add tap device adapter for ethernet protocol

net_tap/Makefile

+CPPFLAGS += -I../proto
+CFLAGS += -Wall -Wextra -Wno-unused-parameter -O3
+
+net_tap: net_tap.o
+
+all: net_tap
+
+clean:
+	rm -f *.o net_tap

net_tap/net_tap.c

+/*
+ * Copyright 2020 Max Planck Institute for Software Systems
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/un.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <linux/if.h>
+#include <linux/if_tun.h>
+
+#include <cosim_eth_proto.h>
+
+static uint8_t *d2n_queue;
+static size_t d2n_pos;
+static size_t d2n_elen;
+static size_t d2n_enum;
+
+static uint8_t *n2d_queue;
+static size_t n2d_pos;
+static size_t n2d_elen;
+static size_t n2d_enum;
+
+static int tap_fd;
+
+int uxsocket_connect(const char *path)
+{
+    int fd;
+    struct sockaddr_un saun;
+
+    /* prepare and connect socket */
+    memset(&saun, 0, sizeof(saun));
+    saun.sun_family = AF_UNIX;
+    strcpy(saun.sun_path, "/tmp/cosim-eth");
+
+    if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
+        perror("socket failed");
+        return -1;
+    }
+
+    if (connect(fd, (struct sockaddr *) &saun, sizeof(saun)) != 0) {
+        perror("connect failed");
+        return -1;
+    }
+
+    return fd;
+}
+
+int uxsocket_recv(int fd, void *data, size_t len, int *pfd)
+{
+    int *ppfd;
+    ssize_t ret;
+    struct cmsghdr *cmsg;
+    union {
+        char buf[CMSG_SPACE(sizeof(int))];
+        struct cmsghdr align;
+    } u;
+    struct iovec iov = {
+        .iov_base = data,
+        .iov_len = len,
+    };
+    struct msghdr msg = {
+        .msg_name = NULL,
+        .msg_namelen = 0,
+        .msg_iov = &iov,
+        .msg_iovlen = 1,
+        .msg_control = u.buf,
+        .msg_controllen = sizeof(u.buf),
+        .msg_flags = 0,
+    };
+
+    if ((ret = recvmsg(fd, &msg, 0)) != (ssize_t) len) {
+        perror("recvmsg failed");
+        return -1;
+    }
+
+    cmsg = CMSG_FIRSTHDR(&msg);
+    ppfd = (int *) CMSG_DATA(cmsg);
+    if (msg.msg_controllen <= 0 || cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
+        fprintf(stderr, "accessing ancillary data failed\n");
+        return -1;
+    }
+
+    *pfd = *ppfd;
+    return 0;
+}
+
+void *shm_map(int shm_fd)
+{
+    void *p;
+    struct stat statbuf;
+
+    if (fstat(shm_fd, &statbuf) != 0) {
+        perror("shm_map: fstat failed");
+        return NULL;
+    }
+
+    p = mmap(NULL, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd,
+            0);
+    if (p == MAP_FAILED) {
+        perror("shm_map: mmap failed");
+        return NULL;
+    }
+
+    return p;
+}
+
+static int tap_open(const char *name)
+{
+    struct ifreq ifr;
+    int fd;
+
+    if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
+        perror("tap_open: open failed");
+        return -1;
+    }
+
+    memset(&ifr, 0, sizeof(ifr));
+    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+    strncpy(ifr.ifr_name, name, IFNAMSIZ);
+
+    if (ioctl(fd, TUNSETIFF, &ifr) != 0) {
+        perror("tap_open: ioctl failed");
+        close(fd);
+        return -1;
+    }
+
+    return fd;
+}
+
+static void d2n_send(volatile struct cosim_eth_proto_d2n_send *s)
+{
+
+    if (write(tap_fd, (void *) s->data, s->len) != (ssize_t) s->len) {
+        perror("d2n_send: send failed");
+    }
+    /*uint16_t i;
+    printf("packet [len=%u]:", s->len);
+    for (i = 0; i < s->len; i++) {
+        printf(" %02x", s->data[i]);
+    }
+    printf("\n");*/
+}
+
+static void poll_d2n(void)
+{
+    uint8_t type;
+    volatile union cosim_eth_proto_d2n *msg =
+        (volatile union cosim_eth_proto_d2n *)
+        (d2n_queue + d2n_pos * d2n_elen);
+
+    /* message not ready */
+    if ((msg->dummy.own_type & COSIM_ETH_PROTO_D2N_OWN_MASK) !=
+            COSIM_ETH_PROTO_D2N_OWN_NET)
+        return;
+
+    type = msg->dummy.own_type & COSIM_ETH_PROTO_D2N_MSG_MASK;
+    switch (type) {
+        case COSIM_ETH_PROTO_D2N_MSG_SEND:
+            d2n_send(&msg->send);
+            break;
+
+        default:
+            fprintf(stderr, "poll_d2n: unsupported type=%u\n", type);
+    }
+
+    msg->dummy.own_type = (msg->dummy.own_type & COSIM_ETH_PROTO_D2N_MSG_MASK)
+        | COSIM_ETH_PROTO_D2N_OWN_DEV;
+    d2n_pos = (d2n_pos + 1) % d2n_enum;
+}
+
+int main(int argc, char *argv[])
+{
+    struct cosim_eth_proto_dev_intro di;
+    struct cosim_eth_proto_net_intro ni;
+    int cfd, shm_fd;
+    void *p;
+
+    if (argc != 2) {
+        fprintf(stderr, "Usage: net_tap TAP_DEVICE_NAME\n");
+        return EXIT_FAILURE;
+    }
+
+    if ((tap_fd = tap_open(argv[1])) < 0) {
+        return -1;
+    }
+
+    if ((cfd = uxsocket_connect("/tmp/cosim-eth")) < 0) {
+        return -1;
+    }
+
+    memset(&ni, 0, sizeof(ni));
+    if (send(cfd, &ni, sizeof(ni), 0) != sizeof(ni)) {
+        perror("sending net intro failed");
+        return -1;
+    }
+
+    if (uxsocket_recv(cfd, &di, sizeof(di), &shm_fd)) {
+        return -1;
+    }
+
+    if ((p = shm_map(shm_fd)) == NULL) {
+        return -1;
+    }
+    close(shm_fd);
+
+    d2n_queue = (uint8_t *) p + di.d2n_offset;
+    n2d_queue = (uint8_t *) p + di.n2d_offset;
+    d2n_elen = di.d2n_elen;
+    n2d_elen = di.n2d_elen;
+    d2n_enum = di.d2n_nentries;
+    n2d_enum = di.n2d_nentries;
+    d2n_pos = n2d_pos = 0;
+
+    printf("start polling\n");
+    while (1) {
+        poll_d2n();
+    }
+    return 0;
+}