first commit

src/microtcp_linux.c

@@ -0,0 +1,181 @@
+#ifdef MICROTCP_LINUX
+
+#include <poll.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <linux/if.h>
+#include <linux/if_tun.h>
+#include <net/if_arp.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include "defs.h"
+#include "microtcp.h"
+
+static int systemf(const char *fmt, ...)
+{
+    char buffer[256];
+
+    va_list va;
+    va_start(va, fmt);
+    vsnprintf(buffer, sizeof(buffer), fmt, va);
+    va_end(va);
+
+    fprintf(stderr, "INFO: Running [%s]\n", buffer);
+
+    return system(buffer);
+}
+
+static int create_tun_device(const char *dev, char dev2[IFNAMSIZ])
+{
+    int fd = open("/dev/net/tun", O_RDWR);
+    if (fd < 0)
+        return -1;
+
+    struct ifreq ifr;
+    memset(&ifr, 0, sizeof(struct ifreq));
+    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+
+    if (dev && *dev)
+        strncpy(ifr.ifr_name, dev, IFNAMSIZ);
+
+    int err = ioctl(fd, TUNSETIFF, &ifr);
+    if (err) {
+        close(fd);
+        return -1;
+    }
+
+    strncpy(dev2, ifr.ifr_name, IFNAMSIZ);
+    return fd;
+}
+
+static int send_callback(void *data, const void *src, size_t len)
+{
+    int tap_fd = (int) data;
+    return write(tap_fd, src, len);
+}
+
+static int recv_callback(void *data, void *dst, size_t len)
+{
+    int tap_fd = (int) data;
+
+    int timeout = 1000;
+
+    struct pollfd pfd = {.fd=tap_fd, .events=POLLIN};
+    int status = poll(&pfd, 1, timeout);
+    if (status < 1) {
+        return status;
+    }
+    
+    int num = read(tap_fd, dst, len);
+    return num;
+}
+
+static void free_callback(void *data)
+{
+    int tap_fd = (int) data;
+    close(tap_fd);
+}
+
+/*
+static bool get_ip_address(const char *dev, microtcp_ip_t *ip)
+{
+    int fd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (fd < 0)
+        return false;
+
+    struct ifreq ifr;
+    memset(&ifr, 0, sizeof(struct ifreq));
+    ifr.ifr_addr.sa_family = AF_INET;
+    strncpy(ifr.ifr_name, dev, IFNAMSIZ-1);
+
+    ioctl(fd, SIOCGIFADDR, &ifr);
+
+    memcpy(ip, &((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr, sizeof(microtcp_ip_t));
+
+    close(fd);
+    return true;
+}
+*/
+
+static bool get_mac_address(const char *dev, microtcp_mac_t *mac)
+{
+    int fd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (fd < 0)
+        return false;
+
+    struct ifreq ifr;
+    memset(&ifr, 0, sizeof(struct ifreq));
+    strncpy(ifr.ifr_name, dev, IFNAMSIZ-1);
+
+    ioctl(fd, SIOCGIFHWADDR, &ifr);
+
+    if (ifr.ifr_hwaddr.sa_family != ARPHRD_ETHER) 
+        return false;
+
+    memcpy(mac, ifr.ifr_hwaddr.sa_data, sizeof(microtcp_mac_t));
+
+    close(fd);
+    return true;
+}
+
+microtcp_t *microtcp_create()
+{
+    char dev[IFNAMSIZ];
+    int tap_fd = create_tun_device("tap0", dev);
+    if (tap_fd < 0) {
+        fprintf(stderr, "ERROR: Failed creating TAP device (%s)\n", strerror(errno));
+        return NULL;
+    }
+    fprintf(stderr, "INFO: Using TAP device %s\n", dev);
+
+    const char *tap_addr  = "10.0.0.5";
+    const char *tap_route = "10.0.0.0/24";
+    
+    systemf("ip link set dev %s up", dev);
+    systemf("ip route add dev %s %s", dev, tap_route);
+    systemf("ip address add dev %s local %s", dev, tap_addr);
+    systemf("sudo sysctl -w net.ipv4.ip_forward=1");
+
+    microtcp_mac_t mac;
+    if (!get_mac_address(dev, &mac)) {
+        fprintf(stderr, "FATAL: Failed to query NIC for IP or MAC (%s)\n", strerror(errno));
+        close(tap_fd);
+        return NULL;
+    }
+
+    mac.data[5]++;
+
+    microtcp_ip_t ip;
+    inet_pton(AF_INET, "10.0.0.4", &ip);
+
+    struct in_addr ip2;
+    ip2.s_addr = ip;
+    fprintf(stderr, "INFO: Using IP %s\n", inet_ntoa(ip2));
+    fprintf(stderr, "INFO: Using MAC %x:%x:%x:%x:%x:%x\n", mac.data[0], mac.data[1], mac.data[2], mac.data[3], mac.data[4], mac.data[5]);
+
+    microtcp_callbacks_t callbacks = {
+        .data = (int) tap_fd,
+        .send = send_callback,
+        .recv = recv_callback,
+        .free = free_callback,
+    };
+
+    microtcp_t *mtcp = microtcp_create_using_callbacks(ip, mac, callbacks);
+    if (!mtcp) {
+        close(tap_fd);
+        return NULL;
+    }
+
+    return mtcp;
+}
+
+#endif /* MICROTCP_LINUX */