[PATCH 3/9] libmsc: Update USSD to use new ss_request structure

Neels Hofmeyr nhofmeyr at sysmocom.de
Tue Apr 26 11:58:04 UTC 2016


On Fri, Apr 22, 2016 at 02:41:32PM +0200, Sergey Kostanbaev wrote:
> ---
>  openbsc/include/openbsc/gsm_04_80.h |  15 +++--
>  openbsc/src/libmsc/gsm_04_80.c      | 128 ++++++++++++++++++++++++------------
>  openbsc/src/libmsc/ussd.c           |  79 ++++++++++++++++++----
>  3 files changed, 162 insertions(+), 60 deletions(-)
> 
> diff --git a/openbsc/include/openbsc/gsm_04_80.h b/openbsc/include/openbsc/gsm_04_80.h
> index 0a60652..371bc17 100644
> --- a/openbsc/include/openbsc/gsm_04_80.h
> +++ b/openbsc/include/openbsc/gsm_04_80.h
> @@ -7,12 +7,17 @@
>  
>  struct gsm_subscriber_connection;
>  
> -int gsm0480_send_ussd_response(struct gsm_subscriber_connection *conn,
> -			       const struct msgb *in_msg, const char* response_text, 
> -			       const struct ussd_request *req);
> +int gsm0480_send_component(struct gsm_subscriber_connection *conn,

Why remove the '_ussd_' name component here while you keep it in the other
functions?

IMHO you should also describe function renames in the log message.

> +			   struct msgb *msg,
> +			   struct ss_header* reqhdr);
> +
>  int gsm0480_send_ussd_reject(struct gsm_subscriber_connection *conn,
> -			     const struct msgb *msg, 
> -			     const struct ussd_request *request);
> +			     uint8_t invoke_id,
> +			     uint8_t transaction_id);
> +
> +struct msgb *gsm0480_compose_ussd_component(struct ss_request* req);

...and additions/out-factorings as well.

> +
> +

^ osmo* is usually sparse on whitespace ;)

>  
>  int gsm0480_send_ussdNotify(struct gsm_subscriber_connection *conn, int level, const char *text);
>  int gsm0480_send_releaseComplete(struct gsm_subscriber_connection *conn);
> diff --git a/openbsc/src/libmsc/gsm_04_80.c b/openbsc/src/libmsc/gsm_04_80.c
> index f1d75f2..e6e4a92 100644
> --- a/openbsc/src/libmsc/gsm_04_80.c
> +++ b/openbsc/src/libmsc/gsm_04_80.c
> @@ -39,6 +39,22 @@
>  #include <osmocom/core/msgb.h>
>  #include <osmocom/gsm/tlv.h>
>  
> +/* This function can handle ASN1 length up to 255 which is enough for USSD */
> +static inline unsigned char *msgb_wrap_with_ASN1_TL(struct msgb *msgb, uint8_t tag)
> +{
> +	uint16_t origlen = msgb->len;
> +	uint8_t *data = msgb_push(msgb, (origlen > 0x7f) ? 3 : 2);
> +	data[0] = tag;
> +	if (origlen > 0x7f) {
> +		data[1] = 0x81;
> +		data[2] = origlen;
> +	} else {
> +		data[1] = origlen;
> +	}
> +	return data;
> +}

Would be good to use constants instead of the two magic values, which
would also improve readability; otherwise I would like to see comments
describing the semantics to the uninformed reader.

> +
> +

^ Again, a single line of whitespace would be usual in osmo*.


...

This patch is rather large, especially for a one-liner commit log; would
it be possible to break this patch down into smaller changes that are
easier to review? That would be great!

Unfortunately I have to redirect my attention to other tasks now and
cannot look at the remaining changes...

Thanks!
~Neels

>  static inline unsigned char *msgb_wrap_with_TL(struct msgb *msgb, uint8_t tag)
>  {
>  	uint8_t *data = msgb_push(msgb, 2);
> @@ -59,83 +75,111 @@ static inline unsigned char *msgb_push_TLV1(struct msgb *msgb, uint8_t tag,
>  	return data;
>  }
>  
> +static inline unsigned char *msgb_wrap_with_L(struct msgb *msgb)
> +{
> +	uint8_t *data = msgb_push(msgb, 1);
>  
> -/* Send response to a mobile-originated ProcessUnstructuredSS-Request */
> -int gsm0480_send_ussd_response(struct gsm_subscriber_connection *conn,
> -			       const struct msgb *in_msg, const char *response_text,
> -			       const struct ussd_request *req)
> +	data[0] = msgb->len - 1;
> +	return data;
> +}
> +
> +/* Compose universial USSD packet invoke/return_result payload */
> +struct msgb *gsm0480_compose_ussd_component(struct ss_request* req)
>  {
>  	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 USSD RSP");
> -	struct gsm48_hdr *gh;
>  	uint8_t *ptr8;
> -	int response_len;
>  
>  	/* First put the payload text into the message */
>  	ptr8 = msgb_put(msg, 0);
> -	gsm_7bit_encode_n_ussd(ptr8, msgb_tailroom(msg), response_text, &response_len);
> -	msgb_put(msg, response_len);
> +
> +	memcpy(ptr8, req->ussd_text, req->ussd_text_len);
> +	msgb_put(msg, req->ussd_text_len);
>  
>  	/* Then wrap it as an Octet String */
> -	msgb_wrap_with_TL(msg, ASN1_OCTET_STRING_TAG);
> +	msgb_wrap_with_ASN1_TL(msg, ASN1_OCTET_STRING_TAG);
>  
>  	/* Pre-pend the DCS octet string */
> -	msgb_push_TLV1(msg, ASN1_OCTET_STRING_TAG, 0x0F);
> +	msgb_push_TLV1(msg, ASN1_OCTET_STRING_TAG, req->ussd_text_language);
>  
>  	/* 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);
> +	msgb_wrap_with_ASN1_TL(msg, GSM_0480_SEQUENCE_TAG);
> +
> +	if (req->component_type == GSM0480_CTYPE_RETURN_RESULT) {
> +		/* Pre-pend the operation code */
> +		msgb_push_TLV1(msg, GSM0480_OPERATION_CODE, req->opcode);
> +
> +		/* Wrap the operation code and IA5 string as a sequence */
> +		msgb_wrap_with_ASN1_TL(msg, GSM_0480_SEQUENCE_TAG);
> +
> +		/* Pre-pend the invoke ID */
> +		msgb_push_TLV1(msg, GSM0480_COMPIDTAG_INVOKE_ID, req->invoke_id);
> +	} else if (req->component_type == GSM0480_CTYPE_INVOKE) {
> +		/* Pre-pend the operation code */
> +		msgb_push_TLV1(msg, GSM0480_OPERATION_CODE, req->opcode);
> +
> +		/* Pre-pend the invoke ID */
> +		msgb_push_TLV1(msg, GSM0480_COMPIDTAG_INVOKE_ID, req->invoke_id);
> +	} else {
> +		abort();
> +	}
> +
> +	/* Wrap this up as an Invoke or a Return Result component */
> +	msgb_wrap_with_ASN1_TL(msg, req->component_type);
> +	return msg;
> +}
>  
> -	/* Pre-pend the invoke ID */
> -	msgb_push_TLV1(msg, GSM0480_COMPIDTAG_INVOKE_ID, req->invoke_id);
> +#ifndef NO_GSM0480_SEND_FUNC
>  
> -	/* Wrap this up as a Return Result component */
> -	msgb_wrap_with_TL(msg, GSM0480_CTYPE_RETURN_RESULT);
> +int gsm0480_send_component(struct gsm_subscriber_connection *conn,
> +			   struct msgb *msg,
> +			   struct ss_header* reqhdr)
> +{
> +	struct gsm48_hdr *gh;
>  
> -	/* Wrap the component in a Facility message */
> -	msgb_wrap_with_TL(msg, GSM0480_IE_FACILITY);
> +	if (reqhdr->message_type == GSM0480_MTYPE_REGISTER ||
> +		reqhdr->message_type == GSM0480_MTYPE_RELEASE_COMPLETE) {
> +		/* Wrap the component in a Facility message, it's not ASN1 */
> +		msgb_wrap_with_TL(msg, GSM0480_IE_FACILITY);
> +	} else if (reqhdr->message_type == GSM0480_MTYPE_FACILITY) {
> +		/* For GSM0480_MTYPE_FACILITY it's LV not TLV */
> +		msgb_wrap_with_L(msg);
> +	} else {
> +		abort();
> +	}
>  
>  	/* 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
> +	gh->proto_discr = GSM48_PDISC_NC_SS | reqhdr->transaction_id
>  					| (1<<7);  /* TI direction = 1 */
> -	gh->msg_type = GSM0480_MTYPE_RELEASE_COMPLETE;
> +	gh->msg_type = reqhdr->message_type;
> +
> +	DEBUGP(DSS, "Sending SS to mobile: %s\n", msgb_hexdump(msg));
>  
>  	return gsm0808_submit_dtap(conn, msg, 0, 0);
>  }
>  
> +
>  int gsm0480_send_ussd_reject(struct gsm_subscriber_connection *conn,
> -			     const struct msgb *in_msg,
> -			     const struct ussd_request *req)
> +			     uint8_t invoke_id,
> +			     uint8_t transaction_id)
>  {
>  	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 USSD REJ");
> -	struct gsm48_hdr *gh;
> +	struct ss_header ssh;
>  
>  	/* 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);
> +	msgb_push_TLV1(msg, GSM0480_COMPIDTAG_INVOKE_ID, 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);
> +	msgb_wrap_with_ASN1_TL(msg, GSM0480_CTYPE_REJECT);
>  
> -	/* 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 gsm0808_submit_dtap(conn, msg, 0, 0);
> +	/* Prepare data for L3 header */
> +	ssh.transaction_id = transaction_id;
> +	ssh.message_type = GSM0480_MTYPE_RELEASE_COMPLETE;
> +	return gsm0480_send_component(conn, msg, &ssh);
>  }
>  
>  int gsm0480_send_ussdNotify(struct gsm_subscriber_connection *conn, int level, const char *text)
> @@ -173,3 +217,5 @@ int gsm0480_send_releaseComplete(struct gsm_subscriber_connection *conn)
>  
>  	return gsm0808_submit_dtap(conn, msg, 0, 0);
>  }
> +
> +#endif
> diff --git a/openbsc/src/libmsc/ussd.c b/openbsc/src/libmsc/ussd.c
> index 7f01eae..3cafe02 100644
> --- a/openbsc/src/libmsc/ussd.c
> +++ b/openbsc/src/libmsc/ussd.c
> @@ -33,41 +33,71 @@
>  #include <openbsc/gsm_subscriber.h>
>  #include <openbsc/debug.h>
>  #include <openbsc/osmo_msc.h>
> +#include <openbsc/ussd.h>
> +#include <osmocom/gsm/gsm_utils.h>
> +#include <osmocom/gsm/gsm0480.h>
>  
>  /* Declarations of USSD strings to be recognised */
>  const char USSD_TEXT_OWN_NUMBER[] = "*#100#";
>  
>  /* Forward declarations of network-specific handler functions */
> -static int send_own_number(struct gsm_subscriber_connection *conn, const struct msgb *msg, const struct ussd_request *req);
> +static int send_own_number(struct gsm_subscriber_connection *conn,
> +			   const struct ss_header *reqhdr,
> +			   const struct ss_request *req);
>  
>  
>  /* Entrypoint - handler function common to all mobile-originated USSDs */
>  int handle_rcv_ussd(struct gsm_subscriber_connection *conn, struct msgb *msg)
>  {
>  	int rc;
> -	struct ussd_request req;
> +	struct ss_header reqhdr;
> +	struct ss_request req;
> +	char request_string[MAX_LEN_USSD_STRING + 1];
>  	struct gsm48_hdr *gh;
>  
>  	memset(&req, 0, sizeof(req));
> +	memset(&reqhdr, 0, sizeof(reqhdr));
>  	gh = msgb_l3(msg);
> -	rc = gsm0480_decode_ussd_request(gh, msgb_l3len(msg), &req);
> +	rc = gsm0480_decode_ss_request(gh, msgb_l3len(msg), &reqhdr);
>  	if (!rc) {
> -		DEBUGP(DMM, "Unhandled SS\n");
> -		rc = gsm0480_send_ussd_reject(conn, msg, &req);
> +		DEBUGP(DSS, "Incorrect SS header\n");
>  		msc_release_connection(conn);
>  		return rc;
>  	}
>  
> -	/* Release-Complete */
> -	if (req.text[0] == '\0')
> +	rc = gsm0480_parse_ss_facility(gh->data + reqhdr.component_offset,
> +				       reqhdr.component_length,
> +				       &req);
> +	if (!rc) {
> +		DEBUGP(DSS, "Unhandled SS\n");
> +		/* TODO req.invoke_id may not be set!!! */
> +		rc = gsm0480_send_ussd_reject(conn, req.invoke_id, reqhdr.transaction_id);
> +		msc_release_connection(conn);
> +		return rc;
> +	}
> +
> +	if (reqhdr.message_type == GSM0480_MTYPE_RELEASE_COMPLETE)
>  		return 0;
>  
> -	if (!strcmp(USSD_TEXT_OWN_NUMBER, (const char *)req.text)) {
> -		DEBUGP(DMM, "USSD: Own number requested\n");
> -		rc = send_own_number(conn, msg, &req);
> +	if (reqhdr.message_type != GSM0480_MTYPE_REGISTER ||
> +			req.component_type != GSM0480_CTYPE_INVOKE ||
> +			req.opcode != GSM0480_OP_CODE_PROCESS_USS_REQ ||
> +			req.ussd_text_language != 0x0f)
> +	{
> +		DEBUGP(DSS, "Unexpected SS\n");
> +		rc = gsm0480_send_ussd_reject(conn, req.invoke_id, reqhdr.transaction_id);
> +		msc_release_connection(conn);
> +		return rc;
> +	}
> +
> +	gsm_7bit_decode_n_ussd(request_string, MAX_LEN_USSD_STRING, req.ussd_text, req.ussd_text_len);
> +
> +	if (!strcmp(USSD_TEXT_OWN_NUMBER, (const char *)request_string)) {
> +		DEBUGP(DSS, "USSD: Own number requested\n");
> +		rc = send_own_number(conn, &reqhdr, &req);
>  	} else {
> -		DEBUGP(DMM, "Unhandled USSD %s\n", req.text);
> -		rc = gsm0480_send_ussd_reject(conn, msg, &req);
> +		DEBUGP(DSS, "Unhandled USSD %s\n", request_string);
> +		rc = gsm0480_send_ussd_reject(conn, req.invoke_id, reqhdr.transaction_id);
>  	}
>  
>  	/* check if we can release it */
> @@ -76,12 +106,33 @@ int handle_rcv_ussd(struct gsm_subscriber_connection *conn, struct msgb *msg)
>  }
>  
>  /* A network-specific handler function */
> -static int send_own_number(struct gsm_subscriber_connection *conn, const struct msgb *msg, const struct ussd_request *req)
> +static int send_own_number(struct gsm_subscriber_connection *conn,
> +			   const struct ss_header *reqhdr,
> +			   const struct ss_request *req)
>  {
> +	struct ss_request rss;
> +	struct ss_header rssh;
> +
>  	char *own_number = conn->subscr->extension;
>  	char response_string[GSM_EXTENSION_LENGTH + 20];
> +	int response_len;
>  
>  	/* Need trailing CR as EOT character */
>  	snprintf(response_string, sizeof(response_string), "Your extension is %s\r", own_number);
> -	return gsm0480_send_ussd_response(conn, msg, response_string, req);
> +
> +	memset(&rss, 0, sizeof(rss));
> +	gsm_7bit_encode_n_ussd(rss.ussd_text, MAX_LEN_USSD_STRING, response_string, &response_len);
> +	rss.ussd_text_len = response_len;
> +	rss.ussd_text_language = 0x0f;
> +
> +	rss.component_type = GSM0480_CTYPE_RETURN_RESULT;
> +	rss.invoke_id = req->invoke_id;
> +	rss.opcode = GSM0480_OP_CODE_PROCESS_USS_REQ;
> +
> +	rssh.message_type = GSM0480_MTYPE_RELEASE_COMPLETE;
> +	rssh.transaction_id = reqhdr->transaction_id;
> +
> +	return gsm0480_send_component(conn,
> +				      gsm0480_compose_ussd_component(&rss),
> +				      &rssh);
>  }
> -- 
> 1.9.1
> 

-- 
- Neels Hofmeyr <nhofmeyr at sysmocom.de>          http://www.sysmocom.de/
=======================================================================
* sysmocom - systems for mobile communications GmbH
* Alt-Moabit 93
* 10559 Berlin, Germany
* Sitz / Registered office: Berlin, HRB 134158 B
* Geschäftsführer / Managing Directors: Holger Freyther, Harald Welte
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