Convert X.25 dissector to use tvbuffs.

svn path=/trunk/; revision=2007

1 files changed, 582 insertions, 544 deletions

diff --git a/packet-x25.c b/packet-x25.c
index 5f004a9d7b..fbc99db69f 100644
--- a/packet-x25.c
+++ b/packet-x25.c
@@ -2,7 +2,7 @@
  * Routines for x25 packet disassembly
  * Olivier Abad <abad@daba.dhis.net>
  *
- * $Id: packet-x25.c,v 1.27 2000/05/19 23:06:09 gram Exp $
+ * $Id: packet-x25.c,v 1.28 2000/05/25 21:34:57 oabad Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@zing.org>
@@ -622,37 +622,38 @@ static char *registration_code(unsigned char code)
 }
 
 void
-dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
+dump_facilities(proto_tree *tree, int *offset, tvbuff_t *tvb)
 {
-    const guint8 *ptr = p;
+    guint8 fac, byte1, byte2, byte3;
     guint32 len;      /* facilities length */
     proto_item *ti=0;
     proto_tree *fac_tree = 0;
     proto_tree *fac_subtree;
 
-    len = *ptr++;
+    len = tvb_get_guint8(tvb, *offset);
     if (len && tree) {
-	ti = proto_tree_add_text(tree, NullTVB, *offset, len + 1,
+	ti = proto_tree_add_text(tree, tvb, *offset, len + 1,
 		                 "Facilities");
 	fac_tree = proto_item_add_subtree(ti, ett_x25_fac);
-	proto_tree_add_text(fac_tree, NullTVB, *offset, 1,
+	proto_tree_add_text(fac_tree, tvb, *offset, 1,
 			    "Facilities length: %d", len);
     }
     (*offset)++;
 
     while (len > 0) {
-	switch(*ptr & X25_FAC_CLASS_MASK) {
+	fac = tvb_get_guint8(tvb, *offset);
+	switch(fac & X25_FAC_CLASS_MASK) {
 	case X25_FAC_CLASS_A:
-	    switch (*ptr) {
+	    switch (fac) {
 	    case X25_FAC_COMP_MARK:
 		if (fac_tree)
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1,
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1,
 			    "Code : 00 (Marker)");
-		switch (ptr[1]) {
+		switch (tvb_get_guint8(tvb, *offset + 1)) {
 		case 0x00:
 		    if (fac_tree) {
 			fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_mark);
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
+			proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
 					    "Parameter : 00 (Network complementary "
 					    "services - calling DTE)");
 		    }
@@ -660,7 +661,7 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		case 0xFF:
 		    if (fac_tree) {
 			fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_mark);
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
+			proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
 					    "Parameter : FF (Network complementary "
 					    "services - called DTE)");
 		    }
@@ -668,7 +669,7 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		case 0x0F:
 		    if (fac_tree) {
 			fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_mark);
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
+			proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
 					    "Parameter : 0F (DTE complementary "
 					    "services)");
 		    }
@@ -676,31 +677,32 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		default:
 		    if (fac_tree) {
 			fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_mark);
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
+			proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
 					    "Parameter : %02X (Unknown marker)",
-					    ptr[1]);
+					    tvb_get_guint8(tvb, *offset+1));
 		    }
 		    break;
 		}
 		break;
 	    case X25_FAC_REVERSE:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Reverse charging / Fast select)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Reverse charging / Fast select)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_reverse);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1, "Parameter : %02X",
-			    ptr[1]);
-		    if (ptr[1] & 0xC0)
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
+		    byte1 = tvb_get_guint8(tvb, *offset + 1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Parameter : %02X", byte1);
+		    if (byte1 & 0xC0)
+			proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
 				"11.. .... = Fast select with restriction");
-		    else if (ptr[1] & 0x80)
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
+		    else if (byte1 & 0x80)
+			proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
 				"10.. .... = Fast select - no restriction");
 		    else
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
+			proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
 				"00.. .... = Fast select not requested");
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    decode_boolean_bitfield(ptr[1], 0x01, 1*8,
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    decode_boolean_bitfield(byte1, 0x01, 1*8,
 				"Reverse charging requested",
 				"Reverse charging not requested"));
 		}
@@ -709,10 +711,11 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		if (fac_tree) {
 		    char tmpbuf[80];
 
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Throughput class negociation)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Throughput class negociation)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_throughput);
-		    switch (ptr[1] >> 4)
+		    byte1 = tvb_get_guint8(tvb, *offset + 1);
+		    switch (byte1 >> 4)
 		    {
 		    case 3:
 		    case 4:
@@ -724,7 +727,7 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		    case 10:
 		    case 11:
 			sprintf(tmpbuf, "From the called DTE : %%u (%d bps)",
-				75*(1<<((ptr[1] >> 4)-3)));
+				75*(1<<((byte1 >> 4)-3)));
 			break;
 		    case 12:
 			sprintf(tmpbuf, "From the called DTE : %%u (48000 bps)");
@@ -735,9 +738,9 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		    default:
 			sprintf(tmpbuf, "From the called DTE : %%u (Reserved)");
 		    }
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    decode_numeric_bitfield(ptr[1], 0xF0, 1*8, tmpbuf));
-		    switch (ptr[1] & 0x0F)
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    decode_numeric_bitfield(byte1, 0xF0, 1*8, tmpbuf));
+		    switch (byte1 & 0x0F)
 		    {
 		    case 3:
 		    case 4:
@@ -749,7 +752,7 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		    case 10:
 		    case 11:
 			sprintf(tmpbuf, "From the calling DTE : %%u (%d bps)",
-				75*(1<<((ptr[1] & 0x0F)-3)));
+				75*(1<<((byte1 & 0x0F)-3)));
 			break;
 		    case 12:
 			sprintf(tmpbuf, "From the calling DTE : %%u (48000 bps)");
@@ -760,85 +763,84 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		    default:
 			sprintf(tmpbuf, "From the calling DTE : %%u (Reserved)");
 		    }
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    decode_numeric_bitfield(ptr[1], 0x0F, 1*8, tmpbuf));
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    decode_numeric_bitfield(byte1, 0x0F, 1*8, tmpbuf));
 		}
 		break;
 	    case X25_FAC_CUG:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Closed user group selection)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Closed user group selection)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_cug);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Closed user group: %02X", ptr[1]);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Closed user group: %02X", tvb_get_guint8(tvb, *offset+1));
 		}
 		break;
 	    case X25_FAC_CALLED_MODIF:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Called address modified)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Called address modified)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_called_modif);
-		    proto_tree_add_text(fac_tree, NullTVB, *offset, 2,
-			    "Parameter %02X", ptr[1]);
+		    proto_tree_add_text(fac_tree, tvb, *offset+1, 1,
+			    "Parameter %02X", tvb_get_guint8(tvb, *offset+1));
 		}
 		break;
 	    case X25_FAC_CUG_OUTGOING_ACC:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
 			    "(Closed user group with outgoing access selection)",
-			    *ptr);
+			    fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_cug_outgoing_acc);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Closed user group: %02X", ptr[1]);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Closed user group: %02X", tvb_get_guint8(tvb, *offset+1));
 		}
 		break;
 	    case X25_FAC_THROUGHPUT_MIN:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Minimum throughput class)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Minimum throughput class)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_throughput_min);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Parameter %02X", ptr[1]);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Parameter %02X", tvb_get_guint8(tvb, *offset+1));
 		}
 		break;
 	    case X25_FAC_EXPRESS_DATA:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Negociation of express data)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Negociation of express data)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_express_data);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Parameter %02X", ptr[1]);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Parameter %02X", tvb_get_guint8(tvb, *offset+1));
 		}
 		break;
 	    default:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1,
-			    "Code : %02X (Unknown class A)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1,
+			    "Code : %02X (Unknown class A)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_unknown);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Parameter %02X", ptr[1]);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Parameter %02X", tvb_get_guint8(tvb, *offset+1));
 		}
 		break;
 	    }
 	    (*offset) += 2;
 	    len -= 2;
-	    ptr += 2;
 	    break;
 	case X25_FAC_CLASS_B:
-	    switch (*ptr) {
+	    switch (fac) {
 	    case X25_FAC_BILATERAL_CUG:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Bilateral closed user group selection)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Bilateral closed user group selection)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_bilateral_cug);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 2,
-					"Bilateral CUG: %02X%02X",
-					ptr[1], ptr[2]);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 2,
+					"Bilateral CUG: %04X",
+					tvb_get_ntohs(tvb, *offset+1));
 		}
 		break;
 	    case X25_FAC_PACKET_SIZE:
@@ -846,10 +848,11 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		{
 		    char tmpbuf[80];
 
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Packet size)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Packet size)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_packet_size);
-		    switch (ptr[1])
+		    byte1 = tvb_get_guint8(tvb, *offset + 1);
+		    switch (byte1)
 		    {
 		    case 0x04:
 			sprintf(tmpbuf, "From the called DTE : %%u (16)");
@@ -882,10 +885,11 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 			sprintf(tmpbuf, "From the called DTE : %%u (Unknown)");
 			break;
 		    }
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    decode_numeric_bitfield(ptr[1], 0x0F, 1*8, tmpbuf));
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    decode_numeric_bitfield(byte1, 0x0F, 1*8, tmpbuf));
 
-		    switch (ptr[2])
+		    byte2 = tvb_get_guint8(tvb, *offset + 1);
+		    switch (byte2)
 		    {
 		    case 0x04:
 			sprintf(tmpbuf, "From the calling DTE : %%u (16)");
@@ -918,128 +922,132 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 			sprintf(tmpbuf, "From the calling DTE : %%u (Unknown)");
 			break;
 		    }
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
-			    decode_numeric_bitfield(ptr[2], 0x0F, 1*8, tmpbuf));
+		    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
+			    decode_numeric_bitfield(byte2, 0x0F, 1*8, tmpbuf));
 		}
 		break;
 	    case X25_FAC_WINDOW_SIZE:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Window size)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Window size)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_window_size);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    decode_numeric_bitfield(ptr[1], 0x7F, 1*8,
-			    "From the called DTE: %u"));
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
-			    decode_numeric_bitfield(ptr[2], 0x7F, 1*8,
-			    "From the calling DTE: %u"));
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    decode_numeric_bitfield(tvb_get_guint8(tvb, *offset+1),
+				0x7F, 1*8, "From the called DTE: %u"));
+		    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
+			    decode_numeric_bitfield(tvb_get_guint8(tvb, *offset+2),
+				0x7F, 1*8, "From the calling DTE: %u"));
 		}
 		break;
 	    case X25_FAC_RPOA_SELECTION:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(RPOA selection)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(RPOA selection)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_rpoa_selection);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 2,
-					"Data network identification code : %02X%02X",
-					ptr[1], ptr[2]);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 2,
+					"Data network identification code : %04X",
+					tvb_get_ntohs(tvb, *offset+1));
 		}
 		break;
 	    case X25_FAC_TRANSIT_DELAY:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Transit delay selection and indication)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Transit delay selection and indication)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_transit_delay);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 2,
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 2,
 					"Transit delay: %d ms",
-					(ptr[1]<<8) + ptr[2]);
+					tvb_get_ntohs(tvb, *offset+1));
 		}
 		break;
 	    default:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1,
-			    "Code : %02X (Unknown class B)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1,
+			    "Code : %02X (Unknown class B)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_unknown);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 2,
-			    "Parameter %02X%02X", ptr[1], ptr[2]);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 2,
+			    "Parameter %04X", tvb_get_ntohs(tvb, *offset+1));
 		}
 		break;
 	    }
 	    (*offset) += 3;
 	    len -= 3;
-	    ptr += 3;
 	    break;
 	case X25_FAC_CLASS_C:
 	    if (fac_tree) {
-		ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1,
-			"Code : %02X (Unknown class C)", *ptr);
+		ti = proto_tree_add_text(fac_tree, tvb, *offset, 1,
+			"Code : %02X (Unknown class C)", fac);
 		fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_unknown);
-		proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 3,
-			"Parameter %02X%02X%02X",
-			ptr[1], ptr[2], ptr[3]);
+		proto_tree_add_text(fac_subtree, tvb, *offset+1, 3,
+			"Parameter %06X",
+			tvb_get_ntoh24(tvb, *offset+1));
 	    }
 	    (*offset) += 4;
 	    len -= 4;
-	    ptr += 4;
 	    break;
 	case X25_FAC_CLASS_D:
-	    switch (*ptr) {
+	    switch (fac) {
 	    case X25_FAC_CALL_TRANSFER:
 		if (fac_tree) {
 		    int i;
 		    char tmpbuf[256];
 
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Call redirection or deflection notification)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Call redirection or deflection notification)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_call_transfer);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Length : %u", ptr[1]);
-		    if ((ptr[2] & 0xC0) == 0xC0) {
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
+		    byte1 = tvb_get_guint8(tvb, *offset+1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Length : %u", byte1);
+		    byte2 = tvb_get_guint8(tvb, *offset+2);
+		    if ((byte2 & 0xC0) == 0xC0) {
+			proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
 				"Reason : call deflection by the originally "
 				"called DTE address");
 		    }
 		    else {
-			switch (ptr[2]) {
+			switch (byte2) {
 			case 0x01:
-			    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
+			    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
 				    "Reason : originally called DTE busy");
 			    break;
 			case 0x07:
-			    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
+			    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
 				    "Reason : call dist. within a hunt group");
 			    break;
 			case 0x09:
-			    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
+			    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
 				    "Reason : originally called DTE out of order");
 			    break;
 			case 0x0F:
-			    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
+			    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
 				    "Reason : systematic call redirection");
 			    break;
 			default:
-			    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
+			    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
 				    "Reason : unknown");
 			    break;
 			}
 		    }
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+3, 1,
-			    "Number of semi-octets in DTE address : %u", ptr[3]);
-		    for (i = 0; i < ptr[3]; i++) {
+		    byte3 = tvb_get_guint8(tvb, *offset+3);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+3, 1,
+			    "Number of semi-octets in DTE address : %u",
+			    byte3);
+		    for (i = 0; i < byte3; i++) {
 			if (i % 2 == 0) {
-			    tmpbuf[i] = ((ptr[4+i/2] >> 4) & 0x0F) + '0';
+			    tmpbuf[i] = ((tvb_get_guint8(tvb, *offset+4+i/2) >> 4)
+				    & 0x0F) + '0';
 			    /* if > 9, convert to the right hexadecimal letter */
 			    if (tmpbuf[i] > '9') tmpbuf[i] += ('A' - '0' - 10);
 			} else {
-			    tmpbuf[i] = (ptr[4+i/2] & 0x0F) + '0';
+			    tmpbuf[i] = (tvb_get_guint8(tvb, *offset+4+i/2)
+				    & 0x0F) + '0';
 			    /* if > 9, convert to the right hexadecimal letter */
 			    if (tmpbuf[i] > '9') tmpbuf[i] += ('A' - '0' - 10);
 			}
 		    }
 		    tmpbuf[i] = 0;
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+4, ptr[1] - 2,
+		    proto_tree_add_text(fac_subtree, tvb, *offset+4, byte1 - 2,
 			    "DTE address : %s", tmpbuf);
 		}
 		break;
@@ -1048,27 +1056,31 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		    int i;
 		    char tmpbuf[256];
 
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Calling address extension)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Calling address extension)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_calling_addr_ext);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Length : %u", ptr[1]);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
-			    "Number of semi-octets in DTE address : %u", ptr[2]);
-		    for (i = 0; i < ptr[2]; i++) {
+		    byte1 = tvb_get_guint8(tvb, *offset+1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Length : %u", byte1);
+		    byte2 = tvb_get_guint8(tvb, *offset+2);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
+			    "Number of semi-octets in DTE address : %u", byte2);
+		    for (i = 0; i < byte2; i++) {
 			if (i % 2 == 0) {
-			    tmpbuf[i] = ((ptr[3+i/2] >> 4) & 0x0F) + '0';
+			    tmpbuf[i] = ((tvb_get_guint8(tvb, *offset+3+i/2) >> 4)
+				    & 0x0F) + '0';
 			    /* if > 9, convert to the right hexadecimal letter */
 			    if (tmpbuf[i] > '9') tmpbuf[i] += ('A' - '0' - 10);
 			} else {
-			    tmpbuf[i] = (ptr[3+i/2] & 0x0F) + '0';
+			    tmpbuf[i] = (tvb_get_guint8(tvb, *offset+3+i/2)
+				    & 0x0F) + '0';
 			    /* if > 9, convert to the right hexadecimal letter */
 			    if (tmpbuf[i] > '9') tmpbuf[i] += ('A' - '0' - 10);
 			}
 		    }
 		    tmpbuf[i] = 0;
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+3, ptr[1] - 1,
+		    proto_tree_add_text(fac_subtree, tvb, *offset+3, byte1 - 1,
 			    "DTE address : %s", tmpbuf);
 		}
 		break;
@@ -1077,39 +1089,44 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		    int i;
 		    char tmpbuf[256];
 
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Called address extension)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Called address extension)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_called_addr_ext);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Length : %u", ptr[1]);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
-			    "Number of semi-octets in DTE address : %u", ptr[2]);
-		    for (i = 0; i < ptr[2]; i++) {
+		    byte1 = tvb_get_guint8(tvb, *offset+1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Length : %u", byte1);
+		    byte2 = tvb_get_guint8(tvb, *offset+2);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
+			    "Number of semi-octets in DTE address : %u", byte2);
+		    for (i = 0; i < byte2; i++) {
 			if (i % 2 == 0) {
-			    tmpbuf[i] = ((ptr[3+i/2] >> 4) & 0x0F) + '0';
+			    tmpbuf[i] = ((tvb_get_guint8(tvb, *offset+3+i/2) >> 4)
+				    & 0x0F) + '0';
 			    /* if > 9, convert to the right hexadecimal letter */
 			    if (tmpbuf[i] > '9') tmpbuf[i] += ('A' - '0' - 10);
 			} else {
-			    tmpbuf[i] = (ptr[3+i/2] & 0x0F) + '0';
+			    tmpbuf[i] = (tvb_get_guint8(tvb, *offset+3+i/2)
+				    & 0x0F) + '0';
 			    /* if > 9, convert to the right hexadecimal letter */
 			    if (tmpbuf[i] > '9') tmpbuf[i] += ('A' - '0' - 10);
 			}
 		    }
 		    tmpbuf[i] = 0;
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+3, ptr[1] - 1,
+		    proto_tree_add_text(fac_subtree, tvb, *offset+3, byte1 - 1,
 			    "DTE address : %s", tmpbuf);
 		}
 		break;
 	    case X25_FAC_ETE_TRANSIT_DELAY:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(End to end transit delay)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(End to end transit delay)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_ete_transit_delay);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Length : %u", ptr[1]);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, ptr[1], "Value");
+		    byte1 = tvb_get_guint8(tvb, *offset+1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Length : %u", byte1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+2, byte1, "Value");
 		}
 		break;
 	    case X25_FAC_CALL_DEFLECT:
@@ -1117,106 +1134,119 @@ dump_facilities(proto_tree *tree, int *offset, const guint8 *p)
 		    int i;
 		    char tmpbuf[256];
 
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1, "Code : %02X "
-			    "(Call deflection selection)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1, "Code : %02X "
+			    "(Call deflection selection)", fac);
 		    fac_subtree = proto_item_add_subtree(ti,
 			    ett_x25_fac_call_deflect);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Length : %u", ptr[1]);
-		    if ((ptr[2] & 0xC0) == 0xC0)
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
+		    byte1 = tvb_get_guint8(tvb, *offset+1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Length : %u", byte1);
+		    byte2 = tvb_get_guint8(tvb, *offset+2);
+		    if ((byte2 & 0xC0) == 0xC0)
+			proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
 				"Reason : call DTE originated");
 		    else
-			proto_tree_add_text(fac_subtree, NullTVB, *offset+2, 1,
+			proto_tree_add_text(fac_subtree, tvb, *offset+2, 1,
 				"Reason : unknown");
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+3, 1,
+		    byte3 = tvb_get_guint8(tvb, *offset+3);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+3, 1,
 			    "Number of semi-octets in the alternative DTE address : %u",
-			    ptr[3]);
-		    for (i = 0; i < ptr[3]; i++) {
+			    byte3);
+		    for (i = 0; i < byte3; i++) {
 			if (i % 2 == 0) {
-			    tmpbuf[i] = ((ptr[4+i/2] >> 4) & 0x0F) + '0';
+			    tmpbuf[i] = ((tvb_get_guint8(tvb, *offset+4+i/2) >> 4)
+				    & 0x0F) + '0';
 			    /* if > 9, convert to the right hexadecimal letter */
 			    if (tmpbuf[i] > '9') tmpbuf[i] += ('A' - '0' - 10);
 			} else {
-			    tmpbuf[i] = (ptr[4+i/2] & 0x0F) + '0';
+			    tmpbuf[i] = (tvb_get_guint8(tvb, *offset+4+i/2)
+				    & 0x0F) + '0';
 			    /* if > 9, convert to the right hexadecimal letter */
 			    if (tmpbuf[i] > '9') tmpbuf[i] += ('A' - '0' - 10);
 			}
 		    }
 		    tmpbuf[i] = 0;
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+4, ptr[1] - 2,
+		    proto_tree_add_text(fac_subtree, tvb, *offset+4, byte1 - 2,
 			    "Alternative DTE address : %s", tmpbuf);
 		}
 		break;
 	    case X25_FAC_PRIORITY:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1,
-			    "Code : %02X (Priority)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1,
+			    "Code : %02X (Priority)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_priority);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Length : %u", ptr[1]);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, ptr[1], "Value");
+		    byte1 = tvb_get_guint8(tvb, *offset+1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Length : %u", byte1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+2, byte1, "Value");
 		}
 		break;
 	    default:
 		if (fac_tree) {
-		    ti = proto_tree_add_text(fac_tree, NullTVB, *offset, 1,
-			    "Code : %02X (Unknown class D)", *ptr);
+		    ti = proto_tree_add_text(fac_tree, tvb, *offset, 1,
+			    "Code : %02X (Unknown class D)", fac);
 		    fac_subtree = proto_item_add_subtree(ti, ett_x25_fac_unknown);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+1, 1,
-			    "Length : %u", ptr[1]);
-		    proto_tree_add_text(fac_subtree, NullTVB, *offset+2, ptr[1], "Value");
+		    byte1 = tvb_get_guint8(tvb, *offset+1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+1, 1,
+			    "Length : %u", byte1);
+		    proto_tree_add_text(fac_subtree, tvb, *offset+2, byte1, "Value");
 		}
 	    }
-	    (*offset) += ptr[1]+2;
-	    len -= ptr[1]+2;
-	    ptr += ptr[1]+2;
+	    byte1 = tvb_get_guint8(tvb, *offset+1);
+	    (*offset) += byte1+2;
+	    len -= byte1+2;
 	    break;
 	}
     }
 }
 
 void
-x25_ntoa(proto_tree *tree, int *offset, const guint8 *p,
+x25_ntoa(proto_tree *tree, int *offset, tvbuff_t *tvb,
 	 frame_data *fd, gboolean toa)
 {
     int len1, len2;
     int i;
     char addr1[16], addr2[16];
     char *first, *second;
+    guint8 byte;
+    int localoffset;
 
-    len1  = (*p >> 4) & 0x0F;
-    len2 = (*p >> 0) & 0x0F;
+    byte = tvb_get_guint8(tvb, *offset);
+    len1 = (byte >> 4) & 0x0F;
+    len2 = (byte >> 0) & 0x0F;
     if (tree) {
-	proto_tree_add_text(tree, NullTVB, *offset, 1,
-		decode_numeric_bitfield(*p, 0xF0, 1*8,
+	proto_tree_add_text(tree, tvb, *offset, 1,
+		decode_numeric_bitfield(byte, 0xF0, 1*8,
 		    toa ? "Called address length : %u" :
 		          "Calling address length : %u"));
-	proto_tree_add_text(tree, NullTVB, *offset, 1,
-		decode_numeric_bitfield(*p, 0x0F, 1*8,
+	proto_tree_add_text(tree, tvb, *offset, 1,
+		decode_numeric_bitfield(byte, 0x0F, 1*8,
 		    toa ? "Calling address length : %u" :
 		          "Called address length : %u"));
     }
     (*offset)++;
 
-    p++;
+    localoffset = *offset;
+    byte = tvb_get_guint8(tvb, localoffset);
 
     first=addr1;
     second=addr2;
     for (i = 0; i < (len1 + len2); i++) {
 	if (i < len1) {
 	    if (i % 2 != 0) {
-		*first++ = ((*p >> 0) & 0x0F) + '0';
-		p++;
+		*first++ = ((byte >> 0) & 0x0F) + '0';
+		localoffset++;
+		byte = tvb_get_guint8(tvb, localoffset);
 	    } else {
-		*first++ = ((*p >> 4) & 0x0F) + '0';
+		*first++ = ((byte >> 4) & 0x0F) + '0';
 	    }
 	} else {
 	    if (i % 2 != 0) {
-		*second++ = ((*p >> 0) & 0x0F) + '0';
-		p++;
+		*second++ = ((byte >> 0) & 0x0F) + '0';
+		localoffset++;
+		byte = tvb_get_guint8(tvb, localoffset);
 	    } else {
-		*second++ = ((*p >> 4) & 0x0F) + '0';
+		*second++ = ((byte >> 4) & 0x0F) + '0';
 	    }
 	}
     }
@@ -1234,7 +1264,7 @@ x25_ntoa(proto_tree *tree, int *offset, const guint8 *p,
 		col_add_str(fd, COL_RES_DL_SRC, addr1);
 	}
 	if (tree)
-	    proto_tree_add_text(tree, NullTVB, *offset,
+	    proto_tree_add_text(tree, tvb, *offset,
 				(len1 + 1) / 2,
 				"%s address : %s",
 				toa ? "Called" : "Calling",
@@ -1250,7 +1280,7 @@ x25_ntoa(proto_tree *tree, int *offset, const guint8 *p,
 		col_add_str(fd, COL_RES_DL_DST, addr2);
 	}
 	if (tree)
-	    proto_tree_add_text(tree, NullTVB, *offset + len1/2,
+	    proto_tree_add_text(tree, tvb, *offset + len1/2,
 				(len2+1)/2+(len1%2+(len2+1)%2)/2,
 				"%s address : %s",
 				toa ? "Calling" : "Called",
@@ -1260,91 +1290,82 @@ x25_ntoa(proto_tree *tree, int *offset, const guint8 *p,
 }
 
 int
-get_x25_pkt_len(const char *data, frame_data *fd, int offset)
+get_x25_pkt_len(tvbuff_t *tvb)
 {
     int length, called_len, calling_len, dte_len, dce_len;
+    guint8 byte2, bytex;
 
-    /* packet size should always be > 3 */
-    if (!BYTES_ARE_IN_FRAME(offset, 3)) return END_OF_FRAME;
-
-    switch ((guint8)data[2])
+    byte2 = tvb_get_guint8(tvb, 2);
+    switch (byte2)
     {
     case X25_CALL_REQUEST:
-	if (BYTES_ARE_IN_FRAME(offset, 4)) /* pkt size >= 4 */
-	{
-	    called_len  = (data[3] >> 0) & 0x0F;
-	    calling_len = (data[3] >> 4) & 0x0F;
-	    length = 4 + (called_len + calling_len + 1) / 2; /* addr */
-	    if (length+offset < pi.captured_len)
-		length += (1 + data[length]); /* facilities */
-	}
-	else length = END_OF_FRAME;
-	return MIN(END_OF_FRAME,length);
+	bytex = tvb_get_guint8(tvb, 3);
+	called_len  = (bytex >> 0) & 0x0F;
+	calling_len = (bytex >> 4) & 0x0F;
+	length = 4 + (called_len + calling_len + 1) / 2; /* addr */
+	if (length < tvb_length(tvb))
+	    length += (1 + tvb_get_guint8(tvb, length)); /* facilities */
+
+	return MIN(tvb_length(tvb),length);
 
     case X25_CALL_ACCEPTED:
-	if (BYTES_ARE_IN_FRAME(offset, 4)) /* pkt size >= 4 */
-	{
-	    called_len  = (data[3] >> 0) & 0x0F;
-	    calling_len = (data[3] >> 4) & 0x0F;
-	    length = 4 + (called_len + calling_len + 1) / 2; /* addr */
-	    if (length+offset < pi.captured_len)
-		length += (1 + data[length]); /* facilities */
-	}
-	else length = END_OF_FRAME;
-	return MIN(END_OF_FRAME,length);
+	bytex = tvb_get_guint8(tvb, 3);
+	called_len  = (bytex >> 0) & 0x0F;
+	calling_len = (bytex >> 4) & 0x0F;
+	length = 4 + (called_len + calling_len + 1) / 2; /* addr */
+	if (length < tvb_length(tvb))
+	    length += (1 + tvb_get_guint8(tvb, length)); /* facilities */
+
+	return MIN(tvb_length(tvb),length);
 
     case X25_CLEAR_REQUEST:
     case X25_RESET_REQUEST:
     case X25_RESTART_REQUEST:
-	return MIN(END_OF_FRAME,5);
+	return MIN(tvb_length(tvb),5);
 
     case X25_DIAGNOSTIC:
-	return MIN(END_OF_FRAME,4);
+	return MIN(tvb_length(tvb),4);
 
     case X25_CLEAR_CONFIRMATION:
     case X25_INTERRUPT:
     case X25_INTERRUPT_CONFIRMATION:
     case X25_RESET_CONFIRMATION:
     case X25_RESTART_CONFIRMATION:
-	return MIN(END_OF_FRAME,3);
+	return MIN(tvb_length(tvb),3);
 
     case X25_REGISTRATION_REQUEST:
-	if (BYTES_ARE_IN_FRAME(offset, 4)) /* pkt size >= 4 */
-	{
-	    dce_len  = (data[3] >> 0) & 0x0F;
-	    dte_len = (data[3] >> 4) & 0x0F;
-	    length = 4 + (dte_len + dce_len + 1) / 2; /* addr */
-	    if (length+offset < pi.captured_len)
-		length += (1 + data[length]); /* registration */
-	}
-	else length = END_OF_FRAME;
-	return MIN(END_OF_FRAME,length);
+	bytex = tvb_get_guint8(tvb, 3);
+	dce_len = (bytex >> 0) & 0x0F;
+	dte_len = (bytex >> 4) & 0x0F;
+	length = 4 + (dte_len + dce_len + 1) / 2; /* addr */
+	if (length < tvb_length(tvb))
+	    length += (1 + tvb_get_guint8(tvb, length)); /* registration */
+
+	return MIN(tvb_length(tvb),length);
 
     case X25_REGISTRATION_CONFIRMATION:
-	if (BYTES_ARE_IN_FRAME(offset, 6)) /* pkt size >= 6 */
-	{
-	    dce_len  = (data[5] >> 0) & 0x0F;
-	    dte_len = (data[5] >> 4) & 0x0F;
-	    length = 6 + (dte_len + dce_len + 1) / 2; /* addr */
-	    if (length+offset < pi.captured_len)
-		length += (1 + data[length]); /* registration */
-	}
-	else length = END_OF_FRAME;
-	return MIN(END_OF_FRAME,length);
+	bytex = tvb_get_guint8(tvb, 5);
+	dce_len = (bytex >> 0) & 0x0F;
+	dte_len = (bytex >> 4) & 0x0F;
+	length = 6 + (dte_len + dce_len + 1) / 2; /* addr */
+	if (length < tvb_length(tvb))
+	    length += (1 + tvb_get_guint8(tvb, length)); /* registration */
+
+	return MIN(tvb_length(tvb),length);
     }
-	    
-    if ((data[2] & 0x01) == X25_DATA) return MIN(END_OF_FRAME,3);
 
-    switch (data[2] & 0x1F)
+    if ((byte2 & 0x01) == X25_DATA) return MIN(tvb_length(tvb),3);
+
+    switch (byte2 & 0x1F)
     {
     case X25_RR:
-	return MIN(END_OF_FRAME,3);
+	return MIN(tvb_length(tvb),3);
 
     case X25_RNR:
-	return MIN(END_OF_FRAME,3);
+	return MIN(tvb_length(tvb),3);
 
     case X25_REJ:
-	return MIN(END_OF_FRAME,3);
+	return MIN(tvb_length(tvb),3);
     }
 
     return 0;
@@ -1366,97 +1387,111 @@ static const value_string sharing_strategy_vals[] = {
 };
 
 void
-dissect_x25(const union wtap_pseudo_header *pseudo_header, const u_char *pd,
-		int offset, frame_data *fd, proto_tree *tree)
+dissect_x25(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 {
     proto_tree *x25_tree=0, *ti;
-    int localoffset=offset;
+    int localoffset=0;
     int x25_pkt_len;
     int modulo;
     guint16 vc;
     void (*dissect)(const u_char *, int, frame_data *, proto_tree *);
     gboolean toa;         /* TOA/NPI address format */
+    guint16 bytes0_1;
+    guint8 pkt_type;
+    tvbuff_t *next_tvb;
+    const guint8 *next_pd;
+    int next_offset;
+
+    pinfo->current_proto = "X.25";
+
+    if (check_col(pinfo->fd, COL_PROTOCOL))
+	col_add_str(pinfo->fd, COL_PROTOCOL, "X.25");
 
-    if (check_col(fd, COL_PROTOCOL))
-	col_add_str(fd, COL_PROTOCOL, "X.25");
+    bytes0_1 = tvb_get_ntohs(tvb, 0);
 
-    modulo = ((pd[localoffset] & 0x20) ? 128 : 8);
+    modulo = ((bytes0_1 & 0x2000) ? 128 : 8);
+    vc     = (int)(bytes0_1 & 0x0FFF);
 
-    if (pd[localoffset] & 0x80) toa = TRUE;
+    if (bytes0_1 & 0x8000) toa = TRUE;
     else toa = FALSE;
 
-    x25_pkt_len = get_x25_pkt_len(&pd[localoffset], fd, offset);
+    x25_pkt_len = get_x25_pkt_len(tvb);
     if (x25_pkt_len < 3) /* packet too short */
     {
-	if (check_col(fd, COL_INFO))
-	    col_add_str(fd, COL_INFO, "Invalid/short X.25 packet");
+	if (check_col(pinfo->fd, COL_INFO))
+	    col_add_str(pinfo->fd, COL_INFO, "Invalid/short X.25 packet");
 	if (tree)
-	    proto_tree_add_protocol_format(tree, (modulo == 8 ? proto_x25 : proto_ex25), NullTVB,
-			    localoffset, END_OF_FRAME,
-			    "Invalid/short X.25 packet");
+	    proto_tree_add_protocol_format(tree,
+		    (modulo == 8 ? proto_x25 : proto_ex25), tvb, 0,
+		    tvb_length(tvb), "Invalid/short X.25 packet");
 	return;
     }
-    vc = (int)(pd[localoffset] & 0x0F)*256 + (int)pd[localoffset+1];
     if (tree) {
-	ti = proto_tree_add_item(tree, (modulo == 8) ? proto_x25 : proto_ex25, NullTVB,
-		localoffset, x25_pkt_len, NULL);
+	ti = proto_tree_add_protocol_format(tree,
+		(modulo == 8) ? proto_x25 : proto_ex25, tvb, 0, x25_pkt_len,
+		"X.25");
 	x25_tree = proto_item_add_subtree(ti, ett_x25);
-	if (pd[localoffset] & 0x80)
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_qbit : hf_ex25_qbit, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
-	if (pd[localoffset] & 0x40)
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_dbit : hf_ex25_dbit, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
-	proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_mod : hf_ex25_mod, NullTVB,
-		localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
+	if (bytes0_1 & 0x8000)
+	    proto_tree_add_item(x25_tree,
+		    (modulo == 8) ? hf_x25_qbit : hf_ex25_qbit, tvb, 0, 2,
+		    bytes0_1);
+	if (bytes0_1 & 0x4000)
+	    proto_tree_add_item(x25_tree,
+		    (modulo == 8) ? hf_x25_dbit : hf_ex25_dbit, tvb, 0, 2,
+		    bytes0_1);
+	proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_mod : hf_ex25_mod,
+		tvb, 0, 2, bytes0_1);
     }
-    switch (pd[localoffset+2]) {
+
+    pkt_type = tvb_get_guint8(tvb, 2);
+    switch (pkt_type) {
     case X25_CALL_REQUEST:
-	if (check_col(fd, COL_INFO))
-	    col_add_fstr(fd, COL_INFO, "%s VC:%d",
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Inc. call"
-		                                          : "Call req." ,
+	if (check_col(pinfo->fd, COL_INFO))
+	    col_add_fstr(pinfo->fd, COL_INFO, "%s VC:%d",
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Inc. call"
+		                                                 : "Call req." ,
                     vc);
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
+	    proto_tree_add_item(x25_tree,
+		    (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, tvb,
+		    0, 2, bytes0_1);
 	    proto_tree_add_uint_format(x25_tree,
-		    (modulo == 8) ? hf_x25_type : hf_ex25_type,
-		    NullTVB, localoffset+2, 1, X25_CALL_REQUEST,
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Incoming call"
-			                                     : "Call request");
+		    (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb, 2, 1,
+		    X25_CALL_REQUEST,
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Incoming call"
+			                                         : "Call request");
 	}
-	localoffset += 3;
-	if (localoffset < x25_pkt_len+offset) /* calling/called addresses */
-	    x25_ntoa(x25_tree, &localoffset, &pd[localoffset], fd, toa);
+	localoffset = 3;
+	if (localoffset < x25_pkt_len) /* calling/called addresses */
+	    x25_ntoa(x25_tree, &localoffset, tvb, pinfo->fd, toa);
 
-	if (localoffset < x25_pkt_len+offset) /* facilities */
-	    dump_facilities(x25_tree, &localoffset, &pd[localoffset]);
+	if (localoffset < x25_pkt_len) /* facilities */
+	    dump_facilities(x25_tree, &localoffset, tvb);
 
-	if (IS_DATA_IN_FRAME(localoffset)) /* user data */
+	if (localoffset < tvb_length(tvb)) /* user data */
 	{
 	    guint8 spi;
 	    guint8 prt_id;
 
 	    /* Compare the first octet of the CALL REQUEST packet with
 	       various ISO 9577 NLPIDs, as per Annex A of ISO 9577. */
-	    spi = pd[localoffset];
+	    spi = tvb_get_guint8(tvb, localoffset);
 	    switch (spi) {
 
 	    /* XXX - handle other NLPIDs, e.g. PPP? */
 
 	    case NLPID_IP:
-		x25_hash_add_proto_start(vc, fd->abs_secs,
-					 fd->abs_usecs, dissect_ip);
+		x25_hash_add_proto_start(vc, pinfo->fd->abs_secs,
+					 pinfo->fd->abs_usecs, dissect_ip);
 		if (x25_tree)
-		    proto_tree_add_text(x25_tree, NullTVB, localoffset, 1,
+		    proto_tree_add_text(x25_tree, tvb, localoffset, 1,
 					"X.224 secondary protocol ID: IP");
 		localoffset++;
 		break;
 
 	    default:
-		if ((pd[localoffset] >= 0x03 && pd[localoffset] <= 0x82)
-		    && pd[localoffset+1] == 0x01) {
+		if ((spi >= 0x03 && spi <= 0x82)
+		    && tvb_get_guint8(tvb, localoffset+1) == 0x01) {
 		    /* ISO 9577 claims that a SPI in that range is a
 		       length field for X.224/ISO 8073 or X.264/ISO 11570;
 		       however, some of them collide with NLPIDs such
@@ -1479,33 +1514,35 @@ dissect_x25(const union wtap_pseudo_header *pseudo_header, const u_char *pd,
 		       So we'll assume that's what it is, as the SPI
 		       is in the right range for a length, and the UN
 		       field is 0x01. */
-		    prt_id = pd[localoffset+2];
+		    prt_id = tvb_get_guint8(tvb, localoffset+2);
 		    if (x25_tree) {
-		        proto_tree_add_text(x25_tree, NullTVB, localoffset, 1,
+		        proto_tree_add_text(x25_tree, tvb, localoffset, 1,
 					"X.264 length indicator: %u",
-					pd[localoffset]);
-		        proto_tree_add_text(x25_tree, NullTVB, localoffset+1, 1,
+					spi);
+		        proto_tree_add_text(x25_tree, tvb, localoffset+1, 1,
 		        		"X.264 UN TPDU identifier: 0x%02X",
-		        		pd[localoffset+1]);
-		        proto_tree_add_text(x25_tree, NullTVB, localoffset+2, 1,
+		        		tvb_get_guint8(tvb, localoffset+1));
+		        proto_tree_add_text(x25_tree, tvb, localoffset+2, 1,
 		        		"X.264 protocol identifier: %s",
-					val_to_str(prt_id, prt_id_vals, "Unknown (0x%02X)"));
-		        proto_tree_add_text(x25_tree, NullTVB, localoffset+3, 1,
+					val_to_str(prt_id, prt_id_vals,
+					    "Unknown (0x%02X)"));
+		        proto_tree_add_text(x25_tree, tvb, localoffset+3, 1,
 		        		"X.264 sharing strategy: %s",
-					val_to_str(pd[localoffset+3], sharing_strategy_vals, "Unknown (0x%02X)"));
+					val_to_str(tvb_get_guint8(tvb, localoffset+3),
+					    sharing_strategy_vals, "Unknown (0x%02X)"));
 		    }
 
 		    /* XXX - dissect the variable part? */
 
 		    /* The length doesn't include the length octet itself. */
-		    localoffset += pd[localoffset] + 1;
+		    localoffset += spi + 1;
 
 		    switch (prt_id) {
 
 		    case PRT_ID_ISO_8073:
 			/* ISO 8073 COTP */
-			x25_hash_add_proto_start(vc, fd->abs_secs,
-					 fd->abs_usecs, dissect_cotp);
+			x25_hash_add_proto_start(vc, pinfo->fd->abs_secs,
+					 pinfo->fd->abs_usecs, dissect_cotp);
 			break;
 
 		    default:
@@ -1514,383 +1551,384 @@ dissect_x25(const union wtap_pseudo_header *pseudo_header, const u_char *pd,
 		} else {
 		unknown:
 		    if (x25_tree) {
-			if (IS_DATA_IN_FRAME(localoffset))
-			   proto_tree_add_text(x25_tree, NullTVB, localoffset,
-					pi.captured_len-localoffset, "Data");
+			proto_tree_add_text(x25_tree, tvb, localoffset,
+				tvb_length(tvb)-localoffset, "Data");
 		    }
-		    localoffset = pi.captured_len;
+		    localoffset = tvb_length(tvb);
 		}
 	    }
 	}
 	break;
     case X25_CALL_ACCEPTED:
-	if(check_col(fd, COL_INFO))
-	    col_add_fstr(fd, COL_INFO, "%s VC:%d",
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Call conn."
-			                                  : "Call acc." ,
+	if(check_col(pinfo->fd, COL_INFO))
+	    col_add_fstr(pinfo->fd, COL_INFO, "%s VC:%d",
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Call conn."
+			                                         : "Call acc." ,
 		    vc);
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn,
+		    tvb, 0, 2, bytes0_1);
 	    proto_tree_add_uint_format(x25_tree,
 		    (modulo == 8) ? hf_x25_type : hf_ex25_type,
-		    NullTVB, localoffset+2, 1, X25_CALL_ACCEPTED,
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Call connected"
-		                                             : "Call accepted");
+		    tvb, 2, 1, X25_CALL_ACCEPTED,
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Call connected"
+		                                                 : "Call accepted");
 	}
-	localoffset += 3;
-        if (localoffset < x25_pkt_len+offset) /* calling/called addresses */
-	    x25_ntoa(x25_tree, &localoffset, &pd[localoffset], fd, toa);
+	localoffset = 3;
+        if (localoffset < x25_pkt_len) /* calling/called addresses */
+	    x25_ntoa(x25_tree, &localoffset, tvb, pinfo->fd, toa);
 
-	if (localoffset < x25_pkt_len+offset) /* facilities */
-	    dump_facilities(x25_tree, &localoffset, &pd[localoffset]);
+	if (localoffset < x25_pkt_len) /* facilities */
+	    dump_facilities(x25_tree, &localoffset, tvb);
 
-	if (IS_DATA_IN_FRAME(localoffset)) { /* user data */
+	if (localoffset < tvb_length(tvb)) { /* user data */
 	    if (x25_tree)
-	        proto_tree_add_text(x25_tree, NullTVB, localoffset,
-				    pi.captured_len-localoffset, "Data");
-	    localoffset=pi.captured_len;
+	        proto_tree_add_text(x25_tree, tvb, localoffset,
+				    tvb_length(tvb)-localoffset, "Data");
+	    localoffset=tvb_length(tvb);
 	}
 	break;
     case X25_CLEAR_REQUEST:
-	if(check_col(fd, COL_INFO)) {
-	    col_add_fstr(fd, COL_INFO, "%s VC:%d %s - %s",
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Clear ind."
-			                                  : "Clear req." ,
-		    vc, clear_code(pd[localoffset+3]),
-		    clear_diag(pd[localoffset+4]));
+	if(check_col(pinfo->fd, COL_INFO)) {
+	    col_add_fstr(pinfo->fd, COL_INFO, "%s VC:%d %s - %s",
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Clear ind."
+			                                         : "Clear req." ,
+		    vc, clear_code(tvb_get_guint8(tvb, 3)),
+		    clear_diag(tvb_get_guint8(tvb, 4)));
 	}
-	x25_hash_add_proto_end(vc, fd->abs_secs, fd->abs_usecs);
+	x25_hash_add_proto_end(vc, pinfo->fd->abs_secs, pinfo->fd->abs_usecs);
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, tvb,
+		    0, 2, bytes0_1);
 	    proto_tree_add_uint_format(x25_tree,
 		    (modulo == 8) ? hf_x25_type : hf_ex25_type,
-		    NullTVB, localoffset+2, 1, X25_CLEAR_REQUEST,
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Clear indication"
-		                                             : "Clear request");
-	    if (localoffset+3 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+3, 1,
-			"Cause : %s", clear_code(pd[localoffset+3]));
-	    if (localoffset+4 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+4, 1,
-			"Diagnostic : %s",
-			clear_diag(pd[localoffset+4]));
+		    tvb, localoffset+2, 1, X25_CLEAR_REQUEST,
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Clear indication"
+		                                                 : "Clear request");
+	    proto_tree_add_text(x25_tree, tvb, 3, 1,
+		    "Cause : %s", clear_code(tvb_get_guint8(tvb, 3)));
+	    proto_tree_add_text(x25_tree, tvb, 4, 1,
+		    "Diagnostic : %s", clear_diag(tvb_get_guint8(tvb, 4)));
 	}
-	localoffset += x25_pkt_len;
+	localoffset = x25_pkt_len;
 	break;
     case X25_CLEAR_CONFIRMATION:
-	if(check_col(fd, COL_INFO))
-	    col_add_fstr(fd, COL_INFO, "Clear Conf. VC:%d", vc);
+	if(check_col(pinfo->fd, COL_INFO))
+	    col_add_fstr(pinfo->fd, COL_INFO, "Clear Conf. VC:%d", vc);
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB,
-		    localoffset+2, 1, X25_CLEAR_CONFIRMATION);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, tvb,
+		    0, 2, bytes0_1);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb,
+		    2, 1, X25_CLEAR_CONFIRMATION);
 	}
-	localoffset += x25_pkt_len;
+	localoffset = x25_pkt_len;
 
-	if (IS_DATA_IN_FRAME(localoffset)) /* extended clear conf format */
-	    x25_ntoa(x25_tree, &localoffset, &pd[localoffset], fd, toa);
+	if (localoffset < tvb_length(tvb)) /* extended clear conf format */
+	    x25_ntoa(x25_tree, &localoffset, tvb, pinfo->fd, toa);
 
-	if (IS_DATA_IN_FRAME(localoffset)) /* facilities */
-	    dump_facilities(x25_tree, &localoffset, &pd[localoffset]);
+	if (localoffset < tvb_length(tvb)) /* facilities */
+	    dump_facilities(x25_tree, &localoffset, tvb);
 	break;
     case X25_DIAGNOSTIC:
-	if(check_col(fd, COL_INFO)) {
-	    col_add_fstr(fd, COL_INFO, "Diag. %d", (int)pd[localoffset+3]);
+	if(check_col(pinfo->fd, COL_INFO)) {
+	    col_add_fstr(pinfo->fd, COL_INFO, "Diag. %d",
+		    (int)tvb_get_guint8(tvb, 3));
 	}
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB,
-		    localoffset+2, 1, X25_DIAGNOSTIC);
-	    if (localoffset+3 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+3, 1,
-			"Diagnostic : %d", (int)pd[localoffset+3]);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb,
+		    2, 1, X25_DIAGNOSTIC);
+	    proto_tree_add_text(x25_tree, tvb, 3, 1,
+		    "Diagnostic : %d", (int)tvb_get_guint8(tvb, 3));
 	}
-	localoffset += x25_pkt_len;
+	localoffset = x25_pkt_len;
 	break;
     case X25_INTERRUPT:
-	if(check_col(fd, COL_INFO))
-	    col_add_fstr(fd, COL_INFO, "Interrupt VC:%d", vc);
+	if(check_col(pinfo->fd, COL_INFO))
+	    col_add_fstr(pinfo->fd, COL_INFO, "Interrupt VC:%d", vc);
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB,
-		    localoffset+2, 1, X25_INTERRUPT);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, tvb,
+		    0, 2, bytes0_1);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb,
+		    2, 1, X25_INTERRUPT);
 	}
-	localoffset += x25_pkt_len;
+	localoffset = x25_pkt_len;
 	break;
     case X25_INTERRUPT_CONFIRMATION:
-	if(check_col(fd, COL_INFO))
-	    col_add_fstr(fd, COL_INFO, "Interrupt Conf. VC:%d", vc);
+	if(check_col(pinfo->fd, COL_INFO))
+	    col_add_fstr(pinfo->fd, COL_INFO, "Interrupt Conf. VC:%d", vc);
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB,
-		    localoffset+2, 1, X25_INTERRUPT_CONFIRMATION);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, tvb,
+		    0, 2, bytes0_1);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb,
+		    2, 1, X25_INTERRUPT_CONFIRMATION);
 	}
-	localoffset += x25_pkt_len;
+	localoffset = x25_pkt_len;
 	break;
     case X25_RESET_REQUEST:
-	if(check_col(fd, COL_INFO)) {
-	    col_add_fstr(fd, COL_INFO, "%s VC:%d %s - Diag.:%d",
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Reset ind."
-		                                          : "Reset req.",
-		    vc, reset_code(pd[localoffset+3]),
-		    (int)pd[localoffset+4]);
+	if(check_col(pinfo->fd, COL_INFO)) {
+	    col_add_fstr(pinfo->fd, COL_INFO, "%s VC:%d %s - Diag.:%d",
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Reset ind."
+		                                                 : "Reset req.",
+		    vc, reset_code(tvb_get_guint8(tvb, 3)),
+		    (int)tvb_get_guint8(tvb, 4));
 	}
-	x25_hash_add_proto_end(vc, fd->abs_secs, fd->abs_usecs);
+	x25_hash_add_proto_end(vc, pinfo->fd->abs_secs, pinfo->fd->abs_usecs);
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, tvb,
+		    0, 2, bytes0_1);
 	    proto_tree_add_uint_format(x25_tree,
-		    (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB, localoffset+2, 1,
+		    (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb, 2, 1,
 		    X25_RESET_REQUEST,
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Reset indication"
-                                                          : "Reset request");
-	    if (localoffset+3 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+3, 1,
-			"Cause : %s", reset_code(pd[localoffset+3]));
-	    if (localoffset+4 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+4, 1,
-			"Diagnostic : %d", (int)pd[localoffset+4]);
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Reset indication"
+                                                                 : "Reset request");
+	    proto_tree_add_text(x25_tree, tvb, 3, 1,
+		    "Cause : %s", reset_code(tvb_get_guint8(tvb, 3)));
+	    proto_tree_add_text(x25_tree, tvb, 4, 1,
+		    "Diagnostic : %d", (int)tvb_get_guint8(tvb, 4));
 	}
-	localoffset += x25_pkt_len;
+	localoffset = x25_pkt_len;
 	break;
     case X25_RESET_CONFIRMATION:
-	if(check_col(fd, COL_INFO))
-	    col_add_fstr(fd, COL_INFO, "Reset conf. VC:%d", vc);
+	if(check_col(pinfo->fd, COL_INFO))
+	    col_add_fstr(pinfo->fd, COL_INFO, "Reset conf. VC:%d", vc);
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-		    localoffset, 2, pd[localoffset]*256+pd[localoffset+1]);
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB,
-		    localoffset+2, 1, X25_RESET_CONFIRMATION);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, tvb,
+		    0, 2, bytes0_1);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb,
+		    2, 1, X25_RESET_CONFIRMATION);
 	}
-	localoffset += x25_pkt_len;
+	localoffset = x25_pkt_len;
 	break;
     case X25_RESTART_REQUEST:
-	if(check_col(fd, COL_INFO)) {
-	    col_add_fstr(fd, COL_INFO, "%s %s - Diag.:%d",
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Restart ind."
-		                                          : "Restart req.",
-		    restart_code(pd[localoffset+3]),
-		    (int)pd[localoffset+4]);
+	if(check_col(pinfo->fd, COL_INFO)) {
+	    col_add_fstr(pinfo->fd, COL_INFO, "%s %s - Diag.:%d",
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Restart ind."
+		                                                 : "Restart req.",
+		    restart_code(tvb_get_guint8(tvb, 3)),
+		    (int)tvb_get_guint8(tvb, 3));
 	}
 	if (x25_tree) {
 	    proto_tree_add_uint_format(x25_tree,
-		    (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB, localoffset+2, 1,
+		    (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb, 2, 1,
 		    X25_RESTART_REQUEST,
-		    (pseudo_header->x25.flags & FROM_DCE) ? "Restart indication"
-		                                          : "Restart request");
-	    if (localoffset+3 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+3, 1,
-			"Cause : %s", restart_code(pd[localoffset+3]));
-	    if (localoffset+4 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+4, 1,
-			"Diagnostic : %d", (int)pd[localoffset+4]);
+		    (pinfo->pseudo_header->x25.flags & FROM_DCE) ? "Restart indication"
+		                                                 : "Restart request");
+	    proto_tree_add_text(x25_tree, tvb, 3, 1,
+		    "Cause : %s", restart_code(tvb_get_guint8(tvb, 3)));
+	    proto_tree_add_text(x25_tree, tvb, 4, 1,
+		    "Diagnostic : %d", (int)tvb_get_guint8(tvb, 4));
 	}
-	localoffset += x25_pkt_len;
+	localoffset = x25_pkt_len;
 	break;
     case X25_RESTART_CONFIRMATION:
-	if(check_col(fd, COL_INFO))
-	    col_add_str(fd, COL_INFO, "Restart conf.");
+	if(check_col(pinfo->fd, COL_INFO))
+	    col_add_str(pinfo->fd, COL_INFO, "Restart conf.");
 	if (x25_tree)
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB,
-		    localoffset+2, 1, X25_RESTART_CONFIRMATION);
-	localoffset += x25_pkt_len;
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb,
+		    2, 1, X25_RESTART_CONFIRMATION);
+	localoffset = x25_pkt_len;
 	break;
     case X25_REGISTRATION_REQUEST:
-	if(check_col(fd, COL_INFO))
-	    col_add_str(fd, COL_INFO, "Registration req.");
+	if(check_col(pinfo->fd, COL_INFO))
+	    col_add_str(pinfo->fd, COL_INFO, "Registration req.");
 	if (x25_tree)
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB,
-		    localoffset+2, 1, X25_REGISTRATION_REQUEST);
-	localoffset += 3;
-	if (localoffset < x25_pkt_len+offset)
-	    x25_ntoa(x25_tree, &localoffset, &pd[localoffset], fd, FALSE);
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb,
+		    2, 1, X25_REGISTRATION_REQUEST);
+	localoffset = 3;
+	if (localoffset < x25_pkt_len)
+	    x25_ntoa(x25_tree, &localoffset, tvb, pinfo->fd, FALSE);
 
 	if (x25_tree) {
-	    if (localoffset < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset, 1,
-			"Registration length: %d", pd[localoffset] & 0x7F);
-	    if (localoffset+1 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+1,
-			pd[localoffset] & 0x7F, "Registration");
+	    if (localoffset < x25_pkt_len)
+		proto_tree_add_text(x25_tree, tvb, localoffset, 1,
+			"Registration length: %d",
+			tvb_get_guint8(tvb, localoffset) & 0x7F);
+	    if (localoffset+1 < x25_pkt_len)
+		proto_tree_add_text(x25_tree, tvb, localoffset+1,
+			tvb_get_guint8(tvb, localoffset) & 0x7F,
+			"Registration");
 	}
-	localoffset = pi.captured_len;
+	localoffset = tvb_length(tvb);
 	break;
     case X25_REGISTRATION_CONFIRMATION:
-	if(check_col(fd, COL_INFO))
-	    col_add_str(fd, COL_INFO, "Registration conf.");
+	if(check_col(pinfo->fd, COL_INFO))
+	    col_add_str(pinfo->fd, COL_INFO, "Registration conf.");
 	if (x25_tree) {
-	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, NullTVB,
-		    localoffset+2, 1, X25_REGISTRATION_CONFIRMATION);
-	    if (localoffset+3 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+3, 1,
-			"Cause: %s", registration_code(pd[localoffset+3]));
-	    if (localoffset+4 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+4, 1,
-			"Diagnostic: %s", registration_code(pd[localoffset+4]));
+	    proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_type : hf_ex25_type, tvb,
+		    2, 1, X25_REGISTRATION_CONFIRMATION);
+	    proto_tree_add_text(x25_tree, tvb, 3, 1,
+		    "Cause: %s", registration_code(tvb_get_guint8(tvb, 3)));
+	    proto_tree_add_text(x25_tree, tvb, 4, 1,
+		    "Diagnostic: %s", registration_code(tvb_get_guint8(tvb, 4)));
 	}
-	localoffset += 5;
-	if (localoffset < x25_pkt_len+offset)
-	    x25_ntoa(x25_tree, &localoffset, &pd[localoffset], fd, TRUE);
+	localoffset = 5;
+	if (localoffset < x25_pkt_len)
+	    x25_ntoa(x25_tree, &localoffset, tvb, pinfo->fd, TRUE);
 
 	if (x25_tree) {
-	    if (localoffset < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset, 1,
-			"Registration length: %d", pd[localoffset] & 0x7F);
-	    if (localoffset+1 < x25_pkt_len+offset)
-		proto_tree_add_text(x25_tree, NullTVB, localoffset+1,
-			pd[localoffset] & 0x7F, "Registration");
+	    if (localoffset < x25_pkt_len)
+		proto_tree_add_text(x25_tree, tvb, localoffset, 1,
+			"Registration length: %d",
+			tvb_get_guint8(tvb, localoffset) & 0x7F);
+	    if (localoffset+1 < x25_pkt_len)
+		proto_tree_add_text(x25_tree, tvb, localoffset+1,
+			tvb_get_guint8(tvb, localoffset) & 0x7F,
+			"Registration");
 	}
-	localoffset = pi.captured_len;
+	localoffset = tvb_length(tvb);
 	break;
     default :
-	localoffset += 2;
-	if ((pd[localoffset] & 0x01) == X25_DATA)
+	localoffset = 2;
+	if ((pkt_type & 0x01) == X25_DATA)
 	{
-	    if(check_col(fd, COL_INFO)) {
+	    if(check_col(pinfo->fd, COL_INFO)) {
 		if (modulo == 8)
-		    col_add_fstr(fd, COL_INFO,
+		    col_add_fstr(pinfo->fd, COL_INFO,
 			    "Data VC:%d P(S):%d P(R):%d %s", vc,
-			    (pd[localoffset] >> 1) & 0x07,
-			    (pd[localoffset] >> 5) & 0x07,
-			    ((pd[localoffset]>>4) & 0x01) ? " M" : "");
+			    (pkt_type >> 1) & 0x07,
+			    (pkt_type >> 5) & 0x07,
+			    ((pkt_type >> 4) & 0x01) ? " M" : "");
 		else
-		    col_add_fstr(fd, COL_INFO,
+		    col_add_fstr(pinfo->fd, COL_INFO,
 			    "Data VC:%d P(S):%d P(R):%d %s", vc,
-			    pd[localoffset+1] >> 1,
-			    pd[localoffset] >> 1,
-			    (pd[localoffset+1] & 0x01) ? " M" : "");
+			    tvb_get_guint8(tvb, localoffset+1) >> 1,
+			    pkt_type >> 1,
+			    (tvb_get_guint8(tvb, localoffset+1) & 0x01) ? " M" : "");
 	    }
 	    if (x25_tree) {
-		proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-			localoffset-2, 2, pd[localoffset-2]*256+pd[localoffset-1]);
+		proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn,
+			tvb, localoffset-2, 2, bytes0_1);
 		if (modulo == 8) {
-		    proto_tree_add_item_hidden(x25_tree, hf_x25_type, NullTVB, localoffset, 1,
-			    X25_DATA);
-		    proto_tree_add_item(x25_tree, hf_x25_p_r, NullTVB, localoffset, 1,
-			    pd[localoffset]);
-		    if (pd[localoffset] & 0x10)
-			proto_tree_add_item(x25_tree, hf_x25_mbit, NullTVB, localoffset, 1,
-			    pd[localoffset]);
-		    proto_tree_add_item(x25_tree, hf_x25_p_s, NullTVB, localoffset, 1,
-			    pd[localoffset]);
-		    proto_tree_add_text(x25_tree, NullTVB, localoffset, 1,
-			    decode_boolean_bitfield(pd[localoffset], 0x01, 1*8,
+		    proto_tree_add_item_hidden(x25_tree, hf_x25_type, tvb,
+			    localoffset, 1, X25_DATA);
+		    proto_tree_add_item(x25_tree, hf_x25_p_r, tvb,
+			    localoffset, 1, pkt_type);
+		    if (pkt_type & 0x10)
+			proto_tree_add_item(x25_tree, hf_x25_mbit, tvb, localoffset, 1,
+			    pkt_type);
+		    proto_tree_add_item(x25_tree, hf_x25_p_s, tvb, localoffset, 1,
+			    pkt_type);
+		    proto_tree_add_text(x25_tree, tvb, localoffset, 1,
+			    decode_boolean_bitfield(pkt_type, 0x01, 1*8,
 				NULL, "DATA"));
 		}
 		else {
-		    proto_tree_add_item_hidden(x25_tree, hf_ex25_type, NullTVB, localoffset, 1,
-			    X25_DATA);
-		    proto_tree_add_item(x25_tree, hf_x25_p_r, NullTVB, localoffset, 1,
-			    pd[localoffset]);
-		    proto_tree_add_item(x25_tree, hf_x25_p_s, NullTVB, localoffset+1, 1,
-			    pd[localoffset+1]);
-		    if (pd[localoffset+1] & 0x01)
-			proto_tree_add_item(x25_tree, hf_ex25_mbit, NullTVB, localoffset+1, 1,
-			    pd[localoffset+1]);
+		    proto_tree_add_item_hidden(x25_tree, hf_ex25_type, tvb,
+			    localoffset, 1, X25_DATA);
+		    proto_tree_add_item(x25_tree, hf_x25_p_r, tvb,
+			    localoffset, 1, pkt_type);
+		    proto_tree_add_item(x25_tree, hf_x25_p_s, tvb,
+			    localoffset+1, 1, tvb_get_guint8(tvb, localoffset+1));
+		    if (tvb_get_guint8(tvb, localoffset+1) & 0x01)
+			proto_tree_add_item(x25_tree, hf_ex25_mbit, tvb,
+				localoffset+1, 1, tvb_get_guint8(tvb, localoffset+1));
 		}
 	    }
 	    localoffset += (modulo == 8) ? 1 : 2;
 	    break;
 	}
-	switch (pd[localoffset] & 0x1F)
+	switch (pkt_type & 0x1F)
 	{
 	case X25_RR:
-	    if(check_col(fd, COL_INFO)) {
+	    if(check_col(pinfo->fd, COL_INFO)) {
 		if (modulo == 8)
-		    col_add_fstr(fd, COL_INFO, "RR VC:%d P(R):%d",
-			    vc, (pd[localoffset] >> 5) & 0x07);
+		    col_add_fstr(pinfo->fd, COL_INFO, "RR VC:%d P(R):%d",
+			    vc, (pkt_type >> 5) & 0x07);
 		else
-		    col_add_fstr(fd, COL_INFO, "RR VC:%d P(R):%d",
-			    vc, pd[localoffset+1] >> 1);
+		    col_add_fstr(pinfo->fd, COL_INFO, "RR VC:%d P(R):%d",
+			    vc, tvb_get_guint8(tvb, localoffset+1) >> 1);
 	    }
 	    if (x25_tree) {
-		proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-			localoffset-2, 2, pd[localoffset-2]*256+pd[localoffset-1]);
+		proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn,
+			tvb, localoffset-2, 2, bytes0_1);
 		if (modulo == 8) {
-		    proto_tree_add_item(x25_tree, hf_x25_p_r, NullTVB,
-			    localoffset, 1, pd[localoffset]);
-		    proto_tree_add_item(x25_tree, hf_x25_type, NullTVB, localoffset, 1, X25_RR);
+		    proto_tree_add_item(x25_tree, hf_x25_p_r, tvb,
+			    localoffset, 1, pkt_type);
+		    proto_tree_add_item(x25_tree, hf_x25_type, tvb,
+			    localoffset, 1, X25_RR);
 		}
 		else {
-		    proto_tree_add_item(x25_tree, hf_ex25_type, NullTVB, localoffset, 1, X25_RR);
-		    proto_tree_add_item(x25_tree, hf_ex25_p_r, NullTVB,
-			    localoffset+1, 1, pd[localoffset+1]);
+		    proto_tree_add_item(x25_tree, hf_ex25_type, tvb,
+			    localoffset, 1, X25_RR);
+		    proto_tree_add_item(x25_tree, hf_ex25_p_r, tvb,
+			    localoffset+1, 1, tvb_get_guint8(tvb, localoffset+1));
 		}
 	    }
 	    break;
 
 	case X25_RNR:
-	    if(check_col(fd, COL_INFO)) {
+	    if(check_col(pinfo->fd, COL_INFO)) {
 		if (modulo == 8)
-		    col_add_fstr(fd, COL_INFO, "RNR VC:%d P(R):%d",
-			    vc, (pd[localoffset] >> 5) & 0x07);
+		    col_add_fstr(pinfo->fd, COL_INFO, "RNR VC:%d P(R):%d",
+			    vc, (pkt_type >> 5) & 0x07);
 		else
-		    col_add_fstr(fd, COL_INFO, "RNR VC:%d P(R):%d",
-			    vc, pd[localoffset+1] >> 1);
+		    col_add_fstr(pinfo->fd, COL_INFO, "RNR VC:%d P(R):%d",
+			    vc, tvb_get_guint8(tvb, localoffset+1) >> 1);
 	    }
 	    if (x25_tree) {
-		proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-			localoffset-2, 2, pd[localoffset-2]*256+pd[localoffset-1]);
+		proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn,
+			tvb, localoffset-2, 2, bytes0_1);
 		if (modulo == 8) {
-		    proto_tree_add_item(x25_tree, hf_x25_p_r, NullTVB,
-			    localoffset, 1, pd[localoffset]);
-		    proto_tree_add_item(x25_tree, hf_x25_type, NullTVB, localoffset, 1, X25_RNR);
+		    proto_tree_add_item(x25_tree, hf_x25_p_r, tvb,
+			    localoffset, 1, pkt_type);
+		    proto_tree_add_item(x25_tree, hf_x25_type, tvb,
+			    localoffset, 1, X25_RNR);
 		}
 		else {
-		    proto_tree_add_item(x25_tree, hf_ex25_type, NullTVB, localoffset, 1, X25_RNR);
-		    proto_tree_add_item(x25_tree, hf_ex25_p_r, NullTVB,
-			    localoffset+1, 1, pd[localoffset+1]);
+		    proto_tree_add_item(x25_tree, hf_ex25_type, tvb,
+			    localoffset, 1, X25_RNR);
+		    proto_tree_add_item(x25_tree, hf_ex25_p_r, tvb,
+			    localoffset+1, 1, tvb_get_guint8(tvb, localoffset+1));
 		}
 	    }
 	    break;
 
 	case X25_REJ:
-	    if(check_col(fd, COL_INFO)) {
+	    if(check_col(pinfo->fd, COL_INFO)) {
 		if (modulo == 8)
-		    col_add_fstr(fd, COL_INFO, "REJ VC:%d P(R):%d",
-			    vc, (pd[localoffset] >> 5) & 0x07);
+		    col_add_fstr(pinfo->fd, COL_INFO, "REJ VC:%d P(R):%d",
+			    vc, (pkt_type >> 5) & 0x07);
 		else
-		    col_add_fstr(fd, COL_INFO, "REJ VC:%d P(R):%d",
-			    vc, pd[localoffset+1] >> 1);
+		    col_add_fstr(pinfo->fd, COL_INFO, "REJ VC:%d P(R):%d",
+			    vc, tvb_get_guint8(tvb, localoffset+1) >> 1);
 	    }
 	    if (x25_tree) {
-		proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn, NullTVB,
-			localoffset-2, 2, pd[localoffset-2]*256+pd[localoffset-1]);
+		proto_tree_add_item(x25_tree, (modulo == 8) ? hf_x25_lcn : hf_ex25_lcn,
+			tvb, localoffset-2, 2, bytes0_1);
 		if (modulo == 8) {
-		    proto_tree_add_item(x25_tree, hf_x25_p_r, NullTVB,
-			    localoffset, 1, pd[localoffset]);
-		    proto_tree_add_item(x25_tree, hf_x25_type, NullTVB, localoffset, 1, X25_REJ);
+		    proto_tree_add_item(x25_tree, hf_x25_p_r, tvb,
+			    localoffset, 1, pkt_type);
+		    proto_tree_add_item(x25_tree, hf_x25_type, tvb,
+			    localoffset, 1, X25_REJ);
 		}
 		else {
-		    proto_tree_add_item(x25_tree, hf_ex25_type, NullTVB, localoffset, 1, X25_REJ);
-		    proto_tree_add_item(x25_tree, hf_ex25_p_r, NullTVB,
-			    localoffset+1, 1, pd[localoffset+1]);
+		    proto_tree_add_item(x25_tree, hf_ex25_type, tvb,
+			    localoffset, 1, X25_REJ);
+		    proto_tree_add_item(x25_tree, hf_ex25_p_r, tvb,
+			    localoffset+1, 1, tvb_get_guint8(tvb, localoffset+1));
 		}
 	    }
 	}
 	localoffset += (modulo == 8) ? 1 : 2;
     }
 
-    if (!IS_DATA_IN_FRAME(localoffset)) return;
+    if (localoffset >= tvb_length(tvb)) return;
 
+    next_tvb = tvb_new_subset(tvb, localoffset, -1, -1);
+    tvb_compat(next_tvb, &next_pd, &next_offset);
     /* search the dissector in the hash table */
-    if ((dissect = x25_hash_get_dissect(fd->abs_secs, fd->abs_usecs, vc)))
-      (*dissect)(pd, localoffset, fd, tree);
+    if ((dissect = x25_hash_get_dissect(pinfo->fd->abs_secs, pinfo->fd->abs_usecs, vc)))
+	(*dissect)(next_pd, next_offset, pinfo->fd, tree);
     else {
-      if (pd[localoffset] == 0x45) /* If the Call Req. has not been captured,
-				    * assume these packets carry IP */
-      {
-	  x25_hash_add_proto_start(vc, fd->abs_secs,
-				   fd->abs_usecs, dissect_ip);
- 	  dissect_ip(pd, localoffset, fd, tree);
-      }
-      else {
-	  dissect_data(pd, localoffset, fd, tree);
-      }
+	/* If the Call Req. has not been captured, assume these packets carry IP */
+	if (tvb_get_guint8(tvb, localoffset) == 0x45) {
+	    x25_hash_add_proto_start(vc, pinfo->fd->abs_secs,
+		    pinfo->fd->abs_usecs, dissect_ip);
+	    dissect_ip(next_pd, next_offset, pinfo->fd, tree);
+	}
+	else {
+	    dissect_data(next_pd, next_offset, pinfo->fd, tree);
+	}
     }
 }