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305 lines
10 KiB
305 lines
10 KiB
Description: Allow one to use and switch between different local_scan functions
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without recompiling exim.
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http://marc.merlins.org/linux/exim/files/sa-exim-current/ Original patch from
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David Woodhouse, modified first by Derrick 'dman' Hudson and then by Marc
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MERLIN for SA-Exim and minor/major API version tracking
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Author: David Woodhouse, Derrick 'dman' Hudson, Marc MERLIN
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Origin: other, http://marc.merlins.org/linux/exim/files/sa-exim-current/
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Forwarded: https://bugs.exim.org/show_bug.cgi?id=2671
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Last-Update: 2021-07-28
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--- a/src/EDITME
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+++ b/src/EDITME
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@@ -883,6 +883,21 @@ HEADERS_CHARSET="ISO-8859-1"
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#------------------------------------------------------------------------------
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+# On systems which support dynamic loading of shared libraries, Exim can
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+# load a local_scan function specified in its config file instead of having
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+# to be recompiled with the desired local_scan function. For a full
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+# description of the API to this function, see the Exim specification.
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+
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+DLOPEN_LOCAL_SCAN=yes
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+
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+# If you set DLOPEN_LOCAL_SCAN, then you need to include -rdynamic in the
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+# linker flags. Without it, the loaded .so won't be able to access any
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+# functions from exim.
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+
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+LDFLAGS += -rdynamic
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+CFLAGS += -fvisibility=hidden
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+
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+#------------------------------------------------------------------------------
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# The default distribution of Exim contains only the plain text form of the
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# documentation. Other forms are available separately. If you want to install
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# the documentation in "info" format, first fetch the Texinfo documentation
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--- a/src/config.h.defaults
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+++ b/src/config.h.defaults
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@@ -35,6 +35,8 @@ Do not put spaces between # and the 'def
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#define AUTH_VARS 4
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+#define DLOPEN_LOCAL_SCAN
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+
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#define BIN_DIRECTORY
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#define CONFIGURE_FILE
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--- a/src/globals.c
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+++ b/src/globals.c
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@@ -121,6 +121,10 @@ int dsn_ret = 0;
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const pcre *regex_DSN = NULL;
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uschar *dsn_advertise_hosts = NULL;
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+#ifdef DLOPEN_LOCAL_SCAN
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+uschar *local_scan_path = NULL;
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+#endif
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+
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#ifndef DISABLE_TLS
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BOOL gnutls_compat_mode = FALSE;
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BOOL gnutls_allow_auto_pkcs11 = FALSE;
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--- a/src/globals.h
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+++ b/src/globals.h
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@@ -156,6 +156,9 @@ extern int dsn_ret; /
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extern const pcre *regex_DSN; /* For recognizing DSN settings */
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extern uschar *dsn_advertise_hosts; /* host for which TLS is advertised */
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+#ifdef DLOPEN_LOCAL_SCAN
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+extern uschar *local_scan_path; /* Path to local_scan() library */
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+#endif
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/* Input-reading functions for messages, so we can use special ones for
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incoming TCP/IP. */
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--- a/src/local_scan.c
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+++ b/src/local_scan.c
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@@ -6,58 +6,133 @@
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/* See the file NOTICE for conditions of use and distribution. */
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-/******************************************************************************
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-This file contains a template local_scan() function that just returns ACCEPT.
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-If you want to implement your own version, you should copy this file to, say
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-Local/local_scan.c, and edit the copy. To use your version instead of the
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-default, you must set
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-
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-HAVE_LOCAL_SCAN=yes
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-LOCAL_SCAN_SOURCE=Local/local_scan.c
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-
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-in your Local/Makefile. This makes it easy to copy your version for use with
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-subsequent Exim releases.
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-
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-For a full description of the API to this function, see the Exim specification.
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-******************************************************************************/
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-
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-
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/* This is the only Exim header that you should include. The effect of
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including any other Exim header is not defined, and may change from release to
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release. Use only the documented interface! */
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#include "local_scan.h"
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-
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-/* This is a "do-nothing" version of a local_scan() function. The arguments
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-are:
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-
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- fd The file descriptor of the open -D file, which contains the
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- body of the message. The file is open for reading and
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- writing, but modifying it is dangerous and not recommended.
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-
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- return_text A pointer to an unsigned char* variable which you can set in
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- order to return a text string. It is initialized to NULL.
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-
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-The return values of this function are:
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-
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- LOCAL_SCAN_ACCEPT
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- The message is to be accepted. The return_text argument is
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- saved in $local_scan_data.
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-
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- LOCAL_SCAN_REJECT
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- The message is to be rejected. The returned text is used
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- in the rejection message.
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-
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- LOCAL_SCAN_TEMPREJECT
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- This specifies a temporary rejection. The returned text
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- is used in the rejection message.
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-*/
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+#ifdef DLOPEN_LOCAL_SCAN
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+#include <dlfcn.h>
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+static int (*local_scan_fn)(int fd, uschar **return_text) = NULL;
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+static int load_local_scan_library(void);
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+#endif
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int
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local_scan(int fd, uschar **return_text)
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{
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-return LOCAL_SCAN_ACCEPT;
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+
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+#ifdef DLOPEN_LOCAL_SCAN
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+/* local_scan_path is defined AND not the empty string */
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+if (local_scan_path && *local_scan_path)
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+ {
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+ if (!local_scan_fn)
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+ {
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+ if (!load_local_scan_library())
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+ {
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+ char *base_msg , *error_msg , *final_msg ;
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+ int final_length = -1 ;
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+
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+ base_msg=US"Local configuration error - local_scan() library failure\n";
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+ error_msg = dlerror() ;
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+
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+ final_length = strlen(base_msg) + strlen(error_msg) + 1 ;
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+ final_msg = (char*)malloc( final_length*sizeof(char) ) ;
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+ *final_msg = '\0' ;
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+
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+ strcat( final_msg , base_msg ) ;
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+ strcat( final_msg , error_msg ) ;
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+
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+ *return_text = final_msg ;
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+ return LOCAL_SCAN_TEMPREJECT;
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+ }
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+ }
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+ return local_scan_fn(fd, return_text);
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+ }
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+else
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+#endif
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+ return LOCAL_SCAN_ACCEPT;
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+}
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+
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+#ifdef DLOPEN_LOCAL_SCAN
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+
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+static int load_local_scan_library(void)
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+{
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+/* No point in keeping local_scan_lib since we'll never dlclose() anyway */
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+void *local_scan_lib = NULL;
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+int (*local_scan_version_fn)(void);
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+int vers_maj;
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+int vers_min;
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+
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+local_scan_lib = dlopen(local_scan_path, RTLD_NOW);
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+if (!local_scan_lib)
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+ {
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+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library open failed - "
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+ "message temporarily rejected");
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+ return FALSE;
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+ }
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+
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+local_scan_version_fn = dlsym(local_scan_lib, "local_scan_version_major");
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+if (!local_scan_version_fn)
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+ {
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+ dlclose(local_scan_lib);
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+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
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+ "local_scan_version_major() function - message temporarily rejected");
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+ return FALSE;
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+ }
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+
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+/* The major number is increased when the ABI is changed in a non
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+ backward compatible way. */
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+vers_maj = local_scan_version_fn();
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+
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+local_scan_version_fn = dlsym(local_scan_lib, "local_scan_version_minor");
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+if (!local_scan_version_fn)
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+ {
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+ dlclose(local_scan_lib);
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+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
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+ "local_scan_version_minor() function - message temporarily rejected");
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+ return FALSE;
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+ }
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+
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+/* The minor number is increased each time a new feature is added (in a
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+ way that doesn't break backward compatibility) -- Marc */
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+vers_min = local_scan_version_fn();
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+
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+
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+if (vers_maj != LOCAL_SCAN_ABI_VERSION_MAJOR)
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+ {
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+ dlclose(local_scan_lib);
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+ local_scan_lib = NULL;
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+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has an incompatible major"
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+ "version number, you need to recompile your module for this version"
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+ "of exim (The module was compiled for version %d.%d and this exim provides"
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+ "ABI version %d.%d)", vers_maj, vers_min, LOCAL_SCAN_ABI_VERSION_MAJOR,
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+ LOCAL_SCAN_ABI_VERSION_MINOR);
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+ return FALSE;
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+ }
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+else if (vers_min > LOCAL_SCAN_ABI_VERSION_MINOR)
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+ {
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+ dlclose(local_scan_lib);
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+ local_scan_lib = NULL;
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+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() has an incompatible minor"
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+ "version number, you need to recompile your module for this version"
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+ "of exim (The module was compiled for version %d.%d and this exim provides"
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+ "ABI version %d.%d)", vers_maj, vers_min, LOCAL_SCAN_ABI_VERSION_MAJOR,
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+ LOCAL_SCAN_ABI_VERSION_MINOR);
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+ return FALSE;
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+ }
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+
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+local_scan_fn = dlsym(local_scan_lib, "local_scan");
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+if (!local_scan_fn)
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+ {
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+ dlclose(local_scan_lib);
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+ log_write(0, LOG_MAIN|LOG_REJECT, "local_scan() library doesn't contain "
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+ "local_scan() function - message temporarily rejected");
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+ return FALSE;
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+ }
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+return TRUE;
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}
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+#endif /* DLOPEN_LOCAL_SCAN */
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+
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/* End of local_scan.c */
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--- a/src/local_scan.h
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+++ b/src/local_scan.h
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@@ -27,6 +27,7 @@ settings, and the store functions. */
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#include <stdarg.h>
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#include <sys/types.h>
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+#pragma GCC visibility push(default)
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#include "config.h"
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#include "mytypes.h"
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#include "store.h"
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@@ -166,6 +167,9 @@ extern header_line *header_list; /
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extern BOOL host_checking; /* Set when checking a host */
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extern uschar *interface_address; /* Interface for incoming call */
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extern int interface_port; /* Port number for incoming call */
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+#ifdef DLOPEN_LOCAL_SCAN
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+extern uschar *local_scan_path;
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+#endif
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extern uschar *message_id; /* Internal id of message being handled */
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extern uschar *received_protocol; /* Name of incoming protocol */
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extern int recipients_count; /* Number of recipients */
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@@ -235,4 +239,6 @@ extern pid_t child_open_exim2_functio
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extern pid_t child_open_function(uschar **, uschar **, int, int *, int *, BOOL, const uschar *);
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#endif
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+#pragma GCC visibility pop
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+
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/* End of local_scan.h */
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--- a/src/readconf.c
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+++ b/src/readconf.c
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@@ -215,6 +215,9 @@ static optionlist optionlist_config[] =
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{ "local_from_prefix", opt_stringptr, {&local_from_prefix} },
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{ "local_from_suffix", opt_stringptr, {&local_from_suffix} },
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{ "local_interfaces", opt_stringptr, {&local_interfaces} },
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+#ifdef DLOPEN_LOCAL_SCAN
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+ { "local_scan_path", opt_stringptr, &local_scan_path },
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+#endif
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#ifdef HAVE_LOCAL_SCAN
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{ "local_scan_timeout", opt_time, {&local_scan_timeout} },
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#endif
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--- a/src/string.c
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+++ b/src/string.c
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@@ -418,6 +418,7 @@ return ss;
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#if (defined(HAVE_LOCAL_SCAN) || defined(EXPAND_DLFUNC)) \
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&& !defined(MACRO_PREDEF) && !defined(COMPILE_UTILITY)
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+#pragma GCC visibility push(default)
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/*************************************************
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* Copy and save string *
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*************************************************/
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@@ -470,6 +471,7 @@ Ustrncpy(ss, s, n);
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ss[n] = 0;
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return ss;
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}
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+#pragma GCC visibility pop
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#endif
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