Netd学习笔记

service netd /system/bin/netd
class main
socket netd stream 0660 root system
socket dnsproxyd stream 0660 root inet

启动/system/bin/netd应用程序为服务，入口函数为main，创建2个名字分别为netd和dnsproxyd的本地socket连接。分别对应：

root@android:/ # ll /dev/socket/
srwxrwxrwx root inet 1970-01-01 00:00 dnsproxyd
srwxrwxrwx root system 1970-01-01 00:00 netd

备注：socket关键字用法，

代码阅读（注：由于说第一次分析netd的代码，我完全跟踪此代码的流程来看，先说init.rc，然后是main，之后依次展开）：
//main.cpp:main
int main() {
//........
if (!(nm = NetlinkManager::Instance())) { //NetlinkManager需要分析，一眼看出它为单根模式。看看他到底做来什么？
LOGE("Unable to create NetlinkManager");
exit(1);
};
cl = new CommandListener();//CommandListener需要分析
nm->setBroadcaster((SocketListener *) cl);
if (nm->start()) { //直接看start函数。
LOGE("Unable to start NetlinkManager (%s)", strerror(errno));
exit(1);
}
/*
* Now that we're up, we can respond to commands
*/
if (cl->startListener()) {
LOGE("Unable to start CommandListener (%s)", strerror(errno));
exit(1);
}
// Eventually we'll become the monitoring thread
while(1) {
sleep(1000);
}
LOGI("Netd exiting");
exit(0);
}

直接跟进看NetlinkManager::start()
int NetlinkManager::start() {
struct sockaddr_nl nladdr;
int sz = 64 * 1024;
memset(&nladdr, 0, sizeof(nladdr));
nladdr.nl_family = AF_NETLINK;
nladdr.nl_pid = getpid();
nladdr.nl_groups = 0xffffffff;
if ((mSock = socket(PF_NETLINK,
SOCK_DGRAM,NETLINK_KOBJECT_UEVENT)) < 0) {
LOGE("Unable to create uevent socket: %s", strerror(errno));
return -1;
}
if (setsockopt(mSock, SOL_SOCKET, SO_RCVBUFFORCE, &sz, sizeof(sz)) < 0) {
LOGE("Unable to set uevent socket options: %s", strerror(errno));
return -1;
}
if (bind(mSock, (struct sockaddr *) &nladdr, sizeof(nladdr)) < 0) {
LOGE("Unable to bind uevent socket: %s", strerror(errno));
return -1;
}
mHandler = new NetlinkHandler(this, mSock);
if (mHandler->start()) {
LOGE("Unable to start NetlinkHandler: %s", strerror(errno));
return -1;
}
return 0;
}

看NetlinkHandler类：
#ifndef _NETLINKHANDLER_H
#define _NETLINKHANDLER_H
#include <sysutils/NetlinkListener.h>
#include "NetlinkManager.h"
class NetlinkHandler: public
NetlinkListener { // NetlinkListener类之前有分析，这个是网络监听的框架实现类。
NetlinkManager *mNm;
public:
NetlinkHandler(NetlinkManager *nm, int listenerSocket);
virtual ~NetlinkHandler();
int start(void);
int stop(void);
protected:
virtual
void onEvent(NetlinkEvent *evt);
void notifyInterfaceAdded(const
char *name);
void notifyInterfaceRemoved(const
char *name);
void notifyInterfaceChanged(const
char *name, bool isUp);
};
#endif

晕死，怎么排版乱完了，而且还丢失了部分数据。

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Netd学习笔记

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