| /* GSM Mobile Radio Interface Layer 3 messages on the A-bis interface |
| * 3GPP TS 04.08 version 7.21.0 Release 1998 / ETSI TS 100 940 V7.21.0 */ |
| |
| /* (C) 2008-2009 by Harald Welte <laforge@gnumonks.org> |
| * (C) 2008, 2009 by Holger Hans Peter Freyther <zecke@selfish.org> |
| * (C) 2009 by Mike Haben <michael.haben@btinternet.com> |
| * |
| * All Rights Reserved |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 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 General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| */ |
| |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <errno.h> |
| |
| #include <osmocore/msgb.h> |
| #include <osmocore/tlv.h> |
| #include <openbsc/debug.h> |
| #include <openbsc/gsm_data.h> |
| #include <osmocore/gsm_utils.h> |
| #include <openbsc/gsm_04_08.h> |
| #include <openbsc/gsm_04_80.h> |
| |
| /* Forward declarations */ |
| static int parse_ussd(u_int8_t *ussd, struct ussd_request *req); |
| static int parse_ussd_info_elements(u_int8_t *ussd_ie, |
| struct ussd_request *req); |
| static int parse_facility_ie(u_int8_t *facility_ie, u_int8_t length, |
| struct ussd_request *req); |
| static int parse_ss_invoke(u_int8_t *invoke_data, u_int8_t length, |
| struct ussd_request *req); |
| static int parse_process_uss_req(u_int8_t *uss_req_data, u_int8_t length, |
| struct ussd_request *req); |
| |
| static inline unsigned char *msgb_wrap_with_TL(struct msgb *msgb, u_int8_t tag) |
| { |
| msgb->data -= 2; |
| msgb->data[0] = tag; |
| msgb->data[1] = msgb->len; |
| msgb->len += 2; |
| return msgb->data; |
| } |
| |
| static inline unsigned char *msgb_push_TLV1(struct msgb *msgb, u_int8_t tag, |
| u_int8_t value) |
| { |
| msgb->data -= 3; |
| msgb->len += 3; |
| msgb->data[0] = tag; |
| msgb->data[1] = 1; |
| msgb->data[2] = value; |
| return msgb->data; |
| } |
| |
| |
| /* Decode a mobile-originated USSD-request message */ |
| int gsm0480_decode_ussd_request(const struct msgb *msg, struct ussd_request *req) |
| { |
| int rc = 0; |
| u_int8_t *parse_ptr = msgb_l3(msg); |
| |
| if ((*parse_ptr & 0x0F) == GSM48_PDISC_NC_SS) { |
| req->transaction_id = *parse_ptr & 0x70; |
| rc = parse_ussd(parse_ptr+1, req); |
| } |
| |
| if (!rc) |
| DEBUGP(DMM, "Error occurred while parsing received USSD!\n"); |
| |
| return rc; |
| } |
| |
| static int parse_ussd(u_int8_t *ussd, struct ussd_request *req) |
| { |
| int rc = 1; |
| u_int8_t msg_type = ussd[0] & 0xBF; /* message-type - section 3.4 */ |
| |
| switch (msg_type) { |
| case GSM0480_MTYPE_RELEASE_COMPLETE: |
| DEBUGP(DMM, "USS Release Complete\n"); |
| /* could also parse out the optional Cause/Facility data */ |
| req->text[0] = 0xFF; |
| break; |
| case GSM0480_MTYPE_REGISTER: |
| case GSM0480_MTYPE_FACILITY: |
| rc &= parse_ussd_info_elements(ussd+1, req); |
| break; |
| default: |
| fprintf(stderr, "Unknown GSM 04.80 message-type field 0x%02x\n", |
| ussd[0]); |
| rc = 0; |
| break; |
| } |
| |
| return rc; |
| } |
| |
| static int parse_ussd_info_elements(u_int8_t *ussd_ie, struct ussd_request *req) |
| { |
| int rc; |
| /* Information Element Identifier - table 3.2 & GSM 04.08 section 10.5 */ |
| u_int8_t iei = ussd_ie[0]; |
| u_int8_t iei_length = ussd_ie[1]; |
| |
| switch (iei) { |
| case GSM48_IE_CAUSE: |
| break; |
| case GSM0480_IE_FACILITY: |
| rc = parse_facility_ie(ussd_ie+2, iei_length, req); |
| break; |
| case GSM0480_IE_SS_VERSION: |
| break; |
| default: |
| fprintf(stderr, "Unhandled GSM 04.08 or 04.80 IEI 0x%02x\n", |
| iei); |
| rc = 0; |
| break; |
| } |
| |
| return rc; |
| } |
| |
| static int parse_facility_ie(u_int8_t *facility_ie, u_int8_t length, |
| struct ussd_request *req) |
| { |
| int rc = 1; |
| u_int8_t offset = 0; |
| |
| do { |
| /* Component Type tag - table 3.7 */ |
| u_int8_t component_type = facility_ie[offset]; |
| u_int8_t component_length = facility_ie[offset+1]; |
| |
| switch (component_type) { |
| case GSM0480_CTYPE_INVOKE: |
| rc &= parse_ss_invoke(facility_ie+2, |
| component_length, |
| req); |
| break; |
| case GSM0480_CTYPE_RETURN_RESULT: |
| break; |
| case GSM0480_CTYPE_RETURN_ERROR: |
| break; |
| case GSM0480_CTYPE_REJECT: |
| break; |
| default: |
| fprintf(stderr, "Unknown GSM 04.80 Facility " |
| "Component Type 0x%02x\n", component_type); |
| rc = 0; |
| break; |
| } |
| offset += (component_length+2); |
| } while (offset < length); |
| |
| return rc; |
| } |
| |
| /* Parse an Invoke component - see table 3.3 */ |
| static int parse_ss_invoke(u_int8_t *invoke_data, u_int8_t length, |
| struct ussd_request *req) |
| { |
| int rc = 1; |
| u_int8_t offset; |
| |
| /* mandatory part */ |
| if (invoke_data[0] != GSM0480_COMPIDTAG_INVOKE_ID) { |
| fprintf(stderr, "Unexpected GSM 04.80 Component-ID tag " |
| "0x%02x (expecting Invoke ID tag)\n", invoke_data[0]); |
| } |
| |
| offset = invoke_data[1] + 2; |
| req->invoke_id = invoke_data[2]; |
| |
| /* optional part */ |
| if (invoke_data[offset] == GSM0480_COMPIDTAG_LINKED_ID) |
| offset += invoke_data[offset+1] + 2; /* skip over it */ |
| |
| /* mandatory part */ |
| if (invoke_data[offset] == GSM0480_OPERATION_CODE) { |
| u_int8_t operation_code = invoke_data[offset+2]; |
| switch (operation_code) { |
| case GSM0480_OP_CODE_PROCESS_USS_REQ: |
| rc = parse_process_uss_req(invoke_data + offset + 3, |
| length - offset - 3, |
| req); |
| break; |
| default: |
| fprintf(stderr, "GSM 04.80 operation code 0x%02x " |
| "is not yet handled\n", operation_code); |
| rc = 0; |
| break; |
| } |
| } else { |
| fprintf(stderr, "Unexpected GSM 04.80 Component-ID tag 0x%02x " |
| "(expecting Operation Code tag)\n", |
| invoke_data[0]); |
| rc = 0; |
| } |
| |
| return rc; |
| } |
| |
| /* Parse the parameters of a Process UnstructuredSS Request */ |
| static int parse_process_uss_req(u_int8_t *uss_req_data, u_int8_t length, |
| struct ussd_request *req) |
| { |
| int rc = 0; |
| int num_chars; |
| u_int8_t dcs; |
| |
| if (uss_req_data[0] == GSM_0480_SEQUENCE_TAG) { |
| if (uss_req_data[2] == ASN1_OCTET_STRING_TAG) { |
| dcs = uss_req_data[4]; |
| if ((dcs == 0x0F) && |
| (uss_req_data[5] == ASN1_OCTET_STRING_TAG)) { |
| num_chars = (uss_req_data[6] * 8) / 7; |
| /* Prevent a mobile-originated buffer-overrun! */ |
| if (num_chars > MAX_LEN_USSD_STRING) |
| num_chars = MAX_LEN_USSD_STRING; |
| gsm_7bit_decode(req->text, |
| &(uss_req_data[7]), num_chars); |
| /* append null-terminator */ |
| req->text[num_chars+1] = 0; |
| rc = 1; |
| } |
| } |
| } |
| return rc; |
| } |
| |
| /* Send response to a mobile-originated ProcessUnstructuredSS-Request */ |
| int gsm0480_send_ussd_response(const struct msgb *in_msg, const char *response_text, |
| const struct ussd_request *req) |
| { |
| struct msgb *msg = gsm48_msgb_alloc(); |
| struct gsm48_hdr *gh; |
| u_int8_t *ptr8; |
| int response_len; |
| |
| response_len = (strlen(response_text) * 7) / 8; |
| if (((strlen(response_text) * 7) % 8) != 0) |
| response_len += 1; |
| |
| msg->bts_link = in_msg->bts_link; |
| msg->lchan = in_msg->lchan; |
| |
| /* First put the payload text into the message */ |
| ptr8 = msgb_put(msg, response_len); |
| gsm_7bit_encode(ptr8, response_text); |
| |
| /* Then wrap it as an Octet String */ |
| msgb_wrap_with_TL(msg, ASN1_OCTET_STRING_TAG); |
| |
| /* Pre-pend the DCS octet string */ |
| msgb_push_TLV1(msg, ASN1_OCTET_STRING_TAG, 0x0F); |
| |
| /* Then wrap these as a Sequence */ |
| msgb_wrap_with_TL(msg, GSM_0480_SEQUENCE_TAG); |
| |
| /* Pre-pend the operation code */ |
| msgb_push_TLV1(msg, GSM0480_OPERATION_CODE, |
| GSM0480_OP_CODE_PROCESS_USS_REQ); |
| |
| /* Wrap the operation code and IA5 string as a sequence */ |
| msgb_wrap_with_TL(msg, GSM_0480_SEQUENCE_TAG); |
| |
| /* Pre-pend the invoke ID */ |
| msgb_push_TLV1(msg, GSM0480_COMPIDTAG_INVOKE_ID, req->invoke_id); |
| |
| /* Wrap this up as a Return Result component */ |
| msgb_wrap_with_TL(msg, GSM0480_CTYPE_RETURN_RESULT); |
| |
| /* Wrap the component in a Facility message */ |
| msgb_wrap_with_TL(msg, GSM0480_IE_FACILITY); |
| |
| /* And finally pre-pend the L3 header */ |
| gh = (struct gsm48_hdr *) msgb_push(msg, sizeof(*gh)); |
| gh->proto_discr = GSM48_PDISC_NC_SS | req->transaction_id |
| | (1<<7); /* TI direction = 1 */ |
| gh->msg_type = GSM0480_MTYPE_RELEASE_COMPLETE; |
| |
| return gsm48_sendmsg(msg, NULL); |
| } |
| |
| int gsm0480_send_ussd_reject(const struct msgb *in_msg, |
| const struct ussd_request *req) |
| { |
| struct msgb *msg = gsm48_msgb_alloc(); |
| struct gsm48_hdr *gh; |
| |
| msg->bts_link = in_msg->bts_link; |
| msg->lchan = in_msg->lchan; |
| |
| /* First insert the problem code */ |
| msgb_push_TLV1(msg, GSM_0480_PROBLEM_CODE_TAG_GENERAL, |
| GSM_0480_GEN_PROB_CODE_UNRECOGNISED); |
| |
| /* Before it insert the invoke ID */ |
| msgb_push_TLV1(msg, GSM0480_COMPIDTAG_INVOKE_ID, req->invoke_id); |
| |
| /* Wrap this up as a Reject component */ |
| msgb_wrap_with_TL(msg, GSM0480_CTYPE_REJECT); |
| |
| /* Wrap the component in a Facility message */ |
| msgb_wrap_with_TL(msg, GSM0480_IE_FACILITY); |
| |
| /* And finally pre-pend the L3 header */ |
| gh = (struct gsm48_hdr *) msgb_push(msg, sizeof(*gh)); |
| gh->proto_discr = GSM48_PDISC_NC_SS; |
| gh->proto_discr |= req->transaction_id | (1<<7); /* TI direction = 1 */ |
| gh->msg_type = GSM0480_MTYPE_RELEASE_COMPLETE; |
| |
| return gsm48_sendmsg(msg, NULL); |
| } |