mtp: Attempt to fix the SCCP restart logic.

The SST is not necessary. We will have to assume the link is
established after having gotten the TRA on the Affected Point Code
and we will need to always handle the restart allowed.

1 files changed, 21 insertions, 26 deletions

diff --git a/src/mtp_layer3.c b/src/mtp_layer3.c
index 78db37c..d71e504 100644
--- a/src/mtp_layer3.c
+++ b/src/mtp_layer3.c
@@ -321,6 +321,9 @@ static int mtp_link_sign_msg(struct mtp_link *link, struct mtp_level_3_hdr *hdr,
 				return -1;
 
 			mtp_link_submit(link, msg);
+			link->sccp_up = 1;
+			link->was_up = 1;
+			LOGP(DINP, LOGL_INFO, "SCCP traffic allowed. %p\n", link);
 			return 0;
 			break;
 		}
@@ -405,6 +408,7 @@ static int mtp_link_sccp_data(struct mtp_link *link, struct mtp_level_3_hdr *hdr
 {
 	struct msgb *out;
 	struct sccp_con_ctrl_prt_mgt *prt;
+	struct sccp_parse_result sccp;
 
 	msg->l2h = &hdr->data[0];
 	if (msgb_l2len(msg) != l3_len) {
@@ -412,36 +416,27 @@ static int mtp_link_sccp_data(struct mtp_link *link, struct mtp_level_3_hdr *hdr
 		return -1;
 	}
 
+	if (!link->sccp_up) {
+		LOGP(DINP, LOGL_ERROR, "SCCP traffic is not allowed.\n");
+		return -1;
+	}
 
-	if (link->sccp_up) {
-		mtp_link_forward_sccp(link, msg, MTP_LINK_SLS(hdr->addr));
-		return 0;
-	} else {
-		struct sccp_parse_result sccp;
-		memset(&sccp, 0, sizeof(sccp));
-		if (sccp_parse_header(msg, &sccp) != 0) {
-			LOGP(DINP, LOGL_ERROR, "Failed to parsed SCCP header.\n");
-			return -1;
-		}
-
-		if (sccp_determine_msg_type(msg) != SCCP_MSG_TYPE_UDT) {
-			LOGP(DINP, LOGL_ERROR, "Dropping sccp data: 0x%x\n",
-			     sccp_determine_msg_type(msg));
-			return -1;
-		}
+	memset(&sccp, 0, sizeof(sccp));
+	if (sccp_parse_header(msg, &sccp) != 0) {
+		LOGP(DINP, LOGL_ERROR, "Failed to parsed SCCP header.\n");
+		return -1;
+	}
 
+	/* check if it is a SST */
+	if (sccp_determine_msg_type(msg) == SCCP_MSG_TYPE_UDT
+	    && msg->l3h[0] == SCCP_SST) {
 		if (msgb_l3len(msg) != 5) {
-			LOGP(DINP, LOGL_ERROR, "SCCP UDT msg of unexpected size: %u\n",
+			LOGP(DINP, LOGL_ERROR,
+			     "SCCP UDT msg of unexpected size: %u\n",
 			     msgb_l3len(msg));
 			return -1;
 		}
 
-		if (msg->l3h[0] != SCCP_SST) {
-			LOGP(DINP, LOGL_ERROR, "Expected SCCP SST but got 0x%x\n",
-			     msg->l3h[0]);
-			return -1;
-		}
-
 		prt = (struct sccp_con_ctrl_prt_mgt *) &msg->l3h[0];
 		if (prt->assn != 254 || prt->apoc != MTP_MAKE_APOC(link->opc)) {
 			LOGP(DINP, LOGL_ERROR, "Unknown SSN/APOC assn: %u, apoc: %u/%u\n",
@@ -453,11 +448,11 @@ static int mtp_link_sccp_data(struct mtp_link *link, struct mtp_level_3_hdr *hdr
 		if (!out)
 			return -1;
 
-		link->sccp_up = 1;
-		link->was_up = 1;
-		LOGP(DINP, LOGL_INFO, "SCCP is established. %p\n", link);
 		mtp_link_submit(link, out);
+		return 0;
 	}
+
+	mtp_link_forward_sccp(link, msg, MTP_LINK_SLS(hdr->addr));
 	return 0;
 }