本文共 4453 字，大约阅读时间需要 14 分钟。
转载者注：网上原文件有个小bug，下面贴的是已修复后的代码
/******* 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, char x) { int i = strlen(s); if(!(*s)) return 0; while(s[i-1]) if(strchr(s + (i - 1), x)) return (s + (i - 1)); else i--; return 0;}/************************************************************** 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 ***************************************************************/void GetHost(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://"); else if(!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); file[strlen(pB) - 1] = 0; } } else memcpy(web, pA, strlen(pA)); if(pB) web[strlen(pA) - strlen(pB)] = 0; else web[strlen(pA)] = 0; pA = strchr(web, ':'); if(pA) *port = atoi(pA + 1); else *port = 80;}/********************************************************************* *filename: httpclient.c *purpose: HTTP协议客户端程序，可以用来下载网页 *wrote by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com) Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言 *date time:2006-03-11 21:49:00 *Note: 任何人可以任意复制代码并运用这些代码，当然包括你的商业用途 * 但请遵循GPL *********************************************************************/int main(int argc, char *argv[]){ int sockfd; char buffer[1024]; struct sockaddr_in server_addr; struct hostent *host; int portnumber,nbytes; char host_addr[256]; char host_file[1024]; char local_file[256]; FILE * fp; char request[1024]; int send, totalsend; int i; char * pt; if(argc!=2) { fprintf(stderr,"Usage:%s web-address\a\n",argv[0]); exit(1); } printf("parameter.1 is: %s\n", argv[1]); GetHost(argv[1], 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=*((struct in_addr *)host->h_addr); /* 客户程序发起连接请求 */ if(connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-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, '/'); else pt = 0; memset(local_file, 0, sizeof(local_file)); if(pt && *pt) { if((pt + 1) && *(pt+1)) strcpy(local_file, pt + 1); else memcpy(local_file, host_file, strlen(host_file) - 1); } else if(host_file && *host_file) strcpy(local_file, host_file); else strcpy(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(totalsend < nbytes) { 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)); return 0; } 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(i < 4) { if(buffer[0] == '\r' || buffer[0] == '\n') i++; else i = 0; printf("%c", buffer[0]);/*把http头信息打印在屏幕上*/ } else { fwrite(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);}//httpclient.c 结束///