diy数据库（二）--网络通信类

一、首先，我们先实现OSS层的ossSocket类。供数据库client和数据库引擎进行通信

友情提示：相应上面的类图的头文件和源码附在了本文的最以下。

int _fd ;//socket的文件描写叙述符

socklen_t _addressLen ;//地址长度

socklen_t _peerAddressLen ;//对方地址的长度

struct sockaddr_in _sockAddress ;//本地的socket地址 ipv4

struct sockaddr_in _peerAddress ;//对方的socket地址 ipv4

bool _init ;//代表是否已经初始化

int _timeout ;//代表超时时间，包含读和写的超时

这是一个基础类，都是对socket的通用的操作，实现方法也比較常见。

这里主要注意的有几点：

1.读写sockt时要注意信号中断带来的错误ENTRY，对于中断。我们要手动处理。

2.因为数据库需的操作须要有实时性。我们须要设置TCP_NODELAY套接字选项，来关闭TCP的Nagle算法

3.我们的ossSocket类中的读写函数有一个特点就是添加了时间限制。即我们要求在给定时间參数的范围类得带可读或可写的socket，不然推断读写超时

4.为了防止socket进入timewait状态，我们须要设置SO_REUSEADDR套接字选项

5.当向一个已经收到RST的套接字运行写操作时，内核会向用户进程发送一个SIGPIPE信号。

该信号的默认行为是终止进程。

send()函数的最后一个參数能够设MSG_NOSIGNAL，来禁止内核发送SIGPIPE信号。

附录：

下面是头文件：ossSocket.hpp

#ifndef OSSNETWORK_HPP_
#define OSSNETWORK_HPP_

#include "core.hpp"
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>
#include <netinet/tcp.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#define SOCKET_GETLASTERROR errno//系统的错误码
#define OSS_EAGAIN	EAGAIN
#define OSS_EINTR	EINTR
#define closesocket	close

// by default 10ms timeout
#define OSS_SOCKET_DFT_TIMEOUT 10000//默认10毫秒的超时

// max hostname
#define OSS_MAX_HOSTNAME NI_MAXHOST//hostname的
#define OSS_MAX_SERVICENAME NI_MAXSERV

#include "core.hpp"

typedef int		SOCKET;

class _ossSocket
{
private ://全部
   int _fd ;//socket的文件描写叙述符
   socklen_t _addressLen ;//地址长度
   socklen_t _peerAddressLen ;//对方地址的长度
   struct sockaddr_in  _sockAddress ;//本地的socket地址 ipv4
   struct sockaddr_in  _peerAddress ;//对方的socket地址 ipv4

   bool _init ;//代表是否已经初始化
   int _timeout ;//代表超时时间，包含读和写的超时
protected:
   unsigned int _getPort ( sockaddr_in *addr ) ;//得到端口
   int _getAddress ( sockaddr_in *addr, char *pAddress, unsigned int length ) ;//得到地址

public :
   int setSocketLi ( int lOnOff, int linger ) ;//设置close连接时对发送缓冲区中数据的操作
   void setAddress(const char * pHostName, unsigned int port );
   // Create a listening socket
   _ossSocket();//设置默认的socket的属性
   _ossSocket ( unsigned int port, int timeout = 0 ) ;//设置socket的属性
   _ossSocket ( const char *pHostname, unsigned int port, int timeout = 0 ) ;<span style="font-family: Arial, Helvetica, sans-serif;">// 创建一个clientsocket</span>
   _ossSocket ( int *sock, int timeout = 0 ) ;<span style="font-family: Arial, Helvetica, sans-serif;">//通过accept的到的socket的fd来构建</span>

   ~_ossSocket ()
   {
      close () ;
   }
   int initSocket () ;//初始化函数
   int bind_listen () ;//将socket绑定到一个端口
   bool isConnected () ;//推断连接状态
   int send ( const char *pMsg, int len,
                int timeout = OSS_SOCKET_DFT_TIMEOUT,
                int flags = 0 ) ;
   int recv ( char *pMsg, int len,
                int timeout = OSS_SOCKET_DFT_TIMEOUT,
                int flags = 0 ) ;//收到固定长度的数据才返回（timeout=0表示永远不会超时）
   int recvNF ( char *pMsg, int &len,
                  int timeout = OSS_SOCKET_DFT_TIMEOUT ) ;//不用收到固定长度的数据

   int connect () ;
   void close () ;
   int accept ( int *sock, struct sockaddr *addr, socklen_t *addrlen,
                  int timeout = OSS_SOCKET_DFT_TIMEOUT ) ;
   //一下是几个辅助函数
   /*当我们发送小包的时候。tcp会把几个小包组合成一个大包来发送。这个功能能够关闭*/
   int disableNagle () ;//关闭打包发送特性，关闭tcp中的Nagle功能，小包的发送会更实时

   unsigned int getPeerPort () ;
   int getPeerAddress ( char *pAddress, unsigned int length ) ;

   unsigned int getLocalPort () ;
   int getLocalAddress ( char *pAddress, unsigned int length ) ;

   int setTimeout ( int seconds ) ;//设置超时

   static int getHostName ( char *pName, int nameLen ) ;//得到域名
   static int getPort ( const char *pServiceName, unsigned short &port ) ;//把服务名转化为端口号。全部的服务都在/etc/server文件中面
   int setAnsyn () ;
};

typedef class _ossSocket ossSocket ;

#endif

下面是实现ossSockt.cpp

#include "ossSocket.hpp"
#include "pd.hpp"

//创建一个监听的socket
_ossSocket::_ossSocket ( unsigned int port, int timeout )
{//设置监听套接字的各种属性
   _init = false ;
   _fd = 0 ;
   _timeout = timeout ;
   memset ( &_sockAddress, 0, sizeof(sockaddr_in) ) ;
   memset ( &_peerAddress, 0, sizeof(sockaddr_in) ) ;
   _peerAddressLen = sizeof(_peerAddress) ;
   _addressLen = sizeof( _sockAddress ) ;
   //监听套接字特有
   _sockAddress.sin_family = AF_INET ;
   _sockAddress.sin_addr.s_addr = htonl ( INADDR_ANY ) ;
   _sockAddress.sin_port = htons ( port ) ;

}

// Create a socket
_ossSocket::_ossSocket ()
{
   _init = false ;
   _fd = 0 ;
   _timeout = 0 ;
   memset ( &_sockAddress, 0, sizeof(sockaddr_in) ) ;
   memset ( &_peerAddress, 0, sizeof(sockaddr_in) ) ;
   _peerAddressLen = sizeof(_peerAddress) ;
   _addressLen = sizeof( _sockAddress ) ;
}

// 创建一个client的套接字
//pHostname是对方机器的机器名（假设不是机器名就当做对方机器的ip地址）。port是对方机器的端口号
_ossSocket::_ossSocket ( const char *pHostname, unsigned int port, int timeout )
{
   struct hostent *hp ;
   _init = false ;
   _timeout = timeout ;
   _fd = 0 ;
   memset ( &_sockAddress, 0, sizeof(sockaddr_in) ) ;
   memset ( &_peerAddress, 0, sizeof(sockaddr_in) ) ;
   _peerAddressLen = sizeof(_peerAddress) ;
   _sockAddress.sin_family = AF_INET ;
   if ( (hp = gethostbyname ( pHostname ) ) )//
      _sockAddress.sin_addr.s_addr = *((int*)hp->h_addr_list[0] ) ;
   else
      _sockAddress.sin_addr.s_addr = inet_addr ( pHostname ) ;
   _sockAddress.sin_port = htons ( port ) ;
   _addressLen = sizeof(_sockAddress ) ;
}

// 由已经得到的套接字来创建socket
_ossSocket::_ossSocket ( int *sock, int timeout )//SOCKET就是int类型
{
   int rc = DIY_OK ;
   _fd = *sock ;
   _init = true ;
   _timeout = timeout ;
   _addressLen = sizeof( _sockAddress ) ;
   memset ( &_peerAddress, 0, sizeof(sockaddr_in) ) ;
   _peerAddressLen = sizeof(_peerAddress) ;
   rc = getsockname ( _fd, (sockaddr*)&_sockAddress, &_addressLen ) ;//得到本地的ip地址
   if ( rc )
   {
      //PD_LOG ( PDERROR, "Failed to get sock name, error = %d",
        //       SOCKET_GETLASTERROR ) ;
      _init = false ;
   }
   else
   {
      rc = getpeername ( _fd, (sockaddr*)&_peerAddress, &_peerAddressLen ) ;//得到远端的ip地址
      //PD_RC_CHECK ( rc, PDERROR, "Failed to get peer name, error = %d",
                    //SOCKET_GETLASTERROR ) ;
   }
done :
   return ;
error :
   goto done ;
}

int _ossSocket::initSocket ()
{
   int rc = DIY_OK ;
   if ( _init )
   {
      goto done ;
   }
   memset ( &_peerAddress, 0, sizeof(sockaddr_in) ) ;
   _peerAddressLen = sizeof(_peerAddress) ;
   _fd =socket ( AF_INET, SOCK_STREAM, IPPROTO_TCP ) ;//创建socket
   if ( -1 == _fd )
   {
      //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
       //             "Failed to initialize socket, error = %d",
         //           SOCKET_GETLASTERROR ) ;
         goto error;
   }
   _init =true ;
   // set timeout
   setTimeout ( _timeout ) ;
done :
   return rc ;
error :
   goto done ;
}

//设置SO_LINGER选项
int _ossSocket::setSocketLi ( int lOnOff, int linger )
{
   int rc = DIY_OK ;
   struct linger _linger ;
   _linger.l_onoff = lOnOff ;
   _linger.l_linger = linger ;
   rc = setsockopt ( _fd, SOL_SOCKET, SO_LINGER,
                     (const char*)&_linger, sizeof(_linger) ) ;
   return rc ;
}

void _ossSocket::setAddress(const char *pHostname, unsigned int port )
{
   struct hostent *hp ;
   memset ( &_sockAddress, 0, sizeof(sockaddr_in ) ) ;
   memset ( &_peerAddress, 0, sizeof(sockaddr_in) ) ;
   _peerAddressLen = sizeof(_peerAddress) ;
   _sockAddress.sin_family = AF_INET ;
   if ( ( hp = gethostbyname ( pHostname )))
      _sockAddress.sin_addr.s_addr = *((int*)hp->h_addr_list[0] ) ;
   else
      _sockAddress.sin_addr.s_addr = inet_addr ( pHostname ) ;

   _sockAddress.sin_port = htons ( port ) ;
   _addressLen = sizeof(_sockAddress ) ;
}

//监听端口
int _ossSocket::bind_listen ()
{
   int rc = DIY_OK ;
   int temp = 1 ;
   rc = setsockopt ( _fd, SOL_SOCKET,
                     SO_REUSEADDR, (char*)&temp, sizeof(int) ) ;//SO_REUSEADDR确定这个端口能够反复使用
   if ( rc )
   {
      //PD_LOG ( PDWARNING, "Failed to setsockopt SO_REUSEADDR, rc = %d",
      //         SOCKET_GETLASTERROR ) ;
      goto error;
   }
   rc = setSocketLi ( 1, 30 ) ;
   if ( rc )
   {
      //PD_LOG ( PDWARNING, "Failed to setsockopt SO_LINGER, rc = %d",
       //        SOCKET_GETLASTERROR ) ;
       goto error;
   }
   rc = ::bind ( _fd, (struct sockaddr*)&_sockAddress, _addressLen ) ;
   if ( rc )
   {
      //PD_RC_CHECK( DIY_NETWORK, PDERROR,
       //            "Failed to bind socket, rc = %d", SOCKET_GETLASTERROR ) ;
       goto error;
   }
   rc = listen ( _fd, SOMAXCONN ) ;
   if ( rc )
   {
      //PD_RC_CHECK( DIY_NETWORK, PDERROR,
       //            "Failed to listen socket, rc = %d", SOCKET_GETLASTERROR ) ;
       goto error;
   }
done :
   return rc ;
error :
   close () ;
   goto done ;
}

//发送函数
//发送函数也有超时timeout
int _ossSocket::send ( const char *pMsg, int len,
                      int timeout, int flags )
{
   int rc = DIY_OK ;
   int	maxFD = _fd ;
   struct timeval maxSelectTime ;
   fd_set fds ;

   maxSelectTime.tv_sec = timeout / 1000000 ;
   maxSelectTime.tv_usec = timeout % 1000000 ;
   // if len == 0, then let's just return
   if ( 0 == len )
   {
      return DIY_OK ;
   }
   //监測在时间范围类socket是否可写
   while ( true )
   {
      FD_ZERO ( &fds ) ;
      FD_SET ( _fd, &fds ) ;
      rc = select ( (int)(maxFD + 1), NULL, &fds, NULL,
                    timeout>=0?&maxSelectTime:NULL ) ;
      if ( 0 == rc )//rc=0表示超时
      {
         // timeout
         rc = DIY_TIMEOUT ;//超时
         goto done ;
      }
      // if < 0, something wrong
      if ( 0 > rc )//rc<0表示有错误
      {
         rc = error ;
         if ( EINTR == rc )//假设失败是由于收到中断，继续
         {
            continue ;
         }
         //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
         //              "Failed to select from socket, rc = %d", rc ) ;
      }
      if ( FD_ISSET ( _fd, &fds ) )
      {
         break ;
      }
   }

   while ( len > 0 )
   {
      rc = ::send ( _fd, pMsg, len, MSG_NOSIGNAL | flags ) ;//禁止send()函数向系统发送异常消息，不收到sigpipe
      if ( rc <= 0 )
	  {
		if(rc<0&&errno==EINTR)
			rc=0;//假设失败是由于中断。继续
		else
        {
         //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
          //             "Failed to send, rc = %d", SOCKET_GETLASTERROR ) ;
          rc=-1;
		  goto error;
        }
	  }
      len -= rc ;
      pMsg += rc ;
   }
   rc = DIY_OK ;
done :
   return rc ;
error :
   goto done ;
}

bool _ossSocket::isConnected ()
{
   int rc = DIY_OK ;
   rc = ::send ( _fd, "", 0, MSG_NOSIGNAL ) ;//尝试发送一个零字节的信息
   if ( 0 > rc )
      return false ;
   return true ;
}

int _ossSocket::recv ( char *pMsg, int len,
                      int timeout, int flags )
{
   int rc = DIY_OK ;
   int retries = 0 ;
   int maxFD = (int)_fd ;
   struct timeval maxSelectTime ;
   fd_set fds ;

   if ( 0 ==len )
      return DIY_OK ;
   maxSelectTime.tv_sec = timeout / 1000000 ;
   maxSelectTime.tv_usec = timeout % 1000000 ;
   while ( true )
   {
      FD_ZERO ( &fds ) ;
      FD_SET ( _fd, &fds ) ;
      rc = select ( maxFD+1, &fds, NULL, NULL,
                    timeout>=0?

&maxSelectTime:NULL ) ;
      // 0 means timeout
      if ( 0 == rc )
      {
         rc = DIY_TIMEOUT ;
         goto done ;
      }
      // if < 0 something wrong
      if ( 0 > rc )
      {
         rc = error ;
         if ( EINTR==rc )
         {
            continue ;
         }
         //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
         //              "Failed to select from socket, rc = %d", rc ) ;
         rc=DIY_NETWORK;
         goto error;
      }
      if ( FD_ISSET ( _fd, &fds ) )
      {
          break ;
      }
   }
   while ( len > 0 )
   {
      rc = ::recv ( _fd, pMsg, len, MSG_NOSIGNAL|flags ) ;
      if ( rc > 0 )
      {
         if ( flags & MSG_PEEK )
         {
             goto done ;
         }
         len -= rc ;
         pMsg += rc ;
      }
      else if ( rc == 0 )//网络关闭。收到fin
      {
         //PD_RC_CHECK ( DIY_NETWORK_CLOSE, PDWARNING,
         //              "Peer unexpected shutdown" ) ;
         goto error;
      }
      else
      {
         rc = error ;
         if (  EINTR == rc  )
         {
            continue ;
         }
         //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
         //              "Recv() Failed: rc = %d", rc ) ;
         goto error;
      }
   }
   rc = DIY_OK ;
done :
   return rc ;
error :
   goto done ;
}

int _ossSocket::recvNF ( char *pMsg, int &len,
                         int timeout )
{
   int rc = DIY_OK ;
   int retries = 0 ;
   int maxFD = (int)_fd ;
   struct timeval maxSelectTime ;
   fd_set fds ;

   // if we don't expect to receive anything, no need to continue
   if ( 0 == len )
      return DIY_OK ;

   maxSelectTime.tv_sec = timeout / 1000000 ;
   maxSelectTime.tv_usec = timeout % 1000000 ;
   // wait loop until either we timeout or get a message
   while ( true )
   {
      FD_ZERO ( &fds ) ;
      FD_SET ( _fd, &fds ) ;
      rc = select ( maxFD + 1, &fds, NULL, NULL,
                    timeout>=0?

&maxSelectTime:NULL ) ;

      // 0 means timeout
      if ( 0 == rc )
      {
         rc = DIY_TIMEOUT ;
         goto done ;
      }
      // if < 0, means something wrong
      if ( 0 > rc )
      {
         rc = error ;
         // if we failed due to interrupt, let's continue
         if ( EINTR == rc )
         {
            continue ;
         }
         //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
         //              "Failed to select from socket, rc = %d", rc ) ;
         goto error;
      }
      if ( FD_ISSET ( _fd, &fds ) )
      {
         break ;
      }
   }
   rc = ::recv ( _fd, pMsg, len, MSG_NOSIGNAL ) ;

   if ( rc > 0 )
   {
      len = rc ;
   }
   else if ( rc == 0 )
   {
      //PD_RC_CHECK ( DIY_NETWORK_CLOSE, PDWARNING,
       //             "Peer unexpected shutdown" ) ;
       goto error;
   }
   else
   {
      rc = error ;
      goto error;
   }
   // Everything is fine when get here
   rc = DIY_OK ;
done :
   return rc ;
error :
   goto done ;
}

int _ossSocket::connect ()
{
   int rc = DIY_OK ;
   rc = ::connect ( _fd, (struct sockaddr *)&_sockAddress, _addressLen ) ;
   if ( rc )
   {
      //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
       //             "Failed to connect, rc = %d", SOCKET_GETLASTERROR ) ;
       goto error;
   }
   rc = getsockname ( _fd, (sockaddr*)&_sockAddress, &_addressLen ) ;
   if ( rc )
   {
      //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
      //              "Failed to get local address, rc = %d", rc ) ;
      goto error;
   }
   // get peer address
   rc = getpeername ( _fd, (sockaddr*)&_peerAddress, &_peerAddressLen ) ;
   if ( rc )
   {
      //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
      //              "Failed to get peer address, rc = %d", rc ) ;
      goto error;
   }
done :
   return rc ;
error :
   goto done ;
}

void _ossSocket::close ()
{
   if ( _init )
   {
      int i = 0 ;
      //i = ::closesocket ( _fd ) ;
      i = ::close ( _fd ) ;
      _init = false ;
   }
}

int _ossSocket::accept ( int *sock, struct sockaddr *addr, socklen_t *addrlen,
                        int timeout )
{
   int rc = DIY_OK ;
   int maxFD = (int)_fd ;
   struct timeval maxSelectTime ;

   fd_set fds ;
   maxSelectTime.tv_sec = timeout / 1000000 ;
   maxSelectTime.tv_usec = timeout % 1000000 ;
   while ( true )
   {
      FD_ZERO ( &fds ) ;
      FD_SET ( _fd, &fds ) ;
      rc = select ( maxFD + 1, &fds, NULL, NULL,
                    timeout>=0?&maxSelectTime:NULL ) ;

      // 0 means timeout
      if ( 0 == rc )
      {
         *sock = 0 ;
         rc = DIY_TIMEOUT ;
         goto done ;
      }
      // if < 0, means something wrong
      if ( 0 > rc )
      {
         rc = SOCKET_GETLASTERROR ;
         // if we failed due to interrupt, let's continue
         if ( EINTR == rc )
         {
            continue ;
         }
         //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
          //             "Failed to select from socket, rc = %d",
          //             SOCKET_GETLASTERROR);
          goto error;
      }

      // if the socket we interested is not receiving anything, let's continue
      if ( FD_ISSET ( _fd, &fds ) )
      {
         break ;
      }
   }
   rc = DIY_OK ;
   *sock = ::accept ( _fd, addr, addrlen );
   if ( -1 == *sock )
   {
      //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
        //            "Failed to accept socket, rc = %d",
        //            SOCKET_GETLASTERROR ) ;
        goto error;
   }
done :
   return rc ;
error :
   close () ;
   goto done ;
}

int _ossSocket::disableNagle ()
{
   int rc = DIY_OK ;
   int temp = 1 ;
   rc = setsockopt ( _fd, IPPROTO_TCP, TCP_NODELAY, (char *) &temp,
                     sizeof ( int ) ) ;
   if ( rc )
   {
      //PD_LOG ( PDWARNING, "Failed to setsockopt, rc = %d", SOCKET_GETLASTERROR ) ;
      return rc;
   }

   rc = setsockopt ( _fd, SOL_SOCKET, SO_KEEPALIVE, (char *) &temp,
                     sizeof ( int ) ) ;
   if ( rc )
   {
      //PD_LOG ( PDWARNING, "Failed to setsockopt, rc = %d", SOCKET_GETLASTERROR ) ;
      return rc;
   }
   return rc ;
}

unsigned int _ossSocket::_getPort ( sockaddr_in *addr )
{
   return ntohs ( addr->sin_port ) ;
}

int _ossSocket::_getAddress ( sockaddr_in *addr, char *pAddress, unsigned int length )
{
   int rc = DIY_OK ;
   length = length < NI_MAXHOST ?

length : NI_MAXHOST ;
   rc = getnameinfo ( (struct sockaddr *)addr, sizeof(sockaddr), pAddress,
                      length,
                      NULL, 0, NI_NUMERICHOST ) ;
   if ( rc )
   {
      //PD_RC_CHECK ( DIY_NETWORK, PDERROR,
      //              "Failed to getnameinfo, rc = %d", SOCKET_GETLASTERROR ) ;
      goto error;
   }
done :
   return rc ;
error :
   goto done ;
}

int _ossSocket::setAnsyn () //异步非堵塞
{
   return fcntl(_fd, F_SETFL, O_NONBLOCK | fcntl(_fd, F_GETFL, 0));
}

unsigned int _ossSocket::getLocalPort ()
{
   return _getPort ( &_sockAddress ) ;
}

unsigned int _ossSocket::getPeerPort ()
{
   return _getPort ( &_peerAddress ) ;
}

int _ossSocket::getLocalAddress ( char * pAddress, unsigned int length )
{
   return _getAddress ( &_sockAddress, pAddress, length ) ;
}

int _ossSocket::getPeerAddress ( char * pAddress, unsigned int length )
{
   return _getAddress ( &_peerAddress, pAddress, length ) ;
}

int _ossSocket::setTimeout ( int seconds )
{
   int rc = DIY_OK ;
   struct timeval tv ;
   tv.tv_sec = seconds ;
   tv.tv_usec = 0 ;
   // windows take milliseconds as parameter
   // but linux takes timeval as input

   rc = setsockopt ( _fd, SOL_SOCKET, SO_RCVTIMEO, ( char* ) &tv,
                     sizeof ( tv ) ) ;
   if ( rc )
   {
      //PD_LOG ( PDWARNING, "Failed to setsockopt, rc = %d",
       //        SOCKET_GETLASTERROR ) ;
       return rc;
   }

   rc = setsockopt ( _fd, SOL_SOCKET, SO_SNDTIMEO, ( char* ) &tv,
                     sizeof ( tv ) ) ;
   if ( rc )
   {
      //PD_LOG ( PDWARNING, "Failed to setsockopt, rc = %d",
      //         SOCKET_GETLASTERROR ) ;
      return rc;
   }

   return rc ;
}

int _ossSocket::getHostName ( char *pName, int nameLen )
{
   return gethostname ( pName, nameLen ) ;
}

int _ossSocket::getPort ( const char *pServiceName, unsigned short &port )
{
   int rc = DIY_OK ;
   struct servent *servinfo ;
   servinfo = getservbyname ( pServiceName, "tcp" ) ;
   if ( !servinfo )
      port = atoi ( pServiceName ) ;
   else
      port = (unsigned short)ntohs(servinfo->s_port) ;
   return rc ;
}