diff mbox

[3/3] gprs: Separate LLC parsing from LLC state handling

Message ID 1401698941-10318-3-git-send-email-jerlbeck@sysmocom.de
State Accepted
Headers show

Commit Message

Jacob Erlbeck June 2, 2014, 8:49 a.m. UTC 
Currently LLC parsing is part of gprs_llc.c which needs large parts
of the SGSN code parsing to fulfill its link dependencies.

This patch moves the functions that just do plain parsing, dumping,
and FCS computation to a different file to avoid these dependencies
if LLC stateful processing is not needed. It also exposes
struct gprs_llc_hdr_parsed and enum gprs_llc_cmd publically.

Sponsored-by: On-Waves ehf
---
 openbsc/include/openbsc/gprs_llc.h |   41 ++++++
 openbsc/src/gprs/Makefile.am       |    2 +-
 openbsc/src/gprs/gprs_llc.c        |  236 ----------------------------------
 openbsc/src/gprs/gprs_llc_parse.c  |  243 ++++++++++++++++++++++++++++++++++++
 4 files changed, 285 insertions(+), 237 deletions(-)
 create mode 100644 openbsc/src/gprs/gprs_llc_parse.c
diff mbox

Patch

diff --git a/openbsc/include/openbsc/gprs_llc.h b/openbsc/include/openbsc/gprs_llc.h
index 4be7b1f..854b968 100644
--- a/openbsc/include/openbsc/gprs_llc.h
+++ b/openbsc/include/openbsc/gprs_llc.h
@@ -165,6 +165,39 @@  struct gprs_llc_llme {
 
 extern struct llist_head gprs_llc_llmes;
 
+/* LLC low level types */
+
+enum gprs_llc_cmd {
+	GPRS_LLC_NULL,
+	GPRS_LLC_RR,
+	GPRS_LLC_ACK,
+	GPRS_LLC_RNR,
+	GPRS_LLC_SACK,
+	GPRS_LLC_DM,
+	GPRS_LLC_DISC,
+	GPRS_LLC_UA,
+	GPRS_LLC_SABM,
+	GPRS_LLC_FRMR,
+	GPRS_LLC_XID,
+	GPRS_LLC_UI,
+};
+
+struct gprs_llc_hdr_parsed {
+	uint8_t sapi;
+	uint8_t is_cmd:1,
+		 ack_req:1,
+		 is_encrypted:1;
+	uint32_t seq_rx;
+	uint32_t seq_tx;
+	uint32_t fcs;
+	uint32_t fcs_calc;
+	uint8_t *data;
+	uint16_t data_len;
+	uint16_t crc_length;
+	enum gprs_llc_cmd cmd;
+};
+
+
 /* BSSGP-UL-UNITDATA.ind */
 int gprs_llc_rcvmsg(struct msgb *msg, struct tlv_parsed *tv);
 
@@ -199,4 +232,12 @@  static inline int gprs_llc_is_retransmit(uint16_t nu, uint16_t vur)
 	return 0 < delta && delta < 32;
 }
 
+/* LLC low level functions */
+
+/* parse a GPRS LLC header, also check for invalid frames */
+int gprs_llc_hdr_parse(struct gprs_llc_hdr_parsed *ghp,
+		       uint8_t *llc_hdr, int len);
+void gprs_llc_hdr_dump(struct gprs_llc_hdr_parsed *gph);
+int gprs_llc_fcs(uint8_t *data, unsigned int len);
+
 #endif
diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index 90c376c..049d41d 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -19,7 +19,7 @@  osmo_gbproxy_LDADD = 	$(top_builddir)/src/libcommon/libcommon.a \
 
 osmo_sgsn_SOURCES =	gprs_gmm.c gprs_sgsn.c gprs_sndcp.c gprs_sndcp_vty.c \
 			sgsn_main.c sgsn_vty.c sgsn_libgtp.c \
-			gprs_llc.c gprs_llc_vty.c crc24.c \
+			gprs_llc.c gprs_llc_parse.c gprs_llc_vty.c crc24.c \
 			sgsn_ctrl.c
 osmo_sgsn_LDADD = 	\
 			$(top_builddir)/src/libctrl/libctrl.a \
diff --git a/openbsc/src/gprs/gprs_llc.c b/openbsc/src/gprs/gprs_llc.c
index 1e40dcb..70fe9dd 100644
--- a/openbsc/src/gprs/gprs_llc.c
+++ b/openbsc/src/gprs/gprs_llc.c
@@ -36,52 +36,6 @@ 
 #include <openbsc/crc24.h>
 #include <openbsc/sgsn.h>
 
-enum gprs_llc_cmd {
-	GPRS_LLC_NULL,
-	GPRS_LLC_RR,
-	GPRS_LLC_ACK,
-	GPRS_LLC_RNR,
-	GPRS_LLC_SACK,
-	GPRS_LLC_DM,
-	GPRS_LLC_DISC,
-	GPRS_LLC_UA,
-	GPRS_LLC_SABM,
-	GPRS_LLC_FRMR,
-	GPRS_LLC_XID,
-	GPRS_LLC_UI,
-};
-
-static const struct value_string llc_cmd_strs[] = {
-	{ GPRS_LLC_NULL,	"NULL" },
-	{ GPRS_LLC_RR,		"RR" },
-	{ GPRS_LLC_ACK,		"ACK" },
-	{ GPRS_LLC_RNR,		"RNR" },
-	{ GPRS_LLC_SACK,	"SACK" },
-	{ GPRS_LLC_DM,		"DM" },
-	{ GPRS_LLC_DISC,	"DISC" },
-	{ GPRS_LLC_UA,		"UA" },
-	{ GPRS_LLC_SABM,	"SABM" },
-	{ GPRS_LLC_FRMR,	"FRMR" },
-	{ GPRS_LLC_XID,		"XID" },
-	{ GPRS_LLC_UI,		"UI" },
-	{ 0, NULL }
-};
-
-struct gprs_llc_hdr_parsed {
-	uint8_t sapi;
-	uint8_t is_cmd:1,
-		 ack_req:1,
-		 is_encrypted:1;
-	uint32_t seq_rx;
-	uint32_t seq_tx;
-	uint32_t fcs;
-	uint32_t fcs_calc;
-	uint8_t *data;
-	uint16_t data_len;
-	uint16_t crc_length;
-	enum gprs_llc_cmd cmd;
-};
-
 static struct gprs_llc_llme *llme_alloc(uint32_t tlli);
 
 /* If the TLLI is foreign, return its local version */
@@ -292,22 +246,6 @@  static void llme_free(struct gprs_llc_llme *llme)
 	talloc_free(llme);
 }
 
-#define LLC_ALLOC_SIZE 16384
-#define UI_HDR_LEN	3
-#define N202		4
-#define CRC24_LENGTH	3
-
-static int gprs_llc_fcs(uint8_t *data, unsigned int len)
-{
-	uint32_t fcs_calc;
-
-	fcs_calc = crc24_calc(INIT_CRC24, data, len);
-	fcs_calc = ~fcs_calc;
-	fcs_calc &= 0xffffff;
-
-	return fcs_calc;
-}
-
 #if 0
 /* FIXME: Unused code... */
 static void t200_expired(void *data)
@@ -550,20 +488,6 @@  static void rx_llc_xid(struct gprs_llc_lle *lle,
 	}
 }
 
-static void gprs_llc_hdr_dump(struct gprs_llc_hdr_parsed *gph)
-{
-	DEBUGP(DLLC, "LLC SAPI=%u %c %c FCS=0x%06x",
-		gph->sapi, gph->is_cmd ? 'C' : 'R', gph->ack_req ? 'A' : ' ',
-		gph->fcs);
-
-	if (gph->cmd)
-		DEBUGPC(DLLC, "CMD=%s ", get_value_string(llc_cmd_strs, gph->cmd));
-
-	if (gph->data)
-		DEBUGPC(DLLC, "DATA ");
-
-	DEBUGPC(DLLC, "\n");
-}
 static int gprs_llc_hdr_rx(struct gprs_llc_hdr_parsed *gph,
 			   struct gprs_llc_lle *lle)
 {
@@ -634,166 +558,6 @@  static int gprs_llc_hdr_rx(struct gprs_llc_hdr_parsed *gph,
 	return 0;
 }
 
-/* parse a GPRS LLC header, also check for invalid frames */
-static int gprs_llc_hdr_parse(struct gprs_llc_hdr_parsed *ghp,
-			      uint8_t *llc_hdr, int len)
-{
-	uint8_t *ctrl = llc_hdr+1;
-
-	if (len <= CRC24_LENGTH)
-		return -EIO;
-
-	ghp->crc_length = len - CRC24_LENGTH;
-
-	ghp->ack_req = 0;
-
-	/* Section 5.5: FCS */
-	ghp->fcs = *(llc_hdr + len - 3);
-	ghp->fcs |= *(llc_hdr + len - 2) << 8;
-	ghp->fcs |= *(llc_hdr + len - 1) << 16;
-
-	/* Section 6.2.1: invalid PD field */
-	if (llc_hdr[0] & 0x80)
-		return -EIO;
-
-	/* This only works for the MS->SGSN direction */
-	if (llc_hdr[0] & 0x40)
-		ghp->is_cmd = 0;
-	else
-		ghp->is_cmd = 1;
-
-	ghp->sapi = llc_hdr[0] & 0xf;
-
-	/* Section 6.2.3: check for reserved SAPI */
-	switch (ghp->sapi) {
-	case 0:
-	case 4:
-	case 6:
-	case 0xa:
-	case 0xc:
-	case 0xd:
-	case 0xf:
-		return -EINVAL;
-	}
-
-	if ((ctrl[0] & 0x80) == 0) {
-		/* I (Information transfer + Supervisory) format */
-		uint8_t k;
-
-		ghp->data = ctrl + 3;
-
-		if (ctrl[0] & 0x40)
-			ghp->ack_req = 1;
-
-		ghp->seq_tx  = (ctrl[0] & 0x1f) << 4;
-		ghp->seq_tx |= (ctrl[1] >> 4);
-
-		ghp->seq_rx  = (ctrl[1] & 0x7) << 6;
-		ghp->seq_rx |= (ctrl[2] >> 2);
-
-		switch (ctrl[2] & 0x03) {
-		case 0:
-			ghp->cmd = GPRS_LLC_RR;
-			break;
-		case 1:
-			ghp->cmd = GPRS_LLC_ACK;
-			break;
-		case 2:
-			ghp->cmd = GPRS_LLC_RNR;
-			break;
-		case 3:
-			ghp->cmd = GPRS_LLC_SACK;
-			k = ctrl[3] & 0x1f;
-			ghp->data += 1 + k;
-			break;
-		}
-		ghp->data_len = (llc_hdr + len - 3) - ghp->data;
-	} else if ((ctrl[0] & 0xc0) == 0x80) {
-		/* S (Supervisory) format */
-		ghp->data = NULL;
-		ghp->data_len = 0;
-
-		if (ctrl[0] & 0x20)
-			ghp->ack_req = 1;
-		ghp->seq_rx  = (ctrl[0] & 0x7) << 6;
-		ghp->seq_rx |= (ctrl[1] >> 2);
-
-		switch (ctrl[1] & 0x03) {
-		case 0:
-			ghp->cmd = GPRS_LLC_RR;
-			break;
-		case 1:
-			ghp->cmd = GPRS_LLC_ACK;
-			break;
-		case 2:
-			ghp->cmd = GPRS_LLC_RNR;
-			break;
-		case 3:
-			ghp->cmd = GPRS_LLC_SACK;
-			break;
-		}
-	} else if ((ctrl[0] & 0xe0) == 0xc0) {
-		/* UI (Unconfirmed Inforamtion) format */
-		ghp->cmd = GPRS_LLC_UI;
-		ghp->data = ctrl + 2;
-		ghp->data_len = (llc_hdr + len - 3) - ghp->data;
-
-		ghp->seq_tx  = (ctrl[0] & 0x7) << 6;
-		ghp->seq_tx |= (ctrl[1] >> 2);
-		if (ctrl[1] & 0x02) {
-			ghp->is_encrypted = 1;
-			/* FIXME: encryption */
-		}
-		if (ctrl[1] & 0x01) {
-			/* FCS over hdr + all inf fields */
-		} else {
-			/* FCS over hdr + N202 octets (4) */
-			if (ghp->crc_length > UI_HDR_LEN + N202)
-				ghp->crc_length = UI_HDR_LEN + N202;
-		}
-	} else {
-		/* U (Unnumbered) format: 1 1 1 P/F M4 M3 M2 M1 */
-		ghp->data = NULL;
-		ghp->data_len = 0;
-
-		switch (ctrl[0] & 0xf) {
-		case GPRS_LLC_U_NULL_CMD:
-			ghp->cmd = GPRS_LLC_NULL;
-			break;
-		case GPRS_LLC_U_DM_RESP:
-			ghp->cmd = GPRS_LLC_DM;
-			break;
-		case GPRS_LLC_U_DISC_CMD:
-			ghp->cmd = GPRS_LLC_DISC;
-			break;
-		case GPRS_LLC_U_UA_RESP:
-			ghp->cmd = GPRS_LLC_UA;
-			break;
-		case GPRS_LLC_U_SABM_CMD:
-			ghp->cmd = GPRS_LLC_SABM;
-			break;
-		case GPRS_LLC_U_FRMR_RESP:
-			ghp->cmd = GPRS_LLC_FRMR;
-			break;
-		case GPRS_LLC_U_XID:
-			ghp->cmd = GPRS_LLC_XID;
-			ghp->data = ctrl + 1;
-			ghp->data_len = (llc_hdr + len - 3) - ghp->data;
-			break;
-		default:
-			return -EIO;
-		}
-	}
-
-	/* FIXME: parse sack frame */
-	if (ghp->cmd == GPRS_LLC_SACK) {
-		LOGP(DLLC, LOGL_NOTICE, "Unsupported SACK frame\n");
-		return -EIO;
-	}
-
-	return 0;
-}
-
 /* receive an incoming LLC PDU (BSSGP-UL-UNITDATA-IND, 7.2.4.2) */
 int gprs_llc_rcvmsg(struct msgb *msg, struct tlv_parsed *tv)
 {
diff --git a/openbsc/src/gprs/gprs_llc_parse.c b/openbsc/src/gprs/gprs_llc_parse.c
new file mode 100644
index 0000000..b1f1a56
--- /dev/null
+++ b/openbsc/src/gprs/gprs_llc_parse.c
@@ -0,0 +1,243 @@ 
+/* GPRS LLC protocol implementation as per 3GPP TS 04.64 */
+
+/* (C) 2009-2010 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * 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 <errno.h>
+#include <stdint.h>
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/gprs/gprs_bssgp.h>
+
+#include <openbsc/gsm_data.h>
+#include <openbsc/debug.h>
+#include <openbsc/gprs_sgsn.h>
+#include <openbsc/gprs_gmm.h>
+#include <openbsc/gprs_llc.h>
+#include <openbsc/crc24.h>
+
+static const struct value_string llc_cmd_strs[] = {
+	{ GPRS_LLC_NULL,	"NULL" },
+	{ GPRS_LLC_RR,		"RR" },
+	{ GPRS_LLC_ACK,		"ACK" },
+	{ GPRS_LLC_RNR,		"RNR" },
+	{ GPRS_LLC_SACK,	"SACK" },
+	{ GPRS_LLC_DM,		"DM" },
+	{ GPRS_LLC_DISC,	"DISC" },
+	{ GPRS_LLC_UA,		"UA" },
+	{ GPRS_LLC_SABM,	"SABM" },
+	{ GPRS_LLC_FRMR,	"FRMR" },
+	{ GPRS_LLC_XID,		"XID" },
+	{ GPRS_LLC_UI,		"UI" },
+	{ 0, NULL }
+};
+
+#define LLC_ALLOC_SIZE 16384
+#define UI_HDR_LEN	3
+#define N202		4
+#define CRC24_LENGTH	3
+
+int gprs_llc_fcs(uint8_t *data, unsigned int len)
+{
+	uint32_t fcs_calc;
+
+	fcs_calc = crc24_calc(INIT_CRC24, data, len);
+	fcs_calc = ~fcs_calc;
+	fcs_calc &= 0xffffff;
+
+	return fcs_calc;
+}
+
+void gprs_llc_hdr_dump(struct gprs_llc_hdr_parsed *gph)
+{
+	DEBUGP(DLLC, "LLC SAPI=%u %c %c FCS=0x%06x",
+		gph->sapi, gph->is_cmd ? 'C' : 'R', gph->ack_req ? 'A' : ' ',
+		gph->fcs);
+
+	if (gph->cmd)
+		DEBUGPC(DLLC, "CMD=%s ", get_value_string(llc_cmd_strs, gph->cmd));
+
+	if (gph->data)
+		DEBUGPC(DLLC, "DATA ");
+
+	DEBUGPC(DLLC, "\n");
+}
+
+/* parse a GPRS LLC header, also check for invalid frames */
+int gprs_llc_hdr_parse(struct gprs_llc_hdr_parsed *ghp,
+		       uint8_t *llc_hdr, int len)
+{
+	uint8_t *ctrl = llc_hdr+1;
+
+	if (len <= CRC24_LENGTH)
+		return -EIO;
+
+	ghp->crc_length = len - CRC24_LENGTH;
+
+	ghp->ack_req = 0;
+
+	/* Section 5.5: FCS */
+	ghp->fcs = *(llc_hdr + len - 3);
+	ghp->fcs |= *(llc_hdr + len - 2) << 8;
+	ghp->fcs |= *(llc_hdr + len - 1) << 16;
+
+	/* Section 6.2.1: invalid PD field */
+	if (llc_hdr[0] & 0x80)
+		return -EIO;
+
+	/* This only works for the MS->SGSN direction */
+	if (llc_hdr[0] & 0x40)
+		ghp->is_cmd = 0;
+	else
+		ghp->is_cmd = 1;
+
+	ghp->sapi = llc_hdr[0] & 0xf;
+
+	/* Section 6.2.3: check for reserved SAPI */
+	switch (ghp->sapi) {
+	case 0:
+	case 4:
+	case 6:
+	case 0xa:
+	case 0xc:
+	case 0xd:
+	case 0xf:
+		return -EINVAL;
+	}
+
+	if ((ctrl[0] & 0x80) == 0) {
+		/* I (Information transfer + Supervisory) format */
+		uint8_t k;
+
+		ghp->data = ctrl + 3;
+
+		if (ctrl[0] & 0x40)
+			ghp->ack_req = 1;
+
+		ghp->seq_tx  = (ctrl[0] & 0x1f) << 4;
+		ghp->seq_tx |= (ctrl[1] >> 4);
+
+		ghp->seq_rx  = (ctrl[1] & 0x7) << 6;
+		ghp->seq_rx |= (ctrl[2] >> 2);
+
+		switch (ctrl[2] & 0x03) {
+		case 0:
+			ghp->cmd = GPRS_LLC_RR;
+			break;
+		case 1:
+			ghp->cmd = GPRS_LLC_ACK;
+			break;
+		case 2:
+			ghp->cmd = GPRS_LLC_RNR;
+			break;
+		case 3:
+			ghp->cmd = GPRS_LLC_SACK;
+			k = ctrl[3] & 0x1f;
+			ghp->data += 1 + k;
+			break;
+		}
+		ghp->data_len = (llc_hdr + len - 3) - ghp->data;
+	} else if ((ctrl[0] & 0xc0) == 0x80) {
+		/* S (Supervisory) format */
+		ghp->data = NULL;
+		ghp->data_len = 0;
+
+		if (ctrl[0] & 0x20)
+			ghp->ack_req = 1;
+		ghp->seq_rx  = (ctrl[0] & 0x7) << 6;
+		ghp->seq_rx |= (ctrl[1] >> 2);
+
+		switch (ctrl[1] & 0x03) {
+		case 0:
+			ghp->cmd = GPRS_LLC_RR;
+			break;
+		case 1:
+			ghp->cmd = GPRS_LLC_ACK;
+			break;
+		case 2:
+			ghp->cmd = GPRS_LLC_RNR;
+			break;
+		case 3:
+			ghp->cmd = GPRS_LLC_SACK;
+			break;
+		}
+	} else if ((ctrl[0] & 0xe0) == 0xc0) {
+		/* UI (Unconfirmed Inforamtion) format */
+		ghp->cmd = GPRS_LLC_UI;
+		ghp->data = ctrl + 2;
+		ghp->data_len = (llc_hdr + len - 3) - ghp->data;
+
+		ghp->seq_tx  = (ctrl[0] & 0x7) << 6;
+		ghp->seq_tx |= (ctrl[1] >> 2);
+		if (ctrl[1] & 0x02) {
+			ghp->is_encrypted = 1;
+			/* FIXME: encryption */
+		}
+		if (ctrl[1] & 0x01) {
+			/* FCS over hdr + all inf fields */
+		} else {
+			/* FCS over hdr + N202 octets (4) */
+			if (ghp->crc_length > UI_HDR_LEN + N202)
+				ghp->crc_length = UI_HDR_LEN + N202;
+		}
+	} else {
+		/* U (Unnumbered) format: 1 1 1 P/F M4 M3 M2 M1 */
+		ghp->data = NULL;
+		ghp->data_len = 0;
+
+		switch (ctrl[0] & 0xf) {
+		case GPRS_LLC_U_NULL_CMD:
+			ghp->cmd = GPRS_LLC_NULL;
+			break;
+		case GPRS_LLC_U_DM_RESP:
+			ghp->cmd = GPRS_LLC_DM;
+			break;
+		case GPRS_LLC_U_DISC_CMD:
+			ghp->cmd = GPRS_LLC_DISC;
+			break;
+		case GPRS_LLC_U_UA_RESP:
+			ghp->cmd = GPRS_LLC_UA;
+			break;
+		case GPRS_LLC_U_SABM_CMD:
+			ghp->cmd = GPRS_LLC_SABM;
+			break;
+		case GPRS_LLC_U_FRMR_RESP:
+			ghp->cmd = GPRS_LLC_FRMR;
+			break;
+		case GPRS_LLC_U_XID:
+			ghp->cmd = GPRS_LLC_XID;
+			ghp->data = ctrl + 1;
+			ghp->data_len = (llc_hdr + len - 3) - ghp->data;
+			break;
+		default:
+			return -EIO;
+		}
+	}
+
+	/* FIXME: parse sack frame */
+	if (ghp->cmd == GPRS_LLC_SACK) {
+		LOGP(DLLC, LOGL_NOTICE, "Unsupported SACK frame\n");
+		return -EIO;
+	}
+
+	return 0;
+}