day36:网编day3，TCP、UDP模型

下载：

#include <myhead.h>#define ERR(s) do\
{\fprintf(stderr,"__%d__",__LINE__);\perror(s);\
}while(0)
#define PORT 69
#define IP "192.168.115.184"int do_download(int cfd,struct sockaddr_in sin);
//int do_upload();
int main(int argc, const char *argv[])
{//创建报式套接字socketint cfd;if((cfd = socket(AF_INET,SOCK_DGRAM,0)) < 0){ERR("socket");return -1;}printf("socket success\n");struct sockaddr_in sin;sin.sin_family = AF_INET;sin.sin_port = htons(PORT);sin.sin_addr.s_addr = inet_addr(IP);char choose = 0;while(1){system("clear");printf("--------------------------------\n");printf("-------------1下载--------------\n");printf("-------------2上传--------------\n");printf("-------------3退出--------------\n");printf("--------------------------------\n");printf("请输入>>>");scanf("%c",&choose);while(getchar()!=10); 	//吸收垃圾字符switch(choose){case '1':do_download(cfd,sin);break;case '2'://do_upload();break;case '3':goto END;break;default :printf("输入错误，请重新输入\n");}printf("请输入任意字符清屏\n");while(getchar()!=10);}
END://关闭套接字close(cfd);return 0;
}int do_download(int cfd,struct sockaddr_in sin)
{/*//组下载请求包char buf[516] = "";char f_n[20] = "";//操作码unsigned short *ptr1 = (unsigned short*)buf;*ptr1 = htons(1); 	//组操作码//文件名char *ptr2 = (char *)(ptr1+1);strcpy(ptr2,f_n);//模式char *ptr3 = ptr2 + strlen(f_n) + 1;strcpy(ptr3,"octet");int size = 2+strlen(ptr2)+1+strlen(ptr3)+1;*/char buf[516] = "";char f_n[20] = "";int num=1;printf("请输入文件名>>> ");//终端输入要下载的文件名fgets(f_n,sizeof(f_n),stdin);f_n[strlen(f_n)-1] = '\0';int fd;if((fd = open(f_n,O_WRONLY|O_CREAT|O_TRUNC,0664)) == -1){ERR("open");return -1;}//用sprintf拼接int size = sprintf(buf,"%c%c%s%c%s%c",0,1,f_n,0,"octet",0);//发送下载请求sendtoif(sendto(cfd,buf,size,0,(struct sockaddr*)&sin,sizeof(sin)) < 0 ){ERR("sendto askpackage");return -1;}printf("sendto askpackage success\n");ssize_t len = 0;struct sockaddr_in addrin;socklen_t addrlen=sizeof(addrin);while(1){//清空bufbzero(buf,sizeof(buf));//接收数据recvfrom，接收地址信息if((len = recvfrom(cfd,buf,sizeof(buf),0,(struct sockaddr*)&addrin,&addrlen)) < 0){ERR("recvfrom datapackage");return -1;}unsigned short ptr2=ntohs(*(unsigned short*)(buf+2));printf("%hu\n",ptr2);	//当操作码为5时if(5 == buf[1]){fprintf(stderr, "错误码：%d，错误信息：%s\n", ntohs(*(unsigned short*)(buf+2)), buf+4);			break;}//当操作码为3,并且块编号正确时else if(3 == buf[1] && num == ptr2){printf("%d\n",fd);//跳过前四个字节，写入文件if(write(fd,buf+4,len-4)<0){ERR("write");return -1;}//组ACK包buf[1] = 4;	//发送ACK包，sendtoif(sendto(cfd,buf,4,0,(struct sockaddr*)&addrin,addrlen) < 0){ERR("sendto ACKpackage");return -1;}num++;//判断数据是否小于512个字节，若小于则下载完成if(len < 516){printf("download success\n");break;}}}close(fd);return 0;
}

思维导图：有道云笔记