Move NetlinkListener relevant files to frameworks/libs/net

NetlinkListener is used by Netd, so move it to frameworks/libs/net
and then it can be used by platform code and mainline module.

Bug: 209935649
Test: m; flash; boot
Change-Id: I4cf0e64eee1dda1e452d76af77642416c9729d42

staticlibs/netd/libnetdutils/Android.bp

@@ -11,6 +11,7 @@ cc_library {
         "Log.cpp",
         "Netfilter.cpp",
         "Netlink.cpp",
+        "NetlinkListener.cpp",
         "Slice.cpp",
         "Socket.cpp",
         "SocketOption.cpp",

staticlibs/netd/libnetdutils/NetlinkListener.cpp

@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#define LOG_TAG "NetlinkListener"
+
+#include <sstream>
+#include <vector>
+
+#include <linux/netfilter/nfnetlink.h>
+
+#include <log/log.h>
+#include <netdutils/Misc.h>
+#include <netdutils/NetlinkListener.h>
+#include <netdutils/Syscalls.h>
+
+namespace android {
+namespace netdutils {
+
+using netdutils::Fd;
+using netdutils::Slice;
+using netdutils::Status;
+using netdutils::UniqueFd;
+using netdutils::findWithDefault;
+using netdutils::forEachNetlinkMessage;
+using netdutils::makeSlice;
+using netdutils::sSyscalls;
+using netdutils::status::ok;
+using netdutils::statusFromErrno;
+
+namespace {
+
+constexpr int kNetlinkMsgErrorType = (NFNL_SUBSYS_NONE << 8) | NLMSG_ERROR;
+
+constexpr sockaddr_nl kKernelAddr = {
+    .nl_family = AF_NETLINK, .nl_pad = 0, .nl_pid = 0, .nl_groups = 0,
+};
+
+const NetlinkListener::DispatchFn kDefaultDispatchFn = [](const nlmsghdr& nlmsg, const Slice) {
+    std::stringstream ss;
+    ss << nlmsg;
+    ALOGE("unhandled netlink message: %s", ss.str().c_str());
+};
+
+}  // namespace
+
+NetlinkListener::NetlinkListener(UniqueFd event, UniqueFd sock, const std::string& name)
+    : mEvent(std::move(event)), mSock(std::move(sock)), mThreadName(name) {
+    const auto rxErrorHandler = [](const nlmsghdr& nlmsg, const Slice msg) {
+        std::stringstream ss;
+        ss << nlmsg << " " << msg << " " << netdutils::toHex(msg, 32);
+        ALOGE("unhandled netlink message: %s", ss.str().c_str());
+    };
+    expectOk(NetlinkListener::subscribe(kNetlinkMsgErrorType, rxErrorHandler));
+
+    mErrorHandler = [& name = mThreadName](const int fd, const int err) {
+        ALOGE("Error on NetlinkListener(%s) fd=%d: %s", name.c_str(), fd, strerror(err));
+    };
+
+    // Start the thread
+    mWorker = std::thread([this]() { run().ignoreError(); });
+}
+
+NetlinkListener::~NetlinkListener() {
+    const auto& sys = sSyscalls.get();
+    const uint64_t data = 1;
+    // eventfd should never enter an error state unexpectedly
+    expectOk(sys.write(mEvent, makeSlice(data)).status());
+    mWorker.join();
+}
+
+Status NetlinkListener::send(const Slice msg) {
+    const auto& sys = sSyscalls.get();
+    ASSIGN_OR_RETURN(auto sent, sys.sendto(mSock, msg, 0, kKernelAddr));
+    if (sent != msg.size()) {
+        return statusFromErrno(EMSGSIZE, "unexpect message size");
+    }
+    return ok;
+}
+
+Status NetlinkListener::subscribe(uint16_t type, const DispatchFn& fn) {
+    std::lock_guard guard(mMutex);
+    mDispatchMap[type] = fn;
+    return ok;
+}
+
+Status NetlinkListener::unsubscribe(uint16_t type) {
+    std::lock_guard guard(mMutex);
+    mDispatchMap.erase(type);
+    return ok;
+}
+
+void NetlinkListener::registerSkErrorHandler(const SkErrorHandler& handler) {
+    mErrorHandler = handler;
+}
+
+Status NetlinkListener::run() {
+    std::vector<char> rxbuf(4096);
+
+    const auto rxHandler = [this](const nlmsghdr& nlmsg, const Slice& buf) {
+        std::lock_guard guard(mMutex);
+        const auto& fn = findWithDefault(mDispatchMap, nlmsg.nlmsg_type, kDefaultDispatchFn);
+        fn(nlmsg, buf);
+    };
+
+    if (mThreadName.length() > 0) {
+        int ret = pthread_setname_np(pthread_self(), mThreadName.c_str());
+        if (ret) {
+            ALOGE("thread name set failed, name: %s, ret: %s", mThreadName.c_str(), strerror(ret));
+        }
+    }
+    const auto& sys = sSyscalls.get();
+    const std::array<Fd, 2> fds{{{mEvent}, {mSock}}};
+    const int events = POLLIN;
+    const double timeout = 3600;
+    while (true) {
+        ASSIGN_OR_RETURN(auto revents, sys.ppoll(fds, events, timeout));
+        // After mEvent becomes readable, we should stop servicing mSock and return
+        if (revents[0] & POLLIN) {
+            break;
+        }
+        if (revents[1] & (POLLIN|POLLERR)) {
+            auto rx = sys.recvfrom(mSock, makeSlice(rxbuf), 0);
+            int err = rx.status().code();
+            if (err) {
+                // Ignore errors. The only error we expect to see here is ENOBUFS, and there's
+                // nothing we can do about that. The recvfrom above will already have cleared the
+                // error indication and ensured we won't get EPOLLERR again.
+                // TODO: Consider using NETLINK_NO_ENOBUFS.
+                mErrorHandler(((Fd) mSock).get(), err);
+                continue;
+            }
+            forEachNetlinkMessage(rx.value(), rxHandler);
+        }
+    }
+    return ok;
+}
+
+}  // namespace netdutils
+}  // namespace android

staticlibs/netd/libnetdutils/include/netdutils/NetlinkListener.h

@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#ifndef NETLINK_LISTENER_H
+#define NETLINK_LISTENER_H
+
+#include <functional>
+#include <map>
+#include <mutex>
+#include <thread>
+
+#include <android-base/thread_annotations.h>
+#include <netdutils/Netlink.h>
+#include <netdutils/Slice.h>
+#include <netdutils/Status.h>
+#include <netdutils/UniqueFd.h>
+
+namespace android {
+namespace netdutils {
+
+class NetlinkListenerInterface {
+  public:
+    using DispatchFn = std::function<void(const nlmsghdr& nlmsg, const netdutils::Slice msg)>;
+
+    using SkErrorHandler = std::function<void(const int fd, const int err)>;
+
+    virtual ~NetlinkListenerInterface() = default;
+
+    // Send message to the kernel using the underlying netlink socket
+    virtual netdutils::Status send(const netdutils::Slice msg) = 0;
+
+    // Deliver future messages with nlmsghdr.nlmsg_type == type to fn.
+    //
+    // Threadsafe.
+    // All dispatch functions invoked on a single service thread.
+    // subscribe() and join() must not be called from the stack of fn().
+    virtual netdutils::Status subscribe(uint16_t type, const DispatchFn& fn) = 0;
+
+    // Halt delivery of future messages with nlmsghdr.nlmsg_type == type.
+    // Threadsafe.
+    virtual netdutils::Status unsubscribe(uint16_t type) = 0;
+
+    virtual void registerSkErrorHandler(const SkErrorHandler& handler) = 0;
+};
+
+// NetlinkListener manages a netlink socket and associated blocking
+// service thread.
+//
+// This class is written in a generic way to allow multiple different
+// netlink subsystems to share this common infrastructure. If multiple
+// subsystems share the same message delivery requirements (drops ok,
+// no drops) they may share a single listener by calling subscribe()
+// with multiple types.
+//
+// This class is suitable for moderate performance message
+// processing. In particular it avoids extra copies of received
+// message data and allows client code to control which message
+// attributes are processed.
+//
+// Note that NetlinkListener is capable of processing multiple batched
+// netlink messages in a single system call. This is useful to
+// netfilter extensions that allow batching of events like NFLOG.
+class NetlinkListener : public NetlinkListenerInterface {
+  public:
+    NetlinkListener(netdutils::UniqueFd event, netdutils::UniqueFd sock, const std::string& name);
+
+    ~NetlinkListener() override;
+
+    netdutils::Status send(const netdutils::Slice msg) override;
+
+    netdutils::Status subscribe(uint16_t type, const DispatchFn& fn) override EXCLUDES(mMutex);
+
+    netdutils::Status unsubscribe(uint16_t type) override EXCLUDES(mMutex);
+
+    void registerSkErrorHandler(const SkErrorHandler& handler) override;
+
+  private:
+    netdutils::Status run();
+
+    const netdutils::UniqueFd mEvent;
+    const netdutils::UniqueFd mSock;
+    const std::string mThreadName;
+    std::mutex mMutex;
+    std::map<uint16_t, DispatchFn> mDispatchMap GUARDED_BY(mMutex);
+    std::thread mWorker;
+    SkErrorHandler mErrorHandler;
+};
+
+}  // namespace netdutils
+}  // namespace android
+
+#endif /* NETLINK_LISTENER_H */