服务器端口为UDP
编写linux服务器软件，收到数据后，返回收到的数据：
#include<stdio.h> #include<stdlib.h> #include<unistd.h> #include<errno.h> #include<sys/types.h> #include<sys/socket.h> #include<netinet/in.h> #include<string.h> #define MYPORT 1501 #define ERR_EXIT(m) \ do { \ perror(m); \ exit(EXIT_FAILURE); \ } while (0) void echo_ser(int sock) { char recvbuf[1024] = {0}; struct sockaddr_in peeraddr; socklen_t peerlen; int n; printf("wait get data from port %d \n",MYPORT); while (1) { peerlen = sizeof(peeraddr); memset(recvbuf, 0, sizeof(recvbuf)); n = recvfrom(sock, recvbuf, sizeof(recvbuf), 0,(struct sockaddr *)&peeraddr, &peerlen); if (n <= 0) { if (errno == EINTR) continue; printf("recvfrom error"); ERR_EXIT("recvfrom error"); } else if(n > 0) { printf("------------------------------------------------------------------------->>\n"); unsigned int IP_peeraddr = ntohl(peeraddr.sin_addr.s_addr); printf("recvfrom IP:%d.%d.%d.%d Port:%d\n",(IP_peeraddr>>24)&0xff,(IP_peeraddr>>16)&0xff,(IP_peeraddr>>8)&0xff,IP_peeraddr&0xff,ntohs(peeraddr.sin_port)); printf("recvfrom data:%s --->> ",recvbuf); printf("sendto data:%s\n",recvbuf); sendto(sock, recvbuf, n, 0,(struct sockaddr *)&peeraddr, peerlen); } } close(sock); } int main(void) { int sock; if ((sock = socket(PF_INET, SOCK_DGRAM, 0)) < 0){ ERR_EXIT("socket error"); } struct sockaddr_in servaddr; memset(&servaddr, 0, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(MYPORT); servaddr.sin_addr.s_addr = htonl(INADDR_ANY); if (bind(sock, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){ ERR_EXIT("bind error"); printf("bind error,port is %d\n",MYPORT); }else{ printf("bind success,port is %d\n",MYPORT); } unsigned int IP_servaddr = ntohl(servaddr.sin_addr.s_addr); printf("bind IP:%d.%d.%d.%d Port:%d\n",(IP_servaddr>>24)&0xff,(IP_servaddr>>16)&0xff,(IP_servaddr>>8)&0xff,IP_servaddr&0xff,ntohs(servaddr.sin_port)); echo_ser(sock); return 0; }
