minor cleanup

- replace TABs with spaces
- add editor modelines
- remove unnecessary NULL checks

Change-Id: Ic6024fc4b6aec56c8cafd39c707e20485fa6cca7
Reviewed-on: https://code.wireshark.org/review/819
Reviewed-by: Martin Kaiser <wireshark@kaiser.cx>
Tested-by: Martin Kaiser <wireshark@kaiser.cx>

1 files changed, 280 insertions, 282 deletions

diff --git a/epan/dissectors/file-png.c b/epan/dissectors/file-png.c
index 24ae5e6593..b47a6c8478 100644
--- a/epan/dissectors/file-png.c
+++ b/epan/dissectors/file-png.c
@@ -42,174 +42,174 @@ static header_field_info *hfi_png = NULL;
 #define PNG_HFI_INIT HFI_INIT(proto_png)
 
 static header_field_info hfi_png_signature PNG_HFI_INIT = {
-	  "PNG Signature", "png.signature", FT_BYTES, BASE_NONE,
-	  NULL, 0, NULL, HFILL };
+    "PNG Signature", "png.signature", FT_BYTES, BASE_NONE,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_chunk_data PNG_HFI_INIT = {
-	  "Data", "png.chunk.data", FT_NONE, BASE_NONE,
-	  NULL, 0, NULL, HFILL };
+    "Data", "png.chunk.data", FT_NONE, BASE_NONE,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_chunk_type PNG_HFI_INIT = {
-	  "Chunk", "png.chunk.type", FT_STRING, BASE_NONE,
-	  NULL, 0, NULL, HFILL };
+    "Chunk", "png.chunk.type", FT_STRING, BASE_NONE,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_chunk_len PNG_HFI_INIT = {
-	  "Len", "png.chunk.len", FT_UINT32, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Len", "png.chunk.len", FT_UINT32, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_chunk_crc PNG_HFI_INIT = {
-	  "CRC", "png.chunk.crc", FT_UINT32, BASE_HEX,
-	  NULL, 0, NULL, HFILL };
+    "CRC", "png.chunk.crc", FT_UINT32, BASE_HEX,
+    NULL, 0, NULL, HFILL };
 
 static const true_false_string png_chunk_anc = {
-	"This is an ANCILLARY chunk",
-	"This is a CRITICAL chunk"
+    "This is an ANCILLARY chunk",
+    "This is a CRITICAL chunk"
 };
 
 static header_field_info hfi_png_chunk_flag_anc PNG_HFI_INIT = {
-	  "Ancillary", "png.chunk.flag.ancillary", FT_BOOLEAN, 32,
-	  TFS(&png_chunk_anc), 0x20000000, NULL, HFILL };
+    "Ancillary", "png.chunk.flag.ancillary", FT_BOOLEAN, 32,
+    TFS(&png_chunk_anc), 0x20000000, NULL, HFILL };
 
 static const true_false_string png_chunk_priv = {
-	"This is a PRIVATE chunk",
-	"This is a PUBLIC chunk"
+    "This is a PRIVATE chunk",
+    "This is a PUBLIC chunk"
 };
 
 static header_field_info hfi_png_chunk_flag_priv PNG_HFI_INIT = {
-	  "Private", "png.chunk.flag.private", FT_BOOLEAN, 32,
-	  TFS(&png_chunk_priv), 0x00200000, NULL, HFILL };
+    "Private", "png.chunk.flag.private", FT_BOOLEAN, 32,
+    TFS(&png_chunk_priv), 0x00200000, NULL, HFILL };
 
 static const true_false_string png_chunk_stc = {
-	"This chunk is SAFE TO COPY",
-	"This chunk is NOT safe to copy"
+    "This chunk is SAFE TO COPY",
+    "This chunk is NOT safe to copy"
 };
 
 static header_field_info hfi_png_chunk_flag_stc PNG_HFI_INIT = {
-	  "Safe To Copy", "png.chunk.flag.stc", FT_BOOLEAN, 32,
-	  TFS(&png_chunk_stc), 0x00000020, NULL, HFILL };
+    "Safe To Copy", "png.chunk.flag.stc", FT_BOOLEAN, 32,
+    TFS(&png_chunk_stc), 0x00000020, NULL, HFILL };
 
 static header_field_info hfi_png_ihdr_width PNG_HFI_INIT = {
-	  "Width", "png.ihdr.width", FT_UINT32, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Width", "png.ihdr.width", FT_UINT32, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_ihdr_height PNG_HFI_INIT = {
-	  "Height", "png.ihdr.height", FT_UINT32, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Height", "png.ihdr.height", FT_UINT32, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_ihdr_bitdepth PNG_HFI_INIT = {
-	  "Bit Depth", "png.ihdr.bitdepth", FT_UINT8, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Bit Depth", "png.ihdr.bitdepth", FT_UINT8, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static const value_string colour_type_vals[] = {
-	{ 0,	"Greyscale"},
-	{ 2,	"Truecolour"},
-	{ 3,	"Indexed-colour"},
-	{ 4,	"Greyscale with alpha"},
-	{ 6,	"Truecolour with alpha"},
-	{ 0, NULL }
+    { 0,    "Greyscale"},
+    { 2,    "Truecolour"},
+    { 3,    "Indexed-colour"},
+    { 4,    "Greyscale with alpha"},
+    { 6,    "Truecolour with alpha"},
+    { 0, NULL }
 };
 
 static header_field_info hfi_png_ihdr_colour_type PNG_HFI_INIT = {
-	  "Colour Type", "png.ihdr.colour_type", FT_UINT8, BASE_DEC,
-	  VALS(colour_type_vals), 0, NULL, HFILL };
+    "Colour Type", "png.ihdr.colour_type", FT_UINT8, BASE_DEC,
+    VALS(colour_type_vals), 0, NULL, HFILL };
 
 static const value_string compression_method_vals[] = {
-	{ 0,	"Deflate"},
-	{ 0, NULL }
+    { 0,    "Deflate"},
+    { 0, NULL }
 };
 
 static header_field_info hfi_png_ihdr_compression_method PNG_HFI_INIT = {
-	  "Compression Method", "png.ihdr.compression_method", FT_UINT8, BASE_DEC,
-	  VALS(compression_method_vals), 0, NULL, HFILL };
+    "Compression Method", "png.ihdr.compression_method", FT_UINT8, BASE_DEC,
+    VALS(compression_method_vals), 0, NULL, HFILL };
 
 static const value_string filter_method_vals[] = {
-	{ 0,	"Adaptive"},
-	{ 0, NULL }
+    { 0,    "Adaptive"},
+    { 0, NULL }
 };
 
 static header_field_info hfi_png_ihdr_filter_method PNG_HFI_INIT = {
-	  "Filter Method", "png.ihdr.filter_method", FT_UINT8, BASE_DEC,
-	  VALS(filter_method_vals), 0, NULL, HFILL };
+    "Filter Method", "png.ihdr.filter_method", FT_UINT8, BASE_DEC,
+    VALS(filter_method_vals), 0, NULL, HFILL };
 
 static const value_string interlace_method_vals[] = {
-	{ 0,	"No interlace"},
-	{ 1,	"Adam7"},
-	{ 0, NULL }
+    { 0,    "No interlace"},
+    { 1,    "Adam7"},
+    { 0, NULL }
 };
 
 static header_field_info hfi_png_ihdr_interlace_method PNG_HFI_INIT = {
-	  "Interlace Method", "png.ihdr.interlace_method", FT_UINT8, BASE_DEC,
-	  VALS(interlace_method_vals), 0, NULL, HFILL };
+    "Interlace Method", "png.ihdr.interlace_method", FT_UINT8, BASE_DEC,
+    VALS(interlace_method_vals), 0, NULL, HFILL };
 
 static header_field_info hfi_png_text_keyword PNG_HFI_INIT = {
-	  "Keyword", "png.text.keyword", FT_STRING, BASE_NONE,
-	  NULL, 0, NULL, HFILL };
+    "Keyword", "png.text.keyword", FT_STRING, BASE_NONE,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_text_string PNG_HFI_INIT = {
-	  "String", "png.text.string", FT_STRING, BASE_NONE,
-	  NULL, 0, NULL, HFILL };
+    "String", "png.text.string", FT_STRING, BASE_NONE,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_time_year PNG_HFI_INIT = {
-	  "Year", "png.time.year", FT_UINT16, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Year", "png.time.year", FT_UINT16, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_time_month PNG_HFI_INIT = {
-	  "Month", "png.time.month", FT_UINT8, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Month", "png.time.month", FT_UINT8, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_time_day PNG_HFI_INIT = {
-	  "Day", "png.time.day", FT_UINT8, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Day", "png.time.day", FT_UINT8, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_time_hour PNG_HFI_INIT = {
-	  "Hour", "png.time.hour", FT_UINT8, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Hour", "png.time.hour", FT_UINT8, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_time_minute PNG_HFI_INIT = {
-	  "Minute", "png.time.minute", FT_UINT8, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Minute", "png.time.minute", FT_UINT8, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_time_second PNG_HFI_INIT = {
-	  "Second", "png.time.second", FT_UINT8, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Second", "png.time.second", FT_UINT8, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_phys_horiz PNG_HFI_INIT = {
-	  "Horizontal pixels per unit", "png.phys.horiz", FT_UINT32, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Horizontal pixels per unit", "png.phys.horiz", FT_UINT32, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_phys_vert PNG_HFI_INIT = {
-	  "Vertical pixels per unit", "png.phys.vert", FT_UINT32, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Vertical pixels per unit", "png.phys.vert", FT_UINT32, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static const value_string phys_unit_vals[] = {
-	{ 0,	"Unit is unknown"},
-	{ 1,	"Unit is METRE"},
-	{ 0, NULL }
+    { 0,    "Unit is unknown"},
+    { 1,    "Unit is METRE"},
+    { 0, NULL }
 };
 
 static header_field_info hfi_png_phys_unit PNG_HFI_INIT = {
-	  "Unit", "png.phys.unit", FT_UINT8, BASE_DEC,
-	  VALS(phys_unit_vals), 0, NULL, HFILL };
+    "Unit", "png.phys.unit", FT_UINT8, BASE_DEC,
+    VALS(phys_unit_vals), 0, NULL, HFILL };
 
 static header_field_info hfi_png_bkgd_palette_index PNG_HFI_INIT = {
-	  "Palette Index", "png.bkgd.palette_index", FT_UINT8, BASE_DEC,
-	  NULL, 0, NULL, HFILL };
+    "Palette Index", "png.bkgd.palette_index", FT_UINT8, BASE_DEC,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_bkgd_greyscale PNG_HFI_INIT = {
-	  "Greyscale", "png.bkgd.greyscale", FT_UINT16, BASE_HEX,
-	  NULL, 0, NULL, HFILL };
+    "Greyscale", "png.bkgd.greyscale", FT_UINT16, BASE_HEX,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_bkgd_red PNG_HFI_INIT = {
-	  "Red", "png.bkgd.red", FT_UINT16, BASE_HEX,
-	  NULL, 0, NULL, HFILL };
+    "Red", "png.bkgd.red", FT_UINT16, BASE_HEX,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_bkgd_green PNG_HFI_INIT = {
-	  "Green", "png.bkgd.green", FT_UINT16, BASE_HEX,
-	  NULL, 0, NULL, HFILL };
+    "Green", "png.bkgd.green", FT_UINT16, BASE_HEX,
+    NULL, 0, NULL, HFILL };
 
 static header_field_info hfi_png_bkgd_blue PNG_HFI_INIT = {
-	  "Blue", "png.bkgd.blue", FT_UINT16, BASE_HEX,
-	  NULL, 0, NULL, HFILL };
+    "Blue", "png.bkgd.blue", FT_UINT16, BASE_HEX,
+    NULL, 0, NULL, HFILL };
 
 static gint ett_png = -1;
 static gint ett_png_chunk = -1;
@@ -220,259 +220,257 @@ static dissector_handle_t png_handle;
 static void
 dissect_png_ihdr(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 {
-
-	proto_tree_add_item(tree, &hfi_png_ihdr_width, tvb, 0, 4, ENC_BIG_ENDIAN);
-
-	proto_tree_add_item(tree, &hfi_png_ihdr_height, tvb, 4, 4, ENC_BIG_ENDIAN);
-
-	proto_tree_add_item(tree, &hfi_png_ihdr_bitdepth, tvb, 8, 1, ENC_BIG_ENDIAN);
-
-	proto_tree_add_item(tree, &hfi_png_ihdr_colour_type, tvb, 9, 1, ENC_BIG_ENDIAN);
-
-	proto_tree_add_item(tree, &hfi_png_ihdr_compression_method, tvb, 10, 1, ENC_BIG_ENDIAN);
-
-	proto_tree_add_item(tree, &hfi_png_ihdr_filter_method, tvb, 11, 1, ENC_BIG_ENDIAN);
-
-	proto_tree_add_item(tree, &hfi_png_ihdr_interlace_method, tvb, 12, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_ihdr_width, tvb, 0, 4, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_ihdr_height, tvb, 4, 4, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_ihdr_bitdepth, tvb, 8, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_ihdr_colour_type, tvb, 9, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_ihdr_compression_method, tvb, 10, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_ihdr_filter_method, tvb, 11, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_ihdr_interlace_method, tvb, 12, 1, ENC_BIG_ENDIAN);
 
 }
 
 static void
 dissect_png_text(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 {
-	int offset=1;
+    int offset=1;
 
-	/* find the null that separates keyword and text string */
-	while(1){
-		if(!tvb_get_guint8(tvb, offset)){
-			break;
-		}
-		offset++;
-	}
+    /* find the null that separates keyword and text string */
+    while(1){
+        if(!tvb_get_guint8(tvb, offset)){
+            break;
+        }
+        offset++;
+    }
 
-	proto_tree_add_item(tree, &hfi_png_text_keyword, tvb, 0, offset, ENC_ASCII|ENC_NA);
-	offset++;
+    proto_tree_add_item(tree, &hfi_png_text_keyword, tvb, 0, offset, ENC_ASCII|ENC_NA);
+    offset++;
 
-	proto_tree_add_item(tree, &hfi_png_text_string, tvb, offset, tvb_length_remaining(tvb, offset), ENC_ASCII|ENC_NA);
+    proto_tree_add_item(tree, &hfi_png_text_string, tvb, offset, tvb_length_remaining(tvb, offset), ENC_ASCII|ENC_NA);
 
 }
 
 static void
 dissect_png_time(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 {
-	proto_tree_add_item(tree, &hfi_png_time_year, tvb, 0, 2, ENC_BIG_ENDIAN);
-	proto_tree_add_item(tree, &hfi_png_time_month, tvb, 2, 1, ENC_BIG_ENDIAN);
-	proto_tree_add_item(tree, &hfi_png_time_day, tvb, 3, 1, ENC_BIG_ENDIAN);
-	proto_tree_add_item(tree, &hfi_png_time_hour, tvb, 4, 1, ENC_BIG_ENDIAN);
-	proto_tree_add_item(tree, &hfi_png_time_minute, tvb, 5, 1, ENC_BIG_ENDIAN);
-	proto_tree_add_item(tree, &hfi_png_time_second, tvb, 6, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_time_year, tvb, 0, 2, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_time_month, tvb, 2, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_time_day, tvb, 3, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_time_hour, tvb, 4, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_time_minute, tvb, 5, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_time_second, tvb, 6, 1, ENC_BIG_ENDIAN);
 }
 
 static void
 dissect_png_phys(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 {
-	proto_tree_add_item(tree, &hfi_png_phys_horiz, tvb, 0, 4, ENC_BIG_ENDIAN);
-	proto_tree_add_item(tree, &hfi_png_phys_vert, tvb, 4, 4, ENC_BIG_ENDIAN);
-	proto_tree_add_item(tree, &hfi_png_phys_unit, tvb, 8, 1, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_phys_horiz, tvb, 0, 4, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_phys_vert, tvb, 4, 4, ENC_BIG_ENDIAN);
+    proto_tree_add_item(tree, &hfi_png_phys_unit, tvb, 8, 1, ENC_BIG_ENDIAN);
 }
 
 static void
 dissect_png_bkgd(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 {
-	switch(tvb_reported_length(tvb)){
-	case 1: /* colour type 3 */
-		proto_tree_add_item(tree, &hfi_png_bkgd_palette_index, tvb, 0, 1, ENC_BIG_ENDIAN);
-		break;
-	case 2: /* colour type 0, 4 */
-		proto_tree_add_item(tree, &hfi_png_bkgd_greyscale, tvb, 0, 2, ENC_BIG_ENDIAN);
-		break;
-	case 6: /* colour type 2, 6 */
-		proto_tree_add_item(tree, &hfi_png_bkgd_red, tvb, 0, 2, ENC_BIG_ENDIAN);
-		proto_tree_add_item(tree, &hfi_png_bkgd_green, tvb, 2, 2, ENC_BIG_ENDIAN);
-		proto_tree_add_item(tree, &hfi_png_bkgd_blue, tvb, 4, 2, ENC_BIG_ENDIAN);
-		break;
-	}
+    switch(tvb_reported_length(tvb)){
+        case 1: /* colour type 3 */
+            proto_tree_add_item(tree, &hfi_png_bkgd_palette_index, tvb, 0, 1, ENC_BIG_ENDIAN);
+            break;
+        case 2: /* colour type 0, 4 */
+            proto_tree_add_item(tree, &hfi_png_bkgd_greyscale, tvb, 0, 2, ENC_BIG_ENDIAN);
+            break;
+        case 6: /* colour type 2, 6 */
+            proto_tree_add_item(tree, &hfi_png_bkgd_red, tvb, 0, 2, ENC_BIG_ENDIAN);
+            proto_tree_add_item(tree, &hfi_png_bkgd_green, tvb, 2, 2, ENC_BIG_ENDIAN);
+            proto_tree_add_item(tree, &hfi_png_bkgd_blue, tvb, 4, 2, ENC_BIG_ENDIAN);
+            break;
+    }
 }
 
 typedef struct _chunk_dissector_t {
-	guint32 type;
-	const char *name;
-	void (*dissector)(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
+    guint32 type;
+    const char *name;
+    void (*dissector)(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
 } chunk_dissector_t;
 
 static chunk_dissector_t chunk_table[] = {
-	{ 0x49484452, "Image Header", dissect_png_ihdr }, 	/* IHDR */
-	{ 0x624b4744, "Background colour", dissect_png_bkgd }, 	/* bKGD */
-	{ 0x70485973, "Physical pixel dimensions",
-					dissect_png_phys }, 	/* pHYs */
-	{ 0x74455874, "Textual data", dissect_png_text }, 	/* tEXt */
-	{ 0x74494d45, "Image last-modification time",
-					dissect_png_time }, 	/* tIME */
-	{ 0x49454e44, "Image Trailer", NULL }, 			/* IEND */
-	{ 0, NULL, NULL }
+    { 0x49484452, "Image Header", dissect_png_ihdr },     /* IHDR */
+    { 0x624b4744, "Background colour", dissect_png_bkgd },     /* bKGD */
+    { 0x70485973, "Physical pixel dimensions",
+                    dissect_png_phys },     /* pHYs */
+    { 0x74455874, "Textual data", dissect_png_text },     /* tEXt */
+    { 0x74494d45, "Image last-modification time",
+                    dissect_png_time },     /* tIME */
+    { 0x49454e44, "Image Trailer", NULL },             /* IEND */
+    { 0, NULL, NULL }
 };
 
 static gint
 dissect_png(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data _U_)
 {
-	proto_tree *tree = NULL;
-	proto_item *ti;
-	int offset=0;
-
-	/* http://libpng.org/pub/png/spec/1.2/PNG-Structure.html#PNG-file-signature */
-	static const guint8 magic[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
-	if (tvb_length(tvb) < 20)
-		return 0;
-
-	if (tvb_memeql(tvb, 0, magic, sizeof(magic)) != 0)
-		return 0;
-
-	col_append_str(pinfo->cinfo, COL_INFO, " (PNG)");
-
-	if(parent_tree){
-		ti=proto_tree_add_item(parent_tree, hfi_png, tvb, offset, -1, ENC_NA);
-		tree=proto_item_add_subtree(ti, ett_png);
-	}
-
-	proto_tree_add_item(tree, &hfi_png_signature, tvb, offset, 8, ENC_NA);
-	offset+=8;
-
-	while(tvb_reported_length_remaining(tvb, offset) > 0){
-		proto_tree *chunk_tree=NULL;
-		proto_item *it=NULL;
-		guint32 len, type;
-		chunk_dissector_t *cd;
-		char str[5];
-
-		len=tvb_get_ntohl(tvb, offset);
-		type=tvb_get_ntohl(tvb, offset+4);
-		str[0]=tvb_get_guint8(tvb, offset+4);
-		str[1]=tvb_get_guint8(tvb, offset+5);
-		str[2]=tvb_get_guint8(tvb, offset+6);
-		str[3]=tvb_get_guint8(tvb, offset+7);
-		str[4]=0;
-
-		if(tree){
-			it=proto_tree_add_text(tree, tvb, offset, offset+8+len+4, "%s", str);
-			chunk_tree=proto_item_add_subtree(it, ett_png_chunk);
-		}
-
-		proto_tree_add_item(chunk_tree, &hfi_png_chunk_len, tvb, offset, 4, ENC_BIG_ENDIAN);
-		offset+=4;
-
-
-		it=proto_tree_add_item(chunk_tree, &hfi_png_chunk_type, tvb, offset, 4, ENC_ASCII|ENC_NA);
-		proto_tree_add_item(chunk_tree, &hfi_png_chunk_flag_anc, tvb, offset, 4, ENC_BIG_ENDIAN);
-		proto_tree_add_item(chunk_tree, &hfi_png_chunk_flag_priv, tvb, offset, 4, ENC_BIG_ENDIAN);
-		proto_tree_add_item(chunk_tree, &hfi_png_chunk_flag_stc, tvb, offset, 4, ENC_BIG_ENDIAN);
-		offset+=4;
-
-		if (len >= 1000000000)
-			THROW(ReportedBoundsError);
-		cd=&chunk_table[0];
-		while(1){
-			if(cd->type==0){
-				cd=NULL;
-				break;
-			}
-			if(cd->type==type){
-				break;
-			}
-			cd++;
-		}
-		if(chunk_tree){
-			proto_item_append_text(chunk_tree, " %s", cd?cd->name:"(don't know how to dissect this)");
-		}
-
-		if(!cd){
-			proto_tree_add_item(chunk_tree, &hfi_png_chunk_data, tvb, offset, len, ENC_NA);
-		} else {
-			if(cd->dissector){
-				tvbuff_t *next_tvb;
-				proto_tree *cti=NULL;
-
-				next_tvb=tvb_new_subset(tvb, offset, MIN(tvb_length_remaining(tvb, offset), (int)len), len);
-				if(it){
-					cti=proto_item_add_subtree(it, ett_png_chunk_item);
-				}
-				cd->dissector(next_tvb, pinfo, cti);
-			}
-		}
-		offset+=len;
-
-		proto_tree_add_item(chunk_tree, &hfi_png_chunk_crc, tvb, offset, 4, ENC_BIG_ENDIAN);
-		offset+=4;
-	}
-	return offset;
+    proto_tree *tree;
+    proto_item *ti;
+    int offset=0;
+
+    /* http://libpng.org/pub/png/spec/1.2/PNG-Structure.html#PNG-file-signature */
+    static const guint8 magic[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
+    if (tvb_length(tvb) < 20)
+        return 0;
+
+    if (tvb_memeql(tvb, 0, magic, sizeof(magic)) != 0)
+        return 0;
+
+    col_append_str(pinfo->cinfo, COL_INFO, " (PNG)");
+
+    ti=proto_tree_add_item(parent_tree, hfi_png, tvb, offset, -1, ENC_NA);
+    tree=proto_item_add_subtree(ti, ett_png);
+
+    proto_tree_add_item(tree, &hfi_png_signature, tvb, offset, 8, ENC_NA);
+    offset+=8;
+
+    while(tvb_reported_length_remaining(tvb, offset) > 0){
+        proto_tree *chunk_tree;
+        proto_item *it;
+        guint32 len, type;
+        chunk_dissector_t *cd;
+        char str[5];
+
+        len=tvb_get_ntohl(tvb, offset);
+        type=tvb_get_ntohl(tvb, offset+4);
+        str[0]=tvb_get_guint8(tvb, offset+4);
+        str[1]=tvb_get_guint8(tvb, offset+5);
+        str[2]=tvb_get_guint8(tvb, offset+6);
+        str[3]=tvb_get_guint8(tvb, offset+7);
+        str[4]=0;
+
+        it=proto_tree_add_text(tree, tvb, offset, offset+8+len+4, "%s", str);
+        chunk_tree=proto_item_add_subtree(it, ett_png_chunk);
+
+        proto_tree_add_item(chunk_tree, &hfi_png_chunk_len, tvb, offset, 4, ENC_BIG_ENDIAN);
+        offset+=4;
+
+
+        it=proto_tree_add_item(chunk_tree, &hfi_png_chunk_type, tvb, offset, 4, ENC_ASCII|ENC_NA);
+        proto_tree_add_item(chunk_tree, &hfi_png_chunk_flag_anc, tvb, offset, 4, ENC_BIG_ENDIAN);
+        proto_tree_add_item(chunk_tree, &hfi_png_chunk_flag_priv, tvb, offset, 4, ENC_BIG_ENDIAN);
+        proto_tree_add_item(chunk_tree, &hfi_png_chunk_flag_stc, tvb, offset, 4, ENC_BIG_ENDIAN);
+        offset+=4;
+
+        if (len >= 1000000000)
+            THROW(ReportedBoundsError);
+        cd=&chunk_table[0];
+        while(1){
+            if(cd->type==0){
+                cd=NULL;
+                break;
+            }
+            if(cd->type==type){
+                break;
+            }
+            cd++;
+        }
+        proto_item_append_text(chunk_tree, " %s", cd?cd->name:"(don't know how to dissect this)");
+
+        if(!cd){
+            proto_tree_add_item(chunk_tree, &hfi_png_chunk_data, tvb, offset, len, ENC_NA);
+        } else {
+            if(cd->dissector){
+                tvbuff_t *next_tvb;
+                proto_tree *cti;
+
+                next_tvb=tvb_new_subset(tvb, offset, MIN(tvb_length_remaining(tvb, offset), (int)len), len);
+                cti=proto_item_add_subtree(it, ett_png_chunk_item);
+                cd->dissector(next_tvb, pinfo, cti);
+            }
+        }
+        offset+=len;
+
+        proto_tree_add_item(chunk_tree, &hfi_png_chunk_crc, tvb, offset, 4, ENC_BIG_ENDIAN);
+        offset+=4;
+    }
+    return offset;
 }
 
 void
 proto_register_png(void)
 {
 #ifndef HAVE_HFI_SECTION_INIT
-	static header_field_info *hfi[] =
-	{
-		&hfi_png_signature,
-		&hfi_png_chunk_type,
-		&hfi_png_chunk_data,
-		&hfi_png_chunk_len,
-		&hfi_png_chunk_crc,
-		&hfi_png_chunk_flag_anc,
-		&hfi_png_chunk_flag_priv,
-		&hfi_png_chunk_flag_stc,
-		&hfi_png_ihdr_width,
-		&hfi_png_ihdr_height,
-		&hfi_png_ihdr_bitdepth,
-		&hfi_png_ihdr_colour_type,
-		&hfi_png_ihdr_compression_method,
-		&hfi_png_ihdr_filter_method,
-		&hfi_png_ihdr_interlace_method,
-		&hfi_png_text_keyword,
-		&hfi_png_text_string,
-		&hfi_png_time_year,
-		&hfi_png_time_month,
-		&hfi_png_time_day,
-		&hfi_png_time_hour,
-		&hfi_png_time_minute,
-		&hfi_png_time_second,
-		&hfi_png_phys_horiz,
-		&hfi_png_phys_vert,
-		&hfi_png_phys_unit,
-		&hfi_png_bkgd_palette_index,
-		&hfi_png_bkgd_greyscale,
-		&hfi_png_bkgd_red,
-		&hfi_png_bkgd_green,
-		&hfi_png_bkgd_blue,
-	};
+    static header_field_info *hfi[] =
+    {
+        &hfi_png_signature,
+        &hfi_png_chunk_type,
+        &hfi_png_chunk_data,
+        &hfi_png_chunk_len,
+        &hfi_png_chunk_crc,
+        &hfi_png_chunk_flag_anc,
+        &hfi_png_chunk_flag_priv,
+        &hfi_png_chunk_flag_stc,
+        &hfi_png_ihdr_width,
+        &hfi_png_ihdr_height,
+        &hfi_png_ihdr_bitdepth,
+        &hfi_png_ihdr_colour_type,
+        &hfi_png_ihdr_compression_method,
+        &hfi_png_ihdr_filter_method,
+        &hfi_png_ihdr_interlace_method,
+        &hfi_png_text_keyword,
+        &hfi_png_text_string,
+        &hfi_png_time_year,
+        &hfi_png_time_month,
+        &hfi_png_time_day,
+        &hfi_png_time_hour,
+        &hfi_png_time_minute,
+        &hfi_png_time_second,
+        &hfi_png_phys_horiz,
+        &hfi_png_phys_vert,
+        &hfi_png_phys_unit,
+        &hfi_png_bkgd_palette_index,
+        &hfi_png_bkgd_greyscale,
+        &hfi_png_bkgd_red,
+        &hfi_png_bkgd_green,
+        &hfi_png_bkgd_blue,
+    };
 #endif
 
-	static gint *ett[] =
-	{
-		&ett_png,
-		&ett_png_chunk,
-		&ett_png_chunk_item,
-	};
+    static gint *ett[] =
+    {
+        &ett_png,
+        &ett_png_chunk,
+        &ett_png_chunk_item,
+    };
 
-	int proto_png;
+    int proto_png;
 
-	proto_png = proto_register_protocol("Portable Network Graphics","PNG","png");
-	hfi_png = proto_registrar_get_nth(proto_png);
+    proto_png = proto_register_protocol("Portable Network Graphics","PNG","png");
+    hfi_png = proto_registrar_get_nth(proto_png);
 
-	proto_register_fields(proto_png, hfi, array_length(hfi));
-	proto_register_subtree_array(ett, array_length(ett));
+    proto_register_fields(proto_png, hfi, array_length(hfi));
+    proto_register_subtree_array(ett, array_length(ett));
 
-	png_handle = new_register_dissector("png", dissect_png, proto_png);
+    png_handle = new_register_dissector("png", dissect_png, proto_png);
 }
 
 static gboolean dissect_png_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
 {
-	return dissect_png(tvb, pinfo, tree, NULL) > 0;
+    return dissect_png(tvb, pinfo, tree, NULL) > 0;
 }
 
 void
 proto_reg_handoff_png(void)
 {
-	dissector_add_string("media_type", "image/png", png_handle);
-	heur_dissector_add("http", dissect_png_heur, hfi_png->id);
-	heur_dissector_add("wtap_file", dissect_png_heur, hfi_png->id);
+    dissector_add_string("media_type", "image/png", png_handle);
+    heur_dissector_add("http", dissect_png_heur, hfi_png->id);
+    heur_dissector_add("wtap_file", dissect_png_heur, hfi_png->id);
 }
+
+/*
+ * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */