客户端

#include <myhead.h>
//定义存储信息结构体
typedef struct _MSG
{char code;  //操作码：'L'表示登录'C表示群聊'S'表示系统消息'S'表示退出char name[128];  char txt[256];}msg_t;//定义保存客户端网络信息的链表
typedef struct _ADDR
{struct sockaddr_in cin;struct _ADDR* next;
}addrlist_t;//登录操作的函数
void do_login(int sfd,msg_t msg,addrlist_t*addr,struct sockaddr_in cin)
{//先遍历链表 将新用户加入群聊的消息发送给所有人addrlist_t* tmp = addr;  //记录链表头结点while(tmp->next != NULL){tmp = tmp->next;if(sendto(sfd, &msg, sizeof(msg), 0, (struct sockaddr*)&(tmp->cin),sizeof(tmp->cin)) == -1){perror("sendto error");return;}}//将新用户的网络信息结构体头插入链表addrlist_t* pnew = NULL;if(NULL == (pnew = (addrlist_t*)malloc(sizeof(addrlist_t)))){printf("malloc error\n");return;}pnew->cin = cin;pnew->next = addr->next;addr->next = pnew;printf("%s已上线\n",msg.name);return;
}//群聊操作函数
void do_chat(int sfd,msg_t msg,addrlist_t*addr,struct sockaddr_in cin)
{//遍历链表，将群聊消息发给除自己以外其他人addrlist_t* ptmp = addr;while(ptmp->next != NULL){ptmp = ptmp->next;if(memcmp(&cin, &(ptmp->cin), sizeof(cin))){//说明不是自己就发送数据if(sendto(sfd, &msg, sizeof(msg), 0, (struct sockaddr*)&(ptmp->cin),sizeof(ptmp->cin)) == -1){perror("sendto error");return;}}}return;
}//退出操作的函数
void do_quit(int sfd,msg_t msg,addrlist_t*addr,struct sockaddr_in cin)
{//遍历链表 是自己就将自己在链表中删除，不是自己就发送退出群聊的数据addrlist_t* ptmp = addr;addrlist_t* del = NULL;while(ptmp->next != NULL){if(memcmp(&(ptmp->next->cin), &cin, sizeof(cin))){//不是自己ptmp = ptmp->next;if((sendto(sfd,&msg,sizeof(msg),0,(struct sockaddr*)&(ptmp->cin),sizeof(ptmp->cin))) == -1){perror("sendto error");return;}}else{del = ptmp->next;ptmp->next = del->next;free(del);del=NULL;}}printf("%s已下线\n",msg.name);return;
}
int main(int argc, const char *argv[])
{if(argc != 3){   //输入ip地址及端口号,进行判断printf("input error\n");printf("usage: %s <IP> <PORT>\n",argv[0]);return -1;}//定义用于接收等待套接字int sfd;if((sfd = socket(AF_INET,SOCK_DGRAM,0)) == -1){perror("socket error");return -1;}printf("socket sfd success\n");//设置端口号快速重用int reuse = 1;if(setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1){perror("setsockopt error");return -1;}printf("设置端口号快速重用_%d_%s_%s_\n",__LINE__,__FILE__,__func__);//绑定(填充服务器信息结构体)struct sockaddr_in sin;sin.sin_family = AF_INET;sin.sin_port   = htons(atoi(argv[2]));sin.sin_addr.s_addr = inet_addr(argv[1]);socklen_t seraddr_len = sizeof(sin);if((bind(sfd, (struct sockaddr*)&sin, seraddr_len)) == -1){perror("bind error");return -1;}printf("bind success\n");//定义客户端网络信息结构体struct sockaddr_in cin;socklen_t cliaddr_len = sizeof(cin);msg_t msg;  //定义接收信息的变量msgpid_t pid;  //进程号pid = fork();  //创建多进程if(pid < 0){perror("fork error");return -1;}else if(pid == 0){   //子进程，用来收发数据//创建保存客户端信息的链表头结点addrlist_t* addr;if(NULL == (addr = (addrlist_t*)malloc(sizeof(addrlist_t)))){printf("malloc error\n");return -1;}memset(addr, 0, sizeof(addr));addr->next = NULL;while(1){  //循环收发数据memset(&msg,0,sizeof(msg));  //每次接收新用户数据清空memset(&cin,0,sizeof(cin)); //接收客户端发送的消息，存放在msg中if((recvfrom(sfd, &msg,sizeof(msg), 0,(struct sockaddr*)&cin, &cliaddr_len)) == -1){perror("recvfrom error\n");return -1;}switch(msg.code){  //判断消息中的操作码，根据操作码执行对应操作case 'L':   //登录操作do_login(sfd,msg,addr,cin);break;case 'C':   //群聊操作do_chat(sfd,msg,addr,cin);break;case 'Q':   //退出操作do_quit(sfd,msg,addr,cin);break;}}}else{//父进程，用来发送系统消息//向子进程发送群聊消息strcpy(msg.name, "系统消息");msg.code = 'C';while(1){memset(msg.txt, 0,sizeof(msg.txt));fgets(msg.txt, 256,stdin);  //终端获取接收消息msg.txt[strlen(msg.txt)-1] = '\0';if((sendto(sfd,&msg,sizeof(msg),0 ,(struct sockaddr*)&sin,seraddr_len)) == -1){perror("sendto error");return -1;}}}close(sfd);return 0;
}

服务器

#include <myhead.h>
typedef struct _MSG
{char code; //操作码：'L'表示登录'C'表示群聊'S'表示系统内存出错'S'表示系统消息char name[128];char txt[256];
}msg_t;   //定义消息结构体类型int main(int argc, const char *argv[])
{if(3 != argc){  //考虑用命令行传参方式输入ip地址及端口号,先进行判断printf("input error!\n");printf("usage:%s <IP> <PORT>\n", argv[0]);return -1;}//定义通信的套接字int sfd = socket(AF_INET, SOCK_DGRAM, 0);if(-1 == sfd){perror("sockfd error");return -1;}//定义服务器地址信息结构体struct sockaddr_in sin;memset(&sin, 0,sizeof(sin));sin.sin_family = AF_INET;sin.sin_port   = htons(atoi(argv[2]));sin.sin_addr.s_addr = inet_addr(argv[1]);socklen_t seraddr_len = sizeof(sin);msg_t msg;memset(&msg,0,sizeof(msg));//输入用户名printf("请输入用户名:");fgets(msg.name,45,stdin);msg.name[strlen(msg.name)-1] = '\0';msg.code = 'L';strcpy(msg.txt,"加入群聊");//给服务器发送登录信息if(sendto(sfd,&msg,sizeof(msg),0,(struct sockaddr*)&sin,seraddr_len) == -1){perror("sendto error");return -1;}//定义父子进程并创建pid_t pid = 0;pid = fork();if(pid < 0){printf("fork error\n");return -1;}else if(pid == 0){  //子进程，循环接收并打印接收的数据while(1){if(recvfrom(sfd,&msg,sizeof(msg),0,NULL,NULL) == -1){perror("sendto error");return -1;}//打印收到的数据printf("[%s]:%s\n",msg.name, msg.txt);}}else{   //父进程循环接收终端数据并发送给客户端while(1){memset(msg.txt,0,sizeof(msg.txt));fgets(msg.txt,128,stdin);  //终端获取聊天消息msg.txt[strlen(msg.txt)-1] = '\0';if(strcmp(msg.txt, "quit") == 0){msg.code = 'Q';strcpy(msg.txt, "退出群聊");}else{msg.code = 'C';}if(sendto(sfd,&msg,sizeof(msg), 0,(struct sockaddr*)&sin,seraddr_len) == -1){perror("sendto error");return -1;}if(strcmp(msg.txt, "退出群聊") == 0){break;}}//杀死子进程kill(pid,SIGKILL);wait(NULL);  //等待回收子进程资源}close(sfd);return 0;
}