http解析之客服端的实现.doc

大家都很熟悉HTTP协议的应用，因为每天都在网络上浏览着不少东西，也都知道是HTTP协议是相当简单的。每次用thunder之类的下载软件下载网页，当用到那个“用thunder下载全部链接”时总觉得很神奇。后来想想，其实要实现这些下载功能也并不难，只要按照HTTP协议发送request，然后对接收到的数据进行分析，如果页面上还有href之类的链接指向标志就可以进行深一层的下载了。HTTP协议目前用的最多的是1.1版本，要全面透彻地搞懂它就参考RFC2616文档吧。我是怕rfc文档了的,要看自己去看吧_源代码如下：/* http客户端程序 httpclient.c */#include#include#include#include#include#include#include#include#include#include#include#include/httpclient.c 开始/*功能：搜索字符串右边起的第一个匹配字符*/char*Rstrchr(char*s,charx)inti=strlen(s);if(!(*s)return0;while(si-1)if(strchr(s+(i-1),x)return(s+(i-1);elsei-;return0;/*功能：把字符串转换为全小写*/voidToLowerCase(char*s)while(s&*s)*s=tolower(*s);s+;/*功能：从字符串src中分析出网站地址和端口，并得到用户要下载的文件*/voidGetHost(char*src,char*web,char*file,int*port)char*pA;char*pB;memset(web,0,sizeof(web);memset(file,0,sizeof(file);*port=0;if(!(*src)return;pA=src;if(!strncmp(pA,http:/,strlen(http:/)pA=src+strlen(http:/);elseif(!strncmp(pA,https:/,strlen(https:/)pA=src+strlen(https:/);pB=strchr(pA,/);if(pB)memcpy(web,pA,strlen(pA)-strlen(pB);if(pB+1)memcpy(file,pB+1,strlen(pB)-1);filestrlen(pB)-1=0;elsememcpy(web,pA,strlen(pA);if(pB)webstrlen(pA)-strlen(pB)=0;elsewebstrlen(pA)=0;pA=strchr(web,:);if(pA)*port=atoi(pA+1);else*port=80;intmain(intargc,char*argv)intsockfd;charbuffer1024;structsockaddr_inserver_addr;structhostent*host;intportnumber,nbytes;charhost_addr256;charhost_file1024;charlocal_file256;FILE*fp;charrequest1024;intsend,totalsend;inti;char*pt;if(argc!=2)fprintf(stderr,Usage:%s web-address/a/n,argv0);exit(1);printf(parameter.1 is: %s/n,argv1);ToLowerCase(argv1);/*将参数转换为全小写*/printf(lowercase parameter.1 is: %s/n,argv1);GetHost(argv1,host_addr,host_file,&portnumber);/*分析网址、端口、文件名等*/printf(webhost:%s/n,host_addr);printf(hostfile:%s/n,host_file);printf(portnumber:%d/n/n,portnumber);if(host=gethostbyname(host_addr)=NULL)/*取得主机IP地址*/fprintf(stderr,Gethostname error, %s/n,strerror(errno);exit(1);/* 客户程序开始建立 sockfd描述符 */if(sockfd=socket(AF_INET,SOCK_STREAM,0)=-1)/*建立SOCKET连接*/fprintf(stderr,Socket Error:%s/a/n,strerror(errno);exit(1);/* 客户程序填充服务端的资料 */bzero(&server_addr,sizeof(server_addr);server_addr.sin_family=AF_INET;server_addr.sin_port=htons(portnumber);server_addr.sin_addr=*(structin_addr*)host-h_addr);/* 客户程序发起连接请求 */if(connect(sockfd,(structsockaddr*)(&server_addr),sizeof(structsockaddr)=-1)/*连接网站*/fprintf(stderr,Connect Error:%s/a/n,strerror(errno);exit(1);sprintf(request,GET /%s HTTP/1.1/r/nAccept: */*/r/nAccept-Language: zh-cn/r/n/User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)/r/n/Host: %s:%d/r/nConnection: Close/r/n/r/n,host_file,host_addr,portnumber);printf(%s,request);/*准备request，将要发送给主机*/*取得真实的文件名*/if(host_file&*host_file)pt=Rstrchr(host_file,/);elsept=0;memset(local_file,0,sizeof(local_file);if(pt&*pt)if(pt+1)&*(pt+1)strcpy(local_file,pt+1);elsememcpy(local_file,host_file,strlen(host_file)-1);elseif(host_file&*host_file)strcpy(local_file,host_file);elsestrcpy(local_file,index.html);printf(local filename to write:%s/n/n,local_file);/*发送http请求request*/send=0;totalsend=0;nbytes=strlen(request);while(totalsendnbytes)send=write(sockfd,request+totalsend,nbytes-totalsend);if(send=-1)printf(send error!%s/n,strerror(errno);exit(0);totalsend+=send;printf(%d bytes send OK!/n,totalsend);fp=fopen(local_file,a);if(!fp)printf(create file error! %s/n,strerror(errno);return0;printf(/nThe following is the response header:/n);i=0;/* 连接成功了，接收http响应，response */while(nbytes=read(sockfd,buffer,1)=1)if(i4)if(buffer0=/r|buffer0=/n)i+;elsei=0;printf(%c,buffer0);/*把http头信息打印在屏幕上*/elsefwrite(buffer,1,1,fp);/*将http主体信息写入文件*/i+;if(i%1024=0)fflush(fp);/*每1K时存盘一次*/fclose(fp);/* 结束通讯 */close(sockfd);exit(0);zjzj:/C_pram/practice/http_client$ lshttpclient httpclient.czjzj:/C_pram/practice/http_client$ ./httpclient /parameter.1 is: /lowercase parameter.1 is: /webhost:hostfile:portnumber:80GET / HTTP/1.1Accept: */*Accept-Language: zh-cnUser-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)Host: :80Connection: Closelocal filename to write:index.html163 bytes send OK!The following is the response header:HTTP/1.1 200 OKDate: Wed, 29 Oct 2008 10:41:40 GMTServer: BWS/1.0Content-Length: 4216Content-Type: text/htmlCache-Control: privateExpires: Wed, 29 Oct 2008 10:41:40 GMTSet-Cookie: BAIDUID=A93059C8DD