（一百八十七）Android P netd 初步学习

参考

https://www.jianshu.com/p/f752b2019c97

https://blog.csdn.net/andytian1991/article/details/80444195

1.netd简介

      所谓 Netd 就是Network Daemon 的缩写，表示Network守护进程，类似的命名还有很多，例如 Vold（Volumn Deamon），Rild（Radio Interface Layer Deamon）
      Netd负责跟一些涉及网络的配置，操作，管理，查询等相关的功能实现，比如，例如带宽控制（Bandwidth），流量统计，带宽控制，网络地址转换（NAT），个人局域网（pan），PPP链接，soft-ap，共享上网（Tether），配置路由表，interface配置管理，等等……
      通过netlink，虚拟文件系统，等linux内核提供的用户接口，通信内核,或者直接执行系统模块，管理网络相关部分。

涉及主要源码位置：

    Netd:
             /system/netd/*
    lib：
             /system/core/libsysutils/src
    Framework:
            /frameworks/base/services/java/com/android/server/NetworkManagementService.java
            /frameworks/base/services/java/com/android/server/NativeDaemonConnector.java

2.代码结构简单学习

2.1 libsysutils

看了下现在Android P上这三个目录都还存在，简单看下libsysutils是个啥

jiatai@jiatai:~/expand/aosp/P_source/system/core/libsysutils$ tree
.
├── Android.bp
├── EventLogTags.logtags
├── include
│   └── sysutils
│       ├── FrameworkClient.h
│       ├── FrameworkCommand.h
│       ├── FrameworkListener.h
│       ├── List.h
│       ├── NetlinkEvent.h
│       ├── NetlinkListener.h
│       ├── ServiceManager.h
│       ├── SocketClientCommand.h
│       ├── SocketClient.h
│       └── SocketListener.h
└── src
    ├── FrameworkClient.cpp
    ├── FrameworkCommand.cpp
    ├── FrameworkListener.cpp
    ├── NetlinkEvent.cpp
    ├── NetlinkListener.cpp
    ├── ServiceManager.cpp
    ├── SocketClient.cpp
    └── SocketListener.cpp

3 directories, 20 files

看下bp文件

jiatai@jiatai:~/expand/aosp/P_source/system/core/libsysutils$ cat Android.bp 
cc_library_shared {
    name: "libsysutils",
    vendor_available: true,
    vndk: {
        enabled: true,
    },

    srcs: [
        "src/SocketListener.cpp",
        "src/FrameworkListener.cpp",
        "src/NetlinkListener.cpp",
        "src/NetlinkEvent.cpp",
        "src/FrameworkCommand.cpp",
        "src/SocketClient.cpp",
        "src/ServiceManager.cpp",
    ],

    logtags: ["EventLogTags.logtags"],

    cflags: ["-Werror"],

    shared_libs: [
        "libbase",
        "libcutils",
        "liblog",
    ],

    export_include_dirs: ["include"],
}

vndk是个啥：参考https://www.jianshu.com/p/92d5d3653dbf

Vendor Native Development Kit (VNDK)

The Vendor Native Development Kit (VNDK) is a set of libraries exclusively for vendors to implement their HALs. The VNDK ships in system.img and is dynamically linked to vendor code at runtime.

VNDK是一系列专为硬件厂商(第三方方案商)设计、用来实现硬件抽象层的库文件、VNDK被存放在system.img这个包中、在运行时被动态链接到三方代码。

export_include_dirs看起来是导出头文件

参考：https://www.jianshu.com/p/da9e9f7803ad

头文件

LOCAL_COPY_HEADERS已弃用。Soong模块不能使用这些头，并且当启用VNDK时，Make中的系统模块也不能声明或使用它们。构建系统提供的全局包含路径集也将被删除。它们已经从使用-isystem切换到用-I，并且在某些环境中完全删除（启用VNDK时的供应商代码）。
取而代之，使用LOCAL_EXPORT_C_INCLUDE_DIRS/export_include_dirs。如果您链接到相关代码，这些允许自动访问头文件。
如果您的库使用LOCAL_EXPORT_C_INCLUDE_DIRS/export_include_dirs，并且导出的头文件引用了一个您链接的库，请使用LOCAL_EXPORT_SHARED_LIBRARY_HEADERS/LOCAL_EXPORT_STATIC_LIBRARY_HEADERS/LOCAL_EXPORT_HEADER_LIBRARY_HEADERS（export_shared_lib_headers/export_static_lib_headers/export_header_lib_headers）将必要的头文件重新导出给您的用户。

2.2 framework

NativeDaemonConnector、NetworkManagementService之前简单看过了，略

https://blog.csdn.net/sinat_20059415/article/details/100822240

2.3 netd

随便看看bp mk文件

jiatai@jiatai:~/expand/aosp/P_source/system/netd/server$ cat Android.mk 
# Copyright (C) 2014 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.

LOCAL_PATH := $(call my-dir)

###
### netd service AIDL interface.
###
include $(CLEAR_VARS)

LOCAL_CFLAGS := -Wall -Werror -Wthread-safety
LOCAL_MODULE := libnetdaidl_static
LOCAL_SHARED_LIBRARIES := \
        libbinder \
        libutils
LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/binder
LOCAL_AIDL_INCLUDES := $(LOCAL_PATH)/binder frameworks/native/aidl/binder
LOCAL_C_INCLUDES := $(LOCAL_PATH)/binder
LOCAL_SRC_FILES := \
        binder/android/net/INetd.aidl \
        binder/android/net/UidRange.cpp

include $(BUILD_STATIC_LIBRARY)

include $(CLEAR_VARS)

LOCAL_CFLAGS := -Wall -Werror -Wthread-safety
LOCAL_MODULE := libnetdaidl
LOCAL_SHARED_LIBRARIES := \
        libbinder \
        libutils
LOCAL_WHOLE_STATIC_LIBRARIES := libnetdaidl_static
LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/binder

include $(BUILD_SHARED_LIBRARY)

###
### netd daemon.
###
include $(CLEAR_VARS)

LOCAL_C_INCLUDES := \
        $(call include-path-for, libhardware_legacy)/hardware_legacy \
        bionic/libc/dns/include \
        external/mdnsresponder/mDNSShared \
        system/netd/include \

LOCAL_CPPFLAGS := -Wall -Werror -Wthread-safety -Wnullable-to-nonnull-conversion
LOCAL_MODULE := netd

# Bug: http://b/29823425 Disable -Wvarargs for Clang update to r271374
LOCAL_CPPFLAGS +=  -Wno-varargs \

ifeq ($(TARGET_ARCH), x86)
ifneq ($(TARGET_PRODUCT), gce_x86_phone)
        LOCAL_CPPFLAGS += -D NETLINK_COMPAT32
endif
endif

LOCAL_INIT_RC := netd.rc

LOCAL_SHARED_LIBRARIES := \
        [email protected] \
        [email protected] \
        libbinder \
        libbpf    \
        libcrypto \
        libcutils \
        libdl \
        libhidlbase \
        libhidltransport \
        liblog \
        liblogwrap \
        libmdnssd \
        libnetdaidl \
        libnetutils \
        libnetdutils \
        libselinux \
        libssl \
        libsysutils \
        libbase \
        libutils \
        libpcap \
        libqtaguid \

LOCAL_SRC_FILES := \
        BandwidthController.cpp \
        ClatdController.cpp \
        CommandListener.cpp \
        Controllers.cpp \
        DnsProxyListener.cpp \
        DummyNetwork.cpp \
        DumpWriter.cpp \
        EventReporter.cpp \
        FirewallController.cpp \
        FwmarkServer.cpp \
        IdletimerController.cpp \
        InterfaceController.cpp \
        IptablesRestoreController.cpp \
        LocalNetwork.cpp \
        MDnsSdListener.cpp \
        NetdCommand.cpp \
        NetdConstants.cpp \
        NetdHwService.cpp \
        NetdNativeService.cpp \
        NetlinkHandler.cpp \
        NetlinkManager.cpp \
        NetlinkCommands.cpp \
        NetlinkListener.cpp \
        Network.cpp \
        NetworkController.cpp \
        NFLogListener.cpp \
        PhysicalNetwork.cpp \
        PppController.cpp \
        ResolverController.cpp \
        RouteController.cpp \
        SockDiag.cpp \
        StrictController.cpp \
        TetherController.cpp \
        TrafficController.cpp \
        UidRanges.cpp \
        VirtualNetwork.cpp \
        WakeupController.cpp \
        XfrmController.cpp \
        TcpSocketMonitor.cpp \
        main.cpp \
        oem_iptables_hook.cpp \
        binder/android/net/UidRange.cpp \
        binder/android/net/metrics/INetdEventListener.aidl \
        dns/DnsTlsDispatcher.cpp \
        dns/DnsTlsQueryMap.cpp \
        dns/DnsTlsTransport.cpp \
        dns/DnsTlsServer.cpp \
        dns/DnsTlsSessionCache.cpp \
        dns/DnsTlsSocket.cpp \

LOCAL_AIDL_INCLUDES := $(LOCAL_PATH)/binder

include $(BUILD_EXECUTABLE)


###
### ndc binary.
###
include $(CLEAR_VARS)

LOCAL_CFLAGS := -Wall -Werror -Wthread-safety
LOCAL_SANITIZE := unsigned-integer-overflow
LOCAL_CLANG := true
LOCAL_MODULE := ndc
LOCAL_SHARED_LIBRARIES := libcutils
LOCAL_SRC_FILES := ndc.cpp

include $(BUILD_EXECUTABLE)

###
### netd unit tests.
###
include $(CLEAR_VARS)
LOCAL_MODULE := netd_unit_test
LOCAL_COMPATIBILITY_SUITE := device-tests
LOCAL_SANITIZE := unsigned-integer-overflow
LOCAL_CFLAGS := -Wall -Werror -Wunused-parameter -Wthread-safety
# Bug: http://b/29823425 Disable -Wvarargs for Clang update to r271374
LOCAL_CFLAGS += -Wno-varargs

LOCAL_C_INCLUDES := \
        bionic/libc/dns/include \
        system/netd/include \
        system/netd/server \
        system/netd/server/binder \
        system/netd/tests \
        system/core/logwrapper/include \

LOCAL_SRC_FILES := \
        InterfaceController.cpp InterfaceControllerTest.cpp \
        Controllers.cpp ControllersTest.cpp \
        NetdConstants.cpp IptablesBaseTest.cpp \
        IptablesRestoreController.cpp IptablesRestoreControllerTest.cpp \
        BandwidthController.cpp BandwidthControllerTest.cpp \
        FirewallControllerTest.cpp FirewallController.cpp \
        IdletimerController.cpp IdletimerControllerTest.cpp \
        NetlinkCommands.cpp NetlinkManager.cpp \
        RouteController.cpp RouteControllerTest.cpp \
        SockDiagTest.cpp SockDiag.cpp \
        StrictController.cpp StrictControllerTest.cpp \
        TetherController.cpp TetherControllerTest.cpp \
        TrafficController.cpp TrafficControllerTest.cpp \
        XfrmController.cpp XfrmControllerTest.cpp \
        TcpSocketMonitor.cpp \
        UidRanges.cpp \
        NetlinkListener.cpp \
        WakeupController.cpp WakeupControllerTest.cpp \
        NFLogListener.cpp NFLogListenerTest.cpp \
        binder/android/net/UidRange.cpp \
        binder/android/net/metrics/INetdEventListener.aidl \
        ../tests/tun_interface.cpp \
        dns/DnsTlsDispatcher.cpp \
        dns/DnsTlsTransport.cpp \
        dns/DnsTlsServer.cpp \
        dns/DnsTlsSessionCache.cpp \
        dns/DnsTlsSocket.cpp \

LOCAL_MODULE_TAGS := tests
LOCAL_STATIC_LIBRARIES := libgmock libpcap
LOCAL_SHARED_LIBRARIES := \
        libbpf    \
        libnetdaidl \
        libbase \
        libbinder \
        libcrypto \
        libcutils \
        liblog \
        liblogwrap \
        libnetutils \
        libnetdutils \
        libqtaguid \
        libsysutils \
        libutils \
        libssl \

include $(BUILD_NATIVE_TEST)

可以看到有用到之前的libsysutils，还看到了一个aidl和netd.rc的使用

aidl

netd.rc

jiatai@jiatai:~/expand/aosp/P_source/system/netd/server$ cat netd.rc 
service netd /system/bin/netd
    class main
    socket netd stream 0660 root system
    socket dnsproxyd stream 0660 root inet
    socket mdns stream 0660 root system
    socket fwmarkd stream 0660 root inet
    onrestart restart zygote
    onrestart restart zygote_secondary

待续。。。

3.总结

初步学习了下netd的概念以及代码架构，待从代码角度开始进一步学习。