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

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 --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 &lt;laforge(a)gnumonks.org&gt; + * + * 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; +} -- 1.7.9.5