) &ifr) < 0) {
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#else
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ifr.ifr_flags = (short) (IFF_UP | IFF_BROADCAST | IFF_MULTICAST);
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if (ioctl(fd, TUNSIFMODE, (void *) &ifr) < 0) {
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#endif
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printf("Failed to setup TAP interface: %s", ifr.ifr_name);
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return EXIT_FAILURE;
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}
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printf("Opened TAP interface: %s\n", iface);
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signal(SIGINT, signal_handler);
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signal(SIGTERM, signal_handler);
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int sockfd;
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struct sockaddr_in tap_addr, port_addr;
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sockfd = socket(AF_INET, SOCK_DGRAM, 0);
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tap_addr.sin_family = AF_INET;
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tap_addr.sin_addr.s_addr = htonl(0x7f000001U); // 127.0.0.1
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tap_addr.sin_port = htons(port);
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if (bind(sockfd, (struct sockaddr *) &tap_addr, sizeof(tap_addr)) < 0) return EXIT_FAILURE;
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printf("Opened UDP socket: 127.0.0.1:%u (0x%04x)\n", port, port);
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memset(&port_addr, 0, sizeof(port_addr));
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while (s_signo == 0) {
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struct pollfd pfd[2];
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int result;
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do {
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pfd[0].fd = fd;
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pfd[0].events = POLLIN | POLLPRI; // will wait for input available (read ready), use POLLOUT for write
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pfd[1].fd = sockfd;
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pfd[1].events = POLLIN | POLLPRI; // will wait for input available (read ready), use POLLOUT for write
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// only read ready shown here, for write ready use the 3rd arg, and the 4th for exceptions
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result = poll(pfd, 2, 1000); // 2 pfd, TIMEOUT in milliseconds
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switch(result) {
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case -1: // error
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break;
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case 0: // timeout (if a timeout struct was passed to select)
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break;
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default: // the number of fd/sockets with data available (see pfd.revents for each one);
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uint8_t buf[1540];
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if (pfd[0].revents & (POLLIN | POLLPRI)) {
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ssize_t nread = read(fd, buf, 1540);
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// printf("Got at TAP: %d bytes\n", (int) nread);
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if (port_addr.sin_family != 0) { // something has been written to this struct (we got a conterpart)
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sendto(sockfd, buf, (size_t) nread, 0, (struct sockaddr *) &port_addr, sizeof(port_addr));
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// printf("Sent to %s port %d\n", inet_ntoa(port_addr.sin_addr), ntohs(port_addr.sin_port));
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}
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}
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if (pfd[1].revents & (POLLIN | POLLPRI)) {
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socklen_t len = sizeof(port_addr);
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ssize_t nread = recvfrom(sockfd, buf, 1540, 0, (struct sockaddr *) &port_addr, &len);
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// printf("Got at UDP: %d bytes from %s port %d\n", nread, inet_ntoa(port_addr.sin_addr), ntohs(port_addr.sin_port));
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write(fd, buf, (size_t) nread);
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// printf("Sent to TAP\n");
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}
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break;
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}
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} while (result >= 0 && s_signo == 0);
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if (result < 0)
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printf("looks like we got an error here... should I quit ? Waiting for CTRL-C\n");
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}
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close(sockfd);
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close(fd);
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}
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