大家好,這次的代碼主要是從另外一位博主的博客上copy下來學習的,主要修改了其中有一點小問題的一段,其他地方略作修改,供大家交流學習。(在第一個函數中調用memset時使用了char *作爲sizeof的參數,這裏是不正確的,因爲函數傳參的時候是將數組轉爲指針傳遞的形參,sizeof大小是指針大小)
原博地址:http://blog.csdn.net/wxhlinux/article/details/8541483
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <unistd.h>
#include <netinet/in.h>
#include <limits.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <ctype.h>
#define HOST_ADDR_LEN 256
#define HOST_FILE_LEN 1024
/********************************************
* 功能:搜索字符串右邊起的第一個匹配字符
* ********************************************/
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:把字符串轉換爲全小寫
* ********************************************/
void ToLowerCase(char *s) {
while(*s=tolower(*s)) {
++s;
}
}
/**************************************************************
* 功能:從字符串src中分析出網站地址和端口,並得到用戶要下載的文件
* ***************************************************************/
void GetHost(char *src, char *web, char *file, int *port) {
char *pA;
char *pB;
memset(web, 0, HOST_ADDR_LEN);
memset(file, 0, HOST_FILE_LEN);
*port = 0;
if(!(*src))
return;
pA = src;
/* GET THE HOST AND TARGET FILE */
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;
/* SET PORT */
pA = strchr(web, ':');
if(pA)
*port = atoi(pA + 1);
else
*port = 80;
}
/*********************************************************************
* *filename: httpclient.c
* *purpose: HTTP協議客戶端程序,可以用來下載網頁
* *wrote by: zhoulifa([email protected]) 周立發
* *update by: wuchunlai([email protected]) 醇霧
* *date time:2006-03-11 21:49:00
* *update time:2015-12-24 16:14:00
* *Note: 任何人可以任意複製代碼並運用這些代碼,當然包括你的商業用途
* ********************************************************************/
int main(int argc, char *argv[])
{
if(argc!=2) {
fprintf(stderr,"Usage:%s web-address\a\n",argv[0]);
exit(1);
}
int sockfd;
char buffer[1024];
struct sockaddr_in server_addr;
struct hostent *host;
int portnumber,nbytes;
char host_addr[HOST_ADDR_LEN];
char host_file[HOST_FILE_LEN];
char local_file[256];
FILE * fp;
char request[1024];
int send, totalsend;
int i;
char * pt;
/*將參數轉換爲全小寫*/
printf("The url you set is: %s\n", argv[1]);
ToLowerCase(argv[1]);
printf("The lowercase url is: %s\n", argv[1]);
/*分析網址、端口、文件名等*/
GetHost(argv[1], host_addr, host_file, &portnumber);
printf("Web host:%s\n", host_addr);
printf("Host file:%s\n", host_file);
printf("Port number:%d\n\n", portnumber);
/*取得主機IP地址*/
if((host=gethostbyname(host_addr))==NULL) {
fprintf(stderr, "Gethostname error, %s\n", strerror(errno));
exit(1);
}
/* 客戶程序開始建立 sockfd描述符 */
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1) {
fprintf(stderr, "Socket Error:%s\a\n", strerror(errno));
exit(1);
}
/* 客戶程序填充服務端的資料 */
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);
/* 客戶程序發起連接請求 */
if(connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1) {
fprintf(stderr, "Connect Error:%s\a\n", strerror(errno));
exit(1);
}
/*準備request,將要發送給主機*/
sprintf(request,"GET /%s HTTP/1.1\r\n"
"Accept: */*\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\n"
"Connection: Close\r\n\r\n", host_file, host_addr, portnumber);
printf("The request header is:\n%s", request);
/*取得真實的文件名*/
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);
}
/*發送http請求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);
}
/*打開文件*/
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;
/* 連接成功了,接收http響應,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頭信息打印在屏幕上*/
}
else {
fwrite(buffer, 1, 1, fp);/*將http主體信息寫入文件*/
i++;
if(i%1024 == 0) fflush(fp);/*每1K時存盤一次*/
}
}
fclose(fp);
/* 結束通訊 */
close(sockfd);
exit(0);
}