UDP服務器

#include <myheader.h>//宏定義打印錯誤信息
#define PRINT_ERR(msg)                                  \do                                                  \{                                                   \printf("%S,%D,%S\n",__FILE__,__LINE__,__func__);\perror(msg);                                    \exit(-1);                                       \}while(0);//定義一個結構體
//由于客戶端給服務器發送第數據內容較多，定義一個結構體來發送
typedef struct
{char code;  //操作碼 ‘L’登錄 ‘C’群聊 ‘Q’退出char name[32];   //保存登錄用戶名char txt[128];   //保存發送的信息
}msg_t;//定義一個鏈表
// 給在線所有客戶端發送數據，將每一個客戶端的信息用鏈表來保存
typedef struct NODE
{struct sockaddr_in c_addr;   //數據域  客戶端第網絡信息結構體struct NODE *next;   // 指針域   保存下一個結點的地址
}node_t;//創建一個鏈表頭第函數，定義鏈表頭結點
//鏈表頭結點函數
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)
{//遍歷鏈表將登錄信息發送給所以人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");}}//將登錄的客戶端信息插入保存在鏈表//頭插//定義一個新的指針保存客戶端信息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)
{//遍歷鏈表，將消息發給除自己之外的所有人node_t *p = phead;while (p->next != NULL){p = p->next;//判斷鏈表客戶端信息是否是自己//是自己就不發送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){//判斷鏈表客戶端信息是否是自己//是自己就不發送并且將自己的客戶端信息在鏈表內刪除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[])
{//入參合理性判斷if(argc != 3){printf("age:%s ip port\n",argv[0]);return -1;}//創建套接字int sfd = socket(AF_INET,SOCK_DGRAM,0);if(sfd == -1){perror("socket error");return -1;}printf("sfd = %d\n",sfd);//創建服務器網絡信息結構體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);//綁定if(bind(sfd,(struct sockaddr*)&sin,sizeof(sin)) == -1){perror("bind error");return -1;}printf("bind success\n");//創建客戶端的網絡信息結構體struct sockaddr_in cin;memset(&cin,0,sizeof(cin));socklen_t cin_len = sizeof(cin);msg_t msg;//建一個父子進程 //用來實現服務器既可以發送系統消息，又可以接收客戶端的信息pid_t pid;pid = fork();if(pid == -1){//創建錯誤perror("fork error");}else if(pid == 0){//子進程//接收數據并處理//循環接收客戶端發來的信息，通過Switch判斷code所存的協議//定義鏈表頭結點node_t *phead = NULL;creat_link(&phead);phead->next = NULL;//循環接受客戶端發來的信息并通過switch進行判斷執行哪個功能函數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){//父進程//發送系統信息//視為一個客戶端，向子進程發送消息給在線客戶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客戶端

#include <myheader.h>//宏定義打印錯誤信息
#define perror(msg)                                      \do                                                      \{                                                       \printf("%s,%d,%s\n", __FILE__, __LINE__, __func__); \perror(msg);                                        \exit(-1);                                           \} while (0)typedef struct
{char code; //操作碼 'L' 登錄  'C' 群聊  'Q' 退出char name[32];char txt[128];
} msg_t;int main(int argc, const char *argv[])
{//入參合理性判斷if (argc != 3){printf("age:%s ip port\n", argv[0]);return -1;}//創建套接字int sfd;if ((sfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1){perror("socket error");}//創建服務器網絡信息結構體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);//給服務器發送登錄數據包msg_t msg;memset(&msg, 0, sizeof(msg_t));msg.code = 'L';printf("請輸入用戶名：");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");}//創建父子進程pid_t pid;pid = fork();if (pid == -1){perror("fork error");}else if (pid == 0){//子進程//接受數據并處理while (1){//每次循環前將msg置零memset(&msg, 0, sizeof(msg));//接受服務器發過來的信息并打印到終端上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){//父進程//發送消息while (1){   //memset會把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;
}