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exim/exim-4.96-dlopen-localscan....

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diff --git a/src/EDITME b/src/EDITME
index cf0b33e..7d4cbf3 100644
--- a/src/EDITME
+++ b/src/EDITME
@@ -878,6 +878,21 @@ HAVE_ICONV=yes
# *** WARNING *** WARNING *** WARNING *** WARNING *** WARNING ***
+#------------------------------------------------------------------------------
+# 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
+HAVE_LOCAL_SCAN=yes
+
+# If you set DLOPEN_LOCAL_SCAN, then you need to include -rdynamic in the
+# linker flags. Without it, the loaded .so won't be able to access any
+# functions from exim.
+
+LFLAGS=-rdynamic -ldl -pie
+
#------------------------------------------------------------------------------
# The default distribution of Exim contains only the plain text form of the
# documentation. Other forms are available separately. If you want to install
diff --git a/src/config.h.defaults b/src/config.h.defaults
index 25ab755..e27a51d 100644
--- a/src/config.h.defaults
+++ b/src/config.h.defaults
@@ -33,6 +33,8 @@ Do not put spaces between # and the 'define'.
#define AUTH_VARS 4
+#define DLOPEN_LOCAL_SCAN
+
#define BIN_DIRECTORY
#define CONFIGURE_FILE
diff --git a/src/globals.c b/src/globals.c
index ff246fe..b9dfbbb 100644
--- a/src/globals.c
+++ b/src/globals.c
@@ -151,6 +151,10 @@ time_t tls_watch_trigger_time = (time_t)0;
uschar *tls_advertise_hosts = NULL;
#endif
+#ifdef DLOPEN_LOCAL_SCAN
+uschar *local_scan_path = NULL;
+#endif
+
#ifndef DISABLE_PRDR
/* Per Recipient Data Response variables */
BOOL prdr_enable = FALSE;
diff --git a/src/globals.h b/src/globals.h
index fe099e4..7530a76 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -148,6 +148,11 @@ extern uschar *tls_verify_hosts; /* Mandatory client verification */
extern int tls_watch_fd; /* for inotify of creds files */
extern time_t tls_watch_trigger_time; /* non-0: triggered */
#endif
+
+#ifdef DLOPEN_LOCAL_SCAN
+extern uschar *local_scan_path; /* Path to local_scan() library */
+#endif
+
extern uschar *tls_advertise_hosts; /* host for which TLS is advertised */
extern uschar *dsn_envid; /* DSN envid string */
diff --git a/src/local_scan.c b/src/local_scan.c
index 7a3bae7..6ea5d2d 100644
--- a/src/local_scan.c
+++ b/src/local_scan.c
@@ -6,59 +6,133 @@
/* Copyright (c) The Exim Maintainers 2021 */
/* See the file NOTICE for conditions of use and distribution. */
+#include <local_scan.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
+#ifdef DLOPEN_LOCAL_SCAN
+extern uschar *local_scan_path; /* Path to local_scan() library */
+#endif
-HAVE_LOCAL_SCAN=yes
-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)
{
-return LOCAL_SCAN_ACCEPT;
+#ifdef DLOPEN_LOCAL_SCAN
+/* local_scan_path is defined AND not the empty string */
+if (local_scan_path && *local_scan_path)
+ {
+ if (!local_scan_fn)
+ {
+ if (!load_local_scan_library())
+ {
+ char *base_msg , *error_msg , *final_msg ;
+ int final_length = -1 ;
+
+ base_msg=US"Local configuration error - local_scan() library failure\n";
+ error_msg = dlerror() ;
+
+ final_length = strlen(base_msg) + strlen(error_msg) + 1 ;
+ final_msg = (char*)malloc( final_length*sizeof(char) ) ;
+ *final_msg = '\0' ;
+
+ strcat( final_msg , base_msg ) ;
+ strcat( final_msg , error_msg ) ;
+
+ *return_text = final_msg ;
+ 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_maj;
+int vers_min;
+
+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_major");
+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_major() function - message temporarily rejected");
+ return FALSE;
+ }
+
+/* The major number is increased when the ABI is changed in a non
+ backward compatible way. */
+vers_maj = local_scan_version_fn();
+
+local_scan_version_fn = dlsym(local_scan_lib, "local_scan_version_minor");
+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_minor() function - message temporarily rejected");
+ return FALSE;
+ }
+
+/* The minor number is increased each time a new feature is added (in a
+ way that doesn't break backward compatibility) -- Marc */
+vers_min = local_scan_version_fn();
+
+
+if (vers_maj != LOCAL_SCAN_ABI_VERSION_MAJOR)
+ {
+ dlclose(local_scan_lib);
+ local_scan_lib = NULL;
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has an incompatible major"
+ "version number, you need to recompile your module for this version"
+ "of exim (The module was compiled for version %d.%d and this exim provides"
+ "ABI version %d.%d)", vers_maj, vers_min, LOCAL_SCAN_ABI_VERSION_MAJOR,
+ LOCAL_SCAN_ABI_VERSION_MINOR);
+ return FALSE;
+ }
+else if (vers_min > LOCAL_SCAN_ABI_VERSION_MINOR)
+ {
+ dlclose(local_scan_lib);
+ local_scan_lib = NULL;
+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has an incompatible minor"
+ "version number, you need to recompile your module for this version"
+ "of exim (The module was compiled for version %d.%d and this exim provides"
+ "ABI version %d.%d)", vers_maj, vers_min, LOCAL_SCAN_ABI_VERSION_MAJOR,
+ LOCAL_SCAN_ABI_VERSION_MINOR);
+ 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 */
diff --git a/src/readconf.c b/src/readconf.c
index 06bc50f..6ecb0af 100644
--- a/src/readconf.c
+++ b/src/readconf.c
@@ -212,6 +212,9 @@ static optionlist optionlist_config[] = {
{ "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
#ifdef HAVE_LOCAL_SCAN
{ "local_scan_timeout", opt_time, {&local_scan_timeout} },
#endif
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