CGI Bits & Pieces #2

// Send form data to an email account
//
// Copyright (c) 1999 by Jürgen Hermann, All Rights Reserved.

#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <fstream>
#include <sstream>


// this is the return address put into the mail (should be in the config file)
const char* POSTMASTER = "David Stiles <pingme@home.com>";


// get delimited substring from "str" and remove it from "str"
std::string strParse(std::string& str, const char* delim)
{
  std::string result;
  std::string::size_type pos = str.find_first_of(delim);

  if (pos == std::string::npos) {
    result = str;
    str    = "";
  } else {
    result = str.substr(0, pos);
    str.erase(0, pos+1);
  }

  return result;
}


// send an environment value to a stream, if it actually exists
void echoEnv(ostream& out, const char* envvar)
{
  char* val = getenv(envvar);
  if (val) out << envvar << '=' << val << '\n';
}


// the main program
int main()
{
  // init
  mode_t oldmask = umask(0);
  umask(oldmask & ~mode_t(0770));

  // scan the .cfg file and check for allowed destinations
  char* query = getenv("QUERY_STRING");
  string mailto;
  string jumpto;

  if (query) {
    ifstream in("wwwmail.cfg");
    string line;
    
    while (!in.eof()) {
      getline(in, line);
      if (!in.good() || in.eof()) break;

      string alias = strParse(line, ";");
      if (alias == query) {
        mailto = strParse(line, ";");
        jumpto = strParse(line, ";");
        break;
      }
    }
  }

  if (!query || mailto.empty() || jumpto.empty()) {
    cout << "Content-Type: text/plain\n"
         << "\n"
         << "Internal error!\n";
    exit(666);
  }

  // build the mail header
  char* formpage = getenv("HTTP_REFERER");
  
  ostringstream mail;
  mail << "To: " << mailto << '\n'
       << "From: " << POSTMASTER << '\n'
       << "Subject: Form submit from '"
       << (formpage ? formpage : "Unknown URL") << "'\n"
       << "\n";

  // send identification of the remote user
  echoEnv(mail, "HTTP_USER_AGENT");
  echoEnv(mail, "REMOTE_ADDR");
  echoEnv(mail, "REMOTE_IDENT");
  echoEnv(mail, "REMOTE_HOST");
  echoEnv(mail, "REMOTE_USER");

  // send form data
  int ch;
  while ((ch = cin.get(), !cin.eof())) {
    switch (ch) {
      default:  mail << char(ch); break;
      case '+': mail << ' ';      break;
      case '&': mail << '\n';     break;
      case '%': {
        char buf[3];
        buf[0] = cin.get();
        buf[1] = cin.get();
        buf[2] = '\0';
        mail << char(strtol(buf, 0, 16));
        break;
      } // case
    } // switch
  } // while
  mail << '\n';

  // send the mail
  FILE* sendmail = popen("/usr/lib/sendmail -i -t", "w");
  if (sendmail) {
    fputs(mail.str().c_str(), sendmail);
    pclose(sendmail);
  }

  // redir to follow-up page
  cout << "Location: " << jumpto << "\n\n";

  return 0;
}