基于无连接(UDP协议)的服务器与客户端编程实例

client.c

#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/un.h>#include <sys/socket.h>#include <sys/unistd.h>#include <arpa/inet.h>#define PORT        8999#define DESIP  "127.0.0.1"#define MAXSIZE     4096int main(int argc, char *argv[]){    int sockfd, addr_len;    struct sockaddr_in des_addr;    char sendmsg[MAXSIZE], recvmsg[MAXSIZE];           sockfd = socket(AF_INET, SOCK_DGRAM, 0);    if (sockfd < 0) {        perror("socket error");        return -1;    }    des_addr.sin_family = AF_INET;    des_addr.sin_port = htons(PORT);    des_addr.sin_addr.s_addr = inet_addr(DESIP);    bzero(&(des_addr.sin_zero), 8);    while (1) {        memset(recvmsg, 0, MAXSIZE);        memset(sendmsg, 0, MAXSIZE);        printf("input:\n");        //gets(sendmsg);        if (read(STDIN_FILENO,sendmsg,10) == -1)        printf("input error");        //printf("sendmsg = %s\n",sendmsg);        if (strcmp(sendmsg, "quit") == 0) {            close(sockfd);            printf("close connection\n");            return -1;        }        if (sendto(sockfd, sendmsg, strlen(sendmsg) + 1, 0, (struct sockaddr *)&des_addr, sizeof(struct sockaddr)) < 0) {            perror("sendto");            continue;        }        printf("send ok...\n");      //  while (1) {/* 所谓的非阻塞I/O */        //    addr_len = sizeof(struct sockaddr);          //  if (recvfrom(sockfd, recvmsg, MAXSIZE, 0, (struct sockaddr *)&des_addr, &addr_len) < 0) {            //    continue;            //}           // printf("recv from %s : %s\n", inet_ntoa(des_addr.sin_addr), recvmsg);         //   break;       // }    }       return 0;   }

server.c

#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/un.h>#include <sys/socket.h>#include <sys/unistd.h>#include <arpa/inet.h>#define PORT        8999#define MAXSIZE     4096int main(int argc, char *argv[]){    int sockfd, addr_len;    struct sockaddr_in serv_addr, clnt_addr;    char recvmsg[MAXSIZE], sendmsg[MAXSIZE];           sockfd = socket(AF_INET, SOCK_DGRAM, 0);    if (sockfd < 0) {        perror("socket error");        return -1;    }    serv_addr.sin_family = AF_INET;    serv_addr.sin_port = htons(PORT);    serv_addr.sin_addr.s_addr = INADDR_ANY;    bzero(&(serv_addr.sin_zero), 8);     if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr)) < 0) {        perror("bind err");        return -1;    }    while(1) {        memset(sendmsg, 0, MAXSIZE);        memset(recvmsg, 0, MAXSIZE);        addr_len = sizeof(struct sockaddr);        /* 所谓的非阻塞I/O */        if (recvfrom(sockfd, recvmsg, MAXSIZE, 0, (struct sockaddr *)&clnt_addr, &addr_len) < 0) {            perror("recv");            continue;        }               printf("begin to accept\n");        printf("recv from %s : %s\n", inet_ntoa(clnt_addr.sin_addr), recvmsg);       // strcpy(sendmsg, "who are you ?? Let me cc!");       // sendto(sockfd, sendmsg, strlen(sendmsg) + 1, 0, (struct sockaddr *)&clnt_addr, addr_len);    }     return 0;}