Init tun interface and define some structures

1 files changed, 130 insertions, 0 deletions

diff --git a/src/fastd.c b/src/fastd.c
index f500090..42478b2 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -23,3 +23,133 @@
   OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
+
+
+#include <fcntl.h>
+#include <linux/if_ether.h>
+#include <linux/if_tun.h>
+#include <net/if.h>
+#include <poll.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include "fastd.h"
+#include "packet.h"
+
+
+extern fastd_method fastd_method_null;
+
+
+static int init_tuntap(const fastd_context *ctx) {
+	int tunfd;
+	struct ifreq ifr;
+
+	pr_debug(ctx, "Initializing tun/tap device...");
+
+	if ((tunfd = open("/dev/net/tun", O_RDWR)) < 0)
+		exit_fatal_errno(ctx, "Could not open tun/tap device file");
+
+	memset(&ifr, 0, sizeof(ifr));
+	// strcpy(ifr.ifr_name, name);
+	ifr.ifr_flags = IFF_TAP;
+	ifr.ifr_flags |= IFF_NO_PI;
+	if (ioctl(tunfd, TUNSETIFF, (void *)&ifr) < 0)
+		exit_fatal_errno(ctx, "TUNSETIFF ioctl failed");
+
+	return tunfd;
+}
+
+static void configure(fastd_context *ctx, fastd_config *conf) {
+	conf->loglevel = LOG_DEBUG;
+	conf->mtu = 1500;
+	conf->protocol = PROTOCOL_ETHERNET;
+	conf->method = &fastd_method_null;
+	conf->n_peers = 0;
+	conf->peers = NULL;
+}
+
+static size_t get_max_packet_size(const fastd_context *ctx) {
+	switch (ctx->conf->protocol) {
+	case PROTOCOL_ETHERNET:
+		return ctx->conf->mtu+ETH_HLEN;
+	case PROTOCOL_IP:
+		return ctx->conf->mtu;
+	default:
+		exit_fatal_bug(ctx, "invalid protocol");
+	}
+}
+
+static void *get_source_address(const fastd_context *ctx, void *buffer) {
+	switch (ctx->conf->protocol) {
+	case PROTOCOL_ETHERNET:
+		return &((struct ethhdr*)buffer)->h_source;
+	case PROTOCOL_IP:
+		return NULL;
+	default:
+		exit_fatal_bug(ctx, "invalid protocol");
+	}
+}
+
+static void *get_dest_address(const fastd_context *ctx, void *buffer) {
+	switch (ctx->conf->protocol) {
+	case PROTOCOL_ETHERNET:
+		return &((struct ethhdr*)buffer)->h_dest;
+	case PROTOCOL_IP:
+		return NULL;
+	default:
+		exit_fatal_bug(ctx, "invalid protocol");
+	}
+}
+
+static void run(const fastd_context *ctx) {
+	int tunfd;
+
+	tunfd = init_tuntap(ctx);
+
+	struct pollfd fds[ctx->conf->n_peers+1];
+	fds[0].fd = tunfd;
+	fds[0].events = POLLIN;
+
+	while (1) {
+		int ret = poll(fds, 1, -1);
+		if (ret < 0)
+			exit_fatal_errno(ctx, "poll error");
+
+		if (fds[0].revents & POLLIN) {
+			size_t max_len = get_max_packet_size(ctx);
+			char buffer[max_len];
+
+			unsigned len = read(tunfd, buffer, max_len);
+			if (len < 0)
+				exit_fatal_errno(ctx, "read");
+
+			uint8_t *src_addr = get_source_address(ctx, buffer);
+			uint8_t *dest_addr = get_dest_address(ctx, buffer);
+
+			pr_debug(ctx, "A packet with length %u was received from %02x:%02x:%02x:%02x:%02x:%02x to %02x:%02x:%02x:%02x:%02x:%02x",
+				 len, src_addr[0], src_addr[1], src_addr[2], src_addr[3], src_addr[4], src_addr[5],
+				 dest_addr[0], dest_addr[1], dest_addr[2], dest_addr[3], dest_addr[4], dest_addr[5]);
+
+			ctx->conf->method->method_send(ctx, buffer, len);
+		}
+	}
+}
+
+
+int main()
+{
+	fastd_context ctx = {
+		.conf = NULL,
+	};
+
+	fastd_config conf;
+	configure(&ctx, &conf);
+	ctx.conf = &conf;
+
+	run(&ctx);
+
+	return 0;
+}