网络编程的学习之udp

Udp编程过程

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服务端需要一个地址，去保留名字和ip地址

交互的时候发结构体

下面这个宏只能在c语言里使用

 ser.sin_port = htons(50000);

上面是端口号50000以上，两边要一样

这里是不要让udp发的太快，发个东西过去

收和发的时候次数要一致

无状态的

为什么右边写在里面比较结束标志

验证了udp发送接收的数据是有边界

Netstat可以查看网络状态

服务器端

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <time.h>
typedef struct sockaddr * (SA);
typedef enum {CMD_LOGIN,CMD_CHAT,CMD_LOGOUT}TYPE;
typedef struct 
{TYPE type;char name[50];char context[128];}MSG;
typedef struct 
{struct sockaddr_in cli;int flag; // 0  free 1 occu
}LIST;
#define MAX 10
LIST list[MAX]={0};
int do_login(int sockfd,MSG* msg,struct sockaddr_in* cli)
{int i = 0 ;for(i=0;i<MAX;i++){if(1 == list[i].flag ){sendto(sockfd,msg,sizeof(MSG),0,(SA)&list[i].cli,sizeof(list[i].cli));}}for(i=0;i<MAX;i++){if(0 == list[i].flag ){list[i].flag =1;//list[i].cli = *cli;memcpy(&list[i].cli,cli,sizeof(*cli));break;}}return 0;
}int do_chat(int sockfd, MSG* msg,struct sockaddr_in*cli)
{int i = 0 ;for(i=0;i<MAX;i++){if(1 == list[i].flag && 0!=memcmp(&list[i].cli,cli,sizeof(*cli)) ){sendto(sockfd,msg,sizeof(MSG),0,(SA)&list[i].cli,sizeof(list[i].cli));}}
}
int do_logout(int sockfd, MSG* msg,struct sockaddr_in*cli)
{return 0;
}
int main(int argc, char *argv[])
{int sockfd = socket(AF_INET,SOCK_DGRAM,0);if(-1 == sockfd){perror("socket");exit(1);}// man 7 ip struct sockaddr_in ser,cli;bzero(&ser,sizeof(ser));bzero(&cli,sizeof(cli));ser.sin_family = AF_INET;// 大小端转化 host to net short ser.sin_port = htons(50000);ser.sin_addr.s_addr = inet_addr("127.0.0.1");int ret = bind(sockfd,(SA)&ser,sizeof(ser));if(-1 == ret){perror("bind");exit(1);}socklen_t len = sizeof(cli);MSG msg;while(1){bzero(&msg,sizeof(msg));recvfrom(sockfd,&msg,sizeof(msg),0,(SA)&cli,&len);switch(msg.type){case CMD_LOGIN:do_login(sockfd,&msg,&cli);break;case CMD_LOGOUT:do_logout(sockfd,&msg,&cli);break;case CMD_CHAT:do_chat(sockfd,&msg,&cli);break;}}close(sockfd);return 0;
}

用户端

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <time.h>
typedef struct sockaddr * (SA);
typedef enum {CMD_LOGIN,CMD_CHAT,CMD_LOGOUT}TYPE;
typedef struct 
{TYPE type;char name[50];char context[128];}MSG;
int main(int argc, char *argv[])
{int sockfd = socket(AF_INET,SOCK_DGRAM,0);if(-1 == sockfd){perror("socket");exit(1);}// man 7 ip struct sockaddr_in ser,cli;bzero(&ser,sizeof(ser));ser.sin_family = AF_INET;// 大小端转化 host to net short ser.sin_port = htons(50000);ser.sin_addr.s_addr = inet_addr("127.0.0.1");socklen_t len = sizeof(cli);MSG msg;char name[50]={0};printf("input name:");fgets(name,sizeof(name),stdin);name[strlen(name)-1]='\0';msg.type = CMD_LOGIN;strcpy(msg.name ,name);strcpy(msg.context,"login");sendto(sockfd,&msg,sizeof(msg),0,(SA)&ser,sizeof(ser));pid_t pid = fork();if(pid>0){while(1){bzero(&msg,sizeof(msg));recvfrom(sockfd,&msg,sizeof(msg),0,NULL,NULL);    printf("%s:%s\n",msg.name,msg.context);}}else if(0==pid){while(1){printf("to all");    char buf[128]={0};strcpy(msg.name,name);msg.type = CMD_CHAT;fgets(msg.context,sizeof(msg.context),stdin);//#quitmsg.context[strlen(msg.context)-1]='\0';if(0==strcmp(msg.context,"#quit")){msg.type = CMD_LOGOUT;strcpy(msg.context,"CMD_LOGOUT");}sendto(sockfd,&msg,sizeof(msg),0,(SA)&ser,sizeof(ser));}}else {perror("fork");exit(1);}close(sockfd);return 0;
}