linux下udp编程

/* ****************************************Copyright (c)************************************************** ** Guangzhou Zhiyuan Electronic Co.,LTD. ** graduate school ** http://www.zyinside.com ** **------------------------------------- File Info ------------------------------------------------------ ** File name: talker.c ** Last modified Date: 2005-12-30 ** Last Version: 1.0 ** Descriptions: talker of UDP. **------------------------------------------------------------------------------------------------------ ** Created by: Ganda ** Created date: 2005-12-27 ** Version: 1.0 ** Descriptions: Preliminary version. ** **------------------------------------------------------------------------------------------------------ ** Modified by: Chenxibing ** Modified date: 2005-12-30 ** Version: 1.0.1 ** Descriptions: modified for MagicARM2410. ** ******************************************************************************************************** */ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <netdb.h> #include <sys/types.h> #include <netinet/in.h> #include <sys/socket.h> #include <unistd.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/select.h> #include <sys/time.h> #define PORT 5000 // The port which is communicate with server #define LENGTH 512 // Buffer length #define DEV_NAME "/dev/ttyS0" //修改这里,填上串口的设备路径，一般在/dev/下 int Open(char *szPath) { int s32Fd = 0; s32Fd = open(szPath, O_RDONLY); if(s32Fd < 0) { fprintf(stderr, "open %s fail\n", szPath); return -1; } return s32Fd; } int DVM_COMRead(int fd, char* buff, int len) { int iRet; fd_set wset; //fd为一组文件描述符（fd）的集合 if(NULL == buff) { fprintf(stderr, "%s read buff is null\n", __FUNCTION__); return -1; } FD_ZERO(&wset);//将wset清零 FD_SET(fd, &wset);//将fd加入wset iRet = select(fd + 1, NULL, &wset, NULL, 0);//监视文件的读写变化 if (iRet < 1) { fprintf(stderr, "%s select fd fail\n", __FUNCTION__); return -1; } if(FD_ISSET(fd, &wset) <= 0) { fprintf(stderr, "%s fd is not ready\n", __FUNCTION__); return -1; } if(len != read(fd, buff, len)) { fprintf(stderr, "%s read fail\n", __FUNCTION__); return -1; } return 0; } int main(int argc, char *argv[]) { int sockfd; // Socket file descriptor int num; // Counter of received bytes char sdbuf[LENGTH]; // Receive buffer struct sockaddr_in addr_remote; // Host address information char sdstr[LENGTH]= {}; // char buff[LENGTH]= {}；//1024为你所需要读入的数据长度 int ret = 0; ret = Open(DEV_NAME); if(ret < 0) { return -1; } ret = DVM_COMRead(ret,sdstr, LENGTH); if(ret < 0) { return -1; } return 0; /* Check parameters number */ if (argc != 2) { printf ("Usage: talker HOST IP (ex: ./talker 192.168.0.94).\n"); return (0); } /* Get the Socket file descriptor */ if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) { printf("ERROR: Failed to obtain Socket Descriptor!\n"); return (0); } /* Fill the socket address struct */ addr_remote.sin_family = AF_INET; // Protocol Family addr_remote.sin_port = htons(PORT); // Port number inet_pton(AF_INET, argv[1], &addr_remote.sin_addr); // Net Address bzero(&(addr_remote.sin_zero), 8); // Flush the rest of struct /* Try to connect the server */ bzero(sdbuf,LENGTH); num = sendto(sockfd, sdstr, strlen(sdstr), 0, (struct sockaddr *)&addr_remote, sizeof(struct sockaddr_in)); if( num < 0 ) { printf ("ERROR: Failed to send your data!\n", argv[1], num); } else { printf ("OK: Sent to %s total %d bytes !\n", argv[1], num); } close (sockfd); return (0); }