[PATCH] openbsc[master]: Added SNDCP-XID encoder / decoder

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dexter gerrit-no-reply at lists.osmocom.org
Thu Aug 4 08:40:42 UTC 2016


Hello Harald Welte,

I'd like you to reexamine a change.  Please visit

    https://gerrit.osmocom.org/641

to look at the new patch set (#4).

Added SNDCP-XID encoder / decoder

The SNDCP-XID (or layer-3 xid) is used to exchange layer-3 parameters
such as compression. The encoder encodes a bytestream that is then
sent as regular XID field from LLC.

We will need the SNDCP-XID to negotiate the parameters for our
upcomming GPRS data and header compression features

Change-Id: If2d63fe2550864cafef3156b1dc0629037c49c1e
---
M openbsc/include/openbsc/Makefile.am
A openbsc/include/openbsc/gprs_sndcp_xid.h
M openbsc/src/gprs/Makefile.am
A openbsc/src/gprs/gprs_sndcp_xid.c
4 files changed, 1,971 insertions(+), 3 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/openbsc refs/changes/41/641/4

diff --git a/openbsc/include/openbsc/Makefile.am b/openbsc/include/openbsc/Makefile.am
index 9e8c554..b37103f 100644
--- a/openbsc/include/openbsc/Makefile.am
+++ b/openbsc/include/openbsc/Makefile.am
@@ -18,7 +18,7 @@
 		 gprs_gb_parse.h smpp.h meas_feed.h \
 		 gprs_gsup_client.h bsc_msg_filter.h \
 		 oap.h oap_messages.h \
-		 gtphub.h gprs_sndcp.h slhc.h gprs_llc_xid.h
+		 gtphub.h gprs_sndcp.h slhc.h gprs_llc_xid.h gprs_sndcp_xid.h
 
 openbsc_HEADERS = gsm_04_08.h meas_rep.h bsc_api.h
 openbscdir = $(includedir)/openbsc
diff --git a/openbsc/include/openbsc/gprs_sndcp_xid.h b/openbsc/include/openbsc/gprs_sndcp_xid.h
new file mode 100644
index 0000000..ec14a55
--- /dev/null
+++ b/openbsc/include/openbsc/gprs_sndcp_xid.h
@@ -0,0 +1,220 @@
+#ifndef _GPRS_SNDCP_XID_H
+#define _GPRS_SNDCP_XID_H
+
+#include <stdint.h>
+#include <osmocom/core/linuxlist.h>
+
+#define CURRENT_SNDCP_VERSION 0	/* See TS 144 065, clause 8 */
+#define MAX_ENTITIES 32	/* TS 144 065 reserves 5 bit for compr. entity num. */
+
+/* According to: TS 144 065 6.5.1.1 Format of the protocol control information 
+				    compression field (Figure 7) 
+
+                 TS 144 065 6.6.1.1 Format of the data compression 
+				    field (Figure 9) */
+
+struct gprs_sndcp_comp_field {
+	struct llist_head list;
+
+	/* Propose bit (P), see also: 6.5.1.1.2 and 6.6.1.1.2 */
+	unsigned int p;
+
+	/* Entity number, see also: 6.5.1.1.3 and 6.6.1.1.3 */
+	unsigned int entity;
+
+	/* Algorithm identifier, see also: 6.5.1.1.4 and 6.6.1.1.4 */
+	unsigned int algo;
+
+	/* Number of contained PCOMP / DCOMP values */
+	unsigned int comp_len;
+
+	/* PCOMP / DCOMP values, see also: 6.5.1.1.5 and 6.6.1.1.5 */
+	unsigned int comp[16];
+
+	/* Note: Only one of the following struct pointers may, 
+	   be used unused pointers must be set to NULL! */
+	struct gprs_sndcp_hdrcomp_rfc1144_params *rfc1144_params;
+	struct gprs_sndcp_hdrcomp_rfc2507_params *rfc2507_params;
+	struct gprs_sndcp_hdrcomp_rohc_params *rohc_params;
+	struct gprs_sndcp_datacomp_v42bis_params *v42bis_params;
+	struct gprs_sndcp_datacomp_v44_params *v44_params;
+};
+
+/* According to: TS 144 065 6.5.1.1.4 Algorithm identifier */
+enum gprs_sndcp_hdr_comp_algo {
+	RFC_1144 = 0,	/* TCP/IP header compression, see also 6.5.2 */
+	RFC_2507 = 1,	/* TCP/UDP/IP header compression, see also: 6.5.3 */
+	ROHC = 2,	/* Robust Header Compression, see also 6.5.4 */
+};
+
+/* According to: TS 144 065 6.5.1.1.4 Algorithm identifier */
+enum gprs_sndcp_data_comp_algo {
+	V42BIS = 0,		/* V42bis data compression, see also 6.6.2 */
+	V44 = 1,		/* V44 data compression, see also: 6.6.3 */
+};
+
+/* According to: TS 144 065 8 SNDCP XID parameters */
+enum gprs_sndcp_xid_param_types {
+	SNDCP_XID_VERSION_NUMBER = 0,
+	SNDCP_XID_DATA_COMPRESSION = 1,		/* See also: subclause 6.6.1 */
+	SNDCP_XID_PROTOCOL_COMPRESSION = 2,	/* See also: subclause 6.5.1 */
+};
+
+/* When the propose bit in an SNDCP-XID compression field is set to zero,
+   the algorithm identifier is stripped. The algoritm parameters are specific
+   for each algorithms. The following struct is used to pass the information
+   about the referenced algorithm to the parser. */
+struct gprs_sndcp_hdrcomp_entity_algo_table {
+	unsigned int entity;	/* see also: 6.5.1.1.3 and 6.6.1.1.3 */
+	unsigned int algo;	/* see also: 6.5.1.1.4 and 6.6.1.1.4 */
+	unsigned int compclass;	/* Can be either SNDCP_XID_DATA_COMPRESSION or
+				   SNDCP_XID_PROTOCOL_COMPRESSION */
+};
+
+
+
+/* According to: TS 144 065 6.5.2.1 Parameters (Table 5) */
+struct gprs_sndcp_hdrcomp_rfc1144_params {
+	unsigned int nsapi_len;	/* Number of applicable NSAPIs (default 0) */
+	unsigned int nsapi[11];	/* Applicable NSAPIs (default 0) */
+	int s01;	/* (default 15) */
+};
+
+/* According to: TS 144 065 6.5.2.2 Assignment of PCOMP values */
+enum gprs_sndcp_hdrcomp_rfc1144_pcomp {
+	RFC1144_PCOMP1 = 0,	/* Uncompressed TCP */
+	RFC1144_PCOMP2 = 1,	/* Compressed TCP */
+	RFC1144_PCOMP_NUM = 2	/* Number of pcomp values */
+};
+
+
+
+/* According to: TS 144 065 6.5.3.1 Parameters (Table 6) */
+struct gprs_sndcp_hdrcomp_rfc2507_params {
+	unsigned int nsapi_len;	/* Number of applicable NSAPIs (default 0) */
+	unsigned int nsapi[11];	/* Applicable NSAPIs (default 0) */
+	int f_max_period;	/* (default 256) */
+	int f_max_time;	/* (default 5) */
+	int max_header;	/* (default 168) */
+	int tcp_space;	/* (default 15) */
+	int non_tcp_space;	/* (default 15) */
+};
+
+/* According to: TS 144 065 6.5.3.2 Assignment of PCOMP values for RFC2507 */
+enum gprs_sndcp_hdrcomp_rfc2507_pcomp {
+	RFC2507_PCOMP1 = 0,	/* Full Header */
+	RFC2507_PCOMP2 = 1,	/* Compressed TCP */
+	RFC2507_PCOMP3 = 2,	/* Compressed TCP non delta */
+	RFC2507_PCOMP4 = 3,	/* Compressed non TCP */
+	RFC2507_PCOMP5 = 4,	/* Context state */
+	RFC2507_PCOMP_NUM = 5	/* Number of pcomp values */
+};
+
+
+
+/* According to: TS 144 065 6.5.4.1 Parameter (Table 10) */
+struct gprs_sndcp_hdrcomp_rohc_params {
+	unsigned int nsapi_len;	/* Number of applicable NSAPIs (default 0) */
+	unsigned int nsapi[11];	/* Applicable NSAPIs (default 0) */
+	int max_cid;	/* (default 15) */
+	int max_header;	/* (default 168) */
+	unsigned int profile_len;	/* (default 1) */
+	uint16_t profile[16];		/* (default 0, ROHC uncompressed) */
+};
+
+/* According to: TS 144 065 6.5.4.2 Assignment of PCOMP values for ROHC */
+enum gprs_sndcp_hdrcomp_rohc_pcomp {
+	ROHC_PCOMP1 = 0,	/* ROHC small CIDs */
+	ROHC_PCOMP2 = 1,	/* ROHC large CIDs */
+	ROHC_PCOMP_NUM = 2	/* Number of pcomp values */
+};
+
+/* ROHC compression profiles, see also: 
+   http://www.iana.org/assignments/rohc-pro-ids/rohc-pro-ids.xhtml */
+enum gprs_sndcp_xid_rohc_profiles {
+	ROHC_UNCOMPRESSED = 0x0000,	/* ROHC uncompressed    [RFC5795] */
+	ROHC_RTP = 0x0001,		/* ROHC RTP             [RFC3095] */
+	ROHCV2_RTP = 0x0101,		/* ROHCv2 RTP           [RFC5225] */
+	ROHC_UDP = 0x0002,		/* ROHC UDP             [RFC3095] */
+	ROHCv2_UDP = 0x0102,		/* ROHCv2 UDP           [RFC5225] */
+	ROHC_ESP = 0x0003,		/* ROHC ESP             [RFC3095] */
+	ROHCV2_ESP = 0x0103,		/* ROHCv2 ESP           [RFC5225] */
+	ROHC_IP = 0x0004,		/* ROHC IP              [RFC3843] */
+	ROHCV2_IP = 0x0104,		/* ROHCv2 IP            [RFC5225] */
+	ROHC_LLA = 0x0005,		/* ROHC LLA             [RFC4362] */
+	ROHC_LLA_WITH_R_MODE = 0x0105,	/* ROHC LLA with R-mode [RFC3408] */
+	ROHC_TCP = 0x0006,		/* ROHC TCP             [RFC6846] */
+	ROHC_RTP_UDP_LITE = 0x0007,	/* ROHC RTP/UDP-Lite    [RFC4019] */
+	ROHCV2_RTP_UDP_LITE = 0x0107,	/* ROHCv2 RTP/UDP-Lite  [RFC5225] */
+	ROHC_UDP_LITE = 0x0008,		/* ROHC UDP-Lite        [RFC4019] */
+	ROHCV2_UDP_LITE = 0x0108,	/* ROHCv2 UDP-Lite      [RFC5225] */
+};
+
+
+
+/* According to: TS 144 065 6.6.2.1 Parameters (Table 7a) */
+struct gprs_sndcp_datacomp_v42bis_params {
+	unsigned int nsapi_len;	/* Number of applicable NSAPIs (default 0) */
+	unsigned int nsapi[11];	/* Applicable NSAPIs (default 0) */
+	int p0;	/* (default 3) */
+	int p1;	/* (default 2048) */
+	int p2;	/* (default 20) */
+
+};
+
+/* According to: ETSI TS 144 065 6.6.2.2 Assignment of DCOMP values */
+enum gprs_sndcp_datacomp_v42bis_dcomp {
+	V42BIS_DCOMP1 = 0,	/* V42bis enabled */
+	V42BIS_DCOMP_NUM = 1	/* Number of dcomp values */
+};
+
+
+
+/* According to: TS 144 065 6.6.3.1 Parameters (Table 7c) */
+struct gprs_sndcp_datacomp_v44_params {
+	unsigned int nsapi_len;	/* Number of applicable NSAPIs (default 0) */
+	unsigned int nsapi[11];	/* Applicable NSAPIs (default 0) */
+	int c0;	/* (default 10000000) */
+	int p0;	/* (default 3) */
+	int p1t;	/* Refer to subclause 6.6.3.1.4 */
+	int p1r;	/* Refer to subclause 6.6.3.1.5 */
+	int p3t;	/* (default 3 x p1t) */
+	int p3r;	/* (default 3 x p1r) */
+};
+
+/* According to: ETSI TS 144 065 6.6.3.2 Assignment of DCOMP values */
+enum gprs_sndcp_datacomp_v44_dcomp {
+	V44_DCOMP1 = 0,		/* Packet method compressed */
+	V44_DCOMP2 = 1,		/* Multi packet method compressed */
+	V44_DCOMP_NUM = 2	/* Number of dcomp values */
+};
+
+/* Transform a list with compression fields into an SNDCP-XID message (dst) */
+int gprs_sndcp_compile_xid(const struct llist_head *comp_fields, uint8_t *dst,
+			   unsigned int dst_maxlen);
+
+/* Transform an SNDCP-XID message (src) into a list of SNDCP-XID fields */
+int gprs_sndcp_parse_xid(struct llist_head *comp_fields, const uint8_t *src,
+			 unsigned int dst_len,
+			 struct gprs_sndcp_hdrcomp_entity_algo_table *lt,
+			 unsigned int lt_len);
+
+/* Free a list with SNDCP-XID fields */
+void gprs_sndcp_free_comp_fields(struct llist_head *comp_fields);
+
+/* Find out to which compression class the specified comp-field belongs
+   (header compression or data compression?) */
+int gprs_sndcp_get_compression_class(const struct gprs_sndcp_comp_field
+				     *comp_field);
+
+/* Fill up lookutable from a list with comression entitiy fields */
+int gprs_sndcp_fill_table(struct gprs_sndcp_hdrcomp_entity_algo_table *lt,
+			  unsigned int lt_len, 
+			  const struct llist_head *comp_fields);
+
+/* Dump a list with SNDCP-XID fields (Debug) */
+void gprs_sndcp_dump_comp_fields(const struct llist_head *comp_fields, 
+				 unsigned int logl);
+
+
+#endif
diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index b3a5137..67e9943 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -21,7 +21,7 @@
 			$(OSMO_LIBS) $(LIBCRYPTO_LIBS) -lrt
 
 osmo_sgsn_SOURCES =	gprs_gmm.c gprs_sgsn.c gprs_sndcp.c gprs_sndcp_vty.c \
-			slhc.c \
+			slhc.c gprs_sndcp_xid.c  \
 			sgsn_main.c sgsn_vty.c sgsn_libgtp.c \
 			gprs_llc.c gprs_llc_parse.c gprs_llc_vty.c \
 			gprs_llc_xid.c crc24.c \
@@ -32,7 +32,7 @@
 osmo_sgsn_LDADD = 	\
 			$(top_builddir)/src/libcommon/libcommon.a \
 			-lgtp $(OSMO_LIBS) $(LIBOSMOABIS_LIBS) $(LIBCARES_LIBS) \
-			$(LIBCRYPTO_LIBS) -lrt
+			$(LIBCRYPTO_LIBS) -lrt -lm
 
 osmo_gtphub_SOURCES =	gtphub_main.c gtphub.c gtphub_sock.c gtphub_ares.c \
 			gtphub_vty.c sgsn_ares.c gprs_utils.c
diff --git a/openbsc/src/gprs/gprs_sndcp_xid.c b/openbsc/src/gprs/gprs_sndcp_xid.c
new file mode 100644
index 0000000..070058c
--- /dev/null
+++ b/openbsc/src/gprs/gprs_sndcp_xid.c
@@ -0,0 +1,1748 @@
+/* GPRS SNDCP XID field encoding/decoding as per 3GPP TS 144 065 */
+
+/* (C) 2016 by Sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+#include <math.h>
+#include <errno.h>
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/gsm/tlv.h>
+
+#include <openbsc/debug.h>
+#include <openbsc/gprs_llc.h>
+#include <openbsc/sgsn.h>
+#include <openbsc/gprs_sndcp_xid.h>
+
+
+/* 
+ * FUNCTIONS RELATED TO SNDCP-XID ENCODING
+ */
+
+/* Encode applicable sapis (works the same in all three compression schemes) */
+static int encode_hdrcomp_applicable_sapis(uint8_t * dst,
+					   const unsigned int *nsapis,
+					   unsigned int nsapis_len)
+{
+	/* 
+	 * NOTE: Buffer *dst needs offer at 2 bytes
+	 * of space to store the generation results
+	 */
+
+	uint16_t blob;
+	unsigned int nsapi;
+	int i;
+
+	/* Encode applicable SAPIs */
+	blob = 0;
+	for (i = 0; i < nsapis_len; i++) {
+		nsapi = nsapis[i];
+		/* 
+		 * Only NSAPI 5 to 15 are applicable for user traffic (PDP-
+		 * contexts). Only for these NSAPIs SNDCP-XID parameters
+		 * can apply. See also ETSI TS 144 065 5.1 Service primitives
+		 */
+		if ((nsapi < 5) || (nsapi > 15))
+			return -EINVAL;
+		blob |= (1 << nsapi);
+	}
+
+	/* Store result */
+	*dst = (blob >> 8) & 0xFF;
+	dst++;
+	*dst = blob & 0xFF;
+
+	return 2;
+}
+
+
+/* 
+ * Encode rfc1144 parameter field 
+ * (see also: ETSI TS 144 065 6.5.2.1, Table 5) 
+ */
+static int encode_hdrcomp_rfc1144_params(uint8_t * dst,
+					 unsigned int dst_maxlen, const struct
+					 gprs_sndcp_hdrcomp_rfc1144_params
+					 *params)
+{
+	/* 
+	 * NOTE: Buffer *dst should offer at least 3 bytes
+	 * of space to store the generation results
+	 */
+
+	int dst_counter = 0;
+	int rc;
+
+	/* Exit immediately if no source struct is available */
+	if (!params)
+		return -EINVAL;
+
+	/* Exit immediately if no sufficient memory space is supplied */
+	if ((dst_maxlen < 3) || !dst)
+		return -EINVAL;
+
+	/*
+	 * Exit if number of possible nsapis exceeds valid range
+	 * (Only 11 nsapis possible for PDP-Contexts) 
+	 */
+	if ((params->nsapi_len < 0) || (params->nsapi_len > 11))
+		return -EINVAL;
+
+	/* Zero out buffer */
+	memset(dst, 0, dst_maxlen);
+
+	/* Encode applicable SAPIs */
+	rc = encode_hdrcomp_applicable_sapis(dst, params->nsapi,
+					     params->nsapi_len);
+	dst += rc;
+	dst_counter += rc;
+
+	/* Encode s01 (see also: ETSI TS 144 065 6.5.2.1, Table 5) */
+	*dst = params->s01;
+	dst++;
+	dst_counter++;
+
+	/* Return generated length */
+	return dst_counter;
+}
+
+
+/* 
+ * Encode rfc2507 parameter field 
+ * (see also: ETSI TS 144 065 6.5.3.1, Table 6)
+ */
+static int encode_hdrcomp_rfc2507_params(uint8_t * dst,
+					 unsigned int dst_maxlen, const struct
+					 gprs_sndcp_hdrcomp_rfc2507_params
+					 *params)
+{
+	/* 
+	 * NOTE: Buffer *dst should offer at least 3 bytes
+	 * of space to store the generation results
+	 */
+
+	int dst_counter = 0;
+	int rc;
+
+	/* Exit immediately if no source struct is available */
+	if (!params)
+		return -EINVAL;
+
+	/* Exit immediately if no sufficient memory space is supplied */
+	if ((dst_maxlen < 9) || !dst)
+		return -EINVAL;
+
+	/*
+	 * Exit if number of possible nsapis exceeds valid range
+	 * (Only 11 nsapis possible for PDP-Contexts) 
+	 */
+	if ((params->nsapi_len < 0) || (params->nsapi_len > 11))
+		return -EINVAL;
+
+	/* Zero out buffer */
+	memset(dst, 0, dst_maxlen);
+
+	/* Encode applicable SAPIs */
+	rc = encode_hdrcomp_applicable_sapis(dst, params->nsapi,
+					     params->nsapi_len);
+	dst += rc;
+	dst_counter += rc;
+
+	/* Encode F_MAX_PERIOD (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	if ((params->f_max_period < 1) || (params->f_max_period > 65535))
+		return -EINVAL;
+	*dst = (params->f_max_period >> 8) & 0xFF;
+	dst++;
+	dst_counter++;
+	*dst = (params->f_max_period) & 0xFF;
+	dst++;
+	dst_counter++;
+
+	/* Encode F_MAX_TIME (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	if ((params->f_max_time < 1) || (params->f_max_time > 255))
+		return -EINVAL;
+	*dst = params->f_max_time;
+	dst++;
+	dst_counter++;
+
+	/* Encode MAX_HEADER (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	if ((params->max_header < 60) || (params->max_header > 255))
+		return -EINVAL;
+	*dst = params->max_header;
+	dst++;
+	dst_counter++;
+
+	/* Encode TCP_SPACE (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	if ((params->tcp_space < 3) || (params->tcp_space > 255))
+		return -EINVAL;
+	*dst = params->tcp_space;
+	dst++;
+	dst_counter++;
+
+	/* Encode NON_TCP_SPACE (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	if ((params->non_tcp_space < 3) || (params->tcp_space > 65535))
+		return -EINVAL;
+	*dst = (params->non_tcp_space >> 8) & 0xFF;
+	dst++;
+	dst_counter++;
+	*dst = (params->non_tcp_space) & 0xFF;
+	dst++;
+	dst_counter++;
+
+	/* Return generated length */
+	return dst_counter;
+}
+
+
+/* 
+ * Encode ROHC parameter field 
+ * (see also: ETSI TS 144 065 6.5.4.1, Table 10)
+ */
+static int encode_hdrcomp_rohc_params(uint8_t * dst,
+				      unsigned int dst_maxlen,
+				      const struct gprs_sndcp_hdrcomp_rohc_params
+				      *params)
+{
+	/* 
+	 * NOTE: Buffer *dst should offer at least 36 
+	 * (2 * 16 Profiles + 2 * 3 Parameter) bytes
+	 * of memory space to store generation results
+	 */
+
+	int i;
+	int dst_counter = 0;
+	int rc;
+
+	/* Exit immediately if no source struct is available */
+	if (!params)
+		return -EINVAL;
+
+	/* Exit immediately if no sufficient memory space is supplied */
+	if ((dst_maxlen < 38) || !dst)
+		return -EINVAL;
+
+	/*
+	 * Exit if number of possible nsapis exceeds valid range
+	 * (Only 11 nsapis possible for PDP-Contexts) 
+	 */
+	if ((params->nsapi_len < 0) || (params->nsapi_len > 11))
+		return -EINVAL;
+
+	/* 
+	 * Exit if number of ROHC profiles exceeds limit 
+	 * (ROHC supports only a maximum of 16 different profiles)
+	 */
+	if ((params->profile_len < 0) || (params->profile_len > 16))
+		return -EINVAL;
+
+	/* Zero out buffer */
+	memset(dst, 0, dst_maxlen);
+
+	/* Encode applicable SAPIs */
+	rc = encode_hdrcomp_applicable_sapis(dst, params->nsapi,
+					     params->nsapi_len);
+	dst += rc;
+	dst_counter += rc;
+
+	/* Encode MAX_CID (see also: ETSI TS 144 065 6.5.4.1, Table 10) */
+	if ((params->max_cid < 0) || (params->max_cid > 16383))
+		return -EINVAL;
+	*dst = (params->max_cid >> 8) & 0xFF;
+	dst++;
+	*dst = params->max_cid & 0xFF;
+	dst++;
+	dst_counter += 2;
+
+	/* Encode MAX_HEADER (see also: ETSI TS 144 065 6.5.4.1, Table 10) */
+	if ((params->max_header < 60) || (params->max_header > 255))
+		return -EINVAL;
+	*dst = (params->max_header >> 8) & 0xFF;
+	dst++;
+	*dst = params->max_header & 0xFF;
+	dst++;
+	dst_counter += 2;
+
+	/* Encode ROHC Profiles (see also: ETSI TS 144 065 6.5.4.1, Table 10) */
+	for (i = 0; i < params->profile_len; i++) {
+		*dst = (params->profile[i] >> 8) & 0xFF;
+		dst++;
+		*dst = params->profile[i] & 0xFF;
+		dst++;
+		dst_counter += 2;
+	}
+
+	/* Return generated length */
+	return dst_counter;
+}
+
+
+/* 
+ * Encode V42bis parameter field 
+ * (see also: ETSI TS 144 065 6.6.2.1, Table 7a)
+ */
+static int encode_datacomp_v42bis_params(uint8_t * dst,
+					 unsigned int dst_maxlen, const struct
+					 gprs_sndcp_datacomp_v42bis_params
+					 *params)
+{
+	/* 
+	 * NOTE: Buffer *dst should offer at least 6 bytes
+	 * of space to store the generation results
+	 */
+
+	int dst_counter = 0;
+	int rc;
+
+	/* Exit immediately if no source struct is available */
+	if (!params)
+		return -EINVAL;
+
+	/* Exit immediately if no sufficient memory space is supplied */
+	if ((dst_maxlen < 6) || !dst)
+		return -EINVAL;
+
+	/*
+	 * Exit if number of possible nsapis exceeds valid range
+	 * (Only 11 nsapis possible for PDP-Contexts) 
+	 */
+	if ((params->nsapi_len < 0) || (params->nsapi_len > 11))
+		return -EINVAL;
+
+	/* Zero out buffer */
+	memset(dst, 0, dst_maxlen);
+
+	/* Encode applicable SAPIs */
+	rc = encode_hdrcomp_applicable_sapis(dst, params->nsapi,
+					     params->nsapi_len);
+	dst += rc;
+	dst_counter += rc;
+
+	/* Encode P0 (see also: ETSI TS 144 065 6.6.2.1, Table 7a) */
+	if ((params->p0 < 0) || (params->p0 > 3))
+		return -EINVAL;
+	*dst = params->p0 & 0x03;
+	dst++;
+	dst_counter++;
+
+	/* Encode P1 (see also: ETSI TS 144 065 6.6.2.1, Table 7a) */
+	if ((params->p1 < 512) || (params->p1 > 65535))
+		return -EINVAL;
+	*dst = (params->p1 >> 8) & 0xFF;
+	dst++;
+	*dst = params->p1 & 0xFF;
+	dst++;
+	dst_counter += 2;
+
+	/* Encode P2 (see also: ETSI TS 144 065 6.6.2.1, Table 7a) */
+	if ((params->p2 < 6) || (params->p2 > 250))
+		return -EINVAL;
+	*dst = params->p2;
+	dst++;
+	dst_counter++;
+
+	/* Return generated length */
+	return dst_counter;
+}
+
+
+/* 
+ * Encode V44 parameter field 
+ * (see also: ETSI TS 144 065 6.6.3.1, Table 7c)
+ */
+static int encode_datacomp_v44_params(uint8_t * dst,
+				      unsigned int dst_maxlen,
+				      const struct gprs_sndcp_datacomp_v44_params
+				      *params)
+{
+	/* 
+	 * NOTE: Buffer *dst should offer at least 12 bytes
+	 * of space to store the generation results
+	 */
+
+	int dst_counter = 0;
+	int rc;
+
+	/* Exit immediately if no source struct is available */
+	if (!params)
+		return -EINVAL;
+
+	/* Exit immediately if no sufficient memory space is supplied */
+	if ((dst_maxlen < 12) || !dst)
+		return -EINVAL;
+
+	/*
+	 * Exit if number of possible nsapis exceeds valid range
+	 * (Only 11 nsapis possible for PDP-Contexts) 
+	 */
+	if ((params->nsapi_len < 0) || (params->nsapi_len > 11))
+		return -EINVAL;
+
+	/* Zero out buffer */
+	memset(dst, 0, dst_maxlen);
+
+	/* Encode applicable SAPIs */
+	rc = encode_hdrcomp_applicable_sapis(dst, params->nsapi,
+					     params->nsapi_len);
+	dst += rc;
+	dst_counter += rc;
+
+	/* Encode C0 (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	if ((params->c0 == 0x80) || (params->c0 == 0xC0)) {
+		*dst = params->c0 & 0xC0;
+		dst++;
+		dst_counter++;
+	} else
+		return -EINVAL;
+
+	/* Encode P0 (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	if ((params->p0 < 0) || (params->p0 > 3))
+		return -EINVAL;
+	*dst = params->p0 & 0x03;
+	dst++;
+	dst_counter++;
+
+	/* Encode P1T (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	if ((params->p1t < 256) || (params->p1t > 65535))
+		return -EINVAL;
+	*dst = (params->p1t >> 8) & 0xFF;
+	dst++;
+	*dst = params->p1t & 0xFF;
+	dst++;
+	dst_counter += 2;
+
+	/* Encode P1R (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	if ((params->p1r < 256) || (params->p1r > 65535))
+		return -EINVAL;
+	*dst = (params->p1r >> 8) & 0xFF;
+	dst++;
+	*dst = params->p1r & 0xFF;
+	dst++;
+	dst_counter += 2;
+
+	/* Encode P3T (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	if ((params->p3t < 0) || (params->p3t > 65535))
+		return -EINVAL;
+	if (params->p3t < 2 * params->p1t)
+		return -EINVAL;
+	*dst = (params->p3t >> 8) & 0xFF;
+	dst++;
+	*dst = params->p3t & 0xFF;
+	dst++;
+	dst_counter += 2;
+
+	/* Encode P3R (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	if ((params->p3r < 0) || (params->p3r > 65535))
+		return -EINVAL;
+	if (params->p3r < 2 * params->p1r)
+		return -EINVAL;
+	*dst = (params->p3r >> 8) & 0xFF;
+	dst++;
+	*dst = params->p3r & 0xFF;
+	dst++;
+	dst_counter += 2;
+
+	/* Return generated length */
+	return dst_counter;
+}
+
+
+/* 
+ * Encode data or protocol control information compression field 
+ * (see also: ETSI TS 144 065 6.6.1.1, Figure 9 and 
+ *            ETSI TS 144 065 6.5.1.1, Figure 7)
+ */
+static int encode_comp_field(uint8_t * dst, unsigned int dst_maxlen,
+			     const struct gprs_sndcp_comp_field *comp_field)
+{
+	int dst_counter = 0;
+	int len;
+	int expected_length;
+	int i;
+
+	uint8_t payload_bytes[256];
+	int payload_bytes_len = -1;
+
+	/* If possible, try do encode payload bytes first */
+	if (comp_field->rfc1144_params)
+		payload_bytes_len =
+		    encode_hdrcomp_rfc1144_params(payload_bytes,
+						  sizeof(payload_bytes),
+						  comp_field->
+						  rfc1144_params);
+	else if (comp_field->rfc2507_params)
+		payload_bytes_len =
+		    encode_hdrcomp_rfc2507_params(payload_bytes,
+						  sizeof(payload_bytes),
+						  comp_field->
+						  rfc2507_params);
+	else if (comp_field->rohc_params)
+		payload_bytes_len =
+		    encode_hdrcomp_rohc_params(payload_bytes,
+					       sizeof(payload_bytes),
+					       comp_field->rohc_params);
+	else if (comp_field->v42bis_params)
+		payload_bytes_len =
+		    encode_datacomp_v42bis_params(payload_bytes,
+						  sizeof(payload_bytes),
+						  comp_field->
+						  v42bis_params);
+	else if (comp_field->v44_params)
+		payload_bytes_len =
+		    encode_datacomp_v44_params(payload_bytes,
+					       sizeof(payload_bytes),
+					       comp_field->v44_params);
+	else
+		return -EINVAL;
+
+	/* Exit immediately if payload byte generation failed */
+	if (payload_bytes_len < 0)
+		return -EINVAL;
+
+	/* Exit immediately if no source struct is available */
+	if (!comp_field)
+		return -EINVAL;
+
+	/* Check if comp_len is within bounds */
+	if ((comp_field->comp_len < 0) || (comp_field->comp_len > 16))
+		return -EINVAL;
+
+	/* Calculate length field of the data block */
+	if (comp_field->p) {
+		len =
+		    payload_bytes_len +
+		    ceil((double) (comp_field->comp_len) / 2.0);
+		expected_length = len + 3;
+	} else {
+		len = payload_bytes_len;
+		expected_length = len + 2;
+	}
+
+	/* Exit immediately if no sufficient memory space is supplied */
+	if ((dst_maxlen < expected_length) || !dst)
+		return -EINVAL;
+
+	/* Check if the entity number is within bounds */
+	if ((comp_field->entity < 0) || (comp_field->entity > 0x1f))
+		return -EINVAL;
+
+	/* Check if the algorithm number is within bounds */
+	if ((comp_field->algo < 0) || (comp_field->algo > 0x1f))
+		return -EINVAL;
+
+	/* Zero out buffer */
+	memset(dst, 0, dst_maxlen);
+
+	/* Encode Propose bit */
+	if (comp_field->p)
+		*dst |= (1 << 7);
+
+	/* Encode entity number */
+	*dst |= comp_field->entity & 0x1F;
+	dst++;
+	dst_counter++;
+
+	/* Encode algorithm number */
+	if (comp_field->p) {
+		*dst |= comp_field->algo & 0x1F;
+		dst++;
+		dst_counter++;
+	}
+
+	/* Encode length field */
+	*dst |= len & 0xFF;
+	dst++;
+	dst_counter++;
+
+	/* Encode PCOMP/DCOMP values */
+	if (comp_field->p) {
+		for (i = 0; i < comp_field->comp_len; i++) {
+			/* Check if submitted PCOMP/DCOMP 
+			   values are within bounds */
+			if ((comp_field->comp[i] < 0)
+			    || (comp_field->comp[i] > 0x0F))
+				return -EINVAL;
+
+			if (i & 1) {
+				*dst |= comp_field->comp[i] & 0x0F;
+				dst++;
+				dst_counter++;
+			} else
+				*dst |= (comp_field->comp[i] << 4) & 0xF0;
+		}
+
+		if (i & 1) {
+			dst++;
+			dst_counter++;
+		}
+	}
+
+	/* Append payload bytes */
+	memcpy(dst, payload_bytes, payload_bytes_len);
+	dst_counter += payload_bytes_len;
+
+	/* Return generated length */
+	return dst_counter;
+}
+
+
+/* Find out to which compression class the specified comp-field belongs 
+   (header compression or data compression?) */
+int gprs_sndcp_get_compression_class(const struct gprs_sndcp_comp_field
+				     *comp_field)
+{
+	if (comp_field->rfc1144_params)
+		return SNDCP_XID_PROTOCOL_COMPRESSION;
+	else if (comp_field->rfc2507_params)
+		return SNDCP_XID_PROTOCOL_COMPRESSION;
+	else if (comp_field->rohc_params)
+		return SNDCP_XID_PROTOCOL_COMPRESSION;
+	else if (comp_field->v42bis_params)
+		return SNDCP_XID_DATA_COMPRESSION;
+	else if (comp_field->v44_params)
+		return SNDCP_XID_DATA_COMPRESSION;
+	else
+		return -EINVAL;
+}
+
+
+/* Convert all compression fields to bytstreams */
+static int gprs_sndcp_pack_fields(const struct llist_head *comp_fields,
+				  uint8_t * dst,
+				  unsigned int dst_maxlen, int class)
+{
+	struct gprs_sndcp_comp_field *comp_field;
+	int byte_counter = 0;
+	int rc;
+
+	llist_for_each_entry(comp_field, comp_fields, list) {
+		if (class == gprs_sndcp_get_compression_class(comp_field)) {
+			rc = encode_comp_field(dst + byte_counter,
+					       dst_maxlen - byte_counter,
+					       comp_field);
+
+			/* Immediately stop on error */
+			if (rc < 0)
+				return rc;
+
+			byte_counter += rc;
+		}
+	}
+
+	/* Return generated length */
+	return byte_counter;
+}
+
+
+/* Transform a list with compression fields into an SNDCP-XID message (dst) */
+int gprs_sndcp_compile_xid(const struct llist_head *comp_fields, uint8_t * dst,
+			   unsigned int dst_maxlen)
+{
+	int rc;
+	int byte_counter = 0;
+	uint8_t comp_bytes[512];
+	uint8_t xid_version_number[1] = { CURRENT_SNDCP_VERSION };
+
+	/* Exit immediately if no sufficient memory space is supplied */
+	if ((dst_maxlen < 2 + sizeof(xid_version_number)) || !dst)
+		return -EINVAL;
+
+	/* Prepend header */
+	dst =
+	    tlv_put(dst, SNDCP_XID_VERSION_NUMBER,
+		    sizeof(xid_version_number), xid_version_number);
+	byte_counter += (sizeof(xid_version_number) + 2);
+
+	/* Add data compression fields */
+	rc = gprs_sndcp_pack_fields(comp_fields, comp_bytes,
+				    sizeof(comp_bytes),
+				    SNDCP_XID_DATA_COMPRESSION);
+	if (rc < 0)
+		return rc;
+	else if (rc > 0) {
+		dst =
+		    tlv_put(dst, SNDCP_XID_DATA_COMPRESSION, rc,
+			    comp_bytes);
+		byte_counter += rc + 2;
+	}
+
+	/* Add header compression fields */
+	rc = gprs_sndcp_pack_fields(comp_fields, comp_bytes,
+				    sizeof(comp_bytes),
+				    SNDCP_XID_PROTOCOL_COMPRESSION);
+	if (rc < 0)
+		return rc;
+	else if (rc > 0) {
+		dst =
+		    tlv_put(dst, SNDCP_XID_PROTOCOL_COMPRESSION, rc,
+			    comp_bytes);
+		byte_counter += rc + 2;
+	}
+
+	/* Return generated length */
+	return byte_counter;
+}
+
+
+
+
+
+
+
+
+
+
+/* 
+ * FUNCTIONS RELATED TO SNDCP-XID DECODING
+ */
+
+/* Decode applicable sapis (works the same in all three compression schemes) */
+static int decode_hdrcomp_applicable_sapis(const uint8_t * src,
+					   unsigned int src_len,
+					   unsigned int *nsapis,
+					   unsigned int *nsapis_len)
+{
+	uint16_t blob;
+	int i;
+	int nsapi_len = 0;
+
+	/* Exit immediately if no result can be stored */
+	if (!nsapis)
+		return -EINVAL;
+
+	/* Exit immediately if not enough input data is available */
+	if (src_len < 2)
+		return -EINVAL;
+
+	/* Read bitmask */
+	blob = *src;
+	blob = (blob << 8) & 0xFF00;
+	src++;
+	blob |= (*src) & 0xFF;
+	blob = (blob >> 5);
+
+	/* Decode applicable SAPIs */
+	for (i = 0; i < 15; i++) {
+		if ((blob >> i) & 1) {
+			nsapis[nsapi_len] = i + 5;
+			nsapi_len++;
+		}
+	}
+
+	/* Return consumed length */
+	*nsapis_len = nsapi_len;
+	return 2;
+}
+
+/* Decode 16 bit field */
+static int decode_hdrcomp_16_bit_field(const uint8_t * src,
+				       unsigned int src_len,
+				       int value_min, int value_max,
+				       int *value_int,
+				       uint16_t * value_uint16)
+{
+	uint16_t blob;
+
+	/* Reset values to zero (just to be sure) */
+	if (value_int)
+		*value_int = -1;
+	if (value_uint16)
+		*value_uint16 = 0;
+
+	/* Exit if not enough src are available */
+	if (src_len < 2)
+		return -EINVAL;
+
+	/* Decode bit value */
+	blob = *src;
+	blob = (blob << 8) & 0xFF00;
+	src++;
+	blob |= *src;
+
+	/* Check if parsed value is within bounds */
+	if (blob < value_min)
+		return -EINVAL;
+	if (blob > value_max)
+		return -EINVAL;
+
+	/* Hand back results to the caller */
+	if (value_int)
+		*value_int = blob;
+	if (value_uint16)
+		*value_uint16 = blob;
+
+	/* Return consumed length */
+	return 2;
+}
+
+/* Decode 8 bit field */
+static int decode_hdrcomp_8_bit_field(const uint8_t * src,
+				      unsigned int src_len,
+				      int value_min, int value_max,
+				      int *value_int,
+				      uint8_t * value_uint8)
+{
+	uint8_t blob;
+
+	/* Reset values to invalid (just to be sure) */
+	if (value_int)
+		*value_int = -1;
+	if (value_uint8)
+		*value_uint8 = 0;
+
+	/* Exit if not enough src are available */
+	if (src_len < 1)
+		return -EINVAL;
+
+	/* Decode bit value */
+	blob = *src;
+
+	/* Check if parsed value is within bounds */
+	if (blob < value_min)
+		return -EINVAL;
+	if (blob > value_max)
+		return -EINVAL;
+
+	/* Hand back results to the caller */
+	if (value_int)
+		*value_int = blob;
+	if (value_uint8)
+		*value_uint8 = blob;
+
+	/* Return consumed length */
+	return 1;
+}
+
+
+
+
+/* Decode rfc1144 parameter field see also: ETSI TS 144 065 6.5.2.1, Table 5) */
+static int decode_hdrcomp_rfc1144_params(const uint8_t * src,
+					 unsigned int src_len, struct
+					 gprs_sndcp_hdrcomp_rfc1144_params
+					 *params)
+{
+	int rc;
+	int byte_counter = 0;
+
+	/* Exit immediately if no result can be stored */
+	if (!params)
+		return -EINVAL;
+
+	/* Mark all optional parameters invalid by default */
+	params->s01=-1;
+
+	/* Decode applicable SAPIs */
+	rc = decode_hdrcomp_applicable_sapis(src, src_len,
+					     params->nsapi,
+					     &params->nsapi_len);
+	if (rc > 0) {
+		byte_counter += rc;
+		src += rc;
+	} else
+		return byte_counter;
+
+	/* 
+	 * Decode parameter S0 -1 
+	 * (see also: ETSI TS 144 065 6.5.2.1, Table 5)
+	 */
+	rc = decode_hdrcomp_8_bit_field(src, src_len - byte_counter, 0,
+					255, &params->s01, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Return consumed length */
+	return byte_counter;
+}
+
+/* 
+ * Decode rfc2507 parameter field 
+ * (see also: ETSI TS 144 065 6.5.3.1, Table 6)
+ */
+static int decode_hdrcomp_rfc2507_params(const uint8_t * src,
+					 unsigned int src_len, struct
+					 gprs_sndcp_hdrcomp_rfc2507_params
+					 *params)
+{
+	int rc;
+	int byte_counter = 0;
+
+	/* Exit immediately if no result can be stored */
+	if (!params)
+		return -EINVAL;
+
+	/* Mark all optional parameters invalid by default */
+	params->f_max_period=-1;
+	params->f_max_time=-1;
+	params->max_header=-1;
+	params->tcp_space=-1;
+	params->non_tcp_space=-1;
+
+	/* Decode applicable SAPIs */
+	rc = decode_hdrcomp_applicable_sapis(src, src_len,
+					     params->nsapi,
+					     &params->nsapi_len);
+	if (rc > 0) {
+		byte_counter += rc;
+		src += rc;
+	} else
+		return byte_counter;
+
+	/* Decode F_MAX_PERIOD (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 1, 65535, &params->f_max_period,
+					 NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode F_MAX_TIME (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	rc = decode_hdrcomp_8_bit_field(src, src_len - byte_counter, 1,
+					255, &params->f_max_time, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode MAX_HEADER (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	rc = decode_hdrcomp_8_bit_field(src, src_len - byte_counter,
+					60, 255, &params->max_header,
+					NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode TCP_SPACE (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	rc = decode_hdrcomp_8_bit_field(src, src_len - byte_counter, 3,
+					255, &params->tcp_space, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode NON_TCP_SPACE (see also: ETSI TS 144 065 6.5.3.1, Table 6) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 3, 65535, &params->non_tcp_space,
+					 NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Return consumed length */
+	return byte_counter;
+}
+
+/* Decode ROHC parameter field (see also: ETSI TS 144 065 6.5.4.1, Table 10) */
+static int decode_hdrcomp_rohc_params(const uint8_t * src,
+				      unsigned int src_len,
+				      struct gprs_sndcp_hdrcomp_rohc_params
+				      *params)
+{
+	int rc;
+	int byte_counter = 0;
+	int i;
+
+	/* Exit immediately if no result can be stored */
+	if (!params)
+		return -EINVAL;
+
+	/* Mark all optional parameters invalid by default */
+	params->max_cid=-1;
+	params->max_header=-1;
+
+	/* Decode applicable SAPIs */
+	rc = decode_hdrcomp_applicable_sapis(src, src_len,
+					     params->nsapi,
+					     &params->nsapi_len);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode MAX_CID (see also: ETSI TS 144 065 6.5.4.1, Table 10) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 0, 16383, &params->max_cid, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode MAX_HEADER (see also: ETSI TS 144 065 6.5.4.1, Table 10) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 60, 255, &params->max_header,
+					 NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode Profiles (see also: ETSI TS 144 065 6.5.4.1, Table 10) */
+	for (i = 0; i < 16; i++) {
+		params->profile_len = 0;
+		rc = decode_hdrcomp_16_bit_field(src,
+						 src_len - byte_counter,
+						 0, 65535, NULL,
+						 &params->profile[i]);
+		if (rc <= 0)
+			return byte_counter;
+		byte_counter += rc;
+		src += rc;
+		params->profile_len = i + 1;
+	}
+
+	/* Return consumed length */
+	return byte_counter;
+}
+
+
+/* 
+ * Decode V42bis parameter field 
+ * (see also: ETSI TS 144 065 6.6.2.1, Table 7a) 
+ */
+static int decode_datacomp_v42bis_params(const uint8_t * src,
+					 unsigned int src_len, struct
+					 gprs_sndcp_datacomp_v42bis_params
+					 *params)
+{
+	int rc;
+	int byte_counter = 0;
+
+	/* Exit immediately if no result can be stored */
+	if (!params)
+		return -EINVAL;
+
+	/* Mark all optional parameters invalid by default */
+	params->p0=-1;
+	params->p1=-1;
+	params->p2=-1;
+
+	/* Decode applicable SAPIs */
+	rc = decode_hdrcomp_applicable_sapis(src, src_len,
+					     params->nsapi,
+					     &params->nsapi_len);
+	if (rc > 0) {
+		byte_counter += rc;
+		src += rc;
+	} else
+		return byte_counter;
+
+	/* Decode P0 (see also: ETSI TS 144 065 6.6.2.1, Table 7a) */
+	rc = decode_hdrcomp_8_bit_field(src, src_len - byte_counter, 0,
+					3, &params->p0, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode P1 (see also: ETSI TS 144 065 6.6.2.1, Table 7a) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 512, 65535, &params->p1, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode P2 (see also: ETSI TS 144 065 6.6.2.1, Table 7a) */
+	rc = decode_hdrcomp_8_bit_field(src, src_len - byte_counter, 6,
+					250, &params->p2, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Return consumed length */
+	return byte_counter;
+}
+
+
+/* Decode V44 parameter field (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+static int decode_datacomp_v44_params(const uint8_t * src,
+				      unsigned int src_len,
+				      struct gprs_sndcp_datacomp_v44_params
+				      *params)
+{
+	int rc;
+	int byte_counter = 0;
+
+	/* Exit immediately if no result can be stored */
+	if (!params)
+		return -EINVAL;
+
+	/* Mark all optional parameters invalid by default */
+	params->c0=-1;
+	params->p0=-1;
+	params->p1t=-1;
+	params->p1r=-1;
+	params->p3t=-1;
+	params->p3r=-1;
+
+	/* Decode applicable SAPIs */
+	rc = decode_hdrcomp_applicable_sapis(src, src_len,
+					     params->nsapi,
+					     &params->nsapi_len);
+	if (rc > 0) {
+		byte_counter += rc;
+		src += rc;
+	} else
+		return byte_counter;
+
+	/* Decode C0 (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	rc = decode_hdrcomp_8_bit_field(src, src_len - byte_counter, 0,
+					255, &params->c0, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	if ((params->c0 != 0x80) && (params->c0 != 0xC0))
+		return -EINVAL;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode P0 (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	rc = decode_hdrcomp_8_bit_field(src, src_len - byte_counter, 0,
+					3, &params->p0, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode P1T (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 265, 65535, &params->p1t, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode P1R (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 265, 65535, &params->p1r, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode P3T (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 265, 65535, &params->p3t, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	if (params->p3t < 2 * params->p1t)
+		return -EINVAL;
+	byte_counter += rc;
+	src += rc;
+
+	/* Decode P3R (see also: ETSI TS 144 065 6.6.3.1, Table 7c) */
+	rc = decode_hdrcomp_16_bit_field(src, src_len - byte_counter,
+					 265, 65535, &params->p3r, NULL);
+	if (rc <= 0)
+		return byte_counter;
+	if (params->p3r < 2 * params->p1r)
+		return -EINVAL;
+	byte_counter += rc;
+	src += rc;
+
+	/* Return consumed length */
+	return byte_counter;
+}
+
+
+/* Lookup algorithm identfier by entity ID */
+static int lookup_algorithm_identifier(int entity, struct
+				       gprs_sndcp_hdrcomp_entity_algo_table
+				       *lt, unsigned int lt_len,
+				       int compclass)
+{
+	int i;
+	if ((lt) && (lt_len > 0)) {
+		for (i = 0; i < lt_len; i++) {
+			if ((lt[i].entity == entity)
+			    && (lt[i].compclass == compclass))
+				return lt[i].algo;
+		}
+	}
+
+	return -1;
+}
+
+/* 
+ * Helper function for decode_comp_field(), decodes
+ * numeric pcomp/dcomp values
+ */
+static int decode_comp_values(struct gprs_sndcp_comp_field *comp_field,
+			      const uint8_t * src, int compclass)
+{
+	int src_counter = 0;
+	int i;
+
+	if (comp_field->p) {
+		/* Determine the number of expected PCOMP/DCOMP values */
+		if (compclass == SNDCP_XID_PROTOCOL_COMPRESSION) {
+			/* For protocol compression */
+			switch (comp_field->algo) {
+			case RFC_1144:
+				comp_field->comp_len = RFC1144_PCOMP_NUM;
+				break;
+			case RFC_2507:
+				comp_field->comp_len = RFC2507_PCOMP_NUM;
+				break;
+			case ROHC:
+				comp_field->comp_len = ROHC_PCOMP_NUM;
+				break;
+
+				/* Exit if the algorithem type encodes
+				   something unknown / unspecified */
+			default:
+				return -EINVAL;
+			}
+		} else {
+			/* For data compression */
+			switch (comp_field->algo) {
+			case V42BIS:
+				comp_field->comp_len = V42BIS_DCOMP_NUM;
+				break;
+			case V44:
+				comp_field->comp_len = V44_DCOMP_NUM;
+				break;
+
+				/* Exit if the algorithem type encodes
+				   something unknown / unspecified */
+			default:
+				return -EINVAL;
+			}
+		}
+
+		for (i = 0; i < comp_field->comp_len; i++) {
+			if (i & 1) {
+				comp_field->comp[i] = (*src) & 0x0F;
+				src++;
+				src_counter++;
+			} else
+				comp_field->comp[i] = ((*src) >> 4) & 0x0F;
+		}
+
+		if (i & 1) {
+			src++;
+			src_counter++;
+		}
+	}
+
+	return src_counter;
+}
+
+/* 
+ * Helper function for decode_comp_field(), decodes the parameters
+ * which are algorithm specific
+ */
+static int decode_comp_params(struct gprs_sndcp_comp_field *comp_field,
+			      const uint8_t * src, int src_len,
+			      int compclass)
+{
+	int rc;
+
+	if (compclass == SNDCP_XID_PROTOCOL_COMPRESSION) {
+		/* For protocol compression */
+		switch (comp_field->algo) {
+		case RFC_1144:
+			comp_field->rfc1144_params = talloc_zero(NULL, struct
+								 gprs_sndcp_hdrcomp_rfc1144_params);
+			rc = decode_hdrcomp_rfc1144_params(src, src_len,
+							   comp_field->
+							   rfc1144_params);
+			if (rc < 0)
+				talloc_free(comp_field->rfc1144_params);
+			break;
+		case RFC_2507:
+			comp_field->rfc2507_params = talloc_zero(NULL, struct
+								 gprs_sndcp_hdrcomp_rfc2507_params);
+			rc = decode_hdrcomp_rfc2507_params(src, src_len,
+							   comp_field->
+							   rfc2507_params);
+			if (rc < 0)
+				talloc_free(comp_field->rfc1144_params);
+			break;
+		case ROHC:
+			comp_field->rohc_params = talloc_zero(NULL, struct
+							      gprs_sndcp_hdrcomp_rohc_params);
+			rc = decode_hdrcomp_rohc_params(src, src_len,
+							comp_field->
+							rohc_params);
+			if (rc < 0)
+				talloc_free(comp_field->rohc_params);
+			break;
+
+			/* If no suitable decoder is detected, 
+			   leave the remaining bytes undecoded */
+		default:
+			rc = src_len;
+		}
+	} else {
+		/* For data compression */
+		switch (comp_field->algo) {
+		case V42BIS:
+			comp_field->v42bis_params = talloc_zero(NULL, struct
+								gprs_sndcp_datacomp_v42bis_params);
+			rc = decode_datacomp_v42bis_params(src, src_len,
+							   comp_field->
+							   v42bis_params);
+			if (rc < 0)
+				talloc_free(comp_field->v42bis_params);
+			break;
+		case V44:
+			comp_field->v44_params = talloc_zero(NULL, struct
+							     gprs_sndcp_datacomp_v44_params);
+			rc = decode_datacomp_v44_params(src, src_len,
+							comp_field->
+							v44_params);
+			if (rc < 0)
+				talloc_free(comp_field->v44_params);
+			break;
+
+			/* If no suitable decoder is detected, 
+			   leave the remaining bytes undecoded */
+		default:
+			rc = src_len;
+		}
+	}
+
+	if (rc < 0) {
+		comp_field->rfc1144_params = NULL;
+		comp_field->rfc2507_params = NULL;
+		comp_field->rohc_params = NULL;
+		comp_field->v42bis_params = NULL;
+		comp_field->v44_params = NULL;
+	}
+
+	return rc;
+}
+
+
+/* 
+ * Decode data or protocol control information compression field 
+ * (see also: ETSI TS 144 065 6.6.1.1, Figure 9 and 
+ *            ETSI TS 144 065 6.5.1.1, Figure 7)
+ */
+static int decode_comp_field(const uint8_t * src, unsigned int src_len,
+			     struct gprs_sndcp_comp_field *comp_field,
+			     struct
+			     gprs_sndcp_hdrcomp_entity_algo_table
+			     *lt, unsigned int lt_len, int compclass)
+{
+	int src_counter = 0;
+	unsigned int len;
+	int rc;
+
+	/* Exit immediately if it is clear that no
+	   parseable data is present */
+	if ((src_len < 1) || !src)
+		return -EINVAL;
+
+	/* Exit immediately if no result can be stored */
+	if (!comp_field)
+		return -EINVAL;
+
+	/* Zero out target struct */
+	memset(comp_field, 0, sizeof(struct gprs_sndcp_comp_field));
+
+	/* Decode Propose bit and Entity number */
+	if ((*src) & 0x80)
+		comp_field->p = 1;
+	comp_field->entity = (*src) & 0x1F;
+	src_counter++;
+	src++;
+
+	/* Decode algorithm number (if present) */
+	if (comp_field->p) {
+		comp_field->algo = (*src) & 0x1F;
+		src_counter++;
+		src++;
+	}
+	/* Alternatively take the information from the lookup table */
+	else
+		comp_field->algo =
+		    lookup_algorithm_identifier(comp_field->entity, lt,
+						lt_len, compclass);
+
+	/* Decode length field */
+	len = *src;
+	src_counter++;
+	src++;
+
+
+	/* Decode PCOMP/DCOMP values */
+	rc = decode_comp_values(comp_field, src, compclass);
+	if (rc < 0)
+		return -EINVAL;
+	src_counter += rc;
+	src += rc;
+	len -= rc;
+
+	/* Decode algorithm specific payload data */
+	rc = decode_comp_params(comp_field, src, len, compclass);
+	if (rc >= 0)
+		src_counter += rc;
+	else
+		return -EINVAL;
+
+
+	/* Return consumed length */
+	return src_counter;
+}
+
+
+/* Transform an SNDCP-XID message (src) into a list of SNDCP-XID fields */
+int gprs_sndcp_parse_xid(struct llist_head *comp_fields, const uint8_t * src,
+			 unsigned int src_len,
+			 struct gprs_sndcp_hdrcomp_entity_algo_table
+			 *lt, unsigned int lt_len)
+{
+	int src_pos = 0;
+	uint8_t tag;
+	uint16_t tag_len;
+	const uint8_t *val;
+	struct gprs_sndcp_comp_field *comp_field;
+	int rc;
+	int byte_counter = 0;
+	int comp_field_count = 0;
+
+	/* Valid TLV-Tag and types */
+	static const struct tlv_definition sndcp_xid_def = {
+		.def = {
+			[SNDCP_XID_VERSION_NUMBER] = {TLV_TYPE_TLV,},
+			[SNDCP_XID_DATA_COMPRESSION] = {TLV_TYPE_TLV,},
+			[SNDCP_XID_PROTOCOL_COMPRESSION] = {TLV_TYPE_TLV,},
+			},
+	};
+
+	/* Parse TLV-Encoded SNDCP-XID message and defer payload 
+	   to the apporpiate sub-parser functions */
+	while (1) {
+		src_pos +=
+		    tlv_parse_one(&tag, &tag_len, &val, &sndcp_xid_def,
+				  src + src_pos, src_len - src_pos);
+
+		/* Decode compression parameters */
+		if ((tag == SNDCP_XID_PROTOCOL_COMPRESSION)
+		    || (tag == SNDCP_XID_DATA_COMPRESSION)) {
+			byte_counter = 0;
+			do {
+				/* Bail if more than the maximum number of
+				   comp_fields is generated */
+				if (comp_field_count > MAX_ENTITIES * 2) {
+					gprs_sndcp_free_comp_fields
+					    (comp_fields);
+					return -EINVAL;
+				}
+
+				/* Parse and add comp_field */
+				comp_field =
+				    talloc_zero(NULL,
+						struct
+						gprs_sndcp_comp_field);
+
+				rc = decode_comp_field(val + byte_counter,
+						       tag_len -
+						       byte_counter,
+						       comp_field, lt,
+						       lt_len, tag);
+
+				if (rc < 0) {
+					talloc_free(comp_field);
+					gprs_sndcp_free_comp_fields
+					    (comp_fields);
+					return -EINVAL;
+				} else {
+					byte_counter += rc;
+					llist_add(&comp_field->list,
+						  comp_fields);
+				}
+
+				comp_field_count++;
+			}
+			while (tag_len - byte_counter > 0);
+		}
+
+		/* Stop when no further TLV elements can be expected */
+		if (src_len - src_pos <= 2)
+			break;
+	}
+
+	return 0;
+}
+
+
+/* Free a list with SNDCP-XID fields */
+void gprs_sndcp_free_comp_fields(struct llist_head *comp_fields)
+{
+	struct gprs_sndcp_comp_field *comp_field;
+	struct llist_head *lh, *lh2;
+
+	/* Exit immediately if no list is present */
+	if (!comp_fields)
+		return;
+
+	llist_for_each_entry(comp_field, comp_fields, list) {
+		if (comp_field->rfc1144_params)
+			talloc_free(comp_field->rfc1144_params);
+		if (comp_field->rfc2507_params)
+			talloc_free(comp_field->rfc2507_params);
+		if (comp_field->rohc_params)
+			talloc_free(comp_field->rohc_params);
+		if (comp_field->v42bis_params)
+			talloc_free(comp_field->v42bis_params);
+		if (comp_field->v44_params)
+			talloc_free(comp_field->v44_params);
+	}
+
+	llist_for_each_safe(lh, lh2, comp_fields) {
+		llist_del(lh);
+		talloc_free(lh);
+	}
+}
+
+
+/* Fill up lookutable from a list with comression entitiy fields */
+int gprs_sndcp_fill_table(struct gprs_sndcp_hdrcomp_entity_algo_table *lt,
+			  unsigned int lt_len,
+			  const struct llist_head *comp_fields)
+{
+	struct gprs_sndcp_comp_field *comp_field;
+	int i = 0;
+
+	if (!(comp_fields))
+		return -EINVAL;
+	if (!(lt))
+		return -EINVAL;
+
+	memset(lt, 0,
+	       lt_len *
+	       sizeof(struct gprs_sndcp_hdrcomp_entity_algo_table));
+
+	llist_for_each_entry(comp_field, comp_fields, list) {
+
+		lt[i].entity = comp_field->entity;
+		lt[i].algo = comp_field->algo;
+		lt[i].compclass =
+		    gprs_sndcp_get_compression_class(comp_field);
+
+		if (lt[i].compclass < 0) {
+			memset(lt, 0, lt_len *
+			       sizeof(struct
+				      gprs_sndcp_hdrcomp_entity_algo_table));
+			return -EINVAL;
+		}
+
+		i++;
+	}
+
+	return i;
+}
+
+
+/* 
+ * Helper for gprs_sndcp_dump_comp_fields(),
+ * dumps protocol compression parameters 
+ */
+static void dump_pcomp_params(const struct gprs_sndcp_comp_field *comp_field, unsigned int logl)
+{
+	int i;
+	switch (comp_field->algo) {
+	case RFC_1144:
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "   gprs_sndcp_hdrcomp_rfc1144_params {\n");
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      nsapi_len=%i;\n",
+		     comp_field->rfc1144_params->nsapi_len);
+		if (comp_field->rfc1144_params->nsapi_len == 0)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[] = NULL;\n");
+		for (i = 0; i < comp_field->rfc1144_params->nsapi_len; i++)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[%i]=%i;\n", i,
+			     comp_field->rfc1144_params->nsapi[i]);
+		LOGP(DSNDCP, logl, "      s01=%i;\n",
+		       comp_field->rfc1144_params->s01);
+		LOGP(DSNDCP, logl, "   }\n");
+		break;
+	case RFC_2507:
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "   gprs_sndcp_hdrcomp_rfc2507_params {\n");
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      nsapi_len=%i;\n",
+		     comp_field->rfc2507_params->nsapi_len);
+		if (comp_field->rfc2507_params->nsapi_len == 0)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[] = NULL;\n");
+		for (i = 0; i < comp_field->rfc2507_params->nsapi_len; i++)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[%i]=%i;\n", i,
+			     comp_field->rfc2507_params->nsapi[i]);
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      f_max_period=%i;\n",
+		     comp_field->rfc2507_params->f_max_period);
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      f_max_time=%i;\n",
+		     comp_field->rfc2507_params->f_max_time);
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      max_header=%i;\n",
+		     comp_field->rfc2507_params->max_header);
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      tcp_space=%i;\n",
+		     comp_field->rfc2507_params->tcp_space);
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      non_tcp_space=%i;\n",
+		     comp_field->rfc2507_params->non_tcp_space);
+		LOGP(DSNDCP, logl, "   }\n");
+		break;
+	case ROHC:
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "   gprs_sndcp_hdrcomp_rohc_params {\n");
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      nsapi_len=%i;\n",
+		     comp_field->rohc_params->nsapi_len);
+		if (comp_field->rohc_params->nsapi_len == 0)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[] = NULL;\n");
+		for (i = 0; i < comp_field->rohc_params->nsapi_len; i++)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[%i]=%i;\n", i,
+			     comp_field->rohc_params->nsapi[i]);
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      max_cid=%i;\n",
+		     comp_field->rohc_params->max_cid);
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      max_header=%i;\n",
+		     comp_field->rohc_params->max_header);
+		if (comp_field->rohc_params->profile_len == 0)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      profile[] = NULL;\n");
+		for (i = 0; i < comp_field->rohc_params->profile_len; i++)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      profile[%i]=%04x;\n",
+			     i, comp_field->rohc_params->profile[i]);
+		LOGP(DSNDCP, logl, "   }\n");
+		break;
+	}
+
+
+}
+
+
+/* 
+ * Helper for gprs_sndcp_dump_comp_fields(),
+ * data protocol compression parameters 
+ */
+static void dump_dcomp_params(const struct gprs_sndcp_comp_field *comp_field, unsigned int logl)
+{
+	int i;
+	switch (comp_field->algo) {
+	case V42BIS:
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "   gprs_sndcp_datacomp_v42bis_params {\n");
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      nsapi_len=%i;\n",
+		     comp_field->v42bis_params->nsapi_len);
+		if (comp_field->v42bis_params->nsapi_len == 0)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[] = NULL;\n");
+		for (i = 0; i < comp_field->v42bis_params->nsapi_len; i++)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[%i]=%i;\n", i,
+			     comp_field->v42bis_params->nsapi[i]);
+		LOGP(DSNDCP, logl, "      p0=%i;\n",
+		       comp_field->v42bis_params->p0);
+		LOGP(DSNDCP, logl, "      p1=%i;\n",
+		       comp_field->v42bis_params->p1);
+		LOGP(DSNDCP, logl, "      p2=%i;\n",
+		       comp_field->v42bis_params->p2);
+		LOGP(DSNDCP, logl, "   }\n");
+		break;
+	case V44:
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "   gprs_sndcp_datacomp_v44_params {\n");
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "      nsapi_len=%i;\n",
+		     comp_field->v44_params->nsapi_len);
+		if (comp_field->v44_params->nsapi_len == 0)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[] = NULL;\n");
+		for (i = 0; i < comp_field->v44_params->nsapi_len; i++)
+			LOGP(DSNDCP, LOGL_DEBUG,
+			     "      nsapi[%i]=%i;\n", i,
+			     comp_field->v44_params->nsapi[i]);
+		LOGP(DSNDCP, logl, "      c0=%i;\n",
+		       comp_field->v44_params->c0);
+		LOGP(DSNDCP, logl, "      p0=%i;\n",
+		       comp_field->v44_params->p0);
+		LOGP(DSNDCP, logl, "      p1t=%i;\n",
+		       comp_field->v44_params->p1t);
+		LOGP(DSNDCP, logl, "      p1r=%i;\n",
+		       comp_field->v44_params->p1r);
+		LOGP(DSNDCP, logl, "      p3t=%i;\n",
+		       comp_field->v44_params->p3t);
+		LOGP(DSNDCP, logl, "      p3r=%i;\n",
+		       comp_field->v44_params->p3r);
+		LOGP(DSNDCP, logl, "   }\n");
+		break;
+	}
+}
+
+
+/* Dump a list with SNDCP-XID fields (Debug) */
+void gprs_sndcp_dump_comp_fields(const struct llist_head *comp_fields, unsigned int logl)
+{
+	struct gprs_sndcp_comp_field *comp_field;
+	int i;
+	int compclass;
+
+	llist_for_each_entry(comp_field, comp_fields, list) {
+		LOGP(DSNDCP, logl, "SNDCP-XID:\n");
+		LOGP(DSNDCP, LOGL_DEBUG,
+		     "struct gprs_sndcp_comp_field {\n");
+		LOGP(DSNDCP, logl, "   entity=%i;\n", comp_field->entity);
+		LOGP(DSNDCP, logl, "   algo=%i;\n", comp_field->algo);
+		LOGP(DSNDCP, logl, "   comp_len=%i;\n", comp_field->comp_len);
+		if (comp_field->comp_len == 0)
+			LOGP(DSNDCP, logl, "   comp[] = NULL;\n");
+		for (i = 0; i < comp_field->comp_len; i++)
+			LOGP(DSNDCP, logl, "   comp[%i]=%i;\n", i,
+			       comp_field->comp[i]);
+
+		compclass = gprs_sndcp_get_compression_class(comp_field);
+
+		if (compclass == SNDCP_XID_PROTOCOL_COMPRESSION) {
+			dump_pcomp_params(comp_field,logl);
+		} else if (compclass == SNDCP_XID_DATA_COMPRESSION) {
+			dump_dcomp_params(comp_field,logl);
+		}
+
+		LOGP(DSNDCP, logl, "}\n");
+		LOGP(DSNDCP, logl, "\n");
+	}
+
+}

-- 
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: If2d63fe2550864cafef3156b1dc0629037c49c1e
Gerrit-PatchSet: 4
Gerrit-Project: openbsc
Gerrit-Branch: master
Gerrit-Owner: dexter <pmaier at sysmocom.de>
Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org>



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