Implement CAN bus HAL tools

These tools are for manual interaction with CAN bus HAL instances.
Meant primarily for testing/debugging, not useful in user builds.

Bug: 135918744
Test: adb shell <tool name>
Change-Id: I1dfbe94c0006f69954806c395cd888f3bf2a4249
diff --git a/automotive/can/1.0/tools/canhalsend.cpp b/automotive/can/1.0/tools/canhalsend.cpp
new file mode 100644
index 0000000..29330c9
--- /dev/null
+++ b/automotive/can/1.0/tools/canhalsend.cpp
@@ -0,0 +1,136 @@
+/*
+ * 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 <android-base/logging.h>
+#include <android/hardware/automotive/can/1.0/ICanBus.h>
+#include <android/hidl/manager/1.2/IServiceManager.h>
+
+#include <iostream>
+#include <string>
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace can {
+
+using ICanBus = V1_0::ICanBus;
+using Result = V1_0::Result;
+
+static void usage() {
+    std::cerr << "cansend - simple command line tool to send raw CAN frames" << std::endl;
+    std::cerr << std::endl << "usage:" << std::endl << std::endl;
+    std::cerr << "canhalsend <bus name> <can id>#<data>" << std::endl;
+    std::cerr << "where:" << std::endl;
+    std::cerr << " bus name - name under which ICanBus is be published" << std::endl;
+    std::cerr << " can id - such as 1a5" << std::endl;
+    std::cerr << " data - such as deadbeef or 010203" << std::endl;
+}
+
+// TODO(b/135918744): extract to a new library
+static sp<ICanBus> tryOpen(const std::string& busname) {
+    auto bus = ICanBus::tryGetService(busname);
+    if (bus != nullptr) return bus;
+
+    /* Fallback for interfaces not registered in manifest. For testing purposes only,
+     * one should not depend on this in production deployment. */
+    auto manager = hidl::manager::V1_2::IServiceManager::getService();
+    auto ret = manager->get(ICanBus::descriptor, busname).withDefault(nullptr);
+    if (ret == nullptr) return nullptr;
+
+    std::cerr << "WARNING: bus " << busname << " is not registered in device manifest, "
+              << "trying to fetch it directly..." << std::endl;
+
+    return ICanBus::castFrom(ret);
+}
+
+static int cansend(const std::string& busname, V1_0::CanMessageId msgid,
+                   std::vector<uint8_t> payload) {
+    auto bus = tryOpen(busname);
+    if (bus == nullptr) {
+        std::cerr << "Bus " << busname << " is not available" << std::endl;
+        return -1;
+    }
+
+    V1_0::CanMessage msg = {};
+    msg.id = msgid;
+    msg.payload = payload;
+
+    const auto result = bus->send(msg);
+    if (result != Result::OK) {
+        std::cerr << "Send call failed: " << toString(result) << std::endl;
+        return -1;
+    }
+    return 0;
+}
+
+static std::optional<std::tuple<V1_0::CanMessageId, std::vector<uint8_t>>> parseCanMessage(
+        const std::string& msg) {
+    const auto hashpos = msg.find("#");
+    if (hashpos == std::string::npos) return std::nullopt;
+
+    const std::string msgidStr = msg.substr(0, hashpos);
+    const std::string payloadStr = msg.substr(hashpos + 1);
+
+    size_t idx = 0;
+    V1_0::CanMessageId msgid = std::stoi(msgidStr, &idx, 16);
+    if (msgidStr[idx] != '\0') return std::nullopt;
+
+    std::vector<uint8_t> payload;
+    if (payloadStr.size() % 2 != 0) return std::nullopt;
+    for (size_t i = 0; i < payloadStr.size(); i += 2) {
+        std::string byteStr(payloadStr, i, 2);
+        payload.emplace_back(std::stoi(byteStr, &idx, 16));
+        if (byteStr[idx] != '\0') return std::nullopt;
+    }
+
+    return {{msgid, payload}};
+}
+
+static int main(int argc, char* argv[]) {
+    base::SetDefaultTag("CanHalSend");
+    base::SetMinimumLogSeverity(android::base::VERBOSE);
+
+    if (argc == 0) {
+        usage();
+        return 0;
+    }
+
+    if (argc != 2) {
+        std::cerr << "Invalid number of arguments" << std::endl;
+        usage();
+        return -1;
+    }
+
+    std::string busname(argv[0]);
+    const auto canmsg = parseCanMessage(argv[1]);
+    if (!canmsg) {
+        std::cerr << "Failed to parse CAN message argument" << std::endl;
+        return -1;
+    }
+    const auto [msgid, payload] = *canmsg;
+
+    return cansend(busname, msgid, payload);
+}
+
+}  // namespace can
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
+int main(int argc, char* argv[]) {
+    if (argc < 1) return -1;
+    return ::android::hardware::automotive::can::main(--argc, ++argv);
+}