#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <syslog.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>

#define VHOST_ROOT "/var/www/vhosts"
#define SITES_ROOT "/var/www/sites"
#define CGI "cgi-bin"
#define SERVER "epochttpd/2.0 (Unix)"

// WARNING: this http software is vulnerable. I'm leaving it that way.

/* just notes for environment variables for CGIs when I need them.

Key             Value
DOCUMENT_ROOT   The root directory of your server
HTTP_COOKIE     The visitor's cookie, if one is set
HTTP_HOST       The hostname of the page being attempted
HTTP_REFERER    The URL of the page that called your program
HTTP_USER_AGENT The browser type of the visitor
HTTPS           "on" if the program is being called through a secure server
PATH            The system path your server is running under
QUERY_STRING    The query string (see GET, below)
REMOTE_ADDR     The IP address of the visitor
REMOTE_HOST     The hostname of the visitor (if your server has
                reverse-name-lookups on; otherwise this is the IP address again)
REMOTE_PORT     The port the visitor is connected to on the web server
REMOTE_USER     The visitor's username (for .htaccess-protected pages)
REQUEST_METHOD  GET or POST
REQUEST_URI     The interpreted pathname of the requested document or CGI
                (relative to the document root)
SCRIPT_FILENAME The full pathname of the current CGI
SCRIPT_NAME     The interpreted pathname of the current CGI (relative to
                the document root)
SERVER_ADMIN    The email address for your server's webmaster
SERVER_NAME     Your server's fully qualified domain name (e.g.
                www.cgi101.com)
SERVER_PORT     The port number your server is listening on
SERVER_SOFTWARE The server software you're using (e.g. Apache 1.3)
*/

void standard_headers() {
 printf("Server: %s\r\n",SERVER);
 printf("Connection: close\r\n");
}

int main(int argc,char *argv[]) {
 int fd;
 char *name[10];
 int s,n;
 char *method;
 char *page;
 char *version;
 char *get_param;
 char line[getpagesize()];
 fgets(line,sizeof(line)-1,stdin);
 struct sockaddr_in6 sa6;
 unsigned int sl=sizeof(sa6);
 char h[NI_MAXHOST];
 openlog("httpd",LOG_PID,LOG_DAEMON);
 if(getpeername(0,(struct sockaddr *)&sa6,&sl) == -1) 
  syslog(LOG_WARNING,"getpeername: %m");
 getnameinfo((struct sockaddr *)&sa6,sl,h,sizeof(h),0,0,NI_NUMERICHOST);
 setenv("REMOTE_ADDR",h,1);
 if(!strchr(line,'\n')) {
  printf("HTTP/1.1 413 Entity Too Large\r\n");
  standard_headers();
  printf("Content-type: text/plain\r\n\r\n");
  printf("use smaller (<%d bytes) headers.\n",getpagesize());
  syslog(LOG_WARNING,"413 Entity Too Large %s len: %d\n",h,strlen(line));
  return 0;
 }
 if(strchr(line,'\r')) *strchr(line,'\r')=0;
 method=strdup(line);
 if((page=strchr(method,' '))) {
  *page=0;
  page++;
  if((version=strchr(page,' '))) {
   *version=0;
   version++;
  }
  if((get_param=strchr(page,'?'))) {
   *get_param=0;
   get_param++;
   setenv("QUERY_STRING",get_param,1);
  }
 }
 signal(SIGALRM,exit);
 alarm(10);//maximum of 10s to receive requests sound good?
 while(fgets(line,sizeof(line)-1,stdin)) {
  if(!strchr(line,'\n')) {
   printf("HTTP/1.1 413 Entity Too Large\r\n");
   standard_headers();
   printf("Content-type: text/plain\r\n\r\n");
   printf("use smaller (<%d bytes) headers.\n",getpagesize());
   syslog(LOG_WARNING,"413 somewhere in request line 2+: %s %d\n",h,strlen(line));
   return 0;
  }
  if(strchr(line,'\r')) *strchr(line,'\r')=0;
  if(!strncasecmp(line,"Host: ",6)) {
   setenv("HTTP_HOST",line+6,1);
  }
  if(!strncasecmp(line,"User-agent: ",12)) {
   setenv("HTTP_USER_AGENT",line+12,1);
  }
  if(!strcmp(line,"")) {
   break;
  }
 }
 alarm(0);//no more timeout.
 //
 syslog(LOG_WARNING,"%s: %s %s %s\n",h,getenv("HTTP_USER_AGENT"),page,get_param);
 //TODO: sanitize this.
 if(chdir(VHOST_ROOT) == -1) {
   printf("HTTP/1.1 500 Internal Server Error\r\n");
   standard_headers();
   printf("Content-type: text/html\r\n\r\ncouldn't chdir(\"%s\");",VHOST_ROOT);
   syslog(LOG_WARNING,"can't chdir to VHOST_ROOT: %s",VHOST_ROOT);
   exit(3);
 }
 //I had fun exploiting this. :)
 if(chdir((char*)getenv("HTTP_HOST")) == -1) {
  if(chdir(SITES_ROOT) != -1) {
   if(chdir("default") == -1) {
    //no backup site to show people. fuck. shit happens.
    printf("HTTP/1.1 500 Internal Server Error\r\n");
    standard_headers();
    printf("Content-type: text/html\r\n\r\nfuck");
    syslog(LOG_WARNING,"can't chdir to default site dir.");
    exit(1);
   }
   //we're good.
  } else {
   printf("HTTP/1.1 500 Internal Server Error\r\n");
   standard_headers();
   printf("Content-type: text/html\r\n\r\ncouldn't chdir(\"%s\");",SITES_ROOT);
   //wtf? no sites dir???
   syslog(LOG_WARNING,"can't chdir to SITES_ROOT: %s",SITES_ROOT);
   exit(2);
  }
 }
 if(strncmp(page,"/cgi-bin/",9)) {
  for(;*page == '/';page++);
  if(page[strlen(page)-1] == '/') {
   printf("HTTP/1.1 302 Moved Permanently\r\n");
   standard_headers();
   printf("Location: /%sindex.html\r\n\r\n",page);
   return 0;
  }
  if((fd=open(page,O_RDONLY)) != -1) {//need to check that the file isn't a directory. :P
   printf("HTTP/1.1 200 OK\r\n");
   standard_headers();
   name[0]="/usr/local/bin/mime-type";
   name[1]=page;
   name[2]=0;
   printf("Content-type: ");
   fflush(stdout);
   switch(fork()) {
    case 0://child
     execv(name[0],name);
     break;
    case -1://error
     printf("fork failed.\n");
     break;
    default://parent
     break;
   }
   wait(&s);
   fflush(stdout);
   printf("\r\n");
   fflush(stdout);
   while((n=read(fd,line,sizeof(line)-1)) > 0) {
    write(STDOUT_FILENO,line,n);
   }
  } else {
   printf("HTTP/1.1 404 Not Found\r\n");
   standard_headers();
   printf("Content-type: text/plain\r\n\r\n");
   printf("Can't open that page.\n");
  }
 } else {
  //attempt to run this bastard!
  chdir(CGI);
  page+=strlen("/cgi-bin/");
  for(;*page == '/';page++);  
  name[0]=page;
  name[1]=0;
  printf("HTTP/1.1 200 OK\r\n");
  standard_headers();
  fflush(stdout);
  execv(name[0],name);
 }
 return 0;
}