move openbsc/* to repos root

This is the first step in creating this repository from the legacy openbsc.git.

Like all other Osmocom repositories, keep the autoconf and automake files in
the repository root. openbsc.git has been the sole exception, which ends now.

Change-Id: I9c6f2a448d9cb1cc088cf1cf6918b69d7e69b4e7

1 files changed, 281 insertions, 0 deletions

diff --git a/src/gprs/gprs_llc_xid.c b/src/gprs/gprs_llc_xid.c
new file mode 100644
index 000000000..fe631715a
--- /dev/null
+++ b/src/gprs/gprs_llc_xid.c
@@ -0,0 +1,281 @@
+/* GPRS LLC XID field encoding/decoding as per 3GPP TS 44.064 */
+
+/* (C) 2016 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * 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 <errno.h>
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/talloc.h>
+
+#include <openbsc/debug.h>
+#include <openbsc/gprs_llc.h>
+#include <openbsc/sgsn.h>
+#include <openbsc/gprs_llc_xid.h>
+
+const struct value_string gprs_llc_xid_type_names[] = {
+	{ GPRS_LLC_XID_T_VERSION,	"VERSION"},
+	{ GPRS_LLC_XID_T_IOV_UI,	"IOV_UI"},
+	{ GPRS_LLC_XID_T_IOV_I,		"IOV_I"},
+	{ GPRS_LLC_XID_T_T200,		"T200"},
+	{ GPRS_LLC_XID_T_N200,		"N200"},
+	{ GPRS_LLC_XID_T_N201_U,	"N201_"},
+	{ GPRS_LLC_XID_T_N201_I,	"N201_I"},
+	{ GPRS_LLC_XID_T_mD,		"mD"},
+	{ GPRS_LLC_XID_T_mU,		"mU"},
+	{ GPRS_LLC_XID_T_kD,		"kD"},
+	{ GPRS_LLC_XID_T_kU,		"kU"},
+	{ GPRS_LLC_XID_T_L3_PAR,	"L3_PAR"},
+	{ GPRS_LLC_XID_T_RESET,		"RESET"},
+	{ 0, NULL },
+};
+
+/* Parse XID parameter field */
+static int decode_xid_field(struct gprs_llc_xid_field *xid_field,
+			    const uint8_t *src, uint8_t src_len)
+{
+	uint8_t xl;
+	uint8_t type;
+	uint8_t len;
+	int src_counter = 0;
+
+	/* Exit immediately if it is clear that no
+	 * parseable data is present */
+	if (src_len < 1 || !src)
+		return -EINVAL;
+
+	/* Extract header info */
+	xl = (*src >> 7) & 1;
+	type = (*src >> 2) & 0x1F;
+
+	/* Extract length field */
+	len = (*src) & 0x3;
+	src++;
+	src_counter++;
+	if (xl) {
+		if (src_len < 2)
+			return -EINVAL;
+		len = (len << 6) & 0xC0;
+		len |= ((*src) >> 2) & 0x3F;
+		src++;
+		src_counter++;
+	}
+
+	/* Fill out struct */
+	xid_field->type = type;
+	xid_field->data_len = len;
+	if (len > 0) {
+		if (src_len < src_counter + len)
+			return -EINVAL;
+		xid_field->data =
+			talloc_memdup(xid_field,src,xid_field->data_len);
+	} else
+		xid_field->data = NULL;
+
+	/* Return consumed length */
+	return src_counter + len;
+}
+
+/* Encode XID parameter field */
+static int encode_xid_field(uint8_t *dst, int dst_maxlen,
+			    const struct gprs_llc_xid_field *xid_field)
+{
+	int xl = 0;
+
+	/* When the length does not fit into 2 bits,
+	 * we need extended length fields */
+	if (xid_field->data_len > 3)
+		xl = 1;
+
+	/* Exit immediately if it is clear that no
+	 * encoding result can be stored */
+	if (dst_maxlen < xid_field->data_len + 1 + xl)
+		return -EINVAL;
+
+	/* There are only 5 bits reserved for the type, exit on exceed */
+	if (xid_field->type > 31)
+		return -EINVAL;
+
+	/* Encode header */
+	memset(dst, 0, dst_maxlen);
+	if (xl)
+		dst[0] |= 0x80;
+	dst[0] |= (((xid_field->type) & 0x1F) << 2);
+
+	if (xl) {
+		dst[0] |= (((xid_field->data_len) >> 6) & 0x03);
+		dst[1] = ((xid_field->data_len) << 2) & 0xFC;
+	} else
+		dst[0] |= ((xid_field->data_len) & 0x03);
+
+	/* Append payload data */
+	if (xid_field->data && xid_field->data_len)
+		memcpy(dst + 1 + xl, xid_field->data, xid_field->data_len);
+
+	/* Return generated length */
+	return xid_field->data_len + 1 + xl;
+}
+
+/* Transform a list with XID fields into a XID message (dst) */
+int gprs_llc_compile_xid(uint8_t *dst, int dst_maxlen,
+			 const struct llist_head *xid_fields)
+{
+	struct gprs_llc_xid_field *xid_field;
+	int rc;
+	int byte_counter = 0;
+
+	OSMO_ASSERT(xid_fields);
+	OSMO_ASSERT(dst);
+
+	llist_for_each_entry_reverse(xid_field, xid_fields, list) {
+		/* Encode XID-Field */
+		rc = encode_xid_field(dst, dst_maxlen, xid_field);
+		if (rc < 0)
+			return -EINVAL;
+
+		/* Advance pointer and lower maxlen for the
+		 * next encoding round */
+		dst += rc;
+		byte_counter += rc;
+		dst_maxlen -= rc;
+	}
+
+	/* Return generated length */
+	return byte_counter;
+}
+
+/* Transform a XID message (dst) into a list of XID fields */
+struct llist_head *gprs_llc_parse_xid(const void *ctx, const uint8_t *src,
+				      int src_len)
+{
+	struct gprs_llc_xid_field *xid_field;
+	struct llist_head *xid_fields;
+
+	int rc;
+	int max_loops = src_len;
+
+	OSMO_ASSERT(src);
+
+	xid_fields = talloc_zero(ctx, struct llist_head);
+	INIT_LLIST_HEAD(xid_fields);
+
+	while (1) {
+		/* Bail in case decode_xid_field() constantly returns zero */
+		if (max_loops <= 0) {
+			talloc_free(xid_fields);
+			return NULL;
+		}
+
+		/* Decode XID field */
+		xid_field = talloc_zero(xid_fields, struct gprs_llc_xid_field);
+		rc = decode_xid_field(xid_field, src, src_len);
+
+		/* Immediately stop on error */
+		if (rc < 0) {
+			talloc_free(xid_fields);
+			return NULL;
+		}
+
+		/* Add parsed XID field to list */
+		llist_add(&xid_field->list, xid_fields);
+
+		/* Advance pointer and lower dst_len for the next
+		 * decoding round */
+		src += rc;
+		src_len -= rc;
+
+		/* We are (scuccessfully) done when no further byes are left */
+		if (src_len == 0)
+			return xid_fields;
+
+		max_loops--;
+	}
+}
+
+/* Create a duplicate of an XID-Field */
+struct gprs_llc_xid_field *gprs_llc_dup_xid_field(const void *ctx, const struct
+						  gprs_llc_xid_field
+						  *xid_field)
+{
+	struct gprs_llc_xid_field *dup;
+
+	OSMO_ASSERT(xid_field);
+
+	/* Create a copy of the XID field in memory */
+	dup = talloc_memdup(ctx, xid_field, sizeof(*xid_field));
+	dup->data = talloc_memdup(ctx, xid_field->data, xid_field->data_len);
+
+	/* Unlink duplicate from source list */
+	INIT_LLIST_HEAD(&dup->list);
+
+	return dup;
+}
+
+/* Copy an llist with xid fields */
+struct llist_head *gprs_llc_copy_xid(const void *ctx,
+				     const struct llist_head *xid_fields)
+{
+	struct gprs_llc_xid_field *xid_field;
+	struct llist_head *xid_fields_copy;
+
+	OSMO_ASSERT(xid_fields);
+
+	xid_fields_copy = talloc_zero(ctx, struct llist_head);
+	INIT_LLIST_HEAD(xid_fields_copy);
+
+	/* Create duplicates and add them to the target list */
+	llist_for_each_entry(xid_field, xid_fields, list) {
+		llist_add(&gprs_llc_dup_xid_field(ctx, xid_field)->list,
+			  xid_fields_copy);
+	}
+
+	return xid_fields_copy;
+}
+
+/* Dump a list with XID fields (Debug) */
+void gprs_llc_dump_xid_fields(const struct llist_head *xid_fields,
+			      unsigned int logl)
+{
+	struct gprs_llc_xid_field *xid_field;
+
+	OSMO_ASSERT(xid_fields);
+
+	llist_for_each_entry(xid_field, xid_fields, list) {
+		if (xid_field->data_len) {
+			OSMO_ASSERT(xid_field->data);
+			LOGP(DLLC, logl,
+			     "XID: type %s, data_len=%d, data=%s\n",
+			     get_value_string(gprs_llc_xid_type_names,
+					      xid_field->type),
+			     xid_field->data_len,
+			     osmo_hexdump_nospc(xid_field->data,
+						xid_field->data_len));
+		} else {
+			LOGP(DLLC, logl,
+			     "XID: type=%d, data_len=%d, data=NULL\n",
+			     xid_field->type, xid_field->data_len);
+		}
+	}
+}