Instead of calling "snmp_set_full_objid()" to cause OIDs to be displayed

symbolically as full sequences, call "snmp_set_suffix_only(2)" to cause
them to be displayed symbolically as a module name and a name within
that module, as that might make it easier to find the RFC or whatever
that describes the object in question.

Don't just statically call it, though, on Linux, as that causes binaries
built on Red Hat releases prior to 6.2 to fail to run on 6.2, due to the
UCD SNMP 4.1.1 library used in RH 6.2 not being 100% binary-compatible
with the UCD SNMP libraries used in those prior releases.  Instead, on
Linux, try to "dlopen()" the "libsnmp.so" library and, if that succeeds,
try to find "snmp_set_suffix_only()" in that library - if that succeeds,
call it, otherwise try to find "ds_set_int()" in that library and, if
*that* succeeds, call it with the arguments that, in UCD SNMP 4.1.1, the
"snmp_set_suffix_only()" macro passes to it.

svn path=/trunk/; revision=2077

1 files changed, 105 insertions, 13 deletions

diff --git a/packet-snmp.c b/packet-snmp.c
index 04efbb6c87..ad72a1ea01 100644
--- a/packet-snmp.c
+++ b/packet-snmp.c
@@ -2,7 +2,7 @@
  * Routines for SNMP (simple network management protocol)
  * D.Jorand (c) 1998
  *
- * $Id: packet-snmp.c,v 1.36 2000/05/31 05:07:46 guy Exp $
+ * $Id: packet-snmp.c,v 1.37 2000/06/17 05:56:22 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@zing.org>
@@ -47,6 +47,10 @@
 
 #define MAX_STRING_LEN 1024	/* TBC */
 
+#ifdef linux
+#include <dlfcn.h>
+#endif
+
 #include <glib.h>
 
 #include "packet.h"
@@ -67,12 +71,12 @@
 #  include <ucd-snmp/mib.h>
 
    /*
-    * Sigh.  UCD SNMP 4.1.1 makes "snmp_set_full_objid()" a macro
-    * that calls "ds_set_boolean()" with the first two arguments
-    * being DS_LIBRARY_ID and DS_LIB_PRINT_FULL_OID; this means that,
+    * Sigh.  UCD SNMP 4.1.1 makes "snmp_set_suffix_only()" a macro
+    * that calls "ds_set_int()" with the first two arguments
+    * being DS_LIBRARY_ID and DS_LIB_PRINT_SUFFIX_ONLY; this means that,
     * when building with 4.1.1, we need to arrange that
     * <ucd-snmp/default_store.h> is included, to define those two values
-    * and to declare "ds_set_boolean()".
+    * and to declare "ds_int()".
     *
     * However:
     *
@@ -86,7 +90,7 @@
     * So we only include it if "snmp_set_full_objid" is defined as
     * a macro.
     */
-#  ifdef snmp_set_full_objid
+#  ifdef snmp_set_suffix_only
 #   include <ucd-snmp/default_store.h>
 #  endif
 
@@ -1849,6 +1853,12 @@ dissect_smux(const u_char *pd, int offset, frame_data *fd, proto_tree *tree)
 void
 proto_register_snmp(void)
 {
+#ifdef linux
+	void *libsnmp_handle;
+	int (*snmp_set_suffix_only_p)(int);
+	int (*ds_set_int_p)(int, int, int);
+#endif
+
         static hf_register_info hf[] = {
 		{ &hf_snmpv3_flags,
 		{ "SNMPv3 Flags", "snmpv3.flags", FT_UINT8, BASE_HEX, NULL,
@@ -1862,10 +1872,6 @@ proto_register_snmp(void)
 		{ &hf_snmpv3_flags_report,
 		{ "Reportable", "snmpv3.flags.report", FT_BOOLEAN, 8,
 		    TFS(&flags_set_truth), TH_REPORT, "" }},
-/*
-                { &hf_variable,
-                { "Name",           "snmp.abbreviation", TYPE, VALS_POINTER }},
-*/
         };
 	static gint *ett[] = {
 		&ett_snmp,
@@ -1879,9 +1885,95 @@ proto_register_snmp(void)
 	/* UCD or CMU SNMP */
 	init_mib();
 #ifdef HAVE_UCD_SNMP_SNMP_H
-	snmp_set_full_objid(TRUE);
-#endif
-#endif
+#ifdef linux
+	/* As per the comment near the beginning of the file, UCD SNMP 4.1.1
+	   changed "snmp_set_suffix_only()" from a function to a macro,
+	   removing "snmp_set_suffix_only()" from the library; this means
+	   that binaries that call "snmp_set_suffix_only()" and
+	   that are linked against shared libraries from earlier versions
+	   of the UCD SNMP library won't run with shared libraries from
+	   4.1.1.
+
+	   This is a problem on Red Hat Linux, as pre-6.2 releases
+	   came with pre-4.1.1 UCD SNMP, while 6.2 comes the 4.1.1.
+	   Versions of Ethereal built on pre-6.2 releases don't run
+	   on 6.2, and the current Ethereal RPMs are built on pre-6.2
+	   releases, causing problems when users running 6.2 download
+	   them and try to use them.
+
+	   Building the releases on 6.2 isn't necessarily the answer,
+	   as "snmp_set_suffix_only()" expands to a call to "ds_set_int()"
+	   with a second argument not supported by at least some pre-4.1.1
+	   versions of the library - it appears that the 4.0.1 library,
+	   at least, checks for invalid arguments and returns an error
+	   rather than stomping random memory, but that means that you
+	   won't get get OIDs displayed as module-name::sub-OID.
+
+	   So we use a trick similar to one I've seen mentioned as
+	   used in Windows applications to let you build binaries
+	   that run on many different versions of Windows 9x and
+	   Windows NT, that use features present on later versions
+	   if run on those later versions, but that avoid calling,
+	   when run on older versions, routines not present on those
+	   older versions.
+
+	   I.e., we load "libsnmp.so" with "dlopen()", and call
+	   "dlsym()" to try to find "snmp_set_suffix_only()"; if we
+	   don't find it, we make the appropriate call to
+	   "ds_set_int()" instead.
+
+	   We do this only on Linux, for now, as we've only seen the
+	   problem on Red Hat; it may show up on other OSes that bundle
+	   UCD SNMP, or on OSes where it's not bundled but for which
+	   binary packages are built that link against a shared version
+	   of the UCD SNMP library.  If we run into one of those, we
+	   can do this under those OSes as well, *if* "dlopen()" makes
+	   the run-time linker use the same search rules as it uses when
+	   loading libraries with which the application is linked.
+
+	   (Perhaps we could use the GLib wrappers for run-time linking,
+	   *if* they're thin enough; however, as this code is currently
+	   used only on Linux, we don't worry about that for now.) */
+
+	libsnmp_handle = dlopen("libsnmp.so", RTLD_LAZY|RTLD_GLOBAL);
+	if (libsnmp_handle == NULL) {
+		/* We didn't find "libsnmp.so"; we may be linked
+		   statically, in which case whatever call the following
+		   line of code makes will presumably work, as
+		   we have the routine it calls wired into our binary. */
+		snmp_set_suffix_only(2);
+	} else {
+		/* OK, we have it loaded.  Do we have
+		   "snmp_set_suffix_only()"? */
+		snmp_set_suffix_only_p = dlsym(libsnmp_handle,
+		    "snmp_set_suffix_only");
+		if (snmp_set_suffix_only_p != NULL) {
+			/* Yes - call it. */
+			(*snmp_set_suffix_only_p)(2);
+		} else {
+			/* No; do we have "ds_set_int()"? */
+			ds_set_int_p = dlsym(libsnmp_handle, "ds_set_int");
+			if (ds_set_int_p != NULL) {
+				/* Yes - cal it with DS_LIBRARY_ID,
+				   DS_LIB_PRINT_SUFFIX_ONLY, and 2 as
+				   arguments.
+
+				   We do *not* use DS_LIBRARY_ID or
+				   DS_LIB_PRINT_SUFFIX_ONLY by name, so that
+				   we don't require that Ethereal be built
+				   with versions of UCD SNMP that include
+				   that value; instead, we use their values
+				   in UCD SNMP 4.1.1, which are 0 and 4,
+				   respectively. */
+				(*ds_set_int_p)(0, 4, 2);
+			}
+		}
+	}
+#else /* linux */
+	snmp_set_suffix_only(2);
+#endif /* linux */
+#endif /* HAVE_UCD_SNMP_SNMP_H */
+#endif /* defined(HAVE_UCD_SNMP_SNMP_H) || defined(HAVE_SNMP_SNMP_H) */
         proto_snmp = proto_register_protocol("Simple Network Management Protocol", "snmp");
         proto_smux = proto_register_protocol("SNMP Multiplex Protocol", "smux");
         proto_register_field_array(proto_snmp, hf, array_length(hf));