C语言 HTTP 下载文件

C语言 HTTP协议下载文件，实现断点续传，socket通讯，目前只支持ip和port方式连接，有兴趣的读者可完善域名方式。
      代码分为 http.c： 实现http协议下载文件 ，socket.c： 封装linux socket函数，移植时只需修改socket.c中的函数即可。
     希望对大家有帮助，本人亲测可用！
http.c

点击(此处)折叠或打开

1. //http.c
   
2. //作者：王振
   
3. #include <stdio.h>
   
4. #include <stdlib.h>
   
5. #include <errno.h>
   
6. #include <string.h>
   
7. 
   
8. #include <sys/types.h>
   
9. #include <sys/stat.h>
   
10. #include <fcntl.h>
    
11. 
    
12. #include "socket.h"
    
13. #include "http.h"
    
14. 
    
15. 
    
16. #define MAX_RECV_SIZE    1440//硬件单包最大的接收字节数
    
17. char g_host[URL_LEN];
    
18. char g_ip[URL_LEN+1];//ip/域名
    
19. char g_port[5+1];
    
20. 
    
21. char g_buf_send[4*1024];//发送数据暂存区
    
22. char g_buf_recv[10*1024];//接收数据暂存区
    
23. 
    
24. BreakPoint_ST g_break_point;
    
25. 
    
26. /*
    
27. 功能:判断断点有效性,现在校验url是否一致
    
28. 参数:
    
29. 返回:
    
30. >0---------有效,已下载文件大小
    
31. -1----------无效
    
32. */
    
33. int Get_Breakpoint_Available(BreakPoint_ST *breakpoint,char *url,char *file_crc)
    
34. {
    
35.     
    
36.     //判断断点是否有效,后续加入文件校验码
    
37.     if((memcmp(breakpoint->url,url,strlen(url))== 0)&&(breakpoint->recv_size== MAX_RECV_SIZE))
    
38.         return breakpoint->download_size;
    
39.     else
    
40.     {
    
41.         return -1;
    
42.     }
    
43.     
    
44. }
    
45. 
    
46. 
    
47. /*
    
48. 功能:判断要下载文件是否存在断点
    
49. 参数:
    
50. filename---要下载的文件名
    
51. file_crc----服务器返回下载文件的校验码
    
52. 返回:
    
53. 0---------无断点
    
54. >0--------有断点,已下载文件大小
    
55. */
    
56. int Get_Breakpoint(char *url,char *filename,char *file_crc)
    
57. {
    
58.     char filename_bp[64];
    
59.     int fd = -1;
    
60.     int ret;
    
61.     BreakPoint_ST break_point;
    
62.     
    
63.     //断点文件名 filename+bp
    
64.     sprintf(filename_bp,"%s.bp",filename);
    
65. 
    
66.     //检测是否存在filename断点文件
    
67.     fd = open(filename_bp,O_RDONLY,S_IRUSR|S_IWUSR);
    
68.     if(fd == -1)
    
69.     {    
    
70.         #ifdef DEBUG_HTTP
    
71.         printf("no exsit %s\n",filename_bp);
    
72.         #endif
    
73.         return 0;
    
74.     }
    
75. 
    
76.     //存在断点
    
77.     ret = read(fd,&break_point,sizeof(break_point));
    
78.     if(ret != sizeof(break_point))
    
79.     {
    
80.         perror("ERR:Get_Breakpoint read");
    
81.         exit(-1);
    
82.     }
    
83. 
    
84.     close(fd);
    
85. 
    
86.     //判断断点是否有效
    
87.     ret = Get_Breakpoint_Available(&break_point,url,file_crc);
    
88.     if(ret > 0)
    
89.         return ret;
    
90.     else
    
91.     {
    
92.         
    
93.         printf("%s not available\n",filename_bp);
    
94.         remove(filename);
    
95.         remove(filename_bp);
    
96.         return 0;
    
97.         
    
98.     }
    
99. }
    
100. 
     
101. /*
     
102. 功能:保存断点信息,文件名filename.bp
     
103. 参数:
     
104. filename---要下载的文件名
     
105. file_crc----服务器返回下载文件的校验码
     
106. 返回:
     
107. 0---------成功
     
108. >0--------有断点,已下载文件大小
     
109. */
     
110. int Save_Breakpoint(char *url,char *filename,int download_size,char *file_crc)
     
111. {
     
112.     int fd;
     
113.     BreakPoint_ST breakpoint;
     
114.     char filename_bp[128];//断点信息文件名，包含路径
     
115. 
     
116.     sprintf(filename_bp,"%s.bp",filename);
     
117.     /* 创建目的文件 */
     
118.     if((fd=open(filename_bp,O_WRONLY|O_CREAT,S_IRUSR|S_IWUSR))==-1)
     
119.     {
     
120.         fprintf(stderr,"Open %s Error：%s\n",filename_bp,strerror(errno));
     
121.         exit(1);
     
122.     }
     
123.     memset(&breakpoint,0x0,sizeof(breakpoint));
     
124.     strcpy(breakpoint.url,url);
     
125.     //strcpy(breakpoint.crc,file_crc);
     
126.     strcpy(breakpoint.filename,filename);
     
127.     breakpoint.download_size = download_size;
     
128.     breakpoint.recv_size= MAX_RECV_SIZE;
     
129.     
     
130.     //xu tioa zheng wei fen ci xie ru
     
131.     if(write(fd,&breakpoint,sizeof(breakpoint)) != sizeof(breakpoint))
     
132.     {
     
133.         perror("ERR:Save_Breakpoint");
     
134.         exit(1);
     
135.     }
     
136. 
     
137.     close(fd);
     
138. 
     
139.     return 0;
     
140. 
     
141. 
     
142. 
     
143. }
     
144. 
     
145. /*
     
146. 功能:保存文件,追加写
     
147. 参数:
     
148. 返回:
     
149. 0---------成功
     
150. */
     
151. 
     
152. int Save_File(char *filebuf,int filelength,char *filename)
     
153. {
     
154.     int fd;
     
155.     /* 创建目的文件追加写 */
     
156.     if((fd=open(filename,O_WRONLY|O_CREAT|O_APPEND,S_IRUSR|S_IWUSR))==-1)
     
157.     {
     
158.         fprintf(stderr,"Open %s Error：%s\n",filename,strerror(errno));
     
159.         exit(1);
     
160.     }
     
161.     //xu tioa zheng wei fen ci xie ru
     
162.     if(write(fd,filebuf,filelength) != filelength)
     
163.     {
     
164.         perror("ERR:Save_File");
     
165.         exit(1);
     
166.     }
     
167. 
     
168.     close(fd);
     
169. 
     
170.     return 0;
     
171. 
     
172. 
     
173. }
     
174. 
     
175.  
     
176. int HTTP_GetResponseCode(void)
     
177. {
     
178.  
     
179.  
     
180. }
     
181. 
     
182.  /*
     
183. 功能:读取http返回的协议实体主体长度
     
184. 参数:
     
185. revbuf--------接收到的返回值
     
186. 返回值:
     
187. >=0---------内容(实体主体)的长度
     
188. -1-----------数据返回错误
     
189. */
     
190. int HTTP_GetRecvLength(char *revbuf)
     
191. {
     
192.     char *p1 = NULL;
     
193.     int HTTP_Body = 0;//内容体长度
     
194.     int HTTP_Head = 0;//HTTP 协议头长度
     
195. 
     
196. 
     
197.     HTTP_Body = HTTP_GetContentLength(revbuf);
     
198.     if(HTTP_Body == -1)
     
199.         return -1;
     
200. 
     
201.     p1=strstr(revbuf,"\r\n\r\n");
     
202.     if(p1==NULL)
     
203.         return -1;
     
204.     else
     
205.     {
     
206.         HTTP_Head = p1- revbuf +4;// 4是\r\n\r\n的长度
     
207.         return HTTP_Body+HTTP_Head;
     
208.     }
     
209. 
     
210. 
     
211. }
     
212. 
     
213. 
     
214. /*
     
215. 功能:读取http返回的Content-Length长度
     
216. 参数:
     
217. revbuf--------接收到的数据
     
218. 返回值:
     
219. >=0---------Content-Length长度
     
220. -1-----------数据返回错误
     
221. */
     
222. int HTTP_GetContentLength(char *revbuf)
     
223. {
     
224.     char *p1 = NULL, *p2 = NULL;
     
225.     int HTTP_Body = 0;//内容体长度
     
226. 
     
227.     p1 = strstr(revbuf,"Content-Length");
     
228.     if(p1 == NULL)
     
229.         return -1;
     
230.     else
     
231.     {
     
232.         p2 = p1+strlen("Content-Length")+ 2; 
     
233.         HTTP_Body = atoi(p2);
     
234.         return HTTP_Body;
     
235.     }
     
236. 
     
237. }
     
238. 
     
239.  /*
     
240.  功能:
     
241.  参数:
     
242.  sockfd--------接收到的返回值
     
243.  返回值:
     
244.  >0---------接收到长度
     
245.  -1----------失败
     
246.  =0---------服务端断开连接
     
247.  注:内部接收缓冲10k
     
248.  */
     
249. 
     
250. int HTTP_Recv(int sockfd,char *buf_recv)
     
251. {
     
252.     int ret;
     
253.     int recvlen=0;
     
254.     int downloadlen = 0;
     
255.     //int contentlen=0;
     
256.     char buf_recv_tmp[10*1024+1];
     
257.     
     
258.     memset(buf_recv_tmp,0x0,sizeof(buf_recv_tmp)); 
     
259.     while(1)
     
260.     {
     
261.         ret = Recv(sockfd,buf_recv_tmp+recvlen,sizeof(buf_recv_tmp)-1,0);
     
262. 
     
263.         if(ret <= 0)//下载失败
     
264.         {
     
265.             perror("ERR:recv fail");
     
266.             return ret;
     
267.         }
     
268.     
     
269.     
     
270.         if(recvlen == 0)
     
271.         {
     
272.             #ifdef DEBUG_HTTP_RECV
     
273.             printf("recv len = %d\n", ret);
     
274.              printf("recv = %s\n", buf_recv_tmp);
     
275.             #endif
     
276.             //获取需要下载长度;
     
277.             downloadlen = HTTP_GetRecvLength(buf_recv_tmp);
     
278. 
     
279. 
     
280.             #ifdef DEBUG_HTTP_RECV
     
281.             printf("downloadlen = %d\n",downloadlen);
     
282.             #endif
     
283.         }
     
284. 
     
285.         recvlen += ret;
     
286.         #ifdef DEBUG_HTTP_RECV
     
287.         printf("total recvlen = %d\n",recvlen);
     
288.         #endif
     
289. 
     
290.         if(downloadlen == recvlen)//下载完成
     
291.             break;
     
292. 
     
293. 
     
294.     }
     
295.     memcpy(buf_recv,buf_recv_tmp,downloadlen);
     
296.     return recvlen;
     
297. 
     
298. }
     
299. 
     
300. /*
     
301. 功能:获取下载url中的文件名,最后一个/后的字符
     
302. 参数:
     
303. 返回值:
     
304. 0-----------成功
     
305. -1----------失败
     
306. 注:内部接收缓冲10k
     
307. */
     
308. 
     
309. int HTTP_GetFileName(char *url,char *filename)
     
310. {
     
311.     //提取url中最后一个/后的内容
     
312.     int len;
     
313.     int i;
     
314. 
     
315.     len = strlen(url);
     
316.     for(i=len-1;i>0;i--)
     
317.     {
     
318.         if(url[i] == '/')
     
319.             break;
     
320.     }
     
321.     if(i == 0)//下载地址错误
     
322.     {
     
323.         printf("url not contain '/'\n");
     
324.         return -1;
     
325.     }
     
326.     else
     
327.     {
     
328.     
     
329.         strcpy(filename,url+i+1);
     
330.         #ifdef DEBUG_HTTP
     
331.         printf("filename=%s\n",filename);
     
332.         #endif
     
333.         return 0;
     
334.     }
     
335. }
     
336. 
     
337. /*
     
338. 功能:获取下载url中的路径,第一个/后的字符
     
339. 参数:
     
340. 返回值:
     
341. 0-----------成功
     
342. -1----------失败
     
343. 注:url ex "http://host:port/path"
     
344. */
     
345. int HTTP_GetPath(char *url,char *path)
     
346. {
     
347.     char *p;
     
348. 
     
349.     p = strstr(url,"http://");
     
350.     if(p == NULL)
     
351.     {
     
352.         p = strchr(url,'/');
     
353.         if(p == NULL)
     
354.             return -1;
     
355.         else
     
356.         {
     
357.             strcpy(path,p);
     
358.             return 0;
     
359.         }
     
360.     }
     
361.     else
     
362.     {
     
363.         p = strchr(url+strlen("http://"),'/');
     
364.         if(p == NULL)
     
365.             return -1;
     
366.         else
     
367.         {
     
368.             strcpy(path,p);
     
369.             return 0;
     
370.         }
     
371.     }
     
372. 
     
373. }
     
374. /*
     
375. 功能:获取下载url中的ip和port,ip支持域名,端口默认为80
     
376. 参数:
     
377. 返回值:
     
378. 1-----------域名式
     
379. 2-----------ip port式
     
380. -1----------失败
     
381. 注:url ex "http://host:port/path"
     
382. */
     
383. 
     
384. int HTTP_Get_IP_PORT(char *url,char *ip,char *port)
     
385. {
     
386.     char *p = NULL;
     
387.     int offset = 0;
     
388.     char DOMAIN_NAME[128];
     
389. 
     
390.     p = strstr(url,"http://");
     
391.     if(p == NULL)
     
392.     {
     
393.         offset = 0;
     
394.     }
     
395.     else
     
396.     {
     
397.         offset = strlen("http://");
     
398.     }
     
399. 
     
400.     p = strchr(url+offset,'/');
     
401.     if(p == NULL)
     
402.     {
     
403.         printf("url:%s format error\n",url);
     
404.         return -1;
     
405.         
     
406.     }
     
407.     else
     
408.     {
     
409. 
     
410.         memset(DOMAIN_NAME,0x0,sizeof(DOMAIN_NAME));
     
411.         memcpy(DOMAIN_NAME,url+offset,(p-url-offset));
     
412.         p = strchr(DOMAIN_NAME,':');
     
413.         if(p == NULL)
     
414.         {
     
415.             strcpy(ip,DOMAIN_NAME);
     
416.             strcpy(port,"80");
     
417.             //printf("ip %p,port %p\n",ip,port);
     
418.             
     
419.             #ifdef DEBUG_HTTP
     
420.             printf("ip=%s,port=%s\n",ip,port);//debug info
     
421.             #endif
     
422.             return 1;
     
423. 
     
424.         }
     
425.         else
     
426.         {    
     
427.             *p = '\0';
     
428. 
     
429.             strcpy(ip,DOMAIN_NAME);
     
430.             strcpy(port,p+1);
     
431.             
     
432.             #ifdef DEBUG_HTTP
     
433.             printf("ip=%s,port=%s\n",ip,port);//debug info
     
434.             #endif
     
435.             return 2;
     
436. 
     
437.         }
     
438. 
     
439. 
     
440.         return 0;
     
441.     }
     
442.     
     
443. }
     
444. void Package_Url_Get_File(char *path, char *range)
     
445. {
     
446.     char buf[64];
     
447.     memset(g_buf_send,0x0,sizeof(g_buf_send));         
     
448.     sprintf(g_buf_send, "GET %s",path);
     
449. 
     
450.     
     
451.     //HTTP/1.1\r\n 前面需要一个空格
     
452.     strcat(g_buf_send," HTTP/1.1\r\n");
     
453.     strcat(g_buf_send, "Host: ");
     
454.     strcat(g_buf_send, g_host);
     
455.     //strcat(g_buf_send, ":");
     
456.     //strcat(g_buf_send, PORT);
     
457.     
     
458.     sprintf(buf, "\r\nRange: bytes=%s",range);
     
459.     strcat(g_buf_send,buf);
     
460.     strcat(g_buf_send, "\r\nKeep-Alive: 200");
     
461.     strcat(g_buf_send,"\r\nConnection: Keep-Alive\r\n\r\n");
     
462.     
     
463. 
     
464. }
     
465. 
     
466. int Package_Url_Get_FileSize(char *url)
     
467. {
     
468.     
     
469.     memset(g_buf_send,0x0,sizeof(g_buf_send));         
     
470.     sprintf(g_buf_send, "HEAD %s",url);
     
471. 
     
472.         //HTTP/1.1\r\n 前面需要一个空格
     
473.     strcat(g_buf_send," HTTP/1.1\r\n");
     
474.     strcat(g_buf_send, "Host: ");
     
475.     strcat(g_buf_send, g_host);
     
476.     //strcat(g_buf_send, ":");
     
477.     //strcat(g_buf_send, PORT);
     
478.     strcat(g_buf_send,"\r\nConnection: Keep-Alive\r\n\r\n");
     
479. 
     
480.     return 0;
     
481. }
     
482. 
     
483. 
     
484. int HTTP_GetFileSize(int sockfd,char *path)
     
485. {
     
486.     int ret = -1;
     
487.     char buf_recv_tmp[10*1024+1];
     
488. 
     
489.     Package_Url_Get_FileSize(path);
     
490. #ifdef DEBUG_HTTP
     
491.     printf("send = %s \n",g_buf_send);
     
492. #endif
     
493. 
     
494.     Send(sockfd, g_buf_send, strlen(g_buf_send), 0);
     
495. 
     
496.     memset(buf_recv_tmp,0x0,sizeof(buf_recv_tmp));                                                 
     
497.     ret = Recv(sockfd,buf_recv_tmp,sizeof(buf_recv_tmp)-1,0);
     
498. #ifdef DEBUG_HTTP
     
499.     printf("recv len = %d\n", ret);
     
500.     printf("recv = %s\n", buf_recv_tmp);
     
501. #endif
     
502.     if(ret <= 0)
     
503.     {
     
504.         perror("ERR:recv fail GetFileSize()");
     
505.         return -1;
     
506. 
     
507.     }
     
508.     ret = HTTP_GetContentLength(buf_recv_tmp);
     
509.     if(ret <= 0)
     
510.         return -1;
     
511.     else
     
512.         return ret;
     
513. 
     
514. 
     
515. }
     
516. 
     
517. 
     
518. 
     
519. 
     
520. /*
     
521. 功能:分段下载文件
     
522. 参数:
     
523. 返回值:
     
524. >0----------已下载文件大小(不包含上次下载)
     
525. -1----------失败
     
526. */
     
527. int HTTP_GetFile(int sockfd,char *path,int filelength,int download_size,char *filebuf)
     
528. {
     
529.     int count;
     
530.     char range[32];
     
531.     int i;
     
532.     int j = 0;//成功下载次数
     
533.     int ret = -1;
     
534.     char *p = NULL;
     
535.     int download_index;//下载开始索引
     
536. 
     
537.     count = (filelength%MAX_RECV_SIZE)?(filelength/MAX_RECV_SIZE +1):(filelength/MAX_RECV_SIZE);
     
538. 
     
539.     download_index = download_size/MAX_RECV_SIZE;
     
540. 
     
541.     for(i=download_index;i<count;i++)
     
542.     {
     
543.         //if(i == 20)//测试断点
     
544.             //break;
     
545. 
     
546. 
     
547.         if((i == (count-1))&&(filelength%MAX_RECV_SIZE))
     
548.             sprintf(range,"%d-%d",i*MAX_RECV_SIZE,filelength-1);
     
549.         else
     
550.             sprintf(range,"%d-%d",i*MAX_RECV_SIZE,(i+1)*MAX_RECV_SIZE-1);
     
551. 
     
552. 
     
553.         Package_Url_Get_File(path,range);
     
554.         #ifdef DEBUG_HTTP
     
555.          printf("send = %s \n",g_buf_send);
     
556.         #endif
     
557.          Send(sockfd, g_buf_send, strlen(g_buf_send), 0);
     
558. 
     
559.         /*需改为提取http 返回协议头和协议体总长,然后定长接收*/
     
560.         memset(g_buf_recv,0x0,sizeof(g_buf_recv));                                              
     
561.         ret = HTTP_Recv(sockfd,g_buf_recv);
     
562.         if(ret < 0)
     
563.             break;
     
564.         if(ret == 0 )//服务端断开连接
     
565.         {
     
566.             sockfd = Socket_Connect(g_ip,g_port);
     
567.              i--;
     
568.             continue;
     
569.         }
     
570.         /*提取协议体数据,保存在filebuf中*/
     
571.         p = strstr(g_buf_recv,"\r\n\r\n");
     
572.         if(p == NULL)//jia ru duan dian baocun
     
573.         {
     
574.             printf("ERR:g_buf_recv not contain end flag\n");
     
575.             break;
     
576.         }
     
577.          else
     
578.          {
     
579.              memcpy(filebuf+j*MAX_RECV_SIZE,p+4,MAX_RECV_SIZE);
     
580.              j++;
     
581. 
     
582.          }
     
583.     }
     
584.     if(i == count)
     
585.         return (filelength-download_size);
     
586.     else
     
587.         return (i*MAX_RECV_SIZE-download_size);
     
588. }
     
589. 
     
590. /*
     
591. 功能:HTTP下载文件
     
592. 参数:
     
593. 返回值:
     
594. 0----------下载完成
     
595. -1---------失败
     
596. -2---------部分下载完成
     
597. 注:保存文件到bin所在目录
     
598. */
     
599. int HTTP_DownloadFile(char *url,char *save_path)
     
600. {
     
601.     int ret;
     
602.     int sockfd;
     
603.     int filesize;
     
604.     int download_size;
     
605.     char filename[FILENAME_LEN+1];
     
606.     char filename_bp[FILENAME_LEN+3+1];
     
607.     char *filebuf;
     
608.     char save_file_path[FILENAME_LEN+1];//保存下载文件的路径+文件名
     
609. 
     
610.     char path[PATH_LEN+1];//url中的path
     
611. 
     
612.     //提取ip和port或url(url 暂不实现,需要gethostbyname linux)
     
613.     ret = HTTP_Get_IP_PORT(url,g_ip,g_port);
     
614.     if(ret == -1)
     
615.         return -1;
     
616.     else
     
617.     {
     
618.         sprintf(g_host,"%s:%s",g_ip,g_port);
     
619.     }
     
620.     //提取下载文件名
     
621.     ret = HTTP_GetFileName(url,filename);
     
622.     if(ret == -1)
     
623.         return -1;
     
624. 
     
625.     ret = HTTP_GetPath(url,path);
     
626.     if(ret == -1)
     
627.         return -1;
     
628.     //sleep(3);//debug info
     
629.     //建立连接
     
630.     sockfd = Socket_Connect(g_ip,g_port);
     
631. 
     
632.     //获取下载文件总大小
     
633.     filesize = HTTP_GetFileSize(sockfd,path);
     
634.     if(filesize == -1)
     
635.         return -1;
     
636.     //#ifdef DEBUG_HTTP
     
637.     printf("http need download size %d\n",filesize);
     
638.     //#endif
     
639.     //malloc分配存储文件空间
     
640.     filebuf = (char *)malloc(filesize);
     
641.     if(filebuf == NULL)
     
642.     {
     
643.         perror("malloc filebuf fail");
     
644.         return -1;
     
645.     }
     
646.     else
     
647.         memset(filebuf,0x0,filesize);
     
648. 
     
649.     download_size = Get_Breakpoint(url,filename,NULL);
     
650.     #ifdef DEBUG_HTTP
     
651.     printf("breakpoint download_size=%d\n",download_size);//debug info
     
652.     sleep(3);//debug info
     
653.     #endif
     
654.     //分段下载文件
     
655.     ret = HTTP_GetFile(sockfd,path,filesize,download_size,filebuf);
     
656.     Close(sockfd);
     
657.     if(ret < 0)
     
658.     {
     
659.         free(filebuf);
     
660.         return -1;
     
661.     }
     
662.     else
     
663.     {
     
664. 
     
665.         sprintf(save_file_path,"%s%s",save_path,filename);
     
666.         
     
667.         #ifdef DEBUG_HTTP
     
668.         printf("save_path=%s\n",save_path);
     
669.         printf("filename=%s\n",filename);
     
670.         printf("save_file_path=%s\n",save_file_path);
     
671.         printf("download_size = %d\n",ret);
     
672.         #endif
     
673.         Save_File(filebuf,ret,save_file_path);
     
674.         free(filebuf);
     
675.         if((ret+download_size) == filesize)//全部下载完成
     
676.         {
     
677.             sprintf(filename_bp,"%s.bp",filename);
     
678.             remove(filename_bp);
     
679.             
     
680.      printf("download success\n");
     
681.             return 0;
     
682.         }
     
683.         else//部分下载完成
     
684.         {
     
685.             printf("part download success\n");
     
686.             //保存断点信息
     
687.             Save_Breakpoint(url,save_file_path,ret+download_size,NULL);
     
688.             return -2;
     
689.         }
     
690.     }
     
691. 
     
692. }

socket.c 

点击(此处)折叠或打开

1. //socket.c
   
2. //作者：王振
   
3. 
   
4. #include <stdio.h>
   
5. #include <stdlib.h>
   
6. #include <errno.h>
   
7. #include <string.h>
   
8. #include <sys/types.h>
   
9. #include <netinet/in.h>
   
10. #include <sys/socket.h>
    
11. #include <sys/wait.h>
    
12. 
    
13. #include "socket.h"
    
14. 
    
15. int Connect(int fd, struct sockaddr *addr, socklen_t len)
    
16. {
    
17.     int result;
    
18.     if ((result = connect(fd, addr, len)) == -1) {
    
19.         perror("connect");
    
20.         exit(EXIT_FAILURE);
    
21.     }
    
22.     return 0;
    
23. }
    
24. 
    
25. int Socket_Connect(char *ip,char *port)
    
26. {
    
27.     struct sockaddr_in addr;
    
28. 
    
29.     int sockfd;
    
30.     int len;
    
31. 
    
32.     
    
33.     addr.sin_family = AF_INET;
    
34.     addr.sin_addr.s_addr = inet_addr(ip);//127.0.0.1为本机ip
    
35.     addr.sin_port = htons(atoi(port));
    
36.     len = sizeof(addr);
    
37.         
    
38.     sockfd = socket(AF_INET, SOCK_STREAM, 0);
    
39.     Connect(sockfd, (struct sockaddr*)&addr, len);
    
40.     return sockfd;
    
41. 
    
42. }
    
43. 
    
44. 
    
45. /*
    
46. 功能:向socketfd发送数据,内部实现了循环发送len长度
    
47. 参数:
    
48. sockfd 是代表你与远程程序连接的套接字描述符。
    
49. msg 是一个指针，指向你想发送的信息的地址。
    
50. len 是你想发送信息的长度。
    
51. flags 发送标记。一般都设为0
    
52. 返回:
    
53. 0-------- 成功
    
54. 退出---失败
    
55. 修改:
    
56. 备注:
    
57. 王振
    
58. */
    
59. int Send(int sockfd, char *sendbuf, int len, int flags)
    
60. {
    
61.     int sendlen = 0;
    
62.     int ret = -1;
    
63. 
    
64.     while(sendlen < len)
    
65.     {
    
66.         ret = send(sockfd, sendbuf+sendlen, len-sendlen, flags); 
    
67.         if(-1 == ret)
    
68.         {
    
69.             perror("send");
    
70.             exit(EXIT_FAILURE);
    
71.         }
    
72.         else
    
73.             sendlen += ret;
    
74. 
    
75.     }
    
76. 
    
77.     return 0;
    
78. 
    
79. }
    
80. 
    
81. int Close(int sockfd)
    
82. {
    
83.     return close(sockfd);
    
84.     
    
85. 
    
86. }
    
87. int Recv(int sockfd, char *recvbuf, int len, int flags)
    
88. {
    
89.     int recv_len;
    
90. 
    
91.     if ((recv_len = recv(sockfd, recvbuf, len, flags)) < 0)
    
92.     {
    
93.         perror("recv error");
    
94.         exit(EXIT_FAILURE);
    
95.     }
    
96. 
    
97.     return recv_len;
    
98. }

很早就有这个想法了，知道今天才实现了一下，参考了周立发的《《C语言实现HTTP下载例子》》和林超旗整理的《《HTTP协议详解》》，特此谢谢！由于今天时间有限，所以大概的实现了一下(目前只在ubuntu环境下测试的)，跨平台部分还需要完善，后面会陆续整理出完整的版本。代码如下：

头文件

/*
	$Id: httpdownload.h, v1.0.0, 2011.6.28, YellowBug $
	$@@: http下载 
*/
#ifndef PENQ_HTTP_DOWNLOAD_H_
#define PENQ_HTTP_DOWNLOAD_H_
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#if defined(__GNUC__)
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <time.h>
#define PATH_SPLIT			'/'
typedef int	HSOCKET;
#define closesocket(s)		close(s)
#elif defined(_WIN32)
#include <windows.h>
#include <winsock2.h>
#define PATH_SPLIT			'//'	
typedef SOCKET HSOCKET;
#endif

#define DEF_HTTP_PORT			80
#define HTTP_MAX_PATH			260
#define HTTP_MAX_REQUESTHEAD	1024
#define HTTP_MAX_RESPONSEHEAD	2048
#define HTTP_DOWN_PERSIZE		128	
#define HTTP_FLUSH_BLOCK		1024

/*
	$@@ 下载状态
	$@ HDL_URLERR: 提供的url非法
	$@ HDL_SERVERFAL: 根据host地址无法找到主机 
	$@ HDL_TIMEOUT: 连接下载地址超时
	$@ HDL_READYOK: 连接下载地址成功,准备下载
	$@ HDL_DOWNING: 正在下载
	$@ HDL_DISCONN: 断开连接了
	$@ HDL_FINISH: 下载完成
*/
enum 
{
	HDL_URLERR = 0xe0,
	HDL_SERVERFAL = 0xe1,
	HDL_SOCKFAL = 0xe2,
	HDL_SNDREQERR = 0xe3,
	HDL_SERVERERR = 0xe4,
	HDL_CRLOCFILEFAL = 0xe5,
	HDL_TIMEOUT = 0x100,
	HDL_NORESPONSE = 0x101,
	HDL_READYOK = 0x104,
	HDL_DOWNING = 0x105,
	HDL_DISCONN = 0x106,
	HDL_FINISH = 0x107
};

/*
	$@@ 下载回调函数,主要用于监听下载过程
	$@ 第一个参数: 下载标识符号(上面枚举中的值)
	$@ 第二个参数: 需要下载的总字节数
	$@ 第三个参数: 已经下载的总字节数
	$@ 第四个参数: 距离上一次下载的时间戳(毫秒)
	$@ 返回值: 下次下载的字节数(0: 表示默认值, 小于0则下载中断, 大于0则位下次下载指定的字节)
*/
typedef int (*HTTPDOWNLOAD_CALLBACK)(int, unsigned int, unsigned int, unsigned int);

/*
	$@@ 通过指定的url下载资源
	$@ url: 下载资源地址
	$@ filepath: 存储在本地的路径(如果为NULL则存储在当前目录)
	$@ filename: 存储的文件名(如果为NULL则位url中分析的文件名)
	$@ http_func: 下载过程监听函数(如果为NULL则不监听下载过程)
*/
void pq_http_download(const char *url, const char *filepath, const char *filename, HTTPDOWNLOAD_CALLBACK http_func);
#endif /* #ifndef PENQ_HTTP_DOWNLOAD_H_ */
/* END */

实现:

/*
	$Id: httpdownload.c, v1.0.0, 2011.6.28, YellowBug $
	$@@: http下载 
*/
#include "httpdownload.h"

#define HERROR(exp, err)	do {														 /
								if (exp) {												 /
									printf("(%s,%d) %s/n", __FILE__, __LINE__, #exp);	 /
									if(S_http_callback) S_http_callback((err), 0, 0, 0); /
									exit(1);                                             /
								}                                                        /
							} while(0)							

#define HCALLBACK(a, b, c, d)		(S_http_callback ? S_http_callback((a), (b), (c), (d)) : 0)
/*
	$@@ 文件域的局部变量
*/
static HTTPDOWNLOAD_CALLBACK 	S_http_callback = NULL;
static const char * S_request_head = "GET %s HTTP/1.1/r/n" /
							  		 "Accept: */*/r/n" /
							  		 "Accept-Language: zh-cn/r/n" /
							  		 "User-Agent: Molliza/4.0(compatible;MSIE6.0;windows NT 5.0)/r/n" /
							  		 "Host: %s/r/n" /
							  		 "Connection: close/r/n/r/n";

#if defined(__GNUC__)
unsigned int get_tick() 
{
	struct timeval tv;
	gettimeofday(&tv, NULL);
	return (unsigned int)(tv.tv_sec*1000+tv.tv_usec/1000);
}
#elif defined(_WIN32)
#define get_tick()		GetTickCount()
#endif

/*
	$@@ 从指定长度(len0)的字符串的右端开始找到第一个位ch的字符
*/
static char * r_strchr(const char *p, int len, char ch)
{
	int last_pos = -1;
	int i = 0;
	while ( *(p+i) != '/0' ) {
		if ( *(p+i) == ch ) last_pos = i;
		if ( ++i >= len ) break;	
	}
	return last_pos >= 0 ? (char *)(p+last_pos) : NULL;
}

/*
 	$@@ 解析url，分析出web地址,端口号,下载的资源名称
*/
static void parse_url(const char *url, char *web, int *port, char *filepath, char *filename)
{
	int web_len = 0;
	int web_start = 0;
	int file_len = 0;
	int file_start = 0;
	int path_len = 0;
	int path_start = 0;
	char *pa = NULL;
	char *pb = NULL;
	if ( !strncmp(url, "http://", 7) ) web_start = 7;
	else if ( !strncmp(url, "https://", 8) ) web_start = 8;
	
	pa = strchr(url+web_start, '/');
	pb = strchr(url+web_start, ':');
	
	/* 获取web */	
	if ( pa ) {
		web_len = (int)(pa - (url+web_start));
	} else {
		if ( pb ) web_len = pb - (url+web_start);
		else web_len = strlen(url+web_start);		
	}
	HERROR(0 == web_len, HDL_URLERR);
	memcpy(web, url+web_start, web_len);
	web[web_len] = '/0';		
	/* 获取filename */
	if ( pb ) {
		pa = r_strchr(url+web_start, (int)(pb-(url+web_start)), '/');
		file_len = (int)(pb - pa - 1);
		file_start = (int)(pa + 1 - url);
		*port = atoi(pb+1);
	} else {
		pa = r_strchr(url+web_start, strlen(url+web_start), '/');
		HERROR(NULL == pa, HDL_URLERR);
		file_len = strlen(pa+1);
		file_start = (int)(pa + 1 - url);
		*port = DEF_HTTP_PORT;
	}
	HERROR(NULL == pa, HDL_URLERR);
	memcpy(filename, url+file_start, file_len);
	filename[file_len] = '/0';
	
	/* 获取filepath */
	path_start = web_start + web_len;
	path_len = file_start - path_start + file_len;
	memcpy(filepath, url+web_start+web_len, file_start - path_start + file_len);
	filepath[path_len] = '/0';
}

/*
	$@@ 封装request报头
*/
int package_request(char *request, const char *web, const char *filepath)
{
	int n = sprintf(request, S_request_head, filepath, web);
	request[n] = '/0';
	return n;
}
/*
	$@@ 发送请求报头
*/
int send_request(HSOCKET sock, const char *buf, int n)
{
	int already_bytes = 0;
	int per_bytes = 0;	
	
	while ( already_bytes < n ) {
		per_bytes = send(sock, buf+already_bytes, n-already_bytes, 0);
		if ( per_bytes < 0 ) {
			break;
		} else if ( 0 == per_bytes ) {
			HCALLBACK(HDL_DISCONN, 0, 0, 0);
			break;
		} else
			already_bytes += per_bytes;	
	}
	return already_bytes;
}

/*
	$@@ 获取响应报头(状态行和消息报头)
*/
int get_response_head(HSOCKET sock, char *response, int max)
{
	int total_bytes = 0;
	int per_bytes = 0;
	int over_flag = 0;
	char ch;
	
	do {		
		per_bytes = recv(sock, &ch, 1, 0);
		if ( per_bytes < 0 ) break;
		else if ( 0 == per_bytes ) {
			HCALLBACK(HDL_DISCONN, 0, 0, 0);
			break;
		} else {
			if ( '/r' == ch || '/n' == ch ) over_flag++;
			else over_flag = 0;
			
			response[total_bytes] = ch;			
			if ( total_bytes >= max ) break;
			else total_bytes += per_bytes;
		}
	} while ( over_flag < 4 );
	response[total_bytes] = '/0';
	return total_bytes;
}
void parse_response_head(char *response, int n, int *server_status, unsigned int *down_total)
{
	int i = 1;
	char *pstatus = strstr(response, "HTTP/1.1");
	char *plen = strstr(response, "Content-Length:");	
	printf("%s/n", response);
	
	if ( pstatus ) {
		pstatus += strlen("HTTP/1.1");
		i = 1;	
		while ( *(pstatus+i) == ' ' ) ++i;
		*server_status = atoi(pstatus+i);
	} else
		*server_status = 0;
	if ( plen ) {
		plen += strlen("Content-Length:");
		i = 1;
		while ( *(plen+i) == ' ' ) ++i;
		*down_total = (unsigned int)atoi(plen+i); 
	} else
		*down_total = 0;
	printf("status: %d/n", *server_status);
	printf("total: %u/n", *down_total);
}
/*
	$@@ 创建本地文件
*/
FILE * create_local_file(const char *local_path, const char *local_file, const char *remote_file)
{
	int len = strlen(local_path);
	static char filename[HTTP_MAX_PATH+1];
	if ( local_path[len-1] != PATH_SPLIT ) {
		if ( local_file ) len = sprintf(filename, "%s%c%s", local_path, PATH_SPLIT, local_file);	
		else len = sprintf(filename, "%s%c%s", local_path, PATH_SPLIT, remote_file);		
 	} else {
		if ( local_file ) len = sprintf(filename, "%s%s", local_path, local_file);	
		else len = sprintf(filename, "%s%s", local_path, remote_file);	
	}
	filename[len] = '/0'; 
	printf("ready to create local file: %s/n", filename);
	return fopen(filename, "wb+");
}
/*
	$@@ 开始下载
*/
void start_download(HSOCKET sock, unsigned int total_bytes, FILE *stream)
{
	unsigned int already_bytes;
	int per_bytes;
	int flush_bytes;
	unsigned int total_tim;
	unsigned int per_tim;
	static char buf[HTTP_DOWN_PERSIZE];
	
	do {
		per_tim = get_tick();
		per_bytes = recv(sock, buf, HTTP_DOWN_PERSIZE, 0);
		per_tim = get_tick() - per_tim;
		if ( per_bytes < 0 ) break;
		else if ( 0 == per_bytes ) {
			HCALLBACK(HDL_DISCONN, total_bytes, already_bytes, 0);
			break;		
		} else {
			fwrite(buf, 1, per_bytes, stream);
			already_bytes += (unsigned int)per_bytes;
			
			flush_bytes += per_bytes;
			if ( flush_bytes >= HTTP_FLUSH_BLOCK ) {
				fflush(stream);
				flush_bytes = 0;	
			}
			HCALLBACK(HDL_DOWNING, total_bytes, already_bytes, per_tim);
		}
	} while ( already_bytes < total_bytes );
	
	if ( flush_bytes > 0 )
		fflush(stream);

	HCALLBACK(HDL_FINISH, total_bytes, already_bytes, total_tim);
}

void pq_http_download(const char *url, const char *local_path, const char *local_file, HTTPDOWNLOAD_CALLBACK http_func)
{
	int port;
	char web[HTTP_MAX_PATH+1];
	char remote_path[HTTP_MAX_PATH+1];
	char remote_file[HTTP_MAX_PATH+1];
	char request[HTTP_MAX_REQUESTHEAD+1];
	char response_head[HTTP_MAX_RESPONSEHEAD+1];
	int request_len = 0;
	int response_len = 0;
	unsigned int down_total = 0;
	int server_status = 404;
	HSOCKET sock = -1;
	struct hostent *host = NULL;
	struct sockaddr_in server_addr;	
	FILE *stream = NULL;
	S_http_callback = http_func;
	parse_url(url, web, &port, remote_path, remote_file);
	request_len = package_request(request, web, remote_path);
	host = gethostbyname(web);
	HERROR(NULL==host, HDL_SERVERFAL);
	
	sock = socket(AF_INET, SOCK_STREAM, 0);
	HERROR(-1==sock, HDL_SOCKFAL);
	
	memset(&server_addr, 0, sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(port);
	server_addr.sin_addr = *((struct in_addr *)host->h_addr);
	HERROR(-1==connect(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)), HDL_TIMEOUT);
	HERROR(request_len != send_request(sock, request, request_len), HDL_SNDREQERR);
	response_len = get_response_head(sock, response_head, HTTP_MAX_RESPONSEHEAD);
	HERROR(response_len <= 0, HDL_NORESPONSE);
	parse_response_head(response_head, response_len, &server_status, &down_total);
	switch ( server_status ) {
		case 200:
			if ( down_total > 0 ) {
				stream = create_local_file(local_path, local_file, remote_file);
				HERROR(NULL == stream, HDL_CRLOCFILEFAL);
				HCALLBACK(HDL_READYOK, down_total, 0, 0);
				start_download(sock, down_total, stream);
				fclose(stream);		
			} else {
				HCALLBACK(HDL_FINISH, 0, 0, 0);
			}
		default:
			HCALLBACK(HDL_SERVERERR, 0, 0, 0);
	}
	closesocket(sock);
}

/* END */

测试代码:

#include <stdio.h>
#include "httpdownload.h"
int http_callback(int status, unsigned int total_bytes, unsigned int already_bytes, unsigned int tim)
{
	switch ( status ) {
		case HDL_READYOK:
			printf("ready to download, total.bytes=%u/n", total_bytes);
			break;
		case HDL_DOWNING:
			printf("downloading... (%u/%u) bytes/n", already_bytes, total_bytes);
			break;
		case HDL_FINISH:
			printf("download finish! download total.bytes=%u/n", already_bytes);
			break;
		default:
			printf("status: %#x/n", status);	
	}	
	return 0;
}

int main(int argc, char *argv[])
{
	pq_http_download(argv[1], argv[2], NULL, http_callback);
}

一个http下载程序的c实现
#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 <sys/stat.h>
#include <fcntl.h>
#include <limits.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <ctype.h>

#define RECVBUFSIZE    2048
#define READBUFSIZE     2048

/********************************************
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：把字符串转换为全小写
********************************************/
void ToLowerCase(char *s)  {
while(*s)  {
*s=tolower(*s);
s++;
}//while
}

/**************************************************************
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;
}


int find_start(char *buf, int size) 
{
int i;
char *p;
p = strstr(buf, "\r\n\r\n");
if(p) {
i = p - buf + 4;
if(i >= size)
i = -1;
}
else
i = -1;
return i;
}

//唯一的参数就是网址网址
int main(int argc, char **argv) {
int sockfd;
int fd;
struct hostent *host;
int portnumber;
char url[128];
char host_addr[256];
char host_file[1024];
char request[1024];
struct sockaddr_in server_sockaddr;
char recvbuf[RECVBUFSIZE];
int sendbytes, recvbytes, totalsend, totalsended;
int file_start_pos;

sprintf(url, "%s", argv[1]);
ToLowerCase(url);
GetHost(url, host_addr, host_file, &portnumber);
host = gethostbyname(host_addr);

sockfd = socket(PF_INET, SOCK_STREAM, 0);
server_sockaddr.sin_family = PF_INET;
server_sockaddr.sin_port = htons(portnumber);
server_sockaddr.sin_addr = *((struct in_addr *)host->h_addr);
bzero(&(server_sockaddr.sin_zero), 8);
connect(sockfd, (struct sockaddr *)&server_sockaddr, sizeof(struct sockaddr));

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: Keep-Alive\r\n\r\n", host_file, host_addr, portnumber);

sendbytes = 0;
totalsended = 0;            //already send
totalsend = strlen(request);        //will send
while(totalsended < totalsend) {    
sendbytes = send(sockfd, request+totalsended, totalsend - totalsended, 0);
totalsended += sendbytes;
}//while

fd = open("download", O_CREAT | O_TRUNC | O_RDWR, 0777);
recvbytes = recv(sockfd, recvbuf, RECVBUFSIZE, 0);    //delete the head
file_start_pos = find_start(recvbuf, recvbytes);
write(fd, recvbuf+file_start_pos, recvbytes-file_start_pos);
while((recvbytes = recv(sockfd, recvbuf, RECVBUFSIZE, 0)) > 0) {
write(fd, recvbuf, recvbytes);
}//while

close(fd);
close(sockfd);
return 0;
}//main()