利用xinetd实现简单web服务器（镜像站）

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浏览效果：

linux服务器安装xinetd后，在/etc/xinetd.d/目录下创建xhttpd文件，并输入内容：

service xhttpd{    socket_type = stream    protocol = tcp    wait = no    user = gongluck    server = /home/gongluck/桌面/xhttpd    server_args = /home/gongluck/桌面/xhttpdir    disable = no    flags = IPv4}

然后在/etc/services文件的最后添加自己使用的端口和进程的名字：

xhttpd      9527/tcp        # xhttpd servicexhttpd      9527/udp        # xhttpd servic

重启服务：

sudo service xinetd restart

xhttpd程序的代码：

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <ctype.h>#include <dirent.h>#define LEN 4096char* get_filetype(const char* file);void send_error(int status,char* title);void send_header(int status,char* title, char* filetype);void decode(char* to, char* from);void encode(char* to, char* from);int main(int argc,const char* argv[]){    if(argc < 2)        send_error(500,"server error : argc < 2");    //if(access(argv[1],R_OK | F_OK) != 0)    if(chdir(argv[1]) < 0)        send_error(500,"server error : chdir error");    char line[LEN],type[LEN],path[LEN],protocol[LEN];    if(fgets(line,sizeof(line),stdin) == NULL)        send_error(500,"server error : type path protocol");    if(sscanf(line,"%[^ ] %[^ ] %[^ ]",type,path,protocol) != 3)        send_error(400,"bad request");    if(strcasecmp(type,"GET") != 0)        send_error(400,"method not allow");    if(path[0] != '/')        send_error(404,"file not found");    while(fgets(line,sizeof(line),stdin) != NULL)    {        if(strcmp(line,"\n") == 0 || strcmp(line,"\r\n") == 0)            break;    }    char file[LEN];    struct stat st;    file[0] = '.';    decode(file+1,path);    //printf("%s\n",&path[1]);    //printf("%s\n",file);    if(stat(file,&st) < 0)    {        printf("file : %s\r\n",file);        send_error(500,"server error : stat");    }    if(S_ISDIR(st.st_mode))    {        send_header(200,"OK","text/html;charset=utf-8");        printf("<html>"                    "<head><title>Index of %s</title></head>"                    "<body bgcolor=\"#cc99cc\">"                        "<h4>Index of %s</h4>"                        "<pre>"                    ,file,file);        struct dirent** dl;        int nf = scandir(file,&dl,NULL,alphasort);        if(nf < 0)            perror("scandir");        else        {            struct stat fst;            char stfile[LEN];            for(int i=0;i<nf; ++i)            {                strcpy(stfile,file);                strcat(stfile,"/");                strcat(stfile,dl[i]->d_name);                if(lstat(stfile,&fst) < 0)                    printf("<a href=\"%s%s/\">%-32.32s/</a>",file+1,dl[i]->d_name,dl[i]->d_name);                else if(S_ISDIR(fst.st_mode))                    printf("<a href=\"%s%s/\">%-32.32s/</a> \t\t%14lld",file+1,dl[i]->d_name,dl[i]->d_name,(long long)fst.st_size);                else                    printf("<a href=\"%s%s\">%-32.32s</a> \t\t%14lld",file+1,dl[i]->d_name,dl[i]->d_name,(long long)fst.st_size);                printf("<br/>");            }        }        printf("</pre>"               "</body>"               "</html>");    }    else    {    //普通文件    FILE* fp = fopen(file,"r");    if(fp == NULL)        send_error(500,"server error : open file");    send_header(200,"send header",get_filetype(file));    int ch;//这里必须用int判断EOF，我真是菜鸡。    while((ch = getc(fp)) != EOF)    {        putchar(ch);    }    fflush(stdout);    fclose(fp);    fp = NULL;    }//    printf("test success !\n");    return 0;}int hex2d(char hex){    if(hex >= '0' && hex <= '9')        return hex-'0';    else if(hex >= 'a' && hex <= 'f')        return hex-'a'+10;    else if(hex >= 'A' && hex <= 'F')        return hex-'A'+10;    else        return hex;}void decode(char* to, char* from){    if(to == NULL || from == NULL)        return;    while(*from != '\0')    {        if(from[0] == '%' && isxdigit(from[1]) && isxdigit(from[2]))        {            *to = hex2d(from[1])*16 + hex2d(from[2]);            from += 3;        }        else        {            *to = *from;            ++from;        }        ++to;    }    *to = '\0';}void encode(char* to, char* from){    if(to == NULL && from == NULL)        return;    while(*from != '\0')    {        if(isalnum(*from) || strchr("/._-~",*from) != NULL)        {            *to = *from;            ++to;            ++from;        }        else        {            sprintf(to,"%%%02x",*from);            to += 3;            from += 3;        }    }    *to = '\0';}char* get_filetype(const char* file){    if(file == NULL)        return NULL;    char* dot = strrchr(file,'.');    if(*dot == '\0')        return "text/plain; charset=utf-8";    else if(strcmp(dot,".html") == 0)        return "text/html; charset=utf-8";    else if(strcmp(dot, ".jpg") == 0)        return "image/jpeg";    else if(strcmp(dot, ".gif") == 0)        return "image/gif";    else if(strcmp(dot, ".png") == 0)        return "image/png";    else if(strcmp(dot, ".wav") == 0)        return "audio/wav";    else if(strcmp(dot, ".avi") == 0)        return "video/x-msvideo";    else if(strcmp(dot, ".mov") == 0)        return "video/quicktime";    else if(strcmp(dot, ".mp3") == 0)        return "audio/mpeg";    else        return "text/plain; charset=utf-8";}void send_header(int status, char* title, char* filetype){    if(title == NULL || filetype == NULL)    {        title = "ERROR";        filetype = "text/plain; charset=utf-8";    }    printf("HTTP/1.1 %d %s\r\n",status,title);    printf("Content-Type:%s\r\n",filetype);    printf("\r\n");}void send_error(int status,char* title){    if(title == NULL)        title = "ERROR";    send_header(status,title,"text/html; charset=utf-8");    printf("<html>\n"                "<head><title>%d %s</title></head>\n"                "<body bgcolor=\"#cc99cc\">\n"                    "<h4>error!</h4>\n"                    "<hr>\n"                    "<address>\n"                        "<a href=\"http://blog.csdn.net/gongluck93/\">gongluck</a>\n"                    "</address>\n"                "</body>\n"            "</html>",           status,title);    fflush(stdout);    exit(1);}

由于xinetd会帮助我们与浏览器建立好连接，并且将stdin重定向到浏览器的发送端，stdout重定向到浏览器的接收端。所以xhttpd程序只需要从标准输入中读取浏览器的请求数据，把响应数据写入标准输出中即可。

这里只是用http协议的很简单的一部分：

GET /请求的文件名 HTTP/1.1

HTTP/1.1 状态码 描述Content-Type:回传文件类型\r\n回传文件数据

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