使用C语言编写基于TCP协议的Socket通讯程序实例分享

tcp客户端示例

#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h> 

typedef struct _NSS_HEADER
{
  unsigned short     ProtocolVersion;    /* 协议版本信息 */
  unsigned short     MsgType;        /* 消息类型 */
  unsigned short     TransactionNo;     /* 传输编号 */
  unsigned short     PacketLength;      /* 数据包长度,包括Header */
}NSS_HEADER;  

int str_echo(int sockfd, unsigned short no)
{
  ssize_t readLen;
  ssize_t writeLen;
  char  buf[8]; 

  NSS_HEADER *hdr = (NSS_HEADER*)buf;
  memset( hdr, 0, sizeof(NSS_HEADER) );
  hdr->TransactionNo = no; 

  // 写数据
  int nWriteLen = 0;
  while ( true )
  {
    writeLen = write(sockfd, &buf[nWriteLen], sizeof(NSS_HEADER)-nWriteLen);
//    printf( "write %d/n", writeLen); 

    if (writeLen < 0 && errno == EINTR)
    {
      continue;
    }
    else if ( writeLen < 0 )
    {
      perror ( "write:" );
      return -1;
    } 

    nWriteLen += writeLen;
    // 已写完，直接返回
    if (nWriteLen >= sizeof(NSS_HEADER) )
    {
      break;
    }
  } 

  printf( "send data successed. trans no: %d/n", no ); 

  // 读数据
  int nReadLen = 8;
  while ( true )
  {
    readLen = read(sockfd, buf, nReadLen);
//    printf( "read: %d/n", readLen );
    if (readLen < 0 && errno == EINTR)
    {
      continue;
    }
    else if ( readLen <= 0 )
    {
      perror( "read:");
      return -1;
    }
    else
    {
      nReadLen -= readLen;
      if (nReadLen <= 0 )
      {
        break;
      }
    }
  } 

  printf( "read response successed./n" ); 

  return 0;
} 

int main(int argc, char **argv)
{
  printf("client ip: %s/n", argv[1]);
  printf("client port: %s/n", argv[2]);
  printf("server ip: %s/n", argv[3]);
  printf("server port: %s/n", argv[4]); 

  printf("/n service starting.../n/n");
  while( true )
  {
    int   socketFd;
    struct sockaddr_in svrAddr;
    struct sockaddr_in localAddr; 

    socketFd = socket (AF_INET, SOCK_STREAM, 0);
    if ( -1 == socketFd )
    {
      perror( "socket:" );
      continue;
    } 

    // 设置地址可复用
    int option = 1;
    setsockopt( socketFd, SOL_SOCKET, SO_REUSEADDR, &option, sizeof(option) );
    // 客户端IP
    memset(&localAddr, 0, sizeof(localAddr));
    localAddr.sin_family = AF_INET;
    localAddr.sin_addr.s_addr = inet_addr( argv[1]);
    localAddr.sin_port = htons (atoi(argv[2])); 

    int bindResult = bind(socketFd, (struct sockaddr *) &localAddr, sizeof(localAddr));
    if ( -1 == bindResult )
    {
      perror( "bind:" );
      sleep(10);
      close(socketFd);
      continue;
    } 

    // 服务器IP
    memset(&svrAddr, 0, sizeof(svrAddr));
    svrAddr.sin_family = AF_INET;
    svrAddr.sin_addr.s_addr = inet_addr( argv[3]);
    svrAddr.sin_port = htons (atoi(argv[4])); 

    // 不断重连
    int connResult = connect(socketFd, (struct sockaddr *) &svrAddr, sizeof(svrAddr));
    if ( -1 == connResult )
    {
      perror( "connect:" );
      sleep(10);
      close(socketFd);
      continue;
    } 

    printf (" connect %s:%s successed./n", argv[3], argv[4] ); 

    static unsigned short no = 0;
    // 连接成功，每分钟发送一次数据
    for ( ; ; )
    {
      if ( -1 == str_echo(socketFd, no++) )
      {
        break;
      } 

      sleep( 60 );
    }
    close(socketFd);
  }
}

tcp服务器源码示例

#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h> 

struct _NSS_HEADER
{
  unsigned short     ProtocolVersion;    /* 协议版本信息 */
  unsigned short     MsgType;        /* 消息类型 */
  unsigned short     TransactionNo;     /* 传输编号 */
  unsigned short     PacketLength;      /* 数据包长度,包括Header */
}NSS_HEADER;  

void str_echo(int sockfd)
{
  ssize_t readLen;
  ssize_t writeLen;
  char  buf[8]; 

  while ( true )
  {
    readLen = read(sockfd, buf, 8);
    if (readLen < 0 && errno == EINTR)
    {
      continue;
    }
    else if ( readLen <= 0 )
    {
      perror( "read:");
      return ;
    }
    printf( "recv data successed. data len: %d/n", readLen ); 

    int nWriteLen = 0;
    while ( true )
    {
      writeLen == write(sockfd, &buf[nWriteLen], readLen-nWriteLen); 

      if (writeLen < 0 && errno == EINTR)
      {
        continue;
      }
      else if ( writeLen < 0 )
      {
        perror ( "write:" );
        return;
      } 

      nWriteLen += writeLen; 

      // 已写完，直接返回
      if (nWriteLen >= readLen )
      {
        break;
      }
    } 

    printf( "send data successed. data len: %d/n", readLen );
  }
} 

int main(int argc, char **argv)
{
  printf( "server ip: %s/n", argv[1] );
  printf( "server port: %s/n", argv[2] ); 

  printf( "/nservice starting ... /n/n" ); 

  int   listenfd, connfd;
  pid_t  childpid;
  socklen_t clilen;
  struct sockaddr_in cliaddr, servaddr; 

  listenfd = socket (AF_INET, SOCK_STREAM, 0);
  if ( -1 == listenfd )
  {
    perror( "socket:" );
    exit(-1);
  } 

  // 设置地址可复用
  int option = 1;
  setsockopt( listenfd, SOL_SOCKET, SO_REUSEADDR, &option, sizeof(option) ); 

  memset(&servaddr, 0, sizeof(servaddr));
  servaddr.sin_family = AF_INET;
  servaddr.sin_addr.s_addr = inet_addr( argv[1]);
  servaddr.sin_port = htons (atoi(argv[2])); 

  int bindResult = bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr));
  if ( -1 == bindResult )
  {
    perror( "bind:" );
    exit(-1);
  } 

  int listenResult = listen(listenfd, 5);
  if ( -1 == listenResult )
  {
    perror( "listen:" );
    exit(-1);
  } 

  for ( ; ; )
  {
    clilen = sizeof(cliaddr);
    connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &clilen);
    if ( -1 == connfd )
    {
      perror( "accept:" );
      continue;
    } 

    printf ("accept %s successed.fd: %d/n", inet_ntoa(cliaddr.sin_addr), connfd ); 

    if ( (childpid = fork()) == 0)
    { /* child process */
      close(listenfd);  /* close listening socket */ 

      str_echo(connfd);  /* process the request */ 

      printf ("disconnect from %d ./n", connfd );  

      exit (0);
    }
  }
  close(connfd);     /* parent closes connected socket */
}