IPerf开源代码中Socket类

骑猪看日落 2021-09-19 11:58 282阅读 0赞

**一 点睛**

Socket的定义和实现分别在文件Socket.hpp和Socket.cpp。

它的主要功能是封装socket文件描述符、此Socket对应的端口号以及socket接口中的listen、accept、connect和close等函数，为用户提供了一个简单易用而又同一的接口。同时作为其他派生类的基类。

**二 类定义**

class Socket {
    public:
        // stores server port and TCP/UDP mode
        Socket( unsigned short inPort, bool inUDP = false );
    
        // destructor
        virtual ~Socket();
    
    protected:
        // get local address
        SocketAddr getLocalAddress( void );
    
        // get remote address
        SocketAddr getRemoteAddress( void );
    
        // server bind and listen
        void Listen( const char *inLocalhost = NULL, bool isIPv6 = false );
    
        // server accept
        int Accept( void );
    
        // client connect
        void Connect( const char *inHostname, const char *inLocalhost = NULL );
    
        // close the socket
        void Close( void );
    
        // to put setsockopt calls before the listen() and connect() calls
        virtual void SetSocketOptions( void ) {
        }
    
        // join the multicast group
        void McastJoin( SocketAddr &inAddr );
    
        // set the multicast ttl
        void McastSetTTL( int val, SocketAddr &inAddr );
    
        int   mSock;             // socket file descriptor (sockfd)
        unsigned short mPort;    // port to listen to
        bool  mUDP;              // true for UDP, false for TCP
    
    }; // end class Socket
    
    #endif // SOCKET_H

该类主要提供了4个函数： Listen、Accept、Connect、Close。

getLocalAddress和getRemoteAddress的作用分别是获得Socket本端的地址和对端的地址，两个地址返回一个SocketAddr实例。

SetSocketOptions的作用是设置Socket的属性，它是一个虚函数，因此不同Socket的派生类在实现此函数时会执行不同的操作。

**三 类的实现**

1 Listen函数

void Socket::Listen( const char *inLocalhost, bool isIPv6 ) {
        int rc;
    
        SocketAddr serverAddr( inLocalhost, mPort, isIPv6 );
    
        // create an internet TCP socket
        int type = (mUDP  ?  SOCK_DGRAM  :  SOCK_STREAM);
        int domain = (serverAddr.isIPv6() ?
    #ifdef IPV6
                      AF_INET6
    #else
                      AF_INET
    #endif
                      : AF_INET);
    
    
    
    
    
        mSock = socket( domain, type, 0 );
        FAIL_errno( mSock == INVALID_SOCKET, "socket" );
    
    
        SetSocketOptions();
    
        // reuse the address, so we can run if a former server was killed off
        int boolean = 1;
        Socklen_t len = sizeof(boolean);
        // this (char*) cast is for old headers that don't use (void*)
        setsockopt( mSock, SOL_SOCKET, SO_REUSEADDR, (char*) &boolean, len );
    
        // bind socket to server address
    
        
        rc = bind( mSock, serverAddr.get_sockaddr(), serverAddr.get_sizeof_sockaddr());
        FAIL_errno( rc == SOCKET_ERROR, "bind" );
        
        // listen for connections (TCP only).
        // default backlog traditionally 5
        if ( ! mUDP ) {
            rc = listen( mSock, 5 );
            FAIL_errno( rc == SOCKET_ERROR, "listen" );
        }
    
    } // end Listen

Socket的Listen方法将地址解析、socket、bind和listen等系统调用组合为一个函数。在应用时，调用一个Listen方法就可以完成Server端socket初始化的所有工作。

2 Accept函数

int Socket::Accept( void ) {
        iperf_sockaddr clientAddr;
        Socklen_t addrLen;
        int connectedSock;
    
        while ( true ) {
            // accept a connection
            addrLen = sizeof( clientAddr );
            connectedSock = accept( mSock, (struct sockaddr*) &clientAddr, &addrLen );
    
            // handle accept being interupted
            if ( connectedSock == INVALID_SOCKET  &&  errno == EINTR ) {
                continue;
            }
    
            return connectedSock;
        }
    
    } // end Accept

Accept函数为Accept系统调用增添了在中断后自动重启的功能。Server线程在执行Accept函数后被阻塞，直到有请求到达，或者接收到某个信号。若是后面一种情况，Accept会返回INVALID\_SOCKET，并设置 errno 为EINTR。Accept方法检查这种情况，并重新调用Accept函数。

3 Connect函数

void Socket::Connect( const char *inHostname, const char *inLocalhost ) {
        int rc;
        SocketAddr serverAddr( inHostname, mPort );
    
        assert( inHostname != NULL );
    
        // create an internet socket
        int type = (mUDP  ?  SOCK_DGRAM : SOCK_STREAM);
    
        int domain = (serverAddr.isIPv6() ?
    #ifdef IPV6
                      AF_INET6
    #else
                      AF_INET
    #endif
                      : AF_INET);
    
        mSock = socket( domain, type, 0 );
        FAIL_errno( mSock == INVALID_SOCKET, "socket" );
    
        SetSocketOptions();
    
    
        if ( inLocalhost != NULL ) {
            SocketAddr localAddr( inLocalhost );
    
    
            // bind socket to local address
            rc = bind( mSock, localAddr.get_sockaddr(), localAddr.get_sizeof_sockaddr());
            FAIL_errno( rc == SOCKET_ERROR, "bind" );
        }
    
    
        // connect socket
        rc = connect( mSock, serverAddr.get_sockaddr(), serverAddr.get_sizeof_sockaddr());
        FAIL_errno( rc == SOCKET_ERROR, "connect" );
    
    } // end Connect

Connect函数是Client端调用的函数，作用是连接指定的Server。