/* This file is part of GNU Pies
   Copyright (C) 2015, 2017 Sergey Poznyakoff
  
   GNU Pies 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 3, or (at your option)
   any later version.

   GNU Pies 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 GNU Pies.  If not, see <http://www.gnu.org/licenses/>. */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include "libpies.h"
#include <unistd.h>
#include <pwd.h>
#include <grecs.h>
#include <wordsplit.h>
#include <errno.h>
#include <netdb.h>

/* Compare two hostnames. Return 0 if they have the same address type,
   address length *and* at least one of the addresses of A matches
   B */
static int
hostcmp (const char *a, const char *b)
{
  struct hostent *hp = gethostbyname (a);
  char **addrlist;
  char *dptr;
  char **addr;
  size_t i, count;
  size_t entry_length;
  int entry_type;

  if (!hp)
    return 1;

  for (count = 1, addr = hp->h_addr_list; *addr; addr++)
    count++;
  addrlist = grecs_malloc (count * (sizeof *addrlist + hp->h_length)
			   - hp->h_length);
  dptr = (char *) (addrlist + count);
  for (i = 0; i < count - 1; i++)
    {
      memcpy (dptr, hp->h_addr_list[i], hp->h_length);
      addrlist[i] = dptr;
      dptr += hp->h_length;
    }
  addrlist[i] = NULL;
  entry_length = hp->h_length;
  entry_type = hp->h_addrtype;

  hp = gethostbyname (b);
  if (!hp || entry_length != hp->h_length || entry_type != hp->h_addrtype)
    {
      grecs_free (addrlist);
      return 1;
    }

  for (addr = addrlist; *addr; addr++)
    {
      char **p;

      for (p = hp->h_addr_list; *p; p++)
	{
	  if (memcmp (*addr, *p, entry_length) == 0)
	    {
	      grecs_free (addrlist);
	      return 0;
	    }
	}
    }
  grecs_free (addrlist);
  return 1;
}

static int
match_url (size_t argc, char **argv, struct pies_url *url)
{
  if (hostcmp (argv[1], url->host ? url->host : "localhost") == 0)
    {
      if (argc >= 4 && strcmp (argv[2], "port") == 0)
	{
          unsigned long n = strtoul (argv[3], NULL, 10);
	  if (n == url->port)
	    return 1;
	}
      else
	return 1;
    }
  return 0;
}

static void
parse_args (struct grecs_locus *loc, char **argv,
	    char **username, char **password)
{
  if (*username)
    {
      grecs_free (*username);
      *username = NULL;
    }
  if (*password)
    {
      grecs_free (*password);
      *password = NULL;
    }
  
  while (*argv)
    {
      if (!argv[1])
	{
	  grecs_error (loc, 0, _("incomplete sentence"));
	  break;
	}
      if (strcmp (*argv, "login") == 0)
	*username = grecs_strdup (argv[1]);
      else if (strcmp (*argv, "password") == 0)
	*password = grecs_strdup (argv[1]);
      argv += 2;
    }
}

/* Parse traditional .netrc file. Set up auth_args fields in accordance with
   it. */
void
netrc_scan_file (FILE *fp, struct grecs_locus *loc, struct pies_url *url)
{
  char *buf = NULL;
  size_t n = 0;
  struct wordsplit ws;
  int wsflags = WRDSF_NOVAR | WRDSF_NOCMD | WRDSF_QUOTE | WRDSF_SQUEEZE_DELIMS;
  char *username = NULL;
  char *password = NULL;

  while (grecs_getline (&buf, &n, fp) > 0)
    {
      loc->beg.line++;

      if (wordsplit (buf, &ws, wsflags))
	{
	  grecs_error (loc, 0, "wordsplit: %s", wordsplit_strerror (&ws));
	  continue;
	}
      wsflags |= WRDSF_REUSE;

      if (ws.ws_wordc == 0)
	continue;

      if (strcmp (ws.ws_wordv[0], "machine") == 0)
	{
	  if (match_url (ws.ws_wordc, ws.ws_wordv, url))
	    {
	      parse_args (loc, ws.ws_wordv + 2, &username, &password);
	      break;
	    }
	}
      else if (strcmp (ws.ws_wordv[0], "default") == 0)
	parse_args (loc, ws.ws_wordv + 1, &username, &password);
      else
	grecs_error (loc, 0, _("ignoring unrecognized line"));
    }
  grecs_free (buf);

  if (wsflags & WRDSF_REUSE)
    wordsplit_free (&ws);

  url->user = username;
  url->passwd = password;
}

void
netrc_scan (struct pies_url *url)
{
  FILE *fp;
  struct grecs_locus loc;
  char *filename;
  char *homedir;

  if (url->user)
    return;
  
  homedir = getenv ("HOME");
  if (!homedir)
    {
      struct passwd *pwd = getpwuid (getuid ());
      if (!pwd)
	return;
      homedir = pwd->pw_dir;
    }

  filename = mkfilename (homedir, ".netrc", NULL);
  fp = fopen (filename, "r");
  if (!fp)
    {
      if (errno != ENOENT)
	grecs_error (NULL, 0,
		     _("cannot open configuration file %s: %s"),
		     filename, strerror (errno));
      free (filename);
      return;
    }

  loc.beg.file = loc.end.file = (char*) filename;
  loc.beg.col = loc.end.col = 0;
  loc.beg.line = 0;
  netrc_scan_file (fp, &loc, url);
  fclose (fp);
  free (filename);
}