Description: Allow one to use and switch between different local_scan functions without recompiling exim. http://marc.merlins.org/linux/exim/files/sa-exim-current/ Original patch from David Woodhouse, modified first by Derrick 'dman' Hudson and then by Marc MERLIN for SA-Exim and minor/major API version tracking Author: David Woodhouse, Derrick 'dman' Hudson, Marc MERLIN Origin: other, http://marc.merlins.org/linux/exim/files/sa-exim-current/ Forwarded: no Last-Update: 2018-12-12 --- a/src/EDITME +++ b/src/EDITME @@ -824,6 +824,21 @@ HEADERS_CHARSET="ISO-8859-1" #------------------------------------------------------------------------------ +# 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 + +# 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. + +LDFLAGS += -rdynamic +CFLAGS += -fvisibility=hidden + +#------------------------------------------------------------------------------ # 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 --- a/src/config.h.defaults +++ b/src/config.h.defaults @@ -32,6 +32,8 @@ Do not put spaces between # and the 'def #define AUTH_VARS 3 +#define DLOPEN_LOCAL_SCAN + #define BIN_DIRECTORY #define CONFIGURE_FILE --- a/src/globals.c +++ b/src/globals.c @@ -141,6 +141,10 @@ int dsn_ret = 0; const pcre *regex_DSN = NULL; uschar *dsn_advertise_hosts = NULL; +#ifdef DLOPEN_LOCAL_SCAN +uschar *local_scan_path = NULL; +#endif + #ifdef SUPPORT_TLS BOOL gnutls_compat_mode = FALSE; BOOL gnutls_allow_auto_pkcs11 = FALSE; --- a/src/globals.h +++ b/src/globals.h @@ -138,6 +138,9 @@ extern int dsn_ret; / extern const pcre *regex_DSN; /* For recognizing DSN settings */ extern uschar *dsn_advertise_hosts; /* host for which TLS is advertised */ +#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. */ --- a/src/local_scan.c +++ b/src/local_scan.c @@ -5,61 +5,131 @@ /* Copyright (c) University of Cambridge 1995 - 2009 */ /* 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 - -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 +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 +/* 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 */ --- a/src/local_scan.h +++ b/src/local_scan.h @@ -17,6 +17,7 @@ settings, and the store functions. */ #include #include +#pragma GCC visibility push(default) #include "config.h" #include "mytypes.h" #include "store.h" @@ -192,4 +193,6 @@ extern uschar *string_copy(const uschar extern uschar *string_copyn(const uschar *, int); extern uschar *string_sprintf(const char *, ...) ALMOST_PRINTF(1,2); +#pragma GCC visibility pop + /* End of local_scan.h */ --- a/src/readconf.c +++ b/src/readconf.c @@ -199,6 +199,9 @@ 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