udp的socket的helloworld

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[root@red54apple test]# cat udpclient.c #include <sys/types.h>#include <sys/socket.h>#include <string.h>#include <netinet/in.h>#include <stdio.h>#include <stdlib.h>#include <arpa/inet.h>#include <unistd.h>#define MAXLINE 80#define SERV_PORT 8888void do_cli(FILE *fp, int sockfd, struct sockaddr *pservaddr, socklen_t servlen){int n;char sendline[MAXLINE], recvline[MAXLINE + 1];/* connect to server */if(connect(sockfd, (struct sockaddr *)pservaddr, servlen) == -1){perror("connect error");exit(1);}while(fgets(sendline, MAXLINE, fp) != NULL){/* read a line and send to server */write(sockfd, sendline, strlen(sendline));/* receive data from server */n = read(sockfd, recvline, MAXLINE);if(n == -1){perror("read error");exit(1);}recvline[n] = 0; /* terminate string */fputs(recvline, stdout);}}int main(int argc, char **argv){int sockfd;struct sockaddr_in servaddr;/* check args */if(argc != 2){printf("usage: udpclient <IPaddress>\n");exit(1);}/* init servaddr */bzero(&servaddr, sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_port = htons(SERV_PORT);if(inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0){printf("[%s] is not a valid IPaddress\n", argv[1]);exit(1);}sockfd = socket(AF_INET, SOCK_DGRAM, 0);do_cli(stdin, sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));return 0;}[root@red54apple test]#


[root@red54apple test]# cat udpserv.c #include <sys/types.h>#include <sys/socket.h>#include <string.h>#include <netinet/in.h>#include <stdio.h>#include <stdlib.h>#define MAXLINE 80#define SERV_PORT 8888void do_echo(int sockfd, struct sockaddr *pcliaddr, socklen_t clilen){int n;socklen_t len;char mesg[MAXLINE];for(;;){len = clilen;/* waiting for receive data */n = recvfrom(sockfd, mesg, MAXLINE, 0, pcliaddr, &len);/* sent data back to client */sendto(sockfd, mesg, n, 0, pcliaddr, len);}}int main(void){int sockfd;struct sockaddr_in servaddr, cliaddr;sockfd = socket(AF_INET, SOCK_DGRAM, 0); /* create a socket *//* init servaddr */bzero(&servaddr, sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_addr.s_addr = htonl(INADDR_ANY);servaddr.sin_port = htons(SERV_PORT);/* bind address and port to socket */if(bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1){perror("bind error");exit(1);}do_echo(sockfd, (struct sockaddr *)&cliaddr, sizeof(cliaddr));return 0;}[root@red54apple test]# 检查方法netstat -ln|grep 8888