lighttpd+CGI+ipkg-遠端韌體更新

這篇文章的主題”遠端韌體更新”,以後簡稱為”UI upgrade”,在一般網路裝置上,最常看到的,就是提供網頁的介面讓使用者更新網路裝置的韌體,而這樣的功能在實作上需要準備
(1)Web server:lighttpd or goahead web server(goahead已經不更新它的web server)
(2)可更新目標板軟體的工具:ipkg or busybox dpkg
(3) html和cgi:自己寫實做時我選擇lighttpd+ipkg,而網頁的部份採用html+cgi,以下會分為三段介紹這三個實作

(1)lighttpd porting:
請至官網下載目前最新的版本1.4.19,並交叉編譯,交叉編譯(Cross-Compiling)這種有configure script的軟體有些小技巧,因為configure script需要使用者目前開發環境的所有設定,所以可以寫一個cross-compile shell script檔案先export開發環境的變數和設定configure的參數(輸入./configure –help可看到更多可設定的選項),這樣子做可以避免libtool地雷, cross-compile shell script的範例如下

1. #! /bin/sh
2.  
3. export PATH=$PATH:/usr/local/eldk/usr/bin/
4. export CPPFLAGS="-I/usr/local/eldk/arm/usr/include" 
5. export LDFLAGS="-ldl" 
6. export CFLAGS="" 
7. export AR=arm-linux-ar 
8. export AS=arm-linux-as 
9. export LD=arm-linux-ld 
10. export RANLIB=arm-linux-ranlib 
11. export CC=arm-linux-gcc 
12. export NM=arm-linux-nm 
13. export ARCH=arm 
14.  
15. ./configure --target=arm-linux \
16. --host=arm-linux \
17. --build=arm-linux-gnu \
18. --prefix=/usr/local/eldk/lighthttpd \
19. --exec-prefix=/usr/local/eldk/lighthttpd \
20. --with-pcre

所以編譯的步驟就是,先執行寫好的cross-compile shell script,然候執行make,最後make install,install的路徑就是上面cross-compile shell script中的—prefix和exec-prefix所指到的資料夾路徑
make install會把要安裝的binary和library都擺在我指定的資料夾/usr/local/eldk/lighthttpd下,把library都複制一份到目標板上,並且把lighttpd執行檔也傳到目標板的/bin資料夾下,接下來就是設定lighttpd.conf檔,設定時要特別注意以下幾段
[server.modules]

1. server.modules = ( 
2. # "mod_rewrite",
3. # "mod_redirect",
4. "mod_alias",
5. "mod_access",
6. # "mod_cml",
7. # "mod_trigger_b4_dl",
8. # "mod_auth",
9. # "mod_status",
10. # "mod_setenv",
11. "mod_fastcgi",
12. # "mod_proxy",
13. # "mod_simple_vhost",
14. # "mod_evhost",
15. # "mod_userdir",
16. "mod_cgi",
17. # "mod_compress",
18. # "mod_ssi",
19. # "mod_usertrack",
20. # "mod_expire",
21. # "mod_secdownload",
22. # "mod_rrdtool",
23. "mod_accesslog" )

[server.document-root]

1. server.document-root = "/www/"

把以下幾段註解掉,因為沒有support PCRE

1. #url.access-deny = ( "~", ".inc" )
2.  
3. #$HTTP["url"] =~ "\.pdf$" { 
4. # server.range-requests = "disable"
5. #}

[CGI module]

1. #### CGI module 
2. cgi.assign = ( ".pl" => "/usr/bin/perl",
3. ".cgi" => "" ) 
4.  
5. alias.url = ( "/cgi-bin" => "/www/cgi-bin" )

記得要把libdl相關的library傳到目標板的/lib資料夾下,執行lighttpd時所下的命令為lighttpd –f [lighttpd config file],用daemon方式執行於背景
(2)ipkg portingipkg cross compile的方式與lighttpd相同,但這邊要先修個bug,lighttpd執行cgi process時並沒有把目前linux環境變數複制到cgi執行環境,所以ipkg用getenv拿到的環境變數都是null,但ipkg沒有檢查指標是否為null,就逕行strdup,所以會讓程式crash
修改ipkg_cmd.c,找到ipkg_prep_intercepts這個function,並修改成如下範例

1. ipkg_intercept_t ipkg_prep_intercepts(ipkg_conf_t *conf) 
2. { 
3. ipkg_intercept_t ctx;
4. char *newpath;
5. int gen;
6.  
7. ctx = malloc (sizeof (*ctx));
8. //ctx->oldpath = strdup (getenv ("PATH"));//經典錯誤,用指標卻不檢查內容
9. if (getenv ("PATH")==NULL) 
10. ctx->oldpath=strdup("/sbin:/usr/sbin:/bin:/usr/bin");
11. else ctx->oldpath = strdup (getenv ("PATH"));
12. sprintf_alloc (&newpath, "%s/ipkg/intercept:%s", DATADIR, ctx->oldpath);
13. setenv ("PATH", newpath, 1);

ipkg詳細的用法請參考ipkg-輕量級套件管理系統
(3) html和cgi
用c寫cgi的方法請參考用pure C寫CGI的輔助工具-CGIC library,底下是我firmware upgrade cgi的c原始碼

1. #include <stdio.h> 
2. #include "cgic.h" 
3. #include <string.h> 
4. #include <stdlib.h> 
5.  
6. #define SERVER_NAME cgiServerName
7.  
8. void File() 
9. { 
10. cgiFilePtr file;
11. char name[1024];
12. char contentType[1024];
13. char buffer[1024];
14. int size;
15. int got;
16. FILE *fp;
17. char temp[256],fwop[1024];
18. int realwrite;
19. int status;
20.  
21. if (cgiFormFileName("file", name, sizeof(name)) != cgiFormSuccess) { 
22. fprintf(cgiOut,"<p>No file was uploaded.<p>\n");
23. return;
24. } 
25. fprintf(cgiOut, "The filename submitted was: ");
26. cgiHtmlEscape(name);
27. sprintf(temp,"touch /tmp/%s",name);
28. system(temp);
29. fprintf(cgiOut, "<p>\n");
30. cgiFormFileSize("file", &size);
31. fprintf(cgiOut, "The file size was: %d bytes<p>\n", size);
32. cgiFormFileContentType("file", contentType, sizeof(contentType));
33. //fprintf(cgiOut, "The alleged content type of the file was: ");
34. //cgiHtmlEscape(contentType);
35. fprintf(cgiOut, "<p>\n");
36. if (cgiFormFileOpen("file", &file) != cgiFormSuccess) 
37. { 
38. fprintf(cgiOut, "Could not open the file.<p>\n");
39. return;
40. } 
41. fprintf(cgiOut, "<pre>\n");
42.  
43. sprintf(temp,"/tmp/%s",name);
44. fp=fopen(temp,"w");
45.  
46. while (cgiFormFileRead(file, buffer, sizeof(buffer), &got) ==cgiFormSuccess) 
47. { 
48.  
49. fwrite(buffer,1,got,fp);
50. //cgiHtmlEscapeData(buffer, got);
51. //cgiHtmlEscapeData(buffer, got);
52. } 
53. fclose(fp);
54. fprintf(cgiOut, "</pre>\n");
55. sprintf(fwop,"/bin/ipkg -V 99 -f /etc/ipkg.conf install %s >/dev/null",temp);
56. system(fwop);
57.  
58. fprintf(cgiOut,"%s\n<p>",fwop);
59. fprintf(cgiOut,"<p>Firmware upgrade finished\n");
60. cgiFormFileClose(file);
61. } 
62. int cgiMain() 
63. { 
64. char name[81],mail[81],homepage[81],suggest[1024];
65.  
66. CookieSet();//set cookies before we read them
67. /* Send the content type, letting the browser know this is HTML */ 
68. cgiHeaderContentType("text/html");
69. /* Top of the page */ 
70. fprintf(cgiOut, "<HTML><HEAD>\n");
71. fprintf(cgiOut, "<TITLE>Firmware upgrade result</TITLE></HEAD>\n");
72. fprintf(cgiOut, "<BODY><H1>Responses</H1>\n");
73.  
74. if ((cgiFormSubmitClicked("send") == cgiFormSuccess)) 
75. { 
76. File();
77. } 
78. fprintf(cgiOut, "</BODY></HTML>\n");
79. return 0;
80. }

Firmware upgrade的html UI原始碼如下

1. <head> 
2. <body> 
3. <title>Firmware upgrade</title> 
4. <H1>QT2410 Firmware upgrade</H1> 
5. <form method="post" enctype="multipart/form-data" action="http://192.168.15.1/cgi-bin/upgrade.cgi"> 
6.  
7. <p>Firmware Upload:<input type="file" name="file" value=""> (Select A Local File)<p> 
8.  
9. <input type="submit" name= "send" value="send"> <input type="reset" value="cancel"> 
10.  
11. </form> 
12. </body> 
13. </head>