Added rlm_unpack

Which makes it easier to unpack binary data

raddb/all.mk

@@ -11,7 +11,7 @@ DEFAULT_MODULES :=	always attr_filter cache_eap chap \
 			detail detail.log digest dhcp dynamic_clients eap \
 			echo exec expiration expr files linelog logintime \
 			mschap ntlm_auth pap passwd preprocess radutmp realm \
-			replicate soh sradutmp unix utf8
+			replicate soh sradutmp unix unpack utf8
 
 LOCAL_MODULES :=	$(addprefix raddb/mods-enabled/,$(DEFAULT_MODULES))
 

raddb/mods-available/unpack

@@ -0,0 +1,38 @@
+# -*- text -*-
+#
+#  $Id$
+
+#
+#  This module is useful only for 'xlat'.  To use it,
+#  add it to the raddb/mods-enabled/ directory.  Then,
+#  use it on the right-hand side of a variable assignment.
+#
+#  ... = "%{unpack:&Attribute-Name 1 integer}"
+#
+#  The arguments are three fields:
+#
+#	&Attribute-Name
+#		the name of the attribute to unpack.
+#		 MUST be a "string" or "octets" type.
+#
+#	1
+#		The offset into the string from which
+#		it starts unpacking.  The offset starts
+#		at zero, for the first attribute.
+#
+#	integer
+#		the data type to unpack at that offset.
+#		e.g. integer, ipaddr, byte, short, etc.
+#
+#  e.g. if we have Class = 0x00000001020304, then
+#
+#	%{unpack:&Class 4 short}
+#
+#  will unpack octets 4 and 5 as a "short", which has
+#  value 0x0304.
+#
+#  This module is used when vendors put multiple fields
+#  into one attribute of type "octets".
+#
+unpack {
+}

src/modules/rlm_unpack/all.mk

@@ -0,0 +1,2 @@
+TARGET		:= rlm_unpack.a
+SOURCES		:= rlm_unpack.c

src/modules/rlm_unpack/rlm_unpack.c

@@ -0,0 +1,196 @@
+/*
+ *   This program is is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License, version 2 if the
+ *   License as published by the Free Software Foundation.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/**
+ * $Id$
+ * @file rlm_unpack.c
+ * @brief Unpack binary data
+ *
+ * @copyright 2014 The FreeRADIUS server project
+ * @copyright 2014 Alan DeKok <aland@freeradius.org>
+ */
+RCSID("$Id$")
+
+#include <freeradius-devel/radiusd.h>
+#include <freeradius-devel/modules.h>
+#include <ctype.h>
+
+#define PW_CAST_BASE (1850)
+
+#define GOTO_ERROR do { RDEBUG("Unexpected text at '%s'", p); goto error;} while (0)
+
+/** Unpack data
+ *
+ *  Example: %{unpack:&Class, 1, integer}
+ *
+ *  Expands Class, treating octet 1 as an "integer".
+ */
+static ssize_t unpack_xlat(UNUSED void *instance, REQUEST *request,
+			 char const *fmt, char *out, size_t outlen)
+{
+	char *data_name, *data_size, *data_type;
+	char *p;
+	size_t len;
+	int offset;
+	PW_TYPE type;
+	DICT_ATTR const *da;
+	VALUE_PAIR *vp, *cast;
+	char buffer[256];
+
+	strlcpy(buffer, fmt, sizeof(buffer));
+
+	p = buffer;
+	if (*p != '&') {
+	error:
+		RDEBUG("Format string should be like '&Class, 1, integer'");
+	nothing:
+		*out = '\0';
+		return 0;
+	}
+
+	p++;
+
+	data_name = p;
+	while (*p && !isspace((int) *p)) p++;
+	if (!*p) GOTO_ERROR;
+
+	while (isspace((int) *p)) *(p++) = '\0';
+	if (!*p) GOTO_ERROR;
+
+	data_size = p;
+
+	while (*p && !isspace((int) *p)) p++;
+	if (!*p) GOTO_ERROR;
+
+	while (isspace((int) *p)) *(p++) = '\0';
+	if (!*p) GOTO_ERROR;
+
+	data_type = p;
+
+	while (*p && !isspace((int) *p)) p++;
+	if (*p) GOTO_ERROR;	/* anything after the type is an error */
+
+	if (radius_get_vp(&vp, request, data_name) < 0) goto nothing;
+
+	if ((vp->da->type != PW_TYPE_OCTETS) &&
+	    (vp->da->type != PW_TYPE_STRING)) {
+		RDEBUG("unpack requires the input attribute to be 'string' or 'octets'");
+		goto nothing;
+	}
+
+	offset = (int) strtoul(data_size, &p, 10);
+	if (*p) {
+		RDEBUG("unpack requires a decimal number, not '%s'", data_size);
+		goto nothing;
+	}
+
+	type = fr_str2int(dict_attr_types, data_type, PW_TYPE_INVALID);
+	if (type == PW_TYPE_INVALID) {
+		RDEBUG("Invalid data type '%s'", data_type);
+		goto nothing;
+	}
+
+	/*
+	 *	Output must be a non-zero limited size.
+	 */
+	if ((dict_attr_sizes[type][0] ==  0) ||
+	    (dict_attr_sizes[type][0] != dict_attr_sizes[type][1])) {
+		RDEBUG("unpack requires fixed-size output type, not '%s'", data_type);
+		goto nothing;
+	}
+
+	if (vp->length < (offset + dict_attr_sizes[type][0])) {
+		RDEBUG("Cannot unpack attribute '%s', it is too short", data_name);
+		goto nothing;
+	}
+
+	da = dict_attrbyvalue(PW_CAST_BASE + type, 0);
+	if (!da) {
+		RDEBUG("Cannot decode type '%s'", data_type);
+		goto nothing;
+	}
+
+	cast = pairalloc(request, da);
+	if (!cast) goto nothing;
+
+	memcpy(&(cast->data), vp->vp_octets + offset, dict_attr_sizes[type][0]);
+	cast->length = dict_attr_sizes[type][0];
+
+	/*
+	 *	Hacks
+	 */
+	switch (type) {
+	case PW_TYPE_SIGNED:
+	case PW_TYPE_INTEGER:
+	case PW_TYPE_DATE:
+		cast->vp_integer = ntohl(cast->vp_integer);
+		break;
+
+	case PW_TYPE_SHORT:
+		cast->vp_short = ((vp->vp_octets[offset] << 8) |
+				vp->vp_octets[offset + 1]);
+		break;
+
+	case PW_TYPE_INTEGER64:
+		cast->vp_integer64 = ntohll(cast->vp_integer64);
+		break;
+
+	default:
+		break;
+	}
+
+	len = vp_prints_value(out, outlen, cast, 0);
+	talloc_free(cast);
+
+	return len;
+}
+
+
+/*
+ *	Register the xlats
+ */
+static int mod_instantiate(UNUSED CONF_SECTION *conf, void *instance)
+{
+	xlat_register("unpack", unpack_xlat, NULL, instance);
+
+	return 0;
+}
+
+/*
+ *	The module name should be the only globally exported symbol.
+ *	That is, everything else should be 'static'.
+ *
+ *	If the module needs to temporarily modify it's instantiation
+ *	data, the type should be changed to RLM_TYPE_THREAD_UNSAFE.
+ *	The server will then take care of ensuring that the module
+ *	is single-threaded.
+ */
+module_t rlm_unpack = {
+	RLM_MODULE_INIT,
+	"unpack",
+	RLM_TYPE_THREAD_SAFE,		/* type */
+	0,
+	NULL,
+	mod_instantiate,		/* instantiation */
+	NULL,			/* detach */
+	{
+		NULL,	/* authentication */
+		NULL,	/* authorization */
+		NULL, NULL, NULL,
+		NULL,			/* pre-proxy */
+		NULL,			/* post-proxy */
+		NULL			/* post-auth */
+	},
+};