UDP服务器

#include <myheader.h>//宏定义打印错误信息
#define PRINT_ERR(msg)                                  \do                                                  \{                                                   \printf("%S,%D,%S\n",__FILE__,__LINE__,__func__);\perror(msg);                                    \exit(-1);                                       \}while(0);//定义一个结构体
//由于客户端给服务器发送第数据内容较多，定义一个结构体来发送
typedef struct
{char code;  //操作码 ‘L’登录 ‘C’群聊 ‘Q’退出char name[32];   //保存登录用户名char txt[128];   //保存发送的信息
}msg_t;//定义一个链表
// 给在线所有客户端发送数据，将每一个客户端的信息用链表来保存
typedef struct NODE
{struct sockaddr_in c_addr;   //数据域  客户端第网络信息结构体struct NODE *next;   // 指针域   保存下一个结点的地址
}node_t;//创建一个链表头第函数，定义链表头结点
//链表头结点函数
void creat_link(node_t **head)
{*head = (node_t *)malloc(sizeof(node_t));
}int do_register(int sockfd, msg_t msg, struct sockaddr_in clientaddr, node_t *phead)
{//遍历链表将登录信息发送给所以人node_t *p = phead;while (p->next != NULL){p = p->next;if (sendto(sockfd, &msg, sizeof(msg_t), 0, (struct sockaddr *)&(p->c_addr), sizeof(p->c_addr)) == -1){perror("recvfrom error");}}//将登录的客户端信息插入保存在链表//头插//定义一个新的指针保存客户端信息node_t *newp = NULL;creat_link(&newp);newp->c_addr = clientaddr;newp->next = phead->next;phead->next = newp;return 0;
}int do_group_chat(int sockfd, msg_t msg, struct sockaddr_in clientaddr, node_t *phead)
{//遍历链表，将消息发给除自己之外的所有人node_t *p = phead;while (p->next != NULL){p = p->next;//判断链表客户端信息是否是自己//是自己就不发送if (memcmp(&(p->c_addr), &clientaddr, sizeof(clientaddr))){if (sendto(sockfd, &msg, sizeof(msg_t), 0, (struct sockaddr *)&(p->c_addr), sizeof(p->c_addr)) == -1){perror("recvfrom error");}}}return 0;
}//退出群聊操作
int quit_group_chat(int sockfd, msg_t msg, struct sockaddr_in clientaddr, node_t *phead)
{node_t *p = phead;while (p->next != NULL){//判断链表客户端信息是否是自己//是自己就不发送并且将自己的客户端信息在链表内删除if (memcmp(&(p->next->c_addr), &clientaddr, sizeof(clientaddr))){p = p->next;if (sendto(sockfd, &msg, sizeof(msg_t), 0, (struct sockaddr *)&(p->c_addr), sizeof(p->c_addr)) == -1){perror("recvfrom error");}}else{node_t *pnew;pnew = p->next;p->next = pnew->next;pnew->next = NULL;free(pnew);pnew = NULL;}}return 0;
}int main(int argc, const char *argv[])
{//入参合理性判断if(argc != 3){printf("age:%s ip port\n",argv[0]);return -1;}//创建套接字int sfd = socket(AF_INET,SOCK_DGRAM,0);if(sfd == -1){perror("socket error");return -1;}printf("sfd = %d\n",sfd);//创建服务器网络信息结构体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 sin_len = sizeof(sin);//绑定if(bind(sfd,(struct sockaddr*)&sin,sizeof(sin)) == -1){perror("bind error");return -1;}printf("bind success\n");//创建客户端的网络信息结构体struct sockaddr_in cin;memset(&cin,0,sizeof(cin));socklen_t cin_len = sizeof(cin);msg_t msg;//建一个父子进程 //用来实现服务器既可以发送系统消息，又可以接收客户端的信息pid_t pid;pid = fork();if(pid == -1){//创建错误perror("fork error");}else if(pid == 0){//子进程//接收数据并处理//循环接收客户端发来的信息，通过Switch判断code所存的协议//定义链表头结点node_t *phead = NULL;creat_link(&phead);phead->next = NULL;//循环接受客户端发来的信息并通过switch进行判断执行哪个功能函数while (1){memset(&msg, 0, sizeof(msg));//清空操作memset(&cin, 0, sizeof(cin));//清空操作if ((recvfrom(sfd, &msg, sizeof(msg), 0, (struct sockaddr *)&cin, &cin_len)) == -1){perror("recvfrom error");}printf("%8s : [%s]\n", msg.name, msg.txt);switch (msg.code){case 'L':do_register(sfd, msg, cin, phead);break;case 'C':do_group_chat(sfd, msg, cin, phead);break;case 'Q':quit_group_chat(sfd, msg, cin, phead);break;}}}else if(pid > 0){//父进程//发送系统信息//视为一个客户端，向子进程发送消息给在线客户msg.code='C';strcpy(msg.name,"server");while(1){fgets(msg.txt,128,stdin);msg.txt[strlen(msg.txt)-1]='\0';if(sendto(sfd,&msg,sizeof(msg_t),0,(struct sockaddr *)&sin,sin_len)==-1){perror("sendto error");}}close(sfd);return 0;}return 0;
}

UDP客户端

#include <myheader.h>//宏定义打印错误信息
#define perror(msg)                                      \do                                                      \{                                                       \printf("%s,%d,%s\n", __FILE__, __LINE__, __func__); \perror(msg);                                        \exit(-1);                                           \} while (0)typedef struct
{char code; //操作码 'L' 登录  'C' 群聊  'Q' 退出char name[32];char txt[128];
} msg_t;int main(int argc, const char *argv[])
{//入参合理性判断if (argc != 3){printf("age:%s ip port\n", argv[0]);return -1;}//创建套接字int sfd;if ((sfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1){perror("socket error");}//创建服务器网络信息结构体struct sockaddr_in sin;memset(&sin, 0, sizeof(sin));sin.sin_family = AF_INET;sin.sin_addr.s_addr = inet_addr(argv[1]);sin.sin_port = htons(atoi(argv[2]));socklen_t sin_len = sizeof(sin);//给服务器发送登录数据包msg_t msg;memset(&msg, 0, sizeof(msg_t));msg.code = 'L';printf("请输入用户名：");fgets(msg.name, 32, stdin);msg.name[strlen(msg.name) - 1] = '\0';strcpy(msg.txt, "加入群聊");if (sendto(sfd, &msg, sizeof(msg_t), 0, (struct sockaddr *)&sin, sin_len) == -1){perror("sendto error");}//创建父子进程pid_t pid;pid = fork();if (pid == -1){perror("fork error");}else if (pid == 0){//子进程//接受数据并处理while (1){//每次循环前将msg置零memset(&msg, 0, sizeof(msg));//接受服务器发过来的信息并打印到终端上if (recvfrom(sfd, &msg, sizeof(msg_t), 0, NULL, NULL) == -1){perror("recvfrom error");}printf("%8s:[%s]\n", msg.name, msg.txt);}}else if (pid > 0){//父进程//发送消息while (1){   //memset会把name清除msg.code = 'C';fgets(msg.txt, 128, stdin);msg.txt[strlen(msg.txt) - 1] = '\0';if (strcmp(msg.txt, "quit") == 0){msg.code = 'Q';strcpy(msg.txt, "退出群聊");}if (sendto(sfd, &msg, sizeof(msg_t), 0, (struct sockaddr *)&sin, sin_len) == -1){perror("sendto error");}if (strcmp(msg.txt, "退出群聊") == 0){break;}}kill(pid,SIGKILL);wait(NULL);close(sfd);}return 0;
}