[USSD] eliminate static global variables

This patch removes the need of static global variables and introduces a new,
caller-allocated 'struct ussd_request' that needs to be passed to the various
functions.

1 files changed, 46 insertions, 44 deletions

diff --git a/openbsc/src/gsm_04_80.c b/openbsc/src/gsm_04_80.c
index 052b0a77a..5d85c8221 100644
--- a/openbsc/src/gsm_04_80.c
+++ b/openbsc/src/gsm_04_80.c
@@ -37,16 +37,16 @@
 #include <openbsc/gsm_04_08.h>
 #include <openbsc/gsm_04_80.h>
 
-static char ussd_string_buff[32];
-static u_int8_t last_transaction_id;
-static u_int8_t last_invoke_id;
-
 /* Forward declarations */
-static int parse_ussd(u_int8_t *ussd);
-static int parse_ussd_information_elements(u_int8_t *ussd_ie);
-static int parse_facility_ie(u_int8_t *facility_ie, u_int8_t length);
-static int parse_ss_invoke(u_int8_t *invoke_data, u_int8_t length);
-static int parse_process_uss_req(u_int8_t *uss_req_data, u_int8_t length);
+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)
 {
@@ -69,26 +69,24 @@ static inline unsigned char *msgb_push_TLV1(struct msgb *msgb, u_int8_t tag,
 }
 
 
-/* Receive a mobile-originated USSD message and return the decoded text */
-char *gsm0480_rcv_ussd(struct msgb *msg)
+/* Decode a mobile-originated USSD-request message */
+int gsm0480_decode_ussd_request(struct msgb *msg, struct ussd_request *req)
 {
 	int rc = 0;
 	u_int8_t *parse_ptr = msgb_l3(msg);
 
-	memset(ussd_string_buff, 0, sizeof(ussd_string_buff));
-
 	if ((*parse_ptr & 0x0F) == GSM48_PDISC_NC_SS) {
-		last_transaction_id = *parse_ptr & 0x70;
-		rc = parse_ussd(parse_ptr + 1);
+		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 ussd_string_buff;
+	return rc;
 }
 
-static int parse_ussd(u_int8_t *ussd)
+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 */
@@ -97,11 +95,11 @@ static int parse_ussd(u_int8_t *ussd)
 	case GSM0480_MTYPE_RELEASE_COMPLETE:
 		DEBUGP(DMM, "USS Release Complete\n");
 		/* could also parse out the optional Cause/Facility data */
-		ussd_string_buff[0] = 0xFF;
+		req->text[0] = 0xFF;
 		break;
 	case GSM0480_MTYPE_REGISTER:
 	case GSM0480_MTYPE_FACILITY:
-		rc &= parse_ussd_information_elements(ussd+1);
+		rc &= parse_ussd_info_elements(ussd+1, req);
 		break;
 	default:
 		fprintf(stderr, "Unknown GSM 04.80 message-type field 0x%02x\n",
@@ -113,7 +111,7 @@ static int parse_ussd(u_int8_t *ussd)
 	return rc;
 }
 
-static int parse_ussd_information_elements(u_int8_t *ussd_ie)
+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 */
@@ -124,7 +122,7 @@ static int parse_ussd_information_elements(u_int8_t *ussd_ie)
 	case GSM48_IE_CAUSE:
 		break;
 	case GSM0480_IE_FACILITY:
-		rc = parse_facility_ie(ussd_ie+2, iei_length);
+		rc = parse_facility_ie(ussd_ie+2, iei_length, req);
 		break;
 	case GSM0480_IE_SS_VERSION:
 		break;
@@ -138,7 +136,8 @@ static int parse_ussd_information_elements(u_int8_t *ussd_ie)
 	return rc;
 }
 
-static int parse_facility_ie(u_int8_t *facility_ie, u_int8_t length)
+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;
@@ -150,7 +149,9 @@ static int parse_facility_ie(u_int8_t *facility_ie, u_int8_t length)
 
 		switch (component_type) {
 		case GSM0480_CTYPE_INVOKE:
-			rc &= parse_ss_invoke(facility_ie+2, component_length);
+			rc &= parse_ss_invoke(facility_ie+2, 
+						component_length, 
+						req);
 			break;
 		case GSM0480_CTYPE_RETURN_RESULT:
 			break;
@@ -171,7 +172,8 @@ static int parse_facility_ie(u_int8_t *facility_ie, u_int8_t length)
 }
 
 /* Parse an Invoke component - see table 3.3 */
-static int parse_ss_invoke(u_int8_t *invoke_data, u_int8_t length)
+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;
@@ -183,7 +185,7 @@ static int parse_ss_invoke(u_int8_t *invoke_data, u_int8_t length)
 	}
 
 	offset = invoke_data[1] + 2;
-	last_invoke_id = invoke_data[2];
+	req->invoke_id = invoke_data[2];
 
 	/* optional part */
 	if (invoke_data[offset] == GSM0480_COMPIDTAG_LINKED_ID)
@@ -195,7 +197,8 @@ static int parse_ss_invoke(u_int8_t *invoke_data, u_int8_t length)
 		switch (operation_code) {
 		case GSM0480_OP_CODE_PROCESS_USS_REQ:
 			rc = parse_process_uss_req(invoke_data + offset + 3,
-						   length - offset - 3);
+						   length - offset - 3,
+						   req);
 			break;
 		default:
 			fprintf(stderr, "GSM 04.80 operation code 0x%02x "
@@ -214,36 +217,33 @@ static int parse_ss_invoke(u_int8_t *invoke_data, u_int8_t length)
 }
 
 /* Parse the parameters of a Process UnstructuredSS Request */
-static int parse_process_uss_req(u_int8_t *uss_req_data, u_int8_t length)
+static int parse_process_uss_req(u_int8_t *uss_req_data, u_int8_t length, 
+					struct ussd_request *req)
 {
-	int rc = 1;
+	int rc = 0;
 	int num_chars;
 	u_int8_t dcs;
 
-	/* FIXME: most phones send USSD text as a 7-bit encoded octet string;
-	 * the following code also handles the case of plain ASCII text
-	 * (IA5String), but other encodings might be used */
-
 	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;
-				gsm_7bit_decode(ussd_string_buff,
+				gsm_7bit_decode(req->text,
 						&(uss_req_data[7]), num_chars);
+				/* append null-terminator */
+				req->text[num_chars+1] = 0;  
+				rc = 1;
 			}
 		}
-	} else if (uss_req_data[0] == ASN1_IA5_STRING_TAG) {
-		num_chars = uss_req_data[1];
-		memcpy(ussd_string_buff, &(uss_req_data[2]), num_chars);
-	}	
-
+	}
 	return rc;
 }
 
 /* Send response to a mobile-originated ProcessUnstructuredSS-Request */
-int gsm0480_send_ussd_response(struct msgb *in_msg, const char* response_text)
+int gsm0480_send_ussd_response(struct msgb *in_msg, const char* response_text, 
+						const struct ussd_request *req)
 {
 	struct msgb *msg = gsm48_msgb_alloc();
 	struct gsm48_hdr *gh;
@@ -278,7 +278,7 @@ int gsm0480_send_ussd_response(struct msgb *in_msg, const char* response_text)
 	msgb_wrap_with_TL(msg, GSM_0480_SEQUENCE_TAG);
 
 	/* Pre-pend the invoke ID */
-	msgb_push_TLV1(msg, GSM0480_COMPIDTAG_INVOKE_ID, last_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);
@@ -288,13 +288,15 @@ int gsm0480_send_ussd_response(struct msgb *in_msg, const char* response_text)
 
 	/* And finally pre-pend the L3 header */
 	gh = (struct gsm48_hdr *) msgb_push(msg, sizeof(*gh));
-	gh->proto_discr = GSM48_PDISC_NC_SS | last_transaction_id | (1<<7);  /* TI direction = 1 */
+	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(struct msgb *in_msg)
+int gsm0480_send_ussd_reject(struct msgb *in_msg, 
+				const struct ussd_request *req)
 {
 	struct msgb *msg = gsm48_msgb_alloc();
 	struct gsm48_hdr *gh;
@@ -307,7 +309,7 @@ int gsm0480_send_ussd_reject(struct msgb *in_msg)
 			GSM_0480_GEN_PROB_CODE_UNRECOGNISED);
 
 	/* Before it insert the invoke ID */
-	msgb_push_TLV1(msg, GSM0480_COMPIDTAG_INVOKE_ID, last_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);
@@ -318,7 +320,7 @@ int gsm0480_send_ussd_reject(struct msgb *in_msg)
 	/* 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 |= last_transaction_id | (1<<7);  /* TI direction = 1 */
+	gh->proto_discr |= req->transaction_id | (1<<7);  /* TI direction = 1 */
 	gh->msg_type = GSM0480_MTYPE_RELEASE_COMPLETE;
 
 	return gsm48_sendmsg(msg, NULL);