Have "get_xdlc_control()" and "dissect_xdlc_control()" return the

xDLC control field, so that its caller can not only determine from it
whether the frame has a payload, but can also determine how long the
control field is.  Put macros in "xdlc.h" to determine both of those.

Have "capture_llc()" and "dissect_llc()" use that information
appropriately.

svn path=/trunk/; revision=727

3 files changed, 71 insertions, 67 deletions

diff --git a/packet-llc.c b/packet-llc.c
index 76aeb58af8..ab02829dcb 100644
--- a/packet-llc.c
+++ b/packet-llc.c
@@ -2,7 +2,7 @@
  * Routines for IEEE 802.2 LLC layer
  * Gilbert Ramirez <gramirez@tivoli.com>
  *
- * $Id: packet-llc.c,v 1.21 1999/08/23 23:24:35 guy Exp $
+ * $Id: packet-llc.c,v 1.22 1999/09/26 20:31:50 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@unicom.net>
@@ -163,7 +163,7 @@ void
 capture_llc(const u_char *pd, int offset, guint32 cap_len, packet_counts *ld) {
 
 	int		is_snap;
-	int		has_payload;
+	guint16		control;
 	guint16		etype;
 	capture_func_t	*capture;
 
@@ -184,10 +184,10 @@ capture_llc(const u_char *pd, int offset, guint32 cap_len, packet_counts *ld) {
 	 * extended operation, so we don't need to determine whether
 	 * it's basic or extended operation; is that the case?
 	 */
-	has_payload = get_xdlc_control(pd, offset+2, pd[offset+1] & 0x01, TRUE);
+	control = get_xdlc_control(pd, offset+2, pd[offset+1] & 0x01, TRUE);
 
 	if (is_snap) {
-		if (has_payload) {
+		if (XDLC_HAS_PAYLOAD(control)) {
 			/*
 			 * This frame has a payload to be analyzed.
 			 */
@@ -197,14 +197,14 @@ capture_llc(const u_char *pd, int offset, guint32 cap_len, packet_counts *ld) {
 		}
 	}		
 	else {
-		if (has_payload) {
+		if (XDLC_HAS_PAYLOAD(control)) {
 			/*
 			 * This frame has a payload to be analyzed.
 			 */
 			capture = sap_capture_func(pd[offset]);
 
 			/* non-SNAP */
-			offset += 3;
+			offset += XDLC_CONTROL_LEN(control, TRUE);
 
 			if (capture) {
 				capture(pd, offset, cap_len, ld);
@@ -220,9 +220,9 @@ void
 dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
 
 	proto_tree	*llc_tree = NULL;
-	proto_item	*ti;
+	proto_item	*ti = NULL;
 	int		is_snap;
-	int		has_payload;
+	guint16		control;
 	guint16		etype;
 	dissect_func_t	*dissect;
 
@@ -255,8 +255,10 @@ dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
 	 * extended operation, so we don't need to determine whether
 	 * it's basic or extended operation; is that the case?
 	 */
-	has_payload = dissect_xdlc_control(pd, offset+2, fd, llc_tree,
+	control = dissect_xdlc_control(pd, offset+2, fd, llc_tree,
 				hf_llc_ctrl, pd[offset+1] & 0x01, TRUE);
+	if (tree)
+		proto_item_set_len(ti, XDLC_CONTROL_LEN(control, TRUE));
 
 	/*
 	 * XXX - do we want to append the SAP information to the stuff
@@ -271,7 +273,7 @@ dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
 			proto_tree_add_item(llc_tree, hf_llc_oui, offset+3, 3,
 				pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5]);
 		}
-		if (has_payload) {
+		if (XDLC_HAS_PAYLOAD(control)) {
 			/*
 			 * This frame has a payload to be analyzed.
 			 */
@@ -288,14 +290,14 @@ dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
 				val_to_str(pd[offset], sap_vals, "%02x"));
 		}
 
-		if (has_payload) {
+		if (XDLC_HAS_PAYLOAD(control)) {
 			/*
 			 * This frame has a payload to be analyzed.
 			 */
 			dissect = sap_dissect_func(pd[offset]);
 
 			/* non-SNAP */
-			offset += 3;
+			offset += XDLC_CONTROL_LEN(control, TRUE);
 
 			if (dissect) {
 				dissect(pd, offset, fd, tree);
diff --git a/xdlc.c b/xdlc.c
index e0203a602e..c5e0cdfcc8 100644
--- a/xdlc.c
+++ b/xdlc.c
@@ -2,7 +2,7 @@
  * Routines for use by various SDLC-derived protocols, such as HDLC
  * and its derivatives LAPB, IEEE 802.2 LLC, etc..
  *
- * $Id: xdlc.c,v 1.8 1999/09/26 13:34:10 gram Exp $
+ * $Id: xdlc.c,v 1.9 1999/09/26 20:31:50 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@unicom.net>
@@ -66,31 +66,6 @@
 #define XDLC_REJ		0x08	/* Reject */
 #define XDLC_SREJ		0x0C	/* Selective reject */
 
-/*
- * U-format modifiers.
- */
-#define XDLC_U_MODIFIER_MASK	0xEC
-#define XDLC_UI		0x00	/* Unnumbered Information */
-#define XDLC_UP		0x20	/* Unnumbered Poll */
-#define XDLC_DISC	0x40	/* Disconnect (command) */
-#define XDLC_RD		0x40	/* Request Disconnect (response) */
-#define XDLC_UA		0x60	/* Unnumbered Acknowledge */
-#define XDLC_SNRM	0x80	/* Set Normal Response Mode */
-#define XDLC_TEST	0xE0	/* Test */
-#define XDLC_SIM	0x04	/* Set Initialization Mode (command) */
-#define XDLC_RIM	0x04	/* Request Initialization Mode (response) */
-#define XDLC_FRMR	0x84	/* Frame reject */
-#define XDLC_CFGR	0xC4	/* Configure */
-#define XDLC_SARM	0x0C	/* Set Asynchronous Response Mode (command) */
-#define XDLC_DM		0x0C	/* Disconnected mode (response) */
-#define XDLC_SABM	0x2C	/* Set Asynchronous Balanced Mode */
-#define XDLC_SARME	0x4C	/* Set Asynchronous Response Mode Extended */
-#define XDLC_SABME	0x6C	/* Set Asynchronous Balanced Mode Extended */
-#define XDLC_RESET	0x8C	/* Reset */
-#define XDLC_XID	0xAC	/* Exchange identification */
-#define XDLC_SNRME	0xCC	/* Set Normal Response Mode Extended */
-#define XDLC_BCN	0xEC	/* Beacon */
-
 static const value_string stype_vals[] = {
     { XDLC_RR,   "Receiver ready" },
     { XDLC_RNR,  "Receiver not ready" },
@@ -192,10 +167,15 @@ get_xdlc_control(const u_char *pd, int offset, int is_response, int is_extended)
     switch (pd[offset] & 0x03) {
 
     case XDLC_S:
+    default:
         /*
-	 * Supervisory frame - no higher-layer payload.
+	 * Supervisory or Information frame.
 	 */
-	return FALSE;
+	if (is_extended)
+		control = pletohs(&pd[offset]);
+	else
+		control = pd[offset];
+	break;
 
     case XDLC_U:
 	/*
@@ -209,18 +189,9 @@ get_xdlc_control(const u_char *pd, int offset, int is_response, int is_extended)
 	 * need for it to be 2 bytes in extended operation.
 	 */
 	control = pd[offset];
-
-	/*
-	 * This frame has payload only if it's a UI frame.
-	 */
-	return (control & XDLC_U_MODIFIER_MASK) == XDLC_UI;
-
-    default:
-	/*
-	 * Information frame - has higher-layer payload.
-	 */
-	return TRUE;
+	break;
     }
+    return control;
 }
 
 int
@@ -321,11 +292,7 @@ dissect_xdlc_control(const u_char *pd, int offset, frame_data *fd,
 			"Supervisory frame", NULL));
 	    }
 	}
-
-	/*
-	 * Supervisory frames have no higher-layer payload to be analyzed.
-	 */
-	return FALSE;
+	break;
 
     case XDLC_U:
 	/*
@@ -375,11 +342,7 @@ dissect_xdlc_control(const u_char *pd, int offset, frame_data *fd,
 		decode_boolean_bitfield(control, 0x03, 1*8,
 		    "Unnumbered frame", NULL));
 	}
-
-	/*
-	 * This frame has payload only if it's a UI frame.
-	 */
-	return (control & XDLC_U_MODIFIER_MASK) == XDLC_UI;
+	break;
 
     default:
 	/*
@@ -444,10 +407,6 @@ dissect_xdlc_control(const u_char *pd, int offset, frame_data *fd,
 			NULL, "Information frame"));
 	    }
 	}
-
-	/*
-	 * Information frames have higher-layer payload to be analyzed.
-	 */
-	return TRUE;
     }
+    return control;
 }
diff --git a/xdlc.h b/xdlc.h
index 69fb908c34..d3092719c0 100644
--- a/xdlc.h
+++ b/xdlc.h
@@ -2,7 +2,7 @@
  * Define *DLC frame types, and routine to dissect the control field of
  * a *DLC frame.
  *
- * $Id: xdlc.h,v 1.3 1999/08/23 23:24:36 guy Exp $
+ * $Id: xdlc.h,v 1.4 1999/09/26 20:31:51 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@unicom.net>
@@ -32,6 +32,49 @@
 #define XDLC_S		0x01	/* Supervisory frames */
 #define XDLC_U		0x03	/* Unnumbered frames */
 
+/*
+ * U-format modifiers.
+ */
+#define XDLC_U_MODIFIER_MASK	0xEC
+#define XDLC_UI		0x00	/* Unnumbered Information */
+#define XDLC_UP		0x20	/* Unnumbered Poll */
+#define XDLC_DISC	0x40	/* Disconnect (command) */
+#define XDLC_RD		0x40	/* Request Disconnect (response) */
+#define XDLC_UA		0x60	/* Unnumbered Acknowledge */
+#define XDLC_SNRM	0x80	/* Set Normal Response Mode */
+#define XDLC_TEST	0xE0	/* Test */
+#define XDLC_SIM	0x04	/* Set Initialization Mode (command) */
+#define XDLC_RIM	0x04	/* Request Initialization Mode (response) */
+#define XDLC_FRMR	0x84	/* Frame reject */
+#define XDLC_CFGR	0xC4	/* Configure */
+#define XDLC_SARM	0x0C	/* Set Asynchronous Response Mode (command) */
+#define XDLC_DM		0x0C	/* Disconnected mode (response) */
+#define XDLC_SABM	0x2C	/* Set Asynchronous Balanced Mode */
+#define XDLC_SARME	0x4C	/* Set Asynchronous Response Mode Extended */
+#define XDLC_SABME	0x6C	/* Set Asynchronous Balanced Mode Extended */
+#define XDLC_RESET	0x8C	/* Reset */
+#define XDLC_XID	0xAC	/* Exchange identification */
+#define XDLC_SNRME	0xCC	/* Set Normal Response Mode Extended */
+#define XDLC_BCN	0xEC	/* Beacon */
+
+/*
+ * This macro takes the control field of an xDLC frame, as returned by
+ * "get_xdlc_control()" or "dissect_xdlc_control()", and evaluates to
+ * TRUE if the frame has a payload (i.e., if it's an Information or
+ * Unnumbered Information frame) and FALSE if it doesn't.
+ */
+#define XDLC_HAS_PAYLOAD(control) \
+	((control) == XDLC_I || (control) == (XDLC_UI|XDLC_U))
+
+/*
+ * This macro takes the control field of an xDLC frame, and a flag saying
+ * whether we're doing basic or extended operation, and evaluates to
+ * the length of that field (if it's an Unnumbered frame, or we're not
+ * in extended mode, it's 3 bytes long, otherwise it's 4 bytes long).
+ */
+#define XDLC_CONTROL_LEN(control, is_extended) \
+	(((control) == XDLC_U || !(is_extended)) ? 3 : 4)
+
 int get_xdlc_control(const u_char *pd, int offset, int is_response,
   int extended);