key/pixie-common.c, progs/pixie.c: Handle error returns better.

[u/mdw/catacomb] / key / pixie-common.c

/* -*-c-*-
 *
 * Common code for Pixie client and server (Unix-specific)
 *
 * (c) 1999 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * Catacomb 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 Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Header files ------------------------------------------------------*/

#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <pwd.h>

#include <sys/socket.h>
#include <sys/un.h>

#include <mLib/alloc.h>
#include <mLib/dstr.h>
#include <mLib/str.h>

#include "pixie.h"

/*----- Main code ---------------------------------------------------------*/

/* --- @pixie_address@ --- *
 *
 * Arguments:	@const char *sock@ = pointer to socket name
 *		@size_t *psz@ = where to write the address size
 *
 * Returns:	Pointer to filled-in Unix-domain socket address.
 *
 * Use:		Returns a Unix-domain socket address to	use to find the
 *		passphrase pixie.
 */

struct sockaddr_un *pixie_address(const char *sock, size_t *psz)
{
  dstr d = DSTR_INIT;

  /* --- Get the default socket path if none specified --- */

  if (!sock)
    sock = getenv("CATACOMB_PIXIE_SOCKET");
  if (!sock)
    sock = "%h/.catacomb/pixie";

  /* --- Substitute interesting sequences in the path --- */

  {
    const char *q, *qq;

    q = sock;
    for (;;) {
      qq = strchr(q, '%');
      if (!qq || !qq[1]) {
	DPUTS(&d, q);
	break;
      }
      DPUTM(&d, q, qq - q);
      q = qq + 1;
      switch (*q) {
	case 'u':
	  qq = getenv("USER");
	  if (!qq)
	    qq = getenv("LOGNAME");
	  if (!qq) {
	    struct passwd *pw = getpwuid(getuid());
	    if (pw)
	      qq = pw->pw_name;
	    else
	      qq = "<unknown>";
	  }
	  DPUTS(&d, qq);
	  break;
	case 'h':
	  qq = getenv("HOME");
	  if (!qq) {
	    struct passwd *pw = getpwuid(getuid());
	    if (pw)
	      qq = pw->pw_dir;
	    else
	      qq = "<unknown>";
	  }
	  DPUTS(&d, qq);
	  break;
	default:
	  DPUTC(&d, '%');
	  DPUTC(&d, *q);
	  break;
      }
      q++;
    }
    DPUTZ(&d);
  }

  /* --- Allocate and initialize the socket address --- */

  {
    struct sockaddr_un *sun;
    size_t bsz = offsetof(struct sockaddr_un, sun_path);
    *psz = bsz + d.len + 1;
    sun = xmalloc(bsz + d.len + 1);
    memset(sun, 0, bsz);
    sun->sun_family = AF_UNIX;
    memcpy(sun->sun_path, d.buf, d.len + 1);
    dstr_destroy(&d);
    return (sun);
  }
}

/* --- @pixie_fdline@ --- *
 *
 * Arguments:	@int fd@ = file descriptor to read from
 *		@char *buf@ = pointer to buffer
 *		@size_t sz@ = size of buffer
 *
 * Returns:	---
 *
 * Use:		Reads a line from a file descriptor.  The read is done one
 *		character at a time.  If the entire line won't fit, the end
 *		is truncated.  The line is null terminated.
 */

void pixie_fdline(int fd, char *buf, size_t sz)
{
  char *p = buf;
  char *q = p + sz - 1;

  for (;;) {
    char c;
    if (read(fd, &c, 1) < 1)
      break;
    if (c == '\n')
      break;
    if (p < q)
      *p++ = c;
  }
  *p = 0;
}

/* --- @pixie_getpass@ --- *
 *
 * Arguments:	@const char *prompt@ = pointer to prompt string
 *		@char *buf@ = pointer to buffer
 *		@size_t sz@ = size of buffer
 *
 * Returns:	Zero if it worked OK, nonzero otherwise.
 *
 * Use:		Reads a passphrase from the terminal or some other requested
 *		source.
 */

int pixie_getpass(const char *prompt, char *buf, size_t sz)
{
  const char *pfd = getenv("CATACOMB_PASSPHRASE_FD");
  struct termios ta;
  struct termios ota;
  char nl = '\n';
  int fd = 0;

  /* --- See whether a terminal is what's wanted --- */

  if (pfd) {
    fd = atoi(pfd);
    pixie_fdline(fd, buf, sz);
  } else {
    if ((fd = open("/dev/tty", O_RDWR)) < 0)
      goto fail_0;
    if (tcgetattr(fd, &ta) < 0)
      goto fail_1;
    ota = ta;
    ta.c_lflag &= ~(ECHO | ISIG);
    if (tcsetattr(fd, TCSAFLUSH, &ta)) goto fail_1;
    if (write(fd, prompt, strlen(prompt)) < 0) goto fail_2;
    pixie_fdline(fd, buf, sz);
    tcsetattr(fd, TCSAFLUSH, &ota);
    if (write(fd, &nl, 1) < 0) goto fail_1;
    close(fd);
  }
  return (0);

  /* --- Tidy up if things went wrong --- */

fail_2:
  tcsetattr(fd, TCSAFLUSH, &ota);
fail_1:
  close(fd);
fail_0:
  return (-1);
}

/* --- @pixie_open@ --- *
 *
 * Arguments:	@const char *sock@ = path to pixie socket
 *
 * Returns:	Less than zero if it failed, or file descriptor.
 *
 * Use:		Opens a connection to a passphrase pixie.
 */

int pixie_open(const char *sock)
{
  struct sockaddr_un *sun;
  size_t sz;
  int fd;

  /* --- Open the connection --- */

  if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
    goto fail_0;
  sun = pixie_address(sock, &sz);
  if (connect(fd, (struct sockaddr *)sun, sz))
    goto fail_1;
  xfree(sun);
  return (fd);

  /* --- Tidy up if things went wrong --- */

fail_1:
  xfree(sun);
  close(fd);
fail_0:
  return (-1);
}

/* --- @pixie_read@ --- *
 *
 * Arguments:	@int fd@ = connection to passphrase pixie
 *		@const char *tag@ = pointer to tag string
 *		@unsigned mode@ = reading mode
 *		@char *buf@ = pointer to destination buffer
 *		@size_t sz@ = size of the buffer
 *
 * Returns:	Zero if all went well, @-1@ if the read fails, @+1@ to
 *		request the passphrase from the user.
 *
 * Use:		Reads a passphrase from the pixie.
 */

int pixie_read(int fd, const char *tag, unsigned mode, char *buf, size_t sz)
{
  dstr d = DSTR_INIT;
  char *p, *q;

  /* --- Send the request --- */

  dstr_putf(&d, "%s %s\n", mode == PMODE_READ ? "PASS" : "VERIFY", tag);
  if (write(fd, d.buf, d.len) < 0) return (-1);
  dstr_destroy(&d);

  /* --- Sort out the result --- */

again:
  pixie_fdline(fd, buf, sz);
  p = buf;
  if ((q = str_getword(&p)) == 0)
    return (-1);
  if (strcmp(q, "INFO") == 0)
    goto again;
  else if (strcmp(q, "MISSING") == 0)
    return (+1);
  else if (strcmp(q, "OK") != 0)
    return (-1);

  /* --- Return the final answer --- */

  if (p)
    memmove(buf, p, strlen(p) + 1);
  else
    *buf = 0;
  return (0);
}

/* --- @pixie_set@ --- *
 *
 * Arguments:	@int fd@ = pixie file descriptor
 *		@const char *tag@ = pointer to tag string
 *		@const char *phrase@ = pointer to passphrase string
 *
 * Returns:	---
 *
 * Use:		Sends a passphrase to the passphrase pixie.
 */

void pixie_set(int fd, const char *tag, const char *phrase)
{
  dstr d = DSTR_INIT;
  char buf[16];
  size_t sz = strlen(phrase);
  char nl = '\n';
  char *p, *q;

  /* --- Send the request --- *
   *
   * I didn't want to copy it out of the caller's buffer.  @writev@ may
   * produce a copy, too, so I didn't do that either.
   */

  dstr_putf(&d, "SET %s -- ", tag);
  if (write(fd, d.buf, d.len) < 0 ||
      write(fd, phrase, sz) < 0 ||
      write(fd, &nl, 1) < 0)
    return;
  dstr_destroy(&d);

  /* --- Pick up the pieces --- */

again:
  pixie_fdline(fd, buf, sizeof(buf));
  p = buf;
  if ((q = str_getword(&p)) != 0 && strcmp(q, "INFO") == 0)
    goto again;
}

/* --- @pixie_cancel@ --- *
 *
 * Arguments:	@int fd@ = pixie file descriptor
 *		@const char *tag@ = pointer to tag string
 *
 * Returns:	---
 *
 * Use:		Cancels a passphrase if it turns out to be bogus.
 */

void pixie_cancel(int fd, const char *tag)
{
  dstr d = DSTR_INIT;
  char buf[16];
  char *p, *q;

  /* --- Send the request --- */

  dstr_putf(&d, "FLUSH %s\n", tag);
  if (write(fd, d.buf, d.len) < 0) return;
  dstr_destroy(&d);

  /* --- Sort out the result --- */

again:
  pixie_fdline(fd, buf, sizeof(buf));
  p = buf;
  if ((q = str_getword(&p)) != 0 && strcmp(q, "INFO") == 0)
    goto again;
}

/*----- That's all, folks -------------------------------------------------*/