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// nullmailer -- a simple relay-only MTA
// Copyright (C) 2012 Bruce Guenter <bruce@untroubled.org>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
// You can contact me at <bruce@untroubled.org>. There is also a mailing list
// available to discuss this package. To subscribe, send an email to
// <nullmailer-subscribe@lists.untroubled.org>.
#include "config.h"
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
#include "itoa.h"
#include "defines.h"
#include "mystring/mystring.h"
#include "fdbuf/fdbuf.h"
#include "configio.h"
#include "hostname.h"
#define fail(MSG) do{ fout << "nullmailer-queue: " << MSG << endl; return false; }while(0)
pid_t pid = getpid();
uid_t uid = getuid();
time_t timesecs = time(0);
mystring adminaddr;
bool remapadmin = false;
bool is_dir(const char* path)
{
struct stat buf;
return !stat(path, &buf) && S_ISDIR(buf.st_mode);
}
bool is_exist(const char* path)
{
struct stat buf;
return !stat(path, &buf);
}
int fsyncdir(const char* path)
{
int fd = open(path, O_RDONLY);
if(fd == -1)
return 0;
int result = fsync(fd);
if(result == -1 && errno != EIO)
result = 0;
close(fd);
return result;
}
void trigger()
{
int fd = open(QUEUE_TRIGGER, O_WRONLY|O_NONBLOCK, 0666);
if(fd == -1)
return;
char x = 0;
write(fd, &x, 1);
close(fd);
}
bool validate_addr(mystring& addr, bool doremap)
{
int i = addr.find_last('@');
if(i < 0)
return false;
mystring hostname = addr.right(i+1);
if(doremap && remapadmin) {
if(hostname == me || hostname == "localhost")
addr = adminaddr;
}
// else if(hostname.find_first('.') < 0)
// return false;
return true;
}
bool copyenv(fdobuf& out)
{
mystring str;
if(!fin.getline(str))
fail("Could not read envelope sender.");
if(!validate_addr(str, false) && str != "")
fail("Envelope sender address is invalid.");
if(!(out << str << endl))
fail("Could not write envelope sender.");
unsigned count=0;
while(fin.getline(str) && !!str) {
if(!validate_addr(str, true))
fail("Envelope recipient address is invalid.");
if(!(out << str << endl))
fail("Could not write envelope recipient.");
++count;
}
if(count == 0)
fail("No envelope recipients read.");
if(!(out << "\n"))
fail("Could not write extra blank line to destination.");
return true;
}
bool makereceived(fdobuf& out)
{
mystring line("Received: (nullmailer pid ");
line += itoa(pid);
line += " invoked by uid ";
line += itoa(uid);
line += ");\n\t";
char buf[100];
if(!strftime(buf, 100, "%a, %d %b %Y %H:%M:%S -0000\n", gmtime(×ecs)))
fail("Error generating a date string.");
line += buf;
if(!(out << line))
fail("Could not write received line to message.");
return true;
}
bool dump(int fd)
{
fdobuf out(fd);
if(!copyenv(out))
return false;
if(!makereceived(out))
return false;
if(!fdbuf_copy(fin, out))
fail("Error copying the message to the queue file.");
if(!out.sync())
fail("Error flushing the output file.");
if(!out.close())
fail("Error closing the output file.");
return true;
}
bool deliver()
{
if(!is_dir(QUEUE_MSG_DIR) || !is_dir(QUEUE_TMP_DIR))
fail("Installation error: queue directory is invalid.");
// Notes:
// - temporary file name is unique to the currently running
// nullmailer-queue program
// - destination file name is unique to the system
// - if the temporary file previously existed, it did so because
// the previous nullmailer-queue process crashed, and it can be
// safely overwritten
const mystring pidstr = itoa(pid);
const mystring timestr = itoa(timesecs);
const mystring tmpfile = QUEUE_TMP_DIR + pidstr;
const mystring newfile = QUEUE_MSG_DIR + timestr + "." + pidstr;
int out = open(tmpfile.c_str(), O_CREAT|O_WRONLY|O_TRUNC, 0600);
if(out < 0)
fail("Could not open temporary file for writing");
if(!dump(out)) {
unlink(tmpfile.c_str());
return false;
}
if(link(tmpfile.c_str(), newfile.c_str()))
fail("Error linking the temp file to the new file.");
if(fsyncdir(QUEUE_MSG_DIR))
fail("Error syncing the new directory.");
if(unlink(tmpfile.c_str()))
fail("Error unlinking the temp file.");
return true;
}
int main(int, char*[])
{
umask(077);
if(config_read("adminaddr", adminaddr) && !!adminaddr) {
adminaddr = adminaddr.subst(',', '\n');
remapadmin = true;
read_hostnames();
}
if(!deliver())
return 1;
trigger();
return 0;
}
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