Default implementation for CAN bus HAL

This implementation supports SocketCAN interfaces.

Bug: 135918744
Test: VTS (separate new change)
Change-Id: I12b93e37fa64e341bee2c64eaf130b39977fcef5
diff --git a/automotive/can/1.0/default/libnetdevice/can.cpp b/automotive/can/1.0/default/libnetdevice/can.cpp
new file mode 100644
index 0000000..87617dd
--- /dev/null
+++ b/automotive/can/1.0/default/libnetdevice/can.cpp
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <libnetdevice/libnetdevice.h>
+
+#include "NetlinkRequest.h"
+#include "NetlinkSocket.h"
+#include "common.h"
+
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+
+#include <linux/can.h>
+#include <linux/can/netlink.h>
+
+namespace android {
+namespace netdevice {
+namespace can {
+
+base::unique_fd socket(const std::string& ifname) {
+    struct sockaddr_can addr = {};
+    addr.can_family = AF_CAN;
+    addr.can_ifindex = nametoindex(ifname);
+    if (addr.can_ifindex == 0) {
+        LOG(ERROR) << "Interface " << ifname << " doesn't exists";
+        return {};
+    }
+
+    base::unique_fd sock(::socket(PF_CAN, SOCK_RAW, CAN_RAW));
+    if (!sock.ok()) {
+        LOG(ERROR) << "Failed to create CAN socket";
+        return {};
+    }
+
+    if (0 != fcntl(sock.get(), F_SETFL, O_RDWR | O_NONBLOCK)) {
+        LOG(ERROR) << "Couldn't put CAN socket in non-blocking mode";
+        return {};
+    }
+
+    if (0 != bind(sock.get(), reinterpret_cast<struct sockaddr*>(&addr), sizeof(addr))) {
+        LOG(ERROR) << "Can't bind to CAN interface " << ifname;
+        return {};
+    }
+
+    return sock;
+}
+
+bool setBitrate(std::string ifname, uint32_t bitrate) {
+    struct can_bittiming bt = {};
+    bt.bitrate = bitrate;
+
+    NetlinkRequest<struct ifinfomsg> req(RTM_NEWLINK, NLM_F_REQUEST);
+
+    const auto ifidx = nametoindex(ifname);
+    if (ifidx == 0) {
+        LOG(ERROR) << "Can't find interface " << ifname;
+        return false;
+    }
+    req.data().ifi_index = ifidx;
+
+    {
+        auto linkinfo = req.nest(IFLA_LINKINFO);
+        req.addattr(IFLA_INFO_KIND, "can");
+        {
+            auto infodata = req.nest(IFLA_INFO_DATA);
+            /* For CAN FD, it would require to add IFLA_CAN_DATA_BITTIMING
+             * and IFLA_CAN_CTRLMODE as well. */
+            req.addattr(IFLA_CAN_BITTIMING, bt);
+        }
+    }
+
+    NetlinkSocket sock(NETLINK_ROUTE);
+    return sock.send(req) && sock.receiveAck();
+}
+
+}  // namespace can
+}  // namespace netdevice
+}  // namespace android