1. 将UDP服务器客户端脱离笔记重新搭建（上交）
2. 完成下载上传（上交，必须完成下载，上传尽力完成）

下载客户端

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<fcntl.h>
#include<sys/stat.h>#define ERR_MSG(msg) do{\fprintf(stderr,"Line:%d",__LINE__);\perror(msg);\
}while(0)#define IP "192.168.0.196"  //本机IP
#define PORT 69int main(int argc, const char *argv[])
{//创建套接字int client_fd = socket(AF_INET,SOCK_DGRAM,0);if(client_fd < 0){ERR_MSG("socket");return -1;}printf("socket create success server_fd=%d__%d__\n",client_fd,__LINE__);//填充客户端的地址信息结构体struct sockaddr_in cin;cin.sin_family = AF_INET;cin.sin_port = htons(PORT);cin.sin_addr.s_addr = inet_addr(IP);//	sockaddr_in addrlen = sizeof(cin);char buf[516] = {0};bzero(buf,sizeof(buf));unsigned short *p1 = (unsigned short*)buf;  		//操作码*p1 = htons(1);char *p2 = buf+2;char filename[128] = "" ;printf("请输入要下载的文件名>>>>>");scanf("%s",filename);getchar();strcpy(p2,filename);  	//要下载的文件名char *p3 = p2+strlen(p2);*p3 = 0;char *p4 = p3+1;strcpy(p4,"octet"); 		//模式char *p5 = p4+strlen(p4);*p5 = 0;int size = 2+1+1+strlen(p2)+strlen(p4);//请求下载ssize_t ret = sendto(client_fd,buf,size,0,(struct sockaddr*)&cin,sizeof(cin)); if(ret < 0){ERR_MSG("sendto");return -1;}printf("sendto success\n");socklen_t addrlen = sizeof(cin);//打开文件int fd;ssize_t recv_len;ssize_t res = 0;unsigned short num = 0;while(1){bzero(buf,sizeof(buf));recv_len = recvfrom(client_fd,buf,sizeof(buf),0,(struct sockaddr*)&cin,&addrlen);if(recv_len < 0){ERR_MSG("recvfrom");return -1;}printf("recvfrom success\n");if(buf[1] == 0x05){fprintf(stderr,"download erro____%d____%s\n",ntohs(*(short*)(buf+2)),buf+4);break;}else if(buf[1] == 0x03)					//此时正常获取到数据包{printf("获取\n");fd = open(filename, O_WRONLY|O_CREAT|O_APPEND, 0666);if(fd < 0){ERR_MSG("open");return -1; }//判断块编号/*	if(*(unsigned short*)(buf+2) == htons(num)){*/printf("kuaibianhao\n");if(write(fd,buf+4,recv_len-4) < 0){ERR_MSG("write");ret = -1;break;}printf("write success\n");buf[1] = 0x04;if(sendto(client_fd,buf,4,0,(struct sockaddr*)&cin,sizeof(cin)) < 0){ERR_MSG("sendto");return -1;}printf("sendto success\n");if(recv_len < 516){break;}close (fd);	}		}printf("下载完成\n");//关闭套接字close(client_fd);return 0;}

UDP服务器

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<unistd.h>
#include<arpa/inet.h>#define ERR_MSG(msg) do{\fprintf(stderr,"Line:%d",__LINE__);\perror(msg);\
}while(0)#define IP "192.168.0.141"  //本机IP
#define PORT 2222int main(int argc, const char *argv[])
{//创建套接字int server_fd = socket(AF_INET,SOCK_DGRAM,0);if(server_fd < 0){ERR_MSG("socket");return -1;}printf("socket create success server_fd=%d__%d__\n",server_fd,__LINE__);//填充服务器的地址信息结构体struct sockaddr_in sin;sin.sin_family = AF_INET;sin.sin_port = htons(PORT);sin.sin_addr.s_addr = inet_addr(IP);//绑定---->>>>>必须绑定if(bind(server_fd,(struct sockaddr*)&sin,sizeof(sin)) < 0){ERR_MSG("bind");return -1;}printf("bind success __%d__\n",__LINE__);//存储客户端地址信息struct sockaddr_in cin;socklen_t cin_addrlen = sizeof(cin);char ch[128] = "" ;ssize_t res = 0;while(1){bzero(ch,sizeof(ch));//接受数据res = recvfrom(server_fd,ch,sizeof(ch),0,(struct sockaddr*)&cin,&cin_addrlen);if(res < 0){ERR_MSG("recvfrom");return -1;}printf(":%s\n",ch);//发送数据strcat(ch,"*-*");sendto(server_fd,ch,sizeof(ch),0,(struct sockaddr*)&cin,sizeof(cin));}//关闭套接字close(server_fd);return 0;
}

UDP客户端

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>#define ERR_MSG(msg){\fprintf(stdout,"cline----->%d",__LINE__);\perror(msg);\
}int main(int argc,const char * argv[])
{//1.socketint cfd = socket(AF_INET,SOCK_DGRAM,0);ssize_t sendto_return;ssize_t recvfrom_return;char buf[128];struct sockaddr_in s;s.sin_family = AF_INET;s.sin_port = htons(6666);s.sin_addr.s_addr = inet_addr(argv[1]);int s_len = sizeof(s);while(1){bzero(buf,sizeof(buf));fgets(buf,sizeof(buf),stdin);//3.sendtosendto_return = sendto(cfd,buf,sizeof(buf),0,(struct sockaddr *)&s,s_len);if(sendto_return < 0){ERR_MSG("sendto");return -1;}bzero(buf,sizeof(buf));//4.recvfromrecvfrom_return = recvfrom(cfd,buf,sizeof(buf),0,(struct sockaddr *)&s,&s_len);if(recvfrom_return < 0){ERR_MSG("recvfrom");return -1;}printf("客户端收到消息是：%s\n",buf);}close(cfd);return 0;
}