自己封装udp接口，实现win32,Linux，solaris,FreeBSD统一调用！

/*****test.c****/
/*
@Author:duanjigang<duanjigang1983@gmail.com>
@CopyRight@2005-2006

It is a easy job to use this program:
For diffrent platform there are diffrent methods to complie and link
Windows: complie it with vc++ 6.0 IDE
RedHat Linux: gcc -o test test.c
Soloaris9:  gcc -o test test.c -lsocket -lresolv
FreeBsd:   gcc -o test test.c  
*/

#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <string.h>
#include <sys/types.h>
#ifdef _WIN32
#define SLEEP(t) Sleep(1000*t)
#include <Winsock2.h>
#include <Windows.h>
#pragma comment(lib,"Ws2_32.lib")
#else
/*
for unix  platform Like Linux8,9 and Fedoral ,Solaris9 and freebsd
*/
#define SLEEP(t) sleep(t)
#include <sys/socket.h>
#include <unistd.h>
#include <netdb.h>
#include <errno.h>
#endif

#ifdef __FreeBSD__
#include <netinet/in.h>
#include <arpa/inet.h>
#endif

#ifdef __SunOS__
/*
you need to link this file with option -lsocket -lresolv
gcc -o test  test.c -lsocket -lresolv
*/
#endif
#define MSG_SIZE 1024
int initSndSock(struct sockaddr_in * addr,char * SERVER_IP,int port);
int SndToSock(int sockfd,struct sockaddr_in * addr,char buffer[]);
int RcvFrmSock(int sockfd, char buffer[]);
int initRcvSockAtPort(int port);
int main(void)
{ 
   int sockfd;
       struct sockaddr_in addr;
       char buffer[MSG_SIZE];
     
       /*
        can be used an server to receive message
        */
       /*
       
          sockfd = initRcvSockAtPort(9001);
          while(1)
          {
          memset(buffer, 0, MSG_SIZE);
          if(RcvFrmSock(sockfd, buffer)>=0)
          printf("Receive : %s", buffer);
          
           }
        */
     
       /*
        can be used as client to send messge
        to test receive functions ,comment code below and delete comment
           flags of codes above ,then run again
        */
       sockfd = initSndSock(&addr, "192.168.1.124",9001);
       while(1)
       {
             
               memset(buffer, 0, MSG_SIZE);
#ifdef _WIN32
               sprintf(buffer, "%s", "I am windows message");
             
               printf("WIN 32 Sending once ..........\n");
#else
               sprintf(buffer, "%s", "I am not Windows message");
             
               printf("Other Unix system Sending once ..........\n");
#endif
               SndToSock(sockfd, &addr, buffer);
               SLEEP(1);
       }
     
     
}
int initSndSock(struct sockaddr_in * addr,char * SERVER_IP,int port)
{
       int sockfd;
       int a1,a2,a3,a4;
#ifdef WIN32
       WSADATA w;
       if(WSAStartup(0x0101, &w) != 0)
   {
               fprintf(stderr, "Could not open Windows connection.\n");
               exit(0);
   }
#endif
       sockfd=socket(AF_INET,SOCK_DGRAM,0);
#ifdef WIN32
   if(sockfd == INVALID_SOCKET)
       {
               fprintf(stderr, "Could not create socket.\n");
               WSACleanup();
               exit(0);
       }
   memset((void *)addr, '\0', sizeof(struct sockaddr_in));
#else
       if(sockfd<0)
       {
               fprintf(stderr,"Socket Error:%s\n",strerror(errno));
               return -1;
       } 
       bzero(addr,sizeof(struct sockaddr_in));  
#endif
          addr->sin_family=AF_INET;
       addr->sin_port=htons((u_short)port);
#ifdef  _WIN32
     
       sscanf(SERVER_IP,"%d.%d.%d.%d",&a1,&a2,&a3,&a4);
       addr->sin_addr.S_un.S_un_b.s_b1 = (unsigned char)a1;
       addr->sin_addr.S_un.S_un_b.s_b2 = (unsigned char)a2;
       addr->sin_addr.S_un.S_un_b.s_b3 = (unsigned char)a3;
       addr->sin_addr.S_un.S_un_b.s_b4 = (unsigned char)a4;
 
#else
       if(inet_aton(SERVER_IP,&(addr->sin_addr))<0)
       {
               fprintf(stderr,"Ip error:%s\n",strerror(errno));
               return -1;
       }
#endif
       return sockfd;
}

int SndToSock(int sockfd,struct sockaddr_in * addr,char buffer[])
{
       int len = sizeof(struct sockaddr_in);
       sendto(sockfd,buffer,strlen(buffer),0,(struct sockaddr*)addr,len);
       return 0;
}

int RcvFrmSock(int sockfd, char buffer[])
{
       int n,len,ll;
       struct sockaddr_in addr;
       len = sizeof(struct sockaddr_in);
   ll = len; 
   memset(buffer, '\0' , MSG_SIZE);
   n=recvfrom(sockfd, buffer, MSG_SIZE, 0, (struct sockaddr*)&addr, &ll);       
       if(n < 0)
       {
               return -1;
       }
       buffer[n] = '\0'; 
       return n;
}

int initRcvSockAtPort(int port)
{
       int sockfd;
   struct sockaddr_in addr;
#ifdef _WIN32
       WSADATA w;
       if (WSAStartup(0x0101, &w) != 0)
       {
               fprintf(stderr, "Could not open Windows connection.\n");
               exit(0);
       }
#endif
       sockfd = socket(AF_INET, SOCK_DGRAM, 0);
       if(sockfd < 0)
       {
#ifdef _WIN32
               WSACleanup();
#endif
               fprintf(stderr, "Socket Error:%s\n", strerror(errno));
               return -1;
       }
     
       memset((void*)&addr, '\0', sizeof(struct sockaddr_in) );
       addr.sin_family = AF_INET;
   addr.sin_addr.s_addr = htons(INADDR_ANY);
     
       addr.sin_port = htons((u_short )port);
       if(bind(sockfd, (struct sockaddr *)&addr, sizeof(struct sockaddr_in)) < 0)
       {
               fprintf(stderr, "Bind Error  :%s\n", strerror(errno));
               return -1;
       }
       return sockfd;
}