net/can: support for connecting to Linux host SocketCAN interface.

Connection to the real host CAN bus network through
SocketCAN network interface is available only for Linux
host system. Mechanism is generic, support for another
CAN API and operating systems can be implemented in future.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 287 insertions, 0 deletions

diff --git a/net/can/Makefile.objs b/net/can/Makefile.objs
index ef97fdb..9f35dc5 100644
--- a/net/can/Makefile.objs
+++ b/net/can/Makefile.objs
@@ -1 +1,2 @@
 common-obj-y += can_core.o can_host.o
+common-obj-$(CONFIG_LINUX) += can_socketcan.o
diff --git a/net/can/can_socketcan.c b/net/can/can_socketcan.c
new file mode 100644
index 0000000..39865e2
--- /dev/null
+++ b/net/can/can_socketcan.c
@@ -0,0 +1,286 @@
+/*
+ * CAN c support to connect to the Linux host SocketCAN interfaces
+ *
+ * Copyright (c) 2013-2014 Jin Yang
+ * Copyright (c) 2014-2018 Pavel Pisa
+ *
+ * Initial development supported by Google GSoC 2013 from RTEMS project slot
+ *
+ * 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 "qemu/osdep.h"
+#include "qemu/log.h"
+#include "qapi/error.h"
+#include "chardev/char.h"
+#include "qemu/sockets.h"
+#include "qemu/error-report.h"
+#include "net/can_emu.h"
+#include "net/can_host.h"
+
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <linux/can.h>
+#include <linux/can/raw.h>
+
+#ifndef DEBUG_CAN
+#define DEBUG_CAN 0
+#endif /*DEBUG_CAN*/
+
+#define TYPE_CAN_HOST_SOCKETCAN "can-host-socketcan"
+#define CAN_HOST_SOCKETCAN(obj) \
+     OBJECT_CHECK(CanHostSocketCAN, (obj), TYPE_CAN_HOST_SOCKETCAN)
+
+#define CAN_READ_BUF_LEN  5
+typedef struct CanHostSocketCAN {
+    CanHostState       parent;
+    char               *ifname;
+
+    qemu_can_filter    *rfilter;
+    int                rfilter_num;
+    can_err_mask_t     err_mask;
+
+    qemu_can_frame     buf[CAN_READ_BUF_LEN];
+    int                bufcnt;
+    int                bufptr;
+
+    int                fd;
+} CanHostSocketCAN;
+
+/* Check that QEMU and Linux kernel flags encoding and structure matches */
+QEMU_BUILD_BUG_ON(QEMU_CAN_EFF_FLAG != CAN_EFF_FLAG);
+QEMU_BUILD_BUG_ON(QEMU_CAN_RTR_FLAG != CAN_RTR_FLAG);
+QEMU_BUILD_BUG_ON(QEMU_CAN_ERR_FLAG != CAN_ERR_FLAG);
+QEMU_BUILD_BUG_ON(QEMU_CAN_INV_FILTER != CAN_INV_FILTER);
+QEMU_BUILD_BUG_ON(offsetof(qemu_can_frame, data)
+                  != offsetof(struct can_frame, data));
+
+static void can_host_socketcan_display_msg(struct qemu_can_frame *msg)
+{
+    int i;
+
+    qemu_log_lock();
+    qemu_log("[cansocketcan]: %03X [%01d] %s %s",
+             msg->can_id & QEMU_CAN_EFF_MASK,
+             msg->can_dlc,
+             msg->can_id & QEMU_CAN_EFF_FLAG ? "EFF" : "SFF",
+             msg->can_id & QEMU_CAN_RTR_FLAG ? "RTR" : "DAT");
+
+    for (i = 0; i < msg->can_dlc; i++) {
+        qemu_log(" %02X", msg->data[i]);
+    }
+    qemu_log("\n");
+    qemu_log_flush();
+    qemu_log_unlock();
+}
+
+static void can_host_socketcan_read(void *opaque)
+{
+    CanHostSocketCAN *c = opaque;
+    CanHostState *ch = CAN_HOST(c);
+
+    /* CAN_READ_BUF_LEN for multiple messages syscall is possible for future */
+    c->bufcnt = read(c->fd, c->buf, sizeof(qemu_can_frame));
+    if (c->bufcnt < 0) {
+        warn_report("CAN bus host read failed (%s)", strerror(errno));
+        return;
+    }
+
+    can_bus_client_send(&ch->bus_client, c->buf, 1);
+
+    if (DEBUG_CAN) {
+        can_host_socketcan_display_msg(c->buf);
+    }
+}
+
+static int can_host_socketcan_can_receive(CanBusClientState *client)
+{
+    return 1;
+}
+
+static ssize_t can_host_socketcan_receive(CanBusClientState *client,
+                            const qemu_can_frame *frames, size_t frames_cnt)
+{
+    CanHostState *ch = container_of(client, CanHostState, bus_client);
+    CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(ch);
+
+    size_t len = sizeof(qemu_can_frame);
+    int res;
+
+    if (c->fd < 0) {
+        return -1;
+    }
+
+    res = write(c->fd, frames, len);
+
+    if (!res) {
+        warn_report("[cansocketcan]: write message to host returns zero");
+        return -1;
+    }
+
+    if (res != len) {
+        if (res < 0) {
+            warn_report("[cansocketcan]: write to host failed (%s)",
+                        strerror(errno));
+        } else {
+            warn_report("[cansocketcan]: write to host truncated");
+        }
+        return -1;
+    }
+
+    return 1;
+}
+
+static void can_host_socketcan_disconnect(CanHostState *ch)
+{
+    CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(ch);
+
+    if (c->fd >= 0) {
+        qemu_set_fd_handler(c->fd, NULL, NULL, c);
+        close(c->fd);
+        c->fd = -1;
+    }
+
+    g_free(c->rfilter);
+    c->rfilter = NULL;
+    c->rfilter_num = 0;
+}
+
+static CanBusClientInfo can_host_socketcan_bus_client_info = {
+    .can_receive = can_host_socketcan_can_receive,
+    .receive = can_host_socketcan_receive,
+};
+
+static void can_host_socketcan_connect(CanHostState *ch, Error **errp)
+{
+    CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(ch);
+    int s; /* can raw socket */
+    struct sockaddr_can addr;
+    struct ifreq ifr;
+
+    /* open socket */
+    s = qemu_socket(PF_CAN, SOCK_RAW, CAN_RAW);
+    if (s < 0) {
+        error_setg_errno(errp, errno, "failed to create CAN_RAW socket");
+        return;
+    }
+
+    addr.can_family = AF_CAN;
+    memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
+    strcpy(ifr.ifr_name, c->ifname);
+    if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
+        error_setg_errno(errp, errno,
+                         "SocketCAN host interface %s not available", c->ifname);
+        goto fail;
+    }
+    addr.can_ifindex = ifr.ifr_ifindex;
+
+    c->err_mask = 0xffffffff; /* Receive error frame. */
+    setsockopt(s, SOL_CAN_RAW, CAN_RAW_ERR_FILTER,
+                   &c->err_mask, sizeof(c->err_mask));
+
+    c->rfilter_num = 1;
+    c->rfilter = g_new(struct qemu_can_filter, c->rfilter_num);
+
+    /* Receive all data frame. If |= CAN_INV_FILTER no data. */
+    c->rfilter[0].can_id = 0;
+    c->rfilter[0].can_mask = 0;
+    c->rfilter[0].can_mask &= ~CAN_ERR_FLAG;
+
+    setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, c->rfilter,
+               c->rfilter_num * sizeof(struct qemu_can_filter));
+
+    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+        error_setg_errno(errp, errno, "failed to bind to host interface %s",
+                         c->ifname);
+        goto fail;
+    }
+
+    c->fd = s;
+    ch->bus_client.info = &can_host_socketcan_bus_client_info;
+    qemu_set_fd_handler(c->fd, can_host_socketcan_read, NULL, c);
+    return;
+
+fail:
+    close(s);
+    g_free(c->rfilter);
+    c->rfilter = NULL;
+    c->rfilter_num = 0;
+}
+
+static char *can_host_socketcan_get_if(Object *obj, Error **errp)
+{
+    CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(obj);
+
+    return g_strdup(c->ifname);
+}
+
+static void can_host_socketcan_set_if(Object *obj, const char *value, Error **errp)
+{
+    CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(obj);
+    struct ifreq ifr;
+
+    if (strlen(value) >= sizeof(ifr.ifr_name)) {
+        error_setg(errp, "CAN interface name longer than %zd characters",
+                   sizeof(ifr.ifr_name) - 1);
+        return;
+    }
+
+    if (c->fd != -1) {
+        error_setg(errp, "CAN interface already connected");
+        return;
+    }
+
+    g_free(c->ifname);
+    c->ifname = g_strdup(value);
+}
+
+static void can_host_socketcan_instance_init(Object *obj)
+{
+    CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(obj);
+
+    c->fd = -1;
+}
+
+static void can_host_socketcan_class_init(ObjectClass *klass,
+                                          void *class_data G_GNUC_UNUSED)
+{
+    CanHostClass *chc = CAN_HOST_CLASS(klass);
+
+    object_class_property_add_str(klass, "if",
+                                  can_host_socketcan_get_if,
+                                  can_host_socketcan_set_if,
+                                  &error_abort);
+    chc->connect = can_host_socketcan_connect;
+    chc->disconnect = can_host_socketcan_disconnect;
+}
+
+static const TypeInfo can_host_socketcan_info = {
+    .parent = TYPE_CAN_HOST,
+    .name = TYPE_CAN_HOST_SOCKETCAN,
+    .instance_size = sizeof(CanHostSocketCAN),
+    .instance_init = can_host_socketcan_instance_init,
+    .class_init = can_host_socketcan_class_init,
+};
+
+static void can_host_register_types(void)
+{
+    type_register_static(&can_host_socketcan_info);
+}
+
+type_init(can_host_register_types);