Adding upstream version 4.94.2.upstream/4.94.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 999 insertions, 0 deletions

diff --git a/src/rda.c b/src/rda.c
new file mode 100644
index 0000000..ce6e7a3
--- /dev/null
+++ b/src/rda.c
@@ -0,0 +1,999 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This module contains code for extracting addresses from a forwarding list
+(from an alias or forward file) or by running the filter interpreter. It may do
+this in a sub-process if a uid/gid are supplied. */
+
+
+#include "exim.h"
+
+enum { FILE_EXIST, FILE_NOT_EXIST, FILE_EXIST_UNCLEAR };
+
+#define REPLY_EXISTS    0x01
+#define REPLY_EXPAND    0x02
+#define REPLY_RETURN    0x04
+
+
+/*************************************************
+*         Check string for filter program        *
+*************************************************/
+
+/* This function checks whether a string is actually a filter program. The rule
+is that it must start with "# Exim filter ..." (any capitalization, spaces
+optional). It is envisaged that in future, other kinds of filter may be
+implemented. That's why it is implemented the way it is. The function is global
+because it is also called from filter.c when checking filters.
+
+Argument:  the string
+
+Returns:   FILTER_EXIM    if it starts with "# Exim filter"
+           FILTER_SIEVE   if it starts with "# Sieve filter"
+           FILTER_FORWARD otherwise
+*/
+
+/* This is an auxiliary function for matching a tag. */
+
+static BOOL
+match_tag(const uschar *s, const uschar *tag)
+{
+for (; *tag; s++, tag++)
+  if (*tag == ' ')
+    {
+    while (*s == ' ' || *s == '\t') s++;
+    s--;
+    }
+  else
+   if (tolower(*s) != tolower(*tag)) break;
+
+return (*tag == 0);
+}
+
+/* This is the real function. It should be easy to add checking different
+tags for other types of filter. */
+
+int
+rda_is_filter(const uschar *s)
+{
+Uskip_whitespace(&s);			/* Skips initial blank lines */
+if (match_tag(s, CUS"# exim filter"))		return FILTER_EXIM;
+else if (match_tag(s, CUS"# sieve filter"))	return FILTER_SIEVE;
+else						return FILTER_FORWARD;
+}
+
+
+
+
+/*************************************************
+*         Check for existence of file            *
+*************************************************/
+
+/* First of all, we stat the file. If this fails, we try to stat the enclosing
+directory, because a file in an unmounted NFS directory will look the same as a
+non-existent file. It seems that in Solaris 2.6, statting an entry in an
+indirect map that is currently unmounted does not cause the mount to happen.
+Instead, dummy data is returned, which defeats the whole point of this test.
+However, if a stat() is done on some object inside the directory, such as the
+"." back reference to itself, then the mount does occur. If an NFS host is
+taken offline, it is possible for the stat() to get stuck until it comes back.
+To guard against this, stick a timer round it. If we can't access the "."
+inside the directory, try the plain directory, just in case that helps.
+
+Argument:
+  filename   the file name
+  error      for message on error
+
+Returns:     FILE_EXIST          the file exists
+             FILE_NOT_EXIST      the file does not exist
+             FILE_EXIST_UNCLEAR  cannot determine existence
+*/
+
+static int
+rda_exists(uschar *filename, uschar **error)
+{
+int rc, saved_errno;
+struct stat statbuf;
+uschar * s;
+
+if ((rc = Ustat(filename, &statbuf)) >= 0) return FILE_EXIST;
+saved_errno = errno;
+
+s = string_copy(filename);
+sigalrm_seen = FALSE;
+
+if (saved_errno == ENOENT)
+  {
+  uschar * slash = Ustrrchr(s, '/');
+  Ustrcpy(slash+1, US".");
+
+  ALARM(30);
+  rc = Ustat(s, &statbuf);
+  if (rc != 0 && errno == EACCES && !sigalrm_seen)
+    {
+    *slash = 0;
+    rc = Ustat(s, &statbuf);
+    }
+  saved_errno = errno;
+  ALARM_CLR(0);
+
+  DEBUG(D_route) debug_printf("stat(%s)=%d\n", s, rc);
+  }
+
+if (sigalrm_seen || rc != 0)
+  {
+  *error = string_sprintf("failed to stat %s (%s)", s,
+    sigalrm_seen?  "timeout" : strerror(saved_errno));
+  return FILE_EXIST_UNCLEAR;
+  }
+
+*error = string_sprintf("%s does not exist", filename);
+DEBUG(D_route) debug_printf("%s\n", *error);
+return FILE_NOT_EXIST;
+}
+
+
+
+/*************************************************
+*     Get forwarding list from a file            *
+*************************************************/
+
+/* Open a file and read its entire contents into a block of memory. Certain
+opening errors are optionally treated the same as "file does not exist".
+
+ENOTDIR means that something along the line is not a directory: there are
+installations that set home directories to be /dev/null for non-login accounts
+but in normal circumstances this indicates some kind of configuration error.
+
+EACCES means there's a permissions failure. Some users turn off read permission
+on a .forward file to suspend forwarding, but this is probably an error in any
+kind of mailing list processing.
+
+The redirect block that contains the file name also contains constraints such
+as who may own the file, and mode bits that must not be set. This function is
+
+Arguments:
+  rdata       rdirect block, containing file name and constraints
+  options     for the RDO_ENOTDIR and RDO_EACCES options
+  error       where to put an error message
+  yield       what to return from rda_interpret on error
+
+Returns:      pointer to string in store; NULL on error
+*/
+
+static uschar *
+rda_get_file_contents(redirect_block *rdata, int options, uschar **error,
+  int *yield)
+{
+FILE *fwd;
+uschar *filebuf;
+uschar *filename = rdata->string;
+BOOL uid_ok = !rdata->check_owner;
+BOOL gid_ok = !rdata->check_group;
+struct stat statbuf;
+
+/* Reading a file is a form of expansion; we wish to deny attackers the
+capability to specify the file name. */
+
+if (is_tainted(filename))
+  {
+  *error = string_sprintf("Tainted name '%s' for file read not permitted\n",
+			filename);
+  *yield = FF_ERROR;
+  return NULL;
+  }
+
+/* Attempt to open the file. If it appears not to exist, check up on the
+containing directory by statting it. If the directory does not exist, we treat
+this situation as an error (which will cause delivery to defer); otherwise we
+pass back FF_NONEXIST, which causes the redirect router to decline.
+
+However, if the ignore_enotdir option is set (to ignore "something on the
+path is not a directory" errors), the right behaviour seems to be not to do the
+directory test. */
+
+if (!(fwd = Ufopen(filename, "rb"))) switch(errno)
+  {
+  case ENOENT:          /* File does not exist */
+    DEBUG(D_route) debug_printf("%s does not exist\n%schecking parent directory\n",
+      filename, options & RDO_ENOTDIR ? "ignore_enotdir set => skip " : "");
+    *yield =
+	options & RDO_ENOTDIR || rda_exists(filename, error) == FILE_NOT_EXIST
+	? FF_NONEXIST : FF_ERROR;
+    return NULL;
+
+  case ENOTDIR:         /* Something on the path isn't a directory */
+    if (!(options & RDO_ENOTDIR)) goto DEFAULT_ERROR;
+    DEBUG(D_route) debug_printf("non-directory on path %s: file assumed not to "
+      "exist\n", filename);
+    *yield = FF_NONEXIST;
+    return NULL;
+
+  case EACCES:           /* Permission denied */
+    if (!(options & RDO_EACCES)) goto DEFAULT_ERROR;
+    DEBUG(D_route) debug_printf("permission denied for %s: file assumed not to "
+      "exist\n", filename);
+    *yield = FF_NONEXIST;
+    return NULL;
+
+DEFAULT_ERROR:
+  default:
+    *error = string_open_failed(errno, "%s", filename);
+    *yield = FF_ERROR;
+    return NULL;
+  }
+
+/* Check that we have a regular file. */
+
+if (fstat(fileno(fwd), &statbuf) != 0)
+  {
+  *error = string_sprintf("failed to stat %s: %s", filename, strerror(errno));
+  goto ERROR_RETURN;
+  }
+
+if ((statbuf.st_mode & S_IFMT) != S_IFREG)
+  {
+  *error = string_sprintf("%s is not a regular file", filename);
+  goto ERROR_RETURN;
+  }
+
+/* Check for unwanted mode bits */
+
+if ((statbuf.st_mode & rdata->modemask) != 0)
+  {
+  *error = string_sprintf("bad mode (0%o) for %s: 0%o bit(s) unexpected",
+    statbuf.st_mode, filename, statbuf.st_mode & rdata->modemask);
+  goto ERROR_RETURN;
+  }
+
+/* Check the file owner and file group if required to do so. */
+
+if (!uid_ok)
+  if (rdata->pw && statbuf.st_uid == rdata->pw->pw_uid)
+    uid_ok = TRUE;
+  else if (rdata->owners)
+    for (int i = 1; i <= (int)(rdata->owners[0]); i++)
+      if (rdata->owners[i] == statbuf.st_uid) { uid_ok = TRUE; break; }
+
+if (!gid_ok)
+  if (rdata->pw && statbuf.st_gid == rdata->pw->pw_gid)
+    gid_ok = TRUE;
+  else if (rdata->owngroups)
+    for (int i = 1; i <= (int)(rdata->owngroups[0]); i++)
+      if (rdata->owngroups[i] == statbuf.st_gid) { gid_ok = TRUE; break; }
+
+if (!uid_ok || !gid_ok)
+  {
+  *error = string_sprintf("bad %s for %s", uid_ok? "group" : "owner", filename);
+  goto ERROR_RETURN;
+  }
+
+/* Put an upper limit on the size of the file, just to stop silly people
+feeding in ridiculously large files, which can easily be created by making
+files that have holes in them. */
+
+if (statbuf.st_size > MAX_FILTER_SIZE)
+  {
+  *error = string_sprintf("%s is too big (max %d)", filename, MAX_FILTER_SIZE);
+  goto ERROR_RETURN;
+  }
+
+/* Read the file in one go in order to minimize the time we have it open. */
+
+filebuf = store_get(statbuf.st_size + 1, is_tainted(filename));
+
+if (fread(filebuf, 1, statbuf.st_size, fwd) != statbuf.st_size)
+  {
+  *error = string_sprintf("error while reading %s: %s",
+    filename, strerror(errno));
+  goto ERROR_RETURN;
+  }
+filebuf[statbuf.st_size] = 0;
+
+DEBUG(D_route) debug_printf(OFF_T_FMT " %sbytes read from %s\n",
+  statbuf.st_size, is_tainted(filename) ? "(tainted) " : "", filename);
+
+(void)fclose(fwd);
+return filebuf;
+
+/* Return an error: the string is already set up. */
+
+ERROR_RETURN:
+*yield = FF_ERROR;
+(void)fclose(fwd);
+return NULL;
+}
+
+
+
+/*************************************************
+*      Extract info from list or filter          *
+*************************************************/
+
+/* This function calls the appropriate function to extract addresses from a
+forwarding list, or to run a filter file and get addresses from there.
+
+Arguments:
+  rdata                     the redirection block
+  options                   the options bits
+  include_directory         restrain to this directory
+  sieve_vacation_directory  passed to sieve_interpret
+  sieve_enotify_mailto_owner passed to sieve_interpret
+  sieve_useraddress         passed to sieve_interpret
+  sieve_subaddress          passed to sieve_interpret
+  generated                 where to hang generated addresses
+  error                     for error messages
+  eblockp                   for details of skipped syntax errors
+                              (NULL => no skip)
+  filtertype                set to the filter type:
+                              FILTER_FORWARD => a traditional .forward file
+                              FILTER_EXIM    => an Exim filter file
+                              FILTER_SIEVE   => a Sieve filter file
+                            a system filter is always forced to be FILTER_EXIM
+
+Returns:                    a suitable return for rda_interpret()
+*/
+
+static int
+rda_extract(redirect_block *rdata, int options, uschar *include_directory,
+  uschar *sieve_vacation_directory, uschar *sieve_enotify_mailto_owner,
+  uschar *sieve_useraddress, uschar *sieve_subaddress,
+  address_item **generated, uschar **error, error_block **eblockp,
+  int *filtertype)
+{
+uschar *data;
+
+if (rdata->isfile)
+  {
+  int yield = 0;
+  if (!(data = rda_get_file_contents(rdata, options, error, &yield)))
+    return yield;
+  }
+else data = rdata->string;
+
+*filtertype = f.system_filtering ? FILTER_EXIM : rda_is_filter(data);
+
+/* Filter interpretation is done by a general function that is also called from
+the filter testing option (-bf). There are two versions: one for Exim filtering
+and one for Sieve filtering. Several features of string expansion may be locked
+out at sites that don't trust users. This is done by setting flags in
+expand_forbid that the expander inspects. */
+
+if (*filtertype != FILTER_FORWARD)
+  {
+  int frc;
+  int old_expand_forbid = expand_forbid;
+
+  DEBUG(D_route) debug_printf("data is %s filter program\n",
+    *filtertype == FILTER_EXIM ? "an Exim" : "a Sieve");
+
+  /* RDO_FILTER is an "allow" bit */
+
+  if (!(options & RDO_FILTER))
+    {
+    *error = US"filtering not enabled";
+    return FF_ERROR;
+    }
+
+  expand_forbid =
+    expand_forbid & ~RDO_FILTER_EXPANSIONS  |  options & RDO_FILTER_EXPANSIONS;
+
+  /* RDO_{EXIM,SIEVE}_FILTER are forbid bits */
+
+  if (*filtertype == FILTER_EXIM)
+    {
+    if ((options & RDO_EXIM_FILTER) != 0)
+      {
+      *error = US"Exim filtering not enabled";
+      return FF_ERROR;
+      }
+    frc = filter_interpret(data, options, generated, error);
+    }
+  else
+    {
+    if (options & RDO_SIEVE_FILTER)
+      {
+      *error = US"Sieve filtering not enabled";
+      return FF_ERROR;
+      }
+    frc = sieve_interpret(data, options, sieve_vacation_directory,
+      sieve_enotify_mailto_owner, sieve_useraddress, sieve_subaddress,
+      generated, error);
+    }
+
+  expand_forbid = old_expand_forbid;
+  return frc;
+  }
+
+/* Not a filter script */
+
+DEBUG(D_route) debug_printf("file is not a filter file\n");
+
+return parse_forward_list(data,
+  options,                           /* specials that are allowed */
+  generated,                         /* where to hang them */
+  error,                             /* for errors */
+  deliver_domain,                    /* to qualify \name */
+  include_directory,                 /* restrain to directory */
+  eblockp);                          /* for skipped syntax errors */
+}
+
+
+
+
+/*************************************************
+*         Write string down pipe                 *
+*************************************************/
+
+/* This function is used for transferring a string down a pipe between
+processes. If the pointer is NULL, a length of zero is written.
+
+Arguments:
+  fd         the pipe
+  s          the string
+
+Returns:     -1 on error, else 0
+*/
+
+static int
+rda_write_string(int fd, const uschar *s)
+{
+int len = (s == NULL)? 0 : Ustrlen(s) + 1;
+return (  write(fd, &len, sizeof(int)) != sizeof(int)
+       || (s != NULL  &&  write(fd, s, len) != len)
+       )
+       ? -1 : 0;
+}
+
+
+
+/*************************************************
+*          Read string from pipe                 *
+*************************************************/
+
+/* This function is used for receiving a string from a pipe.
+
+Arguments:
+  fd         the pipe
+  sp         where to put the string
+
+Returns:     FALSE if data missing
+*/
+
+static BOOL
+rda_read_string(int fd, uschar **sp)
+{
+int len;
+
+if (read(fd, &len, sizeof(int)) != sizeof(int)) return FALSE;
+if (len == 0)
+  *sp = NULL;
+else
+  /* We know we have enough memory so disable the error on "len" */
+  /* coverity[tainted_data] */
+  /* We trust the data source, so untainted */
+  if (read(fd, *sp = store_get(len, FALSE), len) != len) return FALSE;
+return TRUE;
+}
+
+
+
+/*************************************************
+*         Interpret forward list or filter       *
+*************************************************/
+
+/* This function is passed a forward list string (unexpanded) or the name of a
+file (unexpanded) whose contents are the forwarding list. The list may in fact
+be a filter program if it starts with "#Exim filter" or "#Sieve filter". Other
+types of filter, with different initial tag strings, may be introduced in due
+course.
+
+The job of the function is to process the forwarding list or filter. It is
+pulled out into this separate function, because it is used for system filter
+files as well as from the redirect router.
+
+If the function is given a uid/gid, it runs a subprocess that passes the
+results back via a pipe. This provides security for things like :include:s in
+users' .forward files, and "logwrite" calls in users' filter files. A
+sub-process is NOT used when:
+
+  . No uid/gid is provided
+  . The input is a string which is not a filter string, and does not contain
+    :include:
+  . The input is a file whose non-existence can be detected in the main
+    process (which is usually running as root).
+
+Arguments:
+  rdata                     redirect data (file + constraints, or data string)
+  options                   options to pass to the extraction functions,
+                              plus ENOTDIR and EACCES handling bits
+  include_directory         restrain :include: to this directory
+  sieve_vacation_directory  directory passed to sieve_interpret
+  sieve_enotify_mailto_owner passed to sieve_interpret
+  sieve_useraddress         passed to sieve_interpret
+  sieve_subaddress          passed to sieve_interpret
+  ugid                      uid/gid to run under - if NULL, no change
+  generated                 where to hang generated addresses, initially NULL
+  error                     pointer for error message
+  eblockp                   for skipped syntax errors; NULL if no skipping
+  filtertype                set to the type of file:
+                              FILTER_FORWARD => traditional .forward file
+                              FILTER_EXIM    => an Exim filter file
+                              FILTER_SIEVE   => a Sieve filter file
+                            a system filter is always forced to be FILTER_EXIM
+  rname                     router name for error messages in the format
+                              "xxx router" or "system filter"
+
+Returns:        values from extraction function, or FF_NONEXIST:
+                  FF_DELIVERED     success, a significant action was taken
+                  FF_NOTDELIVERED  success, no significant action
+                  FF_BLACKHOLE     :blackhole:
+                  FF_DEFER         defer requested
+                  FF_FAIL          fail requested
+                  FF_INCLUDEFAIL   some problem with :include:
+                  FF_FREEZE        freeze requested
+                  FF_ERROR         there was a problem
+                  FF_NONEXIST      the file does not exist
+*/
+
+int
+rda_interpret(redirect_block *rdata, int options, uschar *include_directory,
+  uschar *sieve_vacation_directory, uschar *sieve_enotify_mailto_owner,
+  uschar *sieve_useraddress, uschar *sieve_subaddress, ugid_block *ugid,
+  address_item **generated, uschar **error, error_block **eblockp,
+  int *filtertype, uschar *rname)
+{
+int fd, rc, pfd[2];
+int yield, status;
+BOOL had_disaster = FALSE;
+pid_t pid;
+uschar *data;
+uschar *readerror = US"";
+void (*oldsignal)(int);
+
+DEBUG(D_route) debug_printf("rda_interpret (%s): '%s'\n",
+  rdata->isfile ? "file" : "string", string_printing(rdata->string));
+
+/* Do the expansions of the file name or data first, while still privileged. */
+
+if (!(data = expand_string(rdata->string)))
+  {
+  if (f.expand_string_forcedfail) return FF_NOTDELIVERED;
+  *error = string_sprintf("failed to expand \"%s\": %s", rdata->string,
+    expand_string_message);
+  return FF_ERROR;
+  }
+rdata->string = data;
+
+DEBUG(D_route)
+  debug_printf("expanded: '%s'%s\n", data, is_tainted(data) ? " (tainted)":"");
+
+if (rdata->isfile && data[0] != '/')
+  {
+  *error = string_sprintf("\"%s\" is not an absolute path", data);
+  return FF_ERROR;
+  }
+
+/* If no uid/gid are supplied, or if we have a data string which does not start
+with #Exim filter or #Sieve filter, and does not contain :include:, do all the
+work in this process. Note that for a system filter, we always have a file, so
+the work is done in this process only if no user is supplied. */
+
+if (!ugid->uid_set ||                         /* Either there's no uid, or */
+    (!rdata->isfile &&                        /* We've got the data, and */
+     rda_is_filter(data) == FILTER_FORWARD && /* It's not a filter script, */
+     Ustrstr(data, ":include:") == NULL))     /* and there's no :include: */
+  return rda_extract(rdata, options, include_directory,
+    sieve_vacation_directory, sieve_enotify_mailto_owner, sieve_useraddress,
+    sieve_subaddress, generated, error, eblockp, filtertype);
+
+/* We need to run the processing code in a sub-process. However, if we can
+determine the non-existence of a file first, we can decline without having to
+create the sub-process. */
+
+if (rdata->isfile && rda_exists(data, error) == FILE_NOT_EXIST)
+  return FF_NONEXIST;
+
+/* If the file does exist, or we can't tell (non-root mounted NFS directory)
+we have to create the subprocess to do everything as the given user. The
+results of processing are passed back via a pipe. */
+
+if (pipe(pfd) != 0)
+  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "creation of pipe for filter or "
+    ":include: failed for %s: %s", rname, strerror(errno));
+
+/* Ensure that SIGCHLD is set to SIG_DFL before forking, so that the child
+process can be waited for. We sometimes get here with it set otherwise. Save
+the old state for resetting on the wait. Ensure that all cached resources are
+freed so that the subprocess starts with a clean slate and doesn't interfere
+with the parent process. */
+
+oldsignal = signal(SIGCHLD, SIG_DFL);
+search_tidyup();
+
+if ((pid = exim_fork(US"router-interpret")) == 0)
+  {
+  header_line *waslast = header_last;   /* Save last header */
+  int fd_flags = -1;
+
+  fd = pfd[pipe_write];
+  (void)close(pfd[pipe_read]);
+
+  if ((fd_flags = fcntl(fd, F_GETFD)) == -1) goto bad;
+  if (fcntl(fd, F_SETFD, fd_flags | FD_CLOEXEC) == -1) goto bad;
+
+  exim_setugid(ugid->uid, ugid->gid, FALSE, rname);
+
+  /* Addresses can get rewritten in filters; if we are not root or the exim
+  user (and we probably are not), turn off rewrite logging, because we cannot
+  write to the log now. */
+
+  if (ugid->uid != root_uid && ugid->uid != exim_uid)
+    {
+    DEBUG(D_rewrite) debug_printf("turned off address rewrite logging (not "
+      "root or exim in this process)\n");
+    BIT_CLEAR(log_selector, log_selector_size, Li_address_rewrite);
+    }
+
+  /* Now do the business */
+
+  yield = rda_extract(rdata, options, include_directory,
+    sieve_vacation_directory, sieve_enotify_mailto_owner, sieve_useraddress,
+    sieve_subaddress, generated, error, eblockp, filtertype);
+
+  /* Pass back whether it was a filter, and the return code and any overall
+  error text via the pipe. */
+
+  if (  write(fd, filtertype, sizeof(int)) != sizeof(int)
+     || write(fd, &yield, sizeof(int)) != sizeof(int)
+     || rda_write_string(fd, *error) != 0
+     )
+    goto bad;
+
+  /* Pass back the contents of any syntax error blocks if we have a pointer */
+
+  if (eblockp)
+    {
+    for (error_block * ep = *eblockp; ep; ep = ep->next)
+      if (  rda_write_string(fd, ep->text1) != 0
+         || rda_write_string(fd, ep->text2) != 0
+	 )
+	goto bad;
+    if (rda_write_string(fd, NULL) != 0)    /* Indicates end of eblocks */
+      goto bad;
+    }
+
+  /* If this is a system filter, we have to pass back the numbers of any
+  original header lines that were removed, and then any header lines that were
+  added but not subsequently removed. */
+
+  if (f.system_filtering)
+    {
+    int i = 0;
+    for (header_line * h = header_list; h != waslast->next; i++, h = h->next)
+      if (  h->type == htype_old
+         && write(fd, &i, sizeof(i)) != sizeof(i)
+	 )
+	goto bad;
+
+    i = -1;
+    if (write(fd, &i, sizeof(i)) != sizeof(i))
+	goto bad;
+
+    while (waslast != header_last)
+      {
+      waslast = waslast->next;
+      if (waslast->type != htype_old)
+	if (  rda_write_string(fd, waslast->text) != 0
+           || write(fd, &(waslast->type), sizeof(waslast->type))
+	      != sizeof(waslast->type)
+	   )
+	  goto bad;
+      }
+    if (rda_write_string(fd, NULL) != 0)    /* Indicates end of added headers */
+      goto bad;
+    }
+
+  /* Write the contents of the $n variables */
+
+  if (write(fd, filter_n, sizeof(filter_n)) != sizeof(filter_n))
+    goto bad;
+
+  /* If the result was DELIVERED or NOTDELIVERED, we pass back the generated
+  addresses, and their associated information, through the pipe. This is
+  just tedious, but it seems to be the only safe way. We do this also for
+  FAIL and FREEZE, because a filter is allowed to set up deliveries that
+  are honoured before freezing or failing. */
+
+  if (yield == FF_DELIVERED || yield == FF_NOTDELIVERED ||
+      yield == FF_FAIL || yield == FF_FREEZE)
+    {
+    for (address_item * addr = *generated; addr; addr = addr->next)
+      {
+      int reply_options = 0;
+      int ig_err = addr->prop.ignore_error ? 1 : 0;
+
+      if (  rda_write_string(fd, addr->address) != 0
+         || write(fd, &addr->mode, sizeof(addr->mode)) != sizeof(addr->mode)
+         || write(fd, &addr->flags, sizeof(addr->flags)) != sizeof(addr->flags)
+         || rda_write_string(fd, addr->prop.errors_address) != 0
+         || write(fd, &ig_err, sizeof(ig_err)) != sizeof(ig_err)
+	 )
+	goto bad;
+
+      if (addr->pipe_expandn)
+        for (uschar ** pp = addr->pipe_expandn; *pp; pp++)
+          if (rda_write_string(fd, *pp) != 0)
+	    goto bad;
+      if (rda_write_string(fd, NULL) != 0)
+        goto bad;
+
+      if (!addr->reply)
+	{
+        if (write(fd, &reply_options, sizeof(int)) != sizeof(int))    /* 0 means no reply */
+	  goto bad;
+	}
+      else
+        {
+        reply_options |= REPLY_EXISTS;
+        if (addr->reply->file_expand) reply_options |= REPLY_EXPAND;
+        if (addr->reply->return_message) reply_options |= REPLY_RETURN;
+        if (  write(fd, &reply_options, sizeof(int)) != sizeof(int)
+           || write(fd, &(addr->reply->expand_forbid), sizeof(int))
+	      != sizeof(int)
+           || write(fd, &(addr->reply->once_repeat), sizeof(time_t))
+	      != sizeof(time_t)
+           || rda_write_string(fd, addr->reply->to) != 0
+           || rda_write_string(fd, addr->reply->cc) != 0
+           || rda_write_string(fd, addr->reply->bcc) != 0
+           || rda_write_string(fd, addr->reply->from) != 0
+           || rda_write_string(fd, addr->reply->reply_to) != 0
+           || rda_write_string(fd, addr->reply->subject) != 0
+           || rda_write_string(fd, addr->reply->headers) != 0
+           || rda_write_string(fd, addr->reply->text) != 0
+           || rda_write_string(fd, addr->reply->file) != 0
+           || rda_write_string(fd, addr->reply->logfile) != 0
+           || rda_write_string(fd, addr->reply->oncelog) != 0
+	   )
+	  goto bad;
+        }
+      }
+
+    if (rda_write_string(fd, NULL) != 0)   /* Marks end of addresses */
+      goto bad;
+    }
+
+  /* OK, this process is now done. Free any cached resources. Must use _exit()
+  and not exit() !! */
+
+out:
+  (void)close(fd);
+  search_tidyup();
+  exim_underbar_exit(EXIT_SUCCESS);
+
+bad:
+  DEBUG(D_rewrite) debug_printf("rda_interpret: failed write to pipe\n");
+  goto out;
+  }
+
+/* Back in the main process: panic if the fork did not succeed. */
+
+if (pid < 0)
+  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "fork failed for %s", rname);
+
+/* Read the pipe to get the data from the filter/forward. Our copy of the
+writing end must be closed first, as otherwise read() won't return zero on an
+empty pipe. Afterwards, close the reading end. */
+
+(void)close(pfd[pipe_write]);
+
+/* Read initial data, including yield and contents of *error */
+
+fd = pfd[pipe_read];
+if (read(fd, filtertype, sizeof(int)) != sizeof(int) ||
+    read(fd, &yield, sizeof(int)) != sizeof(int) ||
+    !rda_read_string(fd, error)) goto DISASTER;
+
+/* Read the contents of any syntax error blocks if we have a pointer */
+
+if (eblockp)
+  {
+  error_block *e;
+  for (error_block ** p = eblockp; ; p = &e->next)
+    {
+    uschar *s;
+    if (!rda_read_string(fd, &s)) goto DISASTER;
+    if (!s) break;
+    e = store_get(sizeof(error_block), FALSE);
+    e->next = NULL;
+    e->text1 = s;
+    if (!rda_read_string(fd, &s)) goto DISASTER;
+    e->text2 = s;
+    *p = e;
+    }
+  }
+
+/* If this is a system filter, read the identify of any original header lines
+that were removed, and then read data for any new ones that were added. */
+
+if (f.system_filtering)
+  {
+  int hn = 0;
+  header_line *h = header_list;
+
+  for (;;)
+    {
+    int n;
+    if (read(fd, &n, sizeof(int)) != sizeof(int)) goto DISASTER;
+    if (n < 0) break;
+    while (hn < n)
+      {
+      hn++;
+      if (!(h = h->next)) goto DISASTER_NO_HEADER;
+      }
+    h->type = htype_old;
+    }
+
+  for (;;)
+    {
+    uschar *s;
+    int type;
+    if (!rda_read_string(fd, &s)) goto DISASTER;
+    if (!s) break;
+    if (read(fd, &type, sizeof(type)) != sizeof(type)) goto DISASTER;
+    header_add(type, "%s", s);
+    }
+  }
+
+/* Read the values of the $n variables */
+
+if (read(fd, filter_n, sizeof(filter_n)) != sizeof(filter_n)) goto DISASTER;
+
+/* If the yield is DELIVERED, NOTDELIVERED, FAIL, or FREEZE there may follow
+addresses and data to go with them. Keep them in the same order in the
+generated chain. */
+
+if (yield == FF_DELIVERED || yield == FF_NOTDELIVERED ||
+    yield == FF_FAIL || yield == FF_FREEZE)
+  {
+  address_item **nextp = generated;
+
+  for (;;)
+    {
+    int i, reply_options;
+    address_item *addr;
+    uschar *recipient;
+    uschar *expandn[EXPAND_MAXN + 2];
+
+    /* First string is the address; NULL => end of addresses */
+
+    if (!rda_read_string(fd, &recipient)) goto DISASTER;
+    if (!recipient) break;
+
+    /* Hang on the end of the chain */
+
+    addr = deliver_make_addr(recipient, FALSE);
+    *nextp = addr;
+    nextp = &(addr->next);
+
+    /* Next comes the mode and the flags fields */
+
+    if (  read(fd, &addr->mode, sizeof(addr->mode)) != sizeof(addr->mode)
+       || read(fd, &addr->flags, sizeof(addr->flags)) != sizeof(addr->flags)
+       || !rda_read_string(fd, &addr->prop.errors_address)
+       || read(fd, &i, sizeof(i)) != sizeof(i)
+       )
+      goto DISASTER;
+    addr->prop.ignore_error = (i != 0);
+
+    /* Next comes a possible setting for $thisaddress and any numerical
+    variables for pipe expansion, terminated by a NULL string. The maximum
+    number of numericals is EXPAND_MAXN. Note that we put filter_thisaddress
+    into the zeroth item in the vector - this is sorted out inside the pipe
+    transport. */
+
+    for (i = 0; i < EXPAND_MAXN + 1; i++)
+      {
+      uschar *temp;
+      if (!rda_read_string(fd, &temp)) goto DISASTER;
+      if (i == 0) filter_thisaddress = temp;           /* Just in case */
+      expandn[i] = temp;
+      if (temp == NULL) break;
+      }
+
+    if (i > 0)
+      {
+      addr->pipe_expandn = store_get((i+1) * sizeof(uschar *), FALSE);
+      addr->pipe_expandn[i] = NULL;
+      while (--i >= 0) addr->pipe_expandn[i] = expandn[i];
+      }
+
+    /* Then an int containing reply options; zero => no reply data. */
+
+    if (read(fd, &reply_options, sizeof(int)) != sizeof(int)) goto DISASTER;
+    if ((reply_options & REPLY_EXISTS) != 0)
+      {
+      addr->reply = store_get(sizeof(reply_item), FALSE);
+
+      addr->reply->file_expand = (reply_options & REPLY_EXPAND) != 0;
+      addr->reply->return_message = (reply_options & REPLY_RETURN) != 0;
+
+      if (read(fd,&(addr->reply->expand_forbid),sizeof(int)) !=
+            sizeof(int) ||
+          read(fd,&(addr->reply->once_repeat),sizeof(time_t)) !=
+            sizeof(time_t) ||
+          !rda_read_string(fd, &addr->reply->to) ||
+          !rda_read_string(fd, &addr->reply->cc) ||
+          !rda_read_string(fd, &addr->reply->bcc) ||
+          !rda_read_string(fd, &addr->reply->from) ||
+          !rda_read_string(fd, &addr->reply->reply_to) ||
+          !rda_read_string(fd, &addr->reply->subject) ||
+          !rda_read_string(fd, &addr->reply->headers) ||
+          !rda_read_string(fd, &addr->reply->text) ||
+          !rda_read_string(fd, &addr->reply->file) ||
+          !rda_read_string(fd, &addr->reply->logfile) ||
+          !rda_read_string(fd, &addr->reply->oncelog))
+        goto DISASTER;
+      }
+    }
+  }
+
+/* All data has been transferred from the sub-process. Reap it, close the
+reading end of the pipe, and we are done. */
+
+WAIT_EXIT:
+while ((rc = wait(&status)) != pid)
+  if (rc < 0 && errno == ECHILD)      /* Process has vanished */
+    {
+    log_write(0, LOG_MAIN, "redirection process %d vanished unexpectedly", pid);
+    goto FINAL_EXIT;
+    }
+
+DEBUG(D_route)
+  debug_printf("rda_interpret: subprocess yield=%d error=%s\n", yield, *error);
+
+if (had_disaster)
+  {
+  *error = string_sprintf("internal problem in %s: failure to transfer "
+    "data from subprocess: status=%04x%s%s%s", rname,
+    status, readerror,
+    (*error == NULL)? US"" : US": error=",
+    (*error == NULL)? US"" : *error);
+  log_write(0, LOG_MAIN|LOG_PANIC, "%s", *error);
+  }
+else if (status != 0)
+  {
+  log_write(0, LOG_MAIN|LOG_PANIC, "internal problem in %s: unexpected status "
+    "%04x from redirect subprocess (but data correctly received)", rname,
+    status);
+  }
+
+FINAL_EXIT:
+(void)close(fd);
+signal(SIGCHLD, oldsignal);   /* restore */
+return yield;
+
+
+/* Come here if the data indicates removal of a header that we can't find */
+
+DISASTER_NO_HEADER:
+readerror = US" readerror=bad header identifier";
+had_disaster = TRUE;
+yield = FF_ERROR;
+goto WAIT_EXIT;
+
+/* Come here is there's a shambles in transferring the data over the pipe. The
+value of errno should still be set. */
+
+DISASTER:
+readerror = string_sprintf(" readerror='%s'", strerror(errno));
+had_disaster = TRUE;
+yield = FF_ERROR;
+goto WAIT_EXIT;
+}
+
+/* End of rda.c */