dsh8290@??? said:
> Dynamic loading of local_scan. This would allow the various
> local_scans to be packaged separately from exim itself and
> configurable at runtime. I don't know how hard this is in C.
Fairly trivial -- see below. I think it's even vaguely portable.
> In fact, this would be nice for the various lookups and mailstore
> formats too. Packages could provide a base exim with the rest as
> separate add-on modules loadable at runtime.
Left as an exercise for the reader.
--- ./src/EDITME.ls Tue Jun 11 11:34:13 2002
+++ ./src/EDITME Tue Jun 11 13:58:15 2002
@@ -343,6 +343,14 @@
#------------------------------------------------------------------------------
+# On systems which support dynamic loading of shared libraries, Exim can
+# load a local_scan function specified in its config file instead of having
+# to be recompiled with the desired local_scan function. For a full
+# description of the API to this function, see the Exim specification.
+
+# DLOPEN_LOCAL_SCAN=yes
+
+#------------------------------------------------------------------------------
# The default distribution of Exim contains only the plain text form of the
# documentation. Other forms are available separately. If you want to install
# the documentation in "info" format, first fetch the Texinfo documentation
--- ./src/config.h.defaults.ls Tue Jun 11 11:37:37 2002
+++ ./src/config.h.defaults Tue Jun 11 11:37:53 2002
@@ -17,6 +17,8 @@
#define AUTH_PLAINTEXT
#define AUTH_SPA
+#define DLOPEN_LOCAL_SCAN
+
#define BIN_DIRECTORY
#define CONFIGURE_FILE
--- ./src/local_scan.c.ls Tue Jun 11 11:38:20 2002
+++ ./src/local_scan.c Tue Jun 11 14:08:47 2002
@@ -5,60 +5,86 @@
/* Copyright (c) University of Cambridge 1995 - 2002 */
/* See the file NOTICE for conditions of use and distribution. */
+#include "exim.h"
-/******************************************************************************
-This file contains a template local_scan() function that just returns ACCEPT.
-If you want to implement your own version, you should copy this file to, say
-Local/local_scan.c, and edit the copy. To use your version instead of the
-default, you must set
-
-LOCAL_SCAN_SOURCE=Local/local_scan.c
-
-in your Local/Makefile. This makes it easy to copy your version for use with
-subsequent Exim releases.
-
-For a full description of the API to this function, see the Exim specification.
-******************************************************************************/
-
-
-/* This is the only Exim header that you should include. The effect of
-including any other Exim header is not defined, and may change from release to
-release. Use only the documented interface! */
-
-#include "local_scan.h"
-
-
-/* This is a "do-nothing" version of a local_scan() function. The arguments
-are:
-
- fd The file descriptor of the open -D file, which contains the
- body of the message. The file is open for reading and
- writing, but modifying it is dangerous and not recommended.
-
- return_text A pointer to an unsigned char* variable which you can set in
- order to return a text string. It is initialized to NULL.
-
-The return values of this function are:
-
- LOCAL_SCAN_ACCEPT
- The message is to be accepted. The return_text argument is
- saved in $local_scan_data.
-
- LOCAL_SCAN_REJECT
- The message is to be rejected. The returned text is used
- in the rejection message.
-
- LOCAL_SCAN_TEMPREJECT
- This specifies a temporary rejection. The returned text
- is used in the rejection message.
-*/
+#ifdef DLOPEN_LOCAL_SCAN
+#include <dlfcn.h>
+static int (*local_scan_fn)(int fd, uschar **return_text) = NULL;
+static int load_local_scan_library(void);
+#endif
int
local_scan(int fd, uschar **return_text)
{
fd = fd; /* Keep picky compilers happy */
return_text = return_text;
-return LOCAL_SCAN_ACCEPT;
+#ifdef DLOPEN_LOCAL_SCAN
+if (local_scan_path)
+ {
+ if (!local_scan_fn)
+ {
+ if (!load_local_scan_library())
+ {
+ *return_text = US"Local configuration error - local_scan() library "
+ "failure";
+ return LOCAL_SCAN_TEMPREJECT;
+ }
+ }
+ return local_scan_fn(fd, return_text);
+ }
+else
+#endif
+ return LOCAL_SCAN_ACCEPT;
+}
+
+#ifdef DLOPEN_LOCAL_SCAN
+
+static int load_local_scan_library(void)
+{
+/* No point in keeping local_scan_lib since we'll never dlclose() anyway */
+void *local_scan_lib = NULL;
+int (*local_scan_version_fn)(void);
+int vers;
+
+local_scan_lib = dlopen(local_scan_path, RTLD_NOW);
+if (!local_scan_lib)
+ {
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library open failed - "
+ "message temporarily rejected");
+ return FALSE;
+ }
+
+local_scan_version_fn = dlsym(local_scan_lib, "local_scan_version");
+if (!local_scan_version_fn)
+ {
+ dlclose(local_scan_lib);
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
+ "local_scan_version() function - message temporarily rejected");
+ return FALSE;
+ }
+
+vers = local_scan_version_fn();
+if (vers != LOCAL_SCAN_ABI_VERSION)
+ {
+ dlclose(local_scan_lib);
+ local_scan_lib = NULL;
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has wrong version "
+ "number %d, expected %d", vers, LOCAL_SCAN_ABI_VERSION);
+ return FALSE;
+ }
+
+local_scan_fn = dlsym(local_scan_lib, "local_scan");
+if (!local_scan_fn)
+ {
+ dlclose(local_scan_lib);
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
+ "local_scan() function - message temporarily rejected");
+ return FALSE;
+ }
+
+return TRUE;
}
+
+#endif /* DLOPEN_LOCAL_SCAN */
/* End of local_scan.c */
--- ./src/readconf.c.ls Tue Jun 11 13:19:01 2002
+++ ./src/readconf.c Tue Jun 11 13:20:50 2002
@@ -102,6 +102,9 @@
{ "local_from_prefix", opt_stringptr, &local_from_prefix },
{ "local_from_suffix", opt_stringptr, &local_from_suffix },
{ "local_interfaces", opt_stringptr, &local_interfaces },
+#ifdef DLOPEN_LOCAL_SCAN
+ { "local_scan_path", opt_stringptr, &local_scan_path },
+#endif
{ "local_scan_timeout", opt_time, &local_scan_timeout },
{ "local_sender_retain", opt_bool, &local_sender_retain },
{ "localhost_number", opt_stringptr, &host_number_string },
--- ./src/globals.h.ls Tue Jun 11 13:49:21 2002
+++ ./src/globals.h Tue Jun 11 14:32:21 2002
@@ -65,6 +65,9 @@
extern uschar *tls_verify_hosts; /* Mandatory client verification */
#endif
+#ifdef DLOPEN_LOCAL_SCAN
+extern uschar *local_scan_path; /* Path to local_scan() library */
+#endif
/* Input-reading functions for messages, so we can use special ones for
incoming TCP/IP. */
--- ./src/globals.c.ls Tue Jun 11 13:20:24 2002
+++ ./src/globals.c Tue Jun 11 14:32:43 2002
@@ -100,6 +100,9 @@
uschar *tls_verify_hosts = NULL;
#endif
+#ifdef DLOPEN_LOCAL_SCAN
+uschar *local_scan_path = NULL;
+#endif
/* Input-reading functions for messages, so we can use special ones for
incoming TCP/IP. The defaults use stdin. We never need these for any
--- ./src/local_scan.h.ls Tue Jun 11 13:35:49 2002
+++ ./src/local_scan.h Tue Jun 11 13:36:22 2002
@@ -83,5 +83,7 @@
extern uschar *string_copyn(uschar *, int);
extern uschar *string_sprintf(char *, ...);
+/* local_scan() ABI version number for dynamic libraries */
+#define LOCAL_SCAN_ABI_VERSION 1
/* End of local_scan.h */
--
dwmw2
