User-defined actions for comsat.

+/* GNU mailutils - a suite of utilities for electronic mail
+   Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
+
+   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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#include "comsat.h"
+#define obstack_chunk_alloc malloc
+#define obstack_chunk_free free
+#include <obstack.h>
+
+/* This module implements user-configurable actions for comsat. The
+   actions are kept in file .biffrc in the user's home directory and
+   are executed in sequence. Possible actions:
+
+   beep              --  Produce audible signal
+   echo STRING       --  Output STRING to the user's tty
+   exec PROG ARGS... --  Execute given program (not yet implemented)
+
+   Following metacharacters are accepted in strings:
+
+   $u        --  Expands to username
+   $h        --  Expands to hostname
+   $H{name}  --  Expands to value of message header `name'
+   $B(C,L)   --  Expands to message body. C and L give maximum
+                 number of characters and line in the expansion.
+		 When omitted, they default to 400, 5. */
+
+int
+act_getline (FILE *fp, char **sptr, size_t *size)
+{
+  char buf[256];
+  int cont = 1;
+  size_t used = 0;
+  
+  while (cont && fgets (buf, sizeof buf, fp))
+    {
+      int len = strlen (buf);
+      if (buf[len-1] == '\n')
+	{
+	  buf[--len] = 0;
+	  if (buf[len-1] == '\\')
+	    {
+	      buf[--len] = 0;
+	      cont = 1;
+	    }
+	  else
+	    cont = 0;
+	}
+      else
+	cont = 1;
+
+      if (len + used + 1 > *size)
+	{
+	  *sptr = realloc (*sptr, len + used + 1);
+	  if (!*sptr)
+	    return -1;
+	  *size = len + used + 1;
+	}
+      memcpy (*sptr + used, buf, len);
+      used += len;
+    }    
+
+  if (*sptr)
+    (*sptr)[used] = 0;
+  
+  return used;
+}
+
+/* Convert second character of a backslash sequence to its ASCII
+   value: */
+int
+backslash(int c)
+{
+  static char transtab[] = "a\ab\bf\fn\nr\rt\t";
+  char *p;
+  
+  for (p = transtab; *p; p += 2)
+    {
+      if (*p == c)
+	return p[1];
+    }
+  return c;
+}
+
+int
+expand_escape (char **pp, message_t msg, struct obstack *stk)
+{
+  char *p = *pp;
+  char *start, *sval, *namep;
+  int len;
+  header_t hdr;
+  body_t body;
+  stream_t stream;
+  int rc = 1;
+  size_t size, lncount;
+  
+  switch (*++p) /* skip past $ */
+    {
+    case 'u':
+      len = strlen (username);
+      obstack_grow (stk, username, len);
+      *pp = p;
+      rc = 0;
+      break;
+    case 'h':
+      len = strlen (hostname);
+      obstack_grow (stk, hostname, len);
+      *pp = p;
+      rc = 0;
+      break;
+    case 'H':
+      /* Header field */
+      if (*++p != '{')
+	break;
+      start = ++p;
+      p = strchr (p, '}');
+      if (!p)
+	break;
+      len = p - start;
+      if (len == 0
+	  || (namep = malloc (len + 1)) == NULL)
+	break;
+      memcpy (namep, start, len);
+      namep[len] = 0;
+      if (message_get_header (msg, &hdr) == 0
+	  && header_aget_value (hdr, namep, &sval) == 0)
+	{
+	  len = strlen (sval);
+	  obstack_grow (stk, sval, len);
+	}
+      free (namep);
+      *pp = p;
+      rc = 0;
+      break;
+    case 'B':
+      /* Message body */
+      if (*++p == '(')
+	{
+	  size = strtoul (p + 1, &p, 0);
+	  if (*p == ',')
+	    lncount = strtoul (p + 1, &p, 0);
+	  if (*p != ')')
+	    break;
+	  p++;
+	}
+      if (size == 0)
+	size = 400;
+      if (lncount == 0)
+	lncount = 5;
+      if (message_get_body (msg, &body) == 0
+	  && body_get_stream (body, &stream) == 0)
+	{
+	  size_t nread;
+	  char *buf = malloc (size+1);
+	  
+	  if (!buf)
+	    break;
+	  if (stream_read (stream, buf, size, 0, &nread) == 0)
+	    {
+	      char *q;
+
+	      buf[nread] = 0;
+	      q = buf;
+	      size = 0;
+	      while (lncount--)
+		{
+		  char *s = strchr (q, '\n');
+		  if (!q)
+		    break;
+		  size += s - q + 1;
+		  q = s + 1;
+		}
+	      obstack_grow (stk, buf, size);
+	    }
+	  free (buf);
+	}
+      *pp = p;
+      rc = 0;
+    }
+  return rc;
+}
+
+char *
+expand_line (char *str, char *cr, message_t msg)
+{
+  char *p;
+  int i, c, len;
+  size_t size;
+  struct obstack stk;
+  
+  if (!*str)
+    return NULL;
+  obstack_init (&stk);
+  for (p = str; *p; p++)
+    {
+      switch (*p)
+	{
+	case '\n':
+	  len = strlen (cr);
+	  obstack_grow (&stk, cr, len);
+	  break;
+	case '\\':
+	  p++;
+	  switch (*p)
+	    {
+	    case 0:
+	      obstack_1grow (&stk, c);
+	      break;
+	    case 'n':
+	      len = strlen (cr);
+ 	      obstack_grow (&stk, cr, len);
+	      break;
+	    default:
+	      c = backslash (*p);
+	      obstack_1grow (&stk, c);
+	    }
+	  break;
+	case '$':
+	  if (expand_escape (&p, msg, &stk) == 0)
+	    break;
+	  /*FALLTHRU*/
+	default:
+	  obstack_1grow (&stk, *p);
+	}
+    }
+  obstack_1grow (&stk, 0);
+  str = strdup (obstack_finish (&stk));
+  obstack_free (&stk, NULL);
+  return str;
+}
+
+char *default_action =
+"Mail to \a$u@$h\a ---\n"
+"From: $H{from}\n"
+"Subject: $H{Subject}\n"
+"---\n"
+"$B(,5)\n"
+"---\n";
+
+/* Take care to clear eighth bit, so we won't upset some stupid terminals */
+#define LB(c) ((c)&0x7f)
+  
+void
+action_beep (FILE *tty)
+{
+  fprintf (tty, "\a\a");
+}
+
+void
+action_echo (FILE *tty, char *str)
+{
+  char *p;
+  
+  if (!str)
+    return;
+  for (p = str; *p; p++)
+    *p = LB (*p);
+  fprintf (tty, "%s", str);
+}
+
+FILE *
+open_rc (char *filename, FILE *tty)
+{
+  struct stat stb;
+  struct passwd *pw = getpwnam (username);
+  
+  if (stat (filename, &stb) == 0)
+    {
+      if (stb.st_uid != pw->pw_uid)
+	{
+	  syslog (LOG_NOTICE, "%s's %s is not owned by %s",
+		  username, filename, username);
+	  return NULL;
+	}
+      if ((stb.st_mode & 0777) != 0600)
+	{
+	  fprintf (tty, "Warning: your .biffrc has wrong permissions\r\n");
+	  syslog (LOG_NOTICE, "%s's %s has wrong permissions",
+		  username, filename);
+	  return NULL;
+	}
+    }
+  return fopen (filename, "r");
+}
+
+void
+run_user_action (FILE *tty, char *cr, message_t msg)
+{
+  FILE *fp;
+  int nact = 0;
+  char *stmt = NULL;
+  size_t size = 0;
+
+  fp = open_rc (BIFF_RC, tty);
+  if (fp)
+    {
+      int line = 0;
+      
+      while (act_getline (fp, &stmt, &size))
+	{
+	  char *str;
+	  int argc;
+	  char **argv;
+
+	  line++;
+	  str = expand_line (stmt, cr, msg);
+	  if (!str)
+	    continue;
+	  if (argcv_get (str, "", &argc, &argv)
+	      || argc == 0
+	      || argv[0][0] == '#')
+	    {
+	      free (str);
+	      argcv_free (argc, argv);
+	      continue;
+	    }
+
+	  if (strcmp (argv[0], "beep") == 0)
+	    {
+	      action_beep (tty);
+	      nact++;
+	    }
+	  else if (strcmp (argv[0], "echo") == 0)
+	    {
+	      action_echo (tty, argv[1]);
+	      nact++;
+	    }
+	  else
+	    {
+	      syslog (LOG_ERR, "%s:.biffrc:%d: unknown keyword %s",
+		      username, line, argv[0]);
+	      break;
+	    }
+	}
+      fclose (fp);
+    }
+  
+  if (nact == 0)
+    {
+      char *str = expand_line (default_action, cr, msg);
+      action_echo (tty, str);
+    }
+}
+
+