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安装&配置

安装请参考参考资料1和2
安装完成以后,可以使用man micro_httpd 来获得更详细的说明

执行流程

代码解析

micro_httpd

/* micro_httpd - really small HTTP server
 **
 ** Copyright � 1999,2005 by Jef Poskanzer <jef@mail.acme.com>.
 ** All rights reserved.
 **
 ** Redistribution and use in source and binary forms, with or without
 ** modification, are permitted provided that the following conditions
 ** are met:
 ** 1. Redistributions of source code must retain the above copyright
 **    notice, this list of conditions and the following disclaimer.
 ** 2. Redistributions in binary form must reproduce the above copyright
 **    notice, this list of conditions and the following disclaimer in the
 **    documentation and/or other materials provided with the distribution.
 ** 
 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ** ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 ** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 ** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 ** SUCH DAMAGE.
 */

/*
#######################################
1.此程序对输入输出使用的是stdin和stdout 
可以猜测它需要依赖其它程序对它的输入输出进行重定向
2.次程序没有创建socket服务
因此需要其它程序为其创建socket服务
######################################
 */

#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <dirent.h>
#include <ctype.h>
#include <time.h>
#include <sys/stat.h>


#define SERVER_NAME "micro_httpd"
#define SERVER_URL "http://www.acme.com/software/micro_httpd/"
#define PROTOCOL "HTTP/1.0"
#define RFC1123FMT "%a, %d %b %Y %H:%M:%S GMT"


/* Forwards. */
//输出文件相关属性的详细信息
static void file_details( char* dir, char* name );
//返回出错页面
static void send_error( int status, char* title, char* extra_header, char* text );
//设置reponse 
static void send_headers( int status, char* title, char* extra_header, char* mime_type, off_t length, time_t mod );
//通过文件名推断文件mime_type
static char* get_mime_type( char* name );
//URL 解码
static void strdecode( char* to, char* from );
//十六进制转换为十进制数
static int hexit( char c );
//用于文件名编码
static void strencode( char* to, size_t tosize, const char* from );


    int
main( int argc, char** argv )
{
    char line[10000], method[10000], path[10000], protocol[10000], idx[20000], location[20000], command[20000];
    char* file;
    size_t len;
    int ich;
    struct stat sb;
    FILE* fp;
    struct dirent **dl;
    int i, n;

    if ( argc != 2 )
        send_error( 500, "Internal Error", (char*) 0, "Config error - no dir specified." );
    //更改工作目录
    if ( chdir( argv[1] ) < 0 )
        send_error( 500, "Internal Error", (char*) 0, "Config error - couldn't chdir()." );
    if ( fgets( line, sizeof(line), stdin ) == (char*) 0 )
        send_error( 400, "Bad Request", (char*) 0, "No request found." );
    //解析请求 形如 GET /abc/index.html   HTTP/1.0
    if ( sscanf( line, "%[^ ] %[^ ] %[^ ]", method, path, protocol ) != 3 )
        send_error( 400, "Bad Request", (char*) 0, "Can't parse request." );
    while ( fgets( line, sizeof(line), stdin ) != (char*) 0 )
    {
        if ( strcmp( line, "\n" ) == 0 || strcmp( line, "\r\n" ) == 0 )
            break;
    }
    if ( strcasecmp( method, "get" ) != 0 )
        send_error( 501, "Not Implemented", (char*) 0, "That method is not implemented." );
    if ( path[0] != '/' )
        send_error( 400, "Bad Request", (char*) 0, "Bad filename." );
    file = &(path[1]);
    strdecode( file, file );
    if ( file[0] == '\0' )
        file = "./";
    len = strlen( file );
    if ( file[0] == '/' || strcmp( file, ".." ) == 0 || strncmp( file, "../", 3 ) == 0 || strstr( file, "/../" ) != (char*) 0 || strcmp( &(file[len-3]), "/.." ) == 0 )
        send_error( 400, "Bad Request", (char*) 0, "Illegal filename." );
    if ( stat( file, &sb ) < 0 )
        send_error( 404, "Not Found", (char*) 0, "File not found." );
    //请求路径是文件夹吗
    if ( S_ISDIR( sb.st_mode ) )
    {
        if ( file[len-1] != '/' )
        {
            (void) snprintf(
                    location, sizeof(location), "Location: %s/", path );
            send_error( 302, "Found", location, "Directories must end with a slash." );
        }
        (void) snprintf( idx, sizeof(idx), "%sindex.html", file );
        if ( stat( idx, &sb ) >= 0 )
        {
            file = idx;
            goto do_file;
        }
        //显示请求文件夹下的文件列表
        send_headers( 200, "Ok", (char*) 0, "text/html", -1, sb.st_mtime );
        (void) printf( "<html><head><title>Index of %s</title></head>\n<body bgcolor=\"#99cc99\"><h4>Index of %s</h4>\n<pre>\n", file, file );
        n = scandir( file, &dl, NULL, alphasort );
        if ( n < 0 )
            perror( "scandir" );
        else
            for ( i = 0; i < n; ++i )
                file_details( file, dl[i]->d_name );
        (void) printf( "</pre>\n<hr>\n<address><a href=\"%s\">%s</a></address>\n</body></html>\n", SERVER_URL, SERVER_NAME );
    }
    else
    {  //返回请求的文件
do_file:
        fp = fopen( file, "r" );
        if ( fp == (FILE*) 0 )
            send_error( 403, "Forbidden", (char*) 0, "File is protected." );
        send_headers( 200, "Ok", (char*) 0, get_mime_type( file ), sb.st_size, sb.st_mtime );
        while ( ( ich = getc( fp ) ) != EOF )
            putchar( ich );
    }

    (void) fflush( stdout );
    exit( 0 );
}

//输出文件相关属性的详细信息
    static void
file_details( char* dir, char* name )
{
    static char encoded_name[1000];
    static char path[2000];
    struct stat sb;
    char timestr[16];

    strencode( encoded_name, sizeof(encoded_name), name );
    (void) snprintf( path, sizeof(path), "%s/%s", dir, name );
    if ( lstat( path, &sb ) < 0 )
        (void) printf( "<a href=\"%s\">%-32.32s</a>    ???\n", encoded_name, name );
    else
    {
        (void) strftime( timestr, sizeof(timestr), "%d%b%Y %H:%M", localtime( &sb.st_mtime ) );
        (void) printf( "<a href=\"%s\">%-32.32s</a>    %15s %14lld\n", encoded_name, name, timestr, (int64_t) sb.st_size );
    }
}

//返回出错页面
    static void
send_error( int status, char* title, char* extra_header, char* text )
{
    send_headers( status, title, extra_header, "text/html", -1, -1 );
    (void) printf( "<html><head><title>%d %s</title></head>\n<body bgcolor=\"#cc9999\"><h4>%d %s</h4>\n", status, title, status, title );
    (void) printf( "%s\n", text );
    (void) printf( "<hr>\n<address><a href=\"%s\">%s</a></address>\n</body></html>\n", SERVER_URL, SERVER_NAME );
    (void) fflush( stdout );
    exit( 1 );
}

//设置reponse  header
//状态 标题  mime_type 文件最后被修改的时间
    static void
send_headers( int status, char* title, char* extra_header, char* mime_type, off_t length, time_t mod )
{
    time_t now;
    char timebuf[100];
    //\015\012 回车换行
    (void) printf( "%s %d %s\015\012", PROTOCOL, status, title );
    (void) printf( "Server: %s\015\012", SERVER_NAME );
    now = time( (time_t*) 0 );
    //将时间格式化后存在timebuf中
    (void) strftime( timebuf, sizeof(timebuf), RFC1123FMT, gmtime( &now ) );
    (void) printf( "Date: %s\015\012", timebuf );
    if ( extra_header != (char*) 0 )
        (void) printf( "%s\015\012", extra_header );
    if ( mime_type != (char*) 0 )
        (void) printf( "Content-Type: %s\015\012", mime_type );
    if ( length >= 0 )
        (void) printf( "Content-Length: %lld\015\012", (int64_t) length );
    if ( mod != (time_t) -1 )
    {
        (void) strftime( timebuf, sizeof(timebuf), RFC1123FMT, gmtime( &mod ) );
        (void) printf( "Last-Modified: %s\015\012", timebuf );
    }
    (void) printf( "Connection: close\015\012" );
    (void) printf( "\015\012" );
}

//通过文件名推断文件mime_type
    static char*
get_mime_type( char* name )
{
    char* dot;

    dot = strrchr( name, '.' );
    if ( dot == (char*) 0 )
        return "text/plain; charset=iso-8859-1";
    if ( strcmp( dot, ".html" ) == 0 || strcmp( dot, ".htm" ) == 0 )
        return "text/html; charset=iso-8859-1";
    if ( strcmp( dot, ".jpg" ) == 0 || strcmp( dot, ".jpeg" ) == 0 )
        return "image/jpeg";
    if ( strcmp( dot, ".gif" ) == 0 )
        return "image/gif";
    if ( strcmp( dot, ".png" ) == 0 )
        return "image/png";
    if ( strcmp( dot, ".css" ) == 0 )
        return "text/css";
    if ( strcmp( dot, ".au" ) == 0 )
        return "audio/basic";
    if ( strcmp( dot, ".wav" ) == 0 )
        return "audio/wav";
    if ( strcmp( dot, ".avi" ) == 0 )
        return "video/x-msvideo";
    if ( strcmp( dot, ".mov" ) == 0 || strcmp( dot, ".qt" ) == 0 )
        return "video/quicktime";
    if ( strcmp( dot, ".mpeg" ) == 0 || strcmp( dot, ".mpe" ) == 0 )
        return "video/mpeg";
    if ( strcmp( dot, ".vrml" ) == 0 || strcmp( dot, ".wrl" ) == 0 )
        return "model/vrml";
    if ( strcmp( dot, ".midi" ) == 0 || strcmp( dot, ".mid" ) == 0 )
        return "audio/midi";
    if ( strcmp( dot, ".mp3" ) == 0 )
        return "audio/mpeg";
    if ( strcmp( dot, ".ogg" ) == 0 )
        return "application/ogg";
    if ( strcmp( dot, ".pac" ) == 0 )
        return "application/x-ns-proxy-autoconfig";
    return "text/plain; charset=iso-8859-1";
}

//用于URL 解码
    static void
strdecode( char* to, char* from )
{
    for ( ; *from != '\0'; ++to, ++from )
    {
        if ( from[0] == '%' && isxdigit( from[1] ) && isxdigit( from[2] ) )
        {
            *to = hexit( from[1] ) * 16 + hexit( from[2] );
            from += 2;
        }
        else
            *to = *from;
    }
    *to = '\0';
}

//十六进制转换为十进制数
    static int
hexit( char c )
{
    if ( c >= '0' && c <= '9' )
        return c - '0';
    if ( c >= 'a' && c <= 'f' )
        return c - 'a' + 10;
    if ( c >= 'A' && c <= 'F' )
        return c - 'A' + 10;
    return 0;       /* shouldn't happen, we're guarded by isxdigit() */
}

//用于文件名编码
    static void
strencode( char* to, size_t tosize, const char* from )
{
    int tolen;

    for ( tolen = 0; *from != '\0' && tolen + 4 < tosize; ++from )
    {
        //ASCII 字符、数字 或者 "/_.-~" 中的一个
        if ( isalnum(*from) || strchr( "/_.-~", *from ) != (char*) 0 )
        {
            *to = *from;
            ++to;
            ++tolen;
        }
        else  //对特殊字符进行编码  问题:什么样的特殊字符需要这样编码?
        {
            (void) sprintf( to, "%%%02x", (int) *from & 0xff );
            to += 3;
            tolen += 3;
        }
    }
    *to = '\0';
}

参考资料

  1. micro_http 下载地址
  2. micro_httpd的安装与配置

后记

这是我2012年的文章,原来发表在ITeye,现在一并迁移过来


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