epan/dissectors/file-png.c

   1 /* file-png.c
   2  *
   3  * Routines for PNG (Portable Network Graphics) image file dissection
   4  *
   5  * Copyright 2006 Ronnie Sahlberg
   6  *
   7  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * SPDX-License-Identifier: GPL-2.0-or-later
  12  */
  13 /* See http://www.w3.org/TR/PNG for specification
  14  */
  15 #include "config.h"
  16
  17 #include <epan/packet.h>
  18 #include <epan/expert.h>
  19 #include <epan/tfs.h>
  20 #include <wsutil/array.h>
  21
  22 #define MAKE_TYPE_VAL(a, b, c, d)   ((a)<<24 | (b)<<16 | (c)<<8 | (d))
  23
  24 #define CHUNK_TYPE_IHDR   MAKE_TYPE_VAL('I', 'H', 'D', 'R')
  25 #define CHUNK_TYPE_bKGD   MAKE_TYPE_VAL('b', 'K', 'G', 'D')
  26 #define CHUNK_TYPE_gAMA   MAKE_TYPE_VAL('g', 'A', 'M', 'A')
  27 #define CHUNK_TYPE_iCCP   MAKE_TYPE_VAL('i', 'C', 'C', 'P')
  28 #define CHUNK_TYPE_cHRM   MAKE_TYPE_VAL('c', 'H', 'R', 'M')
  29 #define CHUNK_TYPE_pHYs   MAKE_TYPE_VAL('p', 'H', 'Y', 's')
  30 #define CHUNK_TYPE_iTXt   MAKE_TYPE_VAL('i', 'T', 'X', 't')
  31 #define CHUNK_TYPE_tEXt   MAKE_TYPE_VAL('t', 'E', 'X', 't')
  32 #define CHUNK_TYPE_sBIT   MAKE_TYPE_VAL('s', 'B', 'I', 'T')
  33 #define CHUNK_TYPE_sRGB   MAKE_TYPE_VAL('s', 'R', 'G', 'B')
  34 #define CHUNK_TYPE_tIME   MAKE_TYPE_VAL('t', 'I', 'M', 'E')
  35 #define CHUNK_TYPE_IDAT   MAKE_TYPE_VAL('I', 'D', 'A', 'T')
  36 #define CHUNK_TYPE_IEND   MAKE_TYPE_VAL('I', 'E', 'N', 'D')
  37 #define CHUNK_TYPE_tRNS   MAKE_TYPE_VAL('t', 'R', 'N', 'S')
  38 #define CHUNK_TYPE_PLTE   MAKE_TYPE_VAL('P', 'L', 'T', 'E')
  39
  40 static const value_string chunk_types[] = {
  41     { CHUNK_TYPE_IHDR, "Image Header" },
  42     { CHUNK_TYPE_bKGD, "Background colour" },
  43     { CHUNK_TYPE_gAMA, "Image gamma" },
  44     { CHUNK_TYPE_iCCP, "Embedded ICC profile" },
  45     { CHUNK_TYPE_cHRM, "Primary chromaticities and white point" },
  46     { CHUNK_TYPE_pHYs, "Physical pixel dimensions" },
  47     { CHUNK_TYPE_iTXt, "International textual data" },
  48     { CHUNK_TYPE_tEXt, "Textual data" },
  49     { CHUNK_TYPE_sBIT, "Significant bits" },
  50     { CHUNK_TYPE_sRGB, "Standard RGB colour space" },
  51     { CHUNK_TYPE_tIME, "Image last-modification time" },
  52     { CHUNK_TYPE_IDAT, "Image data chunk" },
  53     { CHUNK_TYPE_IEND, "Image Trailer" },
  54     { CHUNK_TYPE_tRNS, "Transparency" },
  55     { CHUNK_TYPE_PLTE, "Palette" },
  56     { 0, NULL }
  57 };
  58
  59
  60 void proto_register_png(void);
  61 void proto_reg_handoff_png(void);
  62
  63 static const true_false_string png_chunk_anc = {
  64     "This is an ANCILLARY chunk",
  65     "This is a CRITICAL chunk"
  66 };
  67
  68 static const true_false_string png_chunk_priv = {
  69     "This is a PRIVATE chunk",
  70     "This is a PUBLIC chunk"
  71 };
  72
  73 static const true_false_string png_chunk_stc = {
  74     "This chunk is SAFE TO COPY",
  75     "This chunk is NOT safe to copy"
  76 };
  77
  78 static const value_string colour_type_vals[] = {
  79     { 0,    "Greyscale"},
  80     { 2,    "Truecolour"},
  81     { 3,    "Indexed-colour"},
  82     { 4,    "Greyscale with alpha"},
  83     { 6,    "Truecolour with alpha"},
  84     { 0, NULL }
  85 };
  86
  87 static const value_string compression_method_vals[] = {
  88     { 0,    "Deflate"},
  89     { 0, NULL }
  90 };
  91
  92 static const value_string filter_method_vals[] = {
  93     { 0,    "Adaptive"},
  94     { 0, NULL }
  95 };
  96
  97 static const value_string interlace_method_vals[] = {
  98     { 0,    "No interlace"},
  99     { 1,    "Adam7"},
 100     { 0, NULL }
 101 };
 102
 103 static const value_string srgb_intent_vals[] = {
 104     { 0, "Perceptual" },
 105     { 1, "Relative colorimetric" },
 106     { 2, "Saturation" },
 107     { 3, "Absolute colorimetric" },
 108     { 0, NULL }
 109 };
 110
 111 static const value_string phys_unit_vals[] = {
 112     { 0,    "Unit is unknown"},
 113     { 1,    "Unit is METRE"},
 114     { 0, NULL }
 115 };
 116
 117 static int proto_png;
 118
 119 static int hf_png_bkgd_blue;
 120 static int hf_png_bkgd_green;
 121 static int hf_png_bkgd_greyscale;
 122 static int hf_png_bkgd_palette_index;
 123 static int hf_png_bkgd_red;
 124 static int hf_png_chrm_blue_x;
 125 static int hf_png_chrm_blue_y;
 126 static int hf_png_chrm_green_x;
 127 static int hf_png_chrm_green_y;
 128 static int hf_png_chrm_red_x;
 129 static int hf_png_chrm_red_y;
 130 static int hf_png_chrm_white_x;
 131 static int hf_png_chrm_white_y;
 132 static int hf_png_chunk_crc;
 133 static int hf_png_chunk_data;
 134 static int hf_png_chunk_flag_anc;
 135 static int hf_png_chunk_flag_priv;
 136 static int hf_png_chunk_flag_stc;
 137 static int hf_png_chunk_len;
 138 static int hf_png_chunk_type_str;
 139 static int hf_png_gama_gamma;
 140 static int hf_png_ihdr_bitdepth;
 141 static int hf_png_ihdr_colour_type;
 142 static int hf_png_ihdr_compression_method;
 143 static int hf_png_ihdr_filter_method;
 144 static int hf_png_ihdr_height;
 145 static int hf_png_ihdr_interlace_method;
 146 static int hf_png_ihdr_width;
 147 static int hf_png_phys_horiz;
 148 static int hf_png_phys_unit;
 149 static int hf_png_phys_vert;
 150 static int hf_png_signature;
 151 static int hf_png_srgb_intent;
 152 static int hf_png_text_keyword;
 153 static int hf_png_text_string;
 154 static int hf_png_time_day;
 155 static int hf_png_time_hour;
 156 static int hf_png_time_minute;
 157 static int hf_png_time_month;
 158 static int hf_png_time_second;
 159 static int hf_png_time_year;
 160
 161 static int ett_png;
 162 static int ett_png_chunk;
 163
 164 static expert_field ei_png_chunk_too_large;
 165
 166 static dissector_handle_t png_handle;
 167
 168 static void
 169 dissect_png_ihdr(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 170 {
 171     proto_tree_add_item(tree, hf_png_ihdr_width, tvb, 0, 4, ENC_BIG_ENDIAN);
 172     proto_tree_add_item(tree, hf_png_ihdr_height, tvb, 4, 4, ENC_BIG_ENDIAN);
 173     proto_tree_add_item(tree, hf_png_ihdr_bitdepth, tvb, 8, 1, ENC_BIG_ENDIAN);
 174     proto_tree_add_item(tree, hf_png_ihdr_colour_type, tvb, 9, 1, ENC_BIG_ENDIAN);
 175     proto_tree_add_item(tree, hf_png_ihdr_compression_method, tvb, 10, 1, ENC_BIG_ENDIAN);
 176     proto_tree_add_item(tree, hf_png_ihdr_filter_method, tvb, 11, 1, ENC_BIG_ENDIAN);
 177     proto_tree_add_item(tree, hf_png_ihdr_interlace_method, tvb, 12, 1, ENC_BIG_ENDIAN);
 178
 179 }
 180
 181 static void
 182 dissect_png_srgb(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 183 {
 184     proto_tree_add_item(tree, hf_png_srgb_intent,
 185             tvb, 0, 1, ENC_BIG_ENDIAN);
 186 }
 187
 188 static void
 189 dissect_png_text(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 190 {
 191     int offset=0, nul_offset;
 192
 193     nul_offset = tvb_find_uint8(tvb, offset, tvb_captured_length_remaining(tvb, offset), 0);
 194     /* nul_offset == 0 means empty keyword, this is not allowed by the png standard */
 195     if (nul_offset<=0) {
 196         /* XXX exception */
 197         return;
 198     }
 199
 200     proto_tree_add_item(tree, hf_png_text_keyword, tvb, offset, nul_offset, ENC_ISO_8859_1|ENC_NA);
 201     offset = nul_offset+1; /* length of the key word + 0 character */
 202
 203     proto_tree_add_item(tree, hf_png_text_string, tvb, offset, tvb_captured_length_remaining(tvb, offset), ENC_ISO_8859_1|ENC_NA);
 204
 205 }
 206
 207 static void
 208 dissect_png_time(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 209 {
 210     proto_tree_add_item(tree, hf_png_time_year, tvb, 0, 2, ENC_BIG_ENDIAN);
 211     proto_tree_add_item(tree, hf_png_time_month, tvb, 2, 1, ENC_BIG_ENDIAN);
 212     proto_tree_add_item(tree, hf_png_time_day, tvb, 3, 1, ENC_BIG_ENDIAN);
 213     proto_tree_add_item(tree, hf_png_time_hour, tvb, 4, 1, ENC_BIG_ENDIAN);
 214     proto_tree_add_item(tree, hf_png_time_minute, tvb, 5, 1, ENC_BIG_ENDIAN);
 215     proto_tree_add_item(tree, hf_png_time_second, tvb, 6, 1, ENC_BIG_ENDIAN);
 216 }
 217
 218 static void
 219 dissect_png_phys(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 220 {
 221     proto_tree_add_item(tree, hf_png_phys_horiz, tvb, 0, 4, ENC_BIG_ENDIAN);
 222     proto_tree_add_item(tree, hf_png_phys_vert, tvb, 4, 4, ENC_BIG_ENDIAN);
 223     proto_tree_add_item(tree, hf_png_phys_unit, tvb, 8, 1, ENC_BIG_ENDIAN);
 224 }
 225
 226 static void
 227 dissect_png_bkgd(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 228 {
 229     switch(tvb_reported_length(tvb)){
 230         case 1: /* colour type 3 */
 231             proto_tree_add_item(tree, hf_png_bkgd_palette_index, tvb, 0, 1, ENC_BIG_ENDIAN);
 232             break;
 233         case 2: /* colour type 0, 4 */
 234             proto_tree_add_item(tree, hf_png_bkgd_greyscale, tvb, 0, 2, ENC_BIG_ENDIAN);
 235             break;
 236         case 6: /* colour type 2, 6 */
 237             proto_tree_add_item(tree, hf_png_bkgd_red, tvb, 0, 2, ENC_BIG_ENDIAN);
 238             proto_tree_add_item(tree, hf_png_bkgd_green, tvb, 2, 2, ENC_BIG_ENDIAN);
 239             proto_tree_add_item(tree, hf_png_bkgd_blue, tvb, 4, 2, ENC_BIG_ENDIAN);
 240             break;
 241     }
 242 }
 243
 244 static void
 245 dissect_png_chrm(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 246 {
 247     float  wx, wy, rx, ry, gx, gy, bx, by;
 248     int    offset = 0;
 249
 250     wx = tvb_get_ntohl(tvb, offset) / 100000.0f;
 251     proto_tree_add_float(tree, hf_png_chrm_white_x,
 252             tvb, offset, 4, wx);
 253     offset += 4;
 254
 255     wy = tvb_get_ntohl(tvb, offset) / 100000.0f;
 256     proto_tree_add_float(tree, hf_png_chrm_white_y,
 257             tvb, offset, 4, wy);
 258     offset += 4;
 259
 260     rx = tvb_get_ntohl(tvb, offset) / 100000.0f;
 261     proto_tree_add_float(tree, hf_png_chrm_red_x,
 262             tvb, offset, 4, rx);
 263     offset += 4;
 264
 265     ry = tvb_get_ntohl(tvb, offset) / 100000.0f;
 266     proto_tree_add_float(tree, hf_png_chrm_red_y,
 267             tvb, offset, 4, ry);
 268     offset += 4;
 269
 270     gx = tvb_get_ntohl(tvb, offset) / 100000.0f;
 271     proto_tree_add_float(tree, hf_png_chrm_green_x,
 272             tvb, offset, 4, gx);
 273     offset += 4;
 274
 275     gy = tvb_get_ntohl(tvb, offset) / 100000.0f;
 276     proto_tree_add_float(tree, hf_png_chrm_green_y,
 277             tvb, offset, 4, gy);
 278     offset += 4;
 279
 280     bx = tvb_get_ntohl(tvb, offset) / 100000.0f;
 281     proto_tree_add_float(tree, hf_png_chrm_blue_x,
 282             tvb, offset, 4, bx);
 283     offset += 4;
 284
 285     by = tvb_get_ntohl(tvb, offset) / 100000.0f;
 286     proto_tree_add_float(tree, hf_png_chrm_blue_y,
 287             tvb, offset, 4, by);
 288 }
 289
 290 static void
 291 dissect_png_gama(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
 292 {
 293     float  gamma;
 294
 295     gamma = tvb_get_ntohl(tvb, 0) / 100000.0f;
 296     proto_tree_add_float(tree, hf_png_gama_gamma,
 297             tvb, 0, 4, gamma);
 298 }
 299
 300 static int
 301 dissect_png(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data _U_)
 302 {
 303     proto_tree *tree;
 304     proto_item *ti;
 305     int         offset=0;
 306     /* http://libpng.org/pub/png/spec/1.2/PNG-Structure.html#PNG-file-signature */
 307     static const uint8_t magic[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
 308
 309     if (tvb_captured_length(tvb) < 20)
 310         return 0;
 311     if (tvb_memeql(tvb, 0, magic, sizeof(magic)) != 0)
 312         return 0;
 313
 314     col_append_str(pinfo->cinfo, COL_INFO, " (PNG)");
 315
 316     ti=proto_tree_add_item(parent_tree, proto_png, tvb, offset, -1, ENC_NA);
 317     tree=proto_item_add_subtree(ti, ett_png);
 318
 319     proto_tree_add_item(tree, hf_png_signature, tvb, offset, 8, ENC_NA);
 320     offset+=8;
 321
 322     while(tvb_reported_length_remaining(tvb, offset) > 0){
 323         uint32_t    len_field;
 324         proto_item *len_it;
 325         proto_tree *chunk_tree;
 326         uint32_t    type;
 327         uint8_t    *type_str;
 328         tvbuff_t   *chunk_tvb;
 329
 330         len_field = tvb_get_ntohl(tvb, offset);
 331
 332         type = tvb_get_ntohl(tvb, offset+4);
 333         type_str = tvb_get_string_enc(pinfo->pool,
 334                 tvb, offset+4, 4, ENC_ASCII|ENC_NA);
 335
 336         /* 4 byte len field, 4 byte chunk type, 4 byte CRC */
 337         chunk_tree = proto_tree_add_subtree_format(tree, tvb, offset, 4+4+len_field+4, ett_png_chunk, NULL,
 338                 "%s (%s)", val_to_str_const(type, chunk_types, "unknown"), type_str);
 339
 340         len_it = proto_tree_add_item(chunk_tree, hf_png_chunk_len,
 341                 tvb, offset, 4, ENC_BIG_ENDIAN);
 342         offset+=4;
 343         if (len_field > INT_MAX) {
 344             expert_add_info(pinfo, len_it, &ei_png_chunk_too_large);
 345             return offset;
 346         }
 347
 348         proto_tree_add_item(chunk_tree, hf_png_chunk_type_str,
 349                 tvb, offset, 4, ENC_ASCII);
 350
 351         proto_tree_add_item(chunk_tree, hf_png_chunk_flag_anc, tvb, offset, 4, ENC_BIG_ENDIAN);
 352         proto_tree_add_item(chunk_tree, hf_png_chunk_flag_priv, tvb, offset, 4, ENC_BIG_ENDIAN);
 353         proto_tree_add_item(chunk_tree, hf_png_chunk_flag_stc, tvb, offset, 4, ENC_BIG_ENDIAN);
 354         offset+=4;
 355
 356         chunk_tvb=tvb_new_subset_length(tvb, offset, len_field);
 357         switch (type) {
 358             case CHUNK_TYPE_IHDR:
 359                 dissect_png_ihdr(chunk_tvb, pinfo, chunk_tree);
 360                 break;
 361             case CHUNK_TYPE_bKGD:
 362                 dissect_png_bkgd(chunk_tvb, pinfo, chunk_tree);
 363                 break;
 364             case CHUNK_TYPE_cHRM:
 365                 dissect_png_chrm(chunk_tvb, pinfo, chunk_tree);
 366                 break;
 367             case CHUNK_TYPE_gAMA:
 368                 dissect_png_gama(chunk_tvb, pinfo, chunk_tree);
 369                 break;
 370             case CHUNK_TYPE_pHYs:
 371                 dissect_png_phys(chunk_tvb, pinfo, chunk_tree);
 372                 break;
 373             case CHUNK_TYPE_sRGB:
 374                 dissect_png_srgb(chunk_tvb, pinfo, chunk_tree);
 375                 break;
 376             case CHUNK_TYPE_tEXt:
 377                 dissect_png_text(chunk_tvb, pinfo, chunk_tree);
 378                 break;
 379             case CHUNK_TYPE_tIME:
 380                 dissect_png_time(chunk_tvb, pinfo, chunk_tree);
 381                 break;
 382             default:
 383                 if (len_field>0) {
 384                     proto_tree_add_item(chunk_tree, hf_png_chunk_data,
 385                             tvb, offset, len_field, ENC_NA);
 386                 }
 387                 break;
 388         }
 389         offset += len_field;
 390
 391         proto_tree_add_item(chunk_tree, hf_png_chunk_crc, tvb, offset, 4, ENC_BIG_ENDIAN);
 392         offset+=4;
 393     }
 394     return offset;
 395 }
 396
 397 void
 398 proto_register_png(void)
 399 {
 400     static hf_register_info hf[] = {
 401         { &hf_png_signature,
 402             { "PNG Signature", "png.signature",
 403               FT_BYTES, BASE_NONE, NULL, 0,
 404               NULL, HFILL }
 405         },
 406         { &hf_png_chunk_data,
 407             { "Data", "png.chunk.data",
 408               FT_NONE, BASE_NONE, NULL, 0,
 409               NULL, HFILL }
 410         },
 411         { &hf_png_chunk_type_str,
 412             { "Type", "png.chunk.type",
 413               FT_STRING, BASE_NONE, NULL, 0,
 414               NULL, HFILL }
 415         },
 416         { &hf_png_chunk_len,
 417             { "Len", "png.chunk.len",
 418               FT_UINT32, BASE_DEC, NULL, 0,
 419               NULL, HFILL }
 420         },
 421         { &hf_png_chunk_crc,
 422             { "CRC", "png.chunk.crc",
 423               FT_UINT32, BASE_HEX, NULL, 0,
 424               NULL, HFILL }
 425         },
 426         { &hf_png_chunk_flag_anc,
 427             { "Ancillary", "png.chunk.flag.ancillary",
 428               FT_BOOLEAN, 32, TFS(&png_chunk_anc), 0x20000000,
 429               NULL, HFILL }
 430         },
 431         { &hf_png_chunk_flag_priv,
 432             { "Private", "png.chunk.flag.private",
 433               FT_BOOLEAN, 32, TFS(&png_chunk_priv), 0x00200000,
 434               NULL, HFILL }
 435         },
 436         { &hf_png_chunk_flag_stc,
 437             { "Safe To Copy", "png.chunk.flag.stc",
 438               FT_BOOLEAN, 32, TFS(&png_chunk_stc), 0x00000020,
 439               NULL, HFILL }
 440         },
 441         { &hf_png_ihdr_width,
 442             { "Width", "png.ihdr.width",
 443               FT_UINT32, BASE_DEC, NULL, 0,
 444               NULL, HFILL }
 445         },
 446         { &hf_png_ihdr_height,
 447             { "Height", "png.ihdr.height",
 448               FT_UINT32, BASE_DEC, NULL, 0,
 449               NULL, HFILL }
 450         },
 451         { &hf_png_ihdr_bitdepth,
 452             { "Bit Depth", "png.ihdr.bitdepth",
 453               FT_UINT8, BASE_DEC, NULL, 0,
 454               NULL, HFILL }
 455         },
 456         { &hf_png_ihdr_colour_type,
 457             { "Colour Type", "png.ihdr.colour_type",
 458               FT_UINT8, BASE_DEC, VALS(colour_type_vals), 0,
 459               NULL, HFILL }
 460         },
 461         { &hf_png_ihdr_compression_method,
 462             { "Compression Method", "png.ihdr.compression_method",
 463               FT_UINT8, BASE_DEC, VALS(compression_method_vals), 0,
 464               NULL, HFILL }
 465         },
 466         { &hf_png_ihdr_filter_method,
 467             { "Filter Method", "png.ihdr.filter_method",
 468               FT_UINT8, BASE_DEC, VALS(filter_method_vals), 0,
 469               NULL, HFILL }
 470         },
 471         { &hf_png_ihdr_interlace_method,
 472             { "Interlace Method", "png.ihdr.interlace_method",
 473               FT_UINT8, BASE_DEC, VALS(interlace_method_vals), 0,
 474               NULL, HFILL }
 475         },
 476         { &hf_png_srgb_intent,
 477             { "Intent", "png.srgb.intent",
 478               FT_UINT8, BASE_DEC, VALS(srgb_intent_vals), 0,
 479               NULL, HFILL }
 480         },
 481         { &hf_png_text_keyword,
 482             { "Keyword", "png.text.keyword",
 483               FT_STRING, BASE_NONE, NULL, 0,
 484               NULL, HFILL }
 485         },
 486         { &hf_png_text_string,
 487             { "String", "png.text.string",
 488               FT_STRING, BASE_NONE, NULL, 0,
 489               NULL, HFILL }
 490         },
 491         { &hf_png_time_year,
 492             { "Year", "png.time.year",
 493               FT_UINT16, BASE_DEC, NULL, 0,
 494               NULL, HFILL }
 495         },
 496         { &hf_png_time_month,
 497             { "Month", "png.time.month",
 498               FT_UINT8, BASE_DEC, NULL, 0,
 499               NULL, HFILL }
 500         },
 501         { &hf_png_time_day,
 502             { "Day", "png.time.day",
 503               FT_UINT8, BASE_DEC, NULL, 0,
 504               NULL, HFILL }
 505         },
 506         { &hf_png_time_hour,
 507             { "Hour", "png.time.hour",
 508               FT_UINT8, BASE_DEC, NULL, 0,
 509               NULL, HFILL }
 510         },
 511         { &hf_png_time_minute,
 512             { "Minute", "png.time.minute",
 513               FT_UINT8, BASE_DEC, NULL, 0,
 514               NULL, HFILL }
 515         },
 516         { &hf_png_time_second,
 517             { "Second", "png.time.second",
 518               FT_UINT8, BASE_DEC, NULL, 0,
 519               NULL, HFILL }
 520         },
 521         { &hf_png_phys_horiz,
 522             { "Horizontal pixels per unit", "png.phys.horiz",
 523               FT_UINT32, BASE_DEC, NULL, 0,
 524               NULL, HFILL }
 525         },
 526         { &hf_png_phys_vert,
 527             { "Vertical pixels per unit", "png.phys.vert",
 528               FT_UINT32, BASE_DEC, NULL, 0,
 529               NULL, HFILL }
 530         },
 531         { &hf_png_phys_unit,
 532             { "Unit", "png.phys.unit",
 533               FT_UINT8, BASE_DEC, VALS(phys_unit_vals), 0,
 534               NULL, HFILL }
 535         },
 536         { &hf_png_bkgd_palette_index,
 537             { "Palette Index", "png.bkgd.palette_index",
 538               FT_UINT8, BASE_DEC, NULL, 0,
 539               NULL, HFILL }
 540         },
 541         { &hf_png_bkgd_greyscale,
 542             { "Greyscale", "png.bkgd.greyscale",
 543               FT_UINT16, BASE_HEX, NULL, 0,
 544               NULL, HFILL }
 545         },
 546         { &hf_png_bkgd_red,
 547             { "Red", "png.bkgd.red",
 548               FT_UINT16, BASE_HEX, NULL, 0,
 549               NULL, HFILL }
 550         },
 551         { &hf_png_bkgd_green,
 552             { "Green", "png.bkgd.green",
 553               FT_UINT16, BASE_HEX, NULL, 0,
 554               NULL, HFILL }
 555         },
 556         { &hf_png_bkgd_blue,
 557             { "Blue", "png.bkgd.blue",
 558               FT_UINT16, BASE_HEX, NULL, 0,
 559               NULL, HFILL }
 560         },
 561         { &hf_png_chrm_white_x,
 562             { "White X", "png.chrm.white.x",
 563               FT_FLOAT, BASE_NONE, NULL, 0,
 564               NULL, HFILL }
 565         },
 566         { &hf_png_chrm_white_y,
 567             { "White Y", "png.chrm.white.y",
 568               FT_FLOAT, BASE_NONE, NULL, 0,
 569               NULL, HFILL }
 570         },
 571         { &hf_png_chrm_red_x,
 572             { "Red X", "png.chrm.red.x",
 573               FT_FLOAT, BASE_NONE, NULL, 0,
 574               NULL, HFILL }
 575         },
 576         { &hf_png_chrm_red_y,
 577             { "Red Y", "png.chrm.red.y",
 578               FT_FLOAT, BASE_NONE, NULL, 0,
 579               NULL, HFILL }
 580         },
 581         { &hf_png_chrm_green_x,
 582             { "Green X", "png.chrm.green.x",
 583               FT_FLOAT, BASE_NONE, NULL, 0,
 584               NULL, HFILL }
 585         },
 586         { &hf_png_chrm_green_y,
 587             { "Green Y", "png.chrm.green.y",
 588               FT_FLOAT, BASE_NONE, NULL, 0,
 589               NULL, HFILL }
 590         },
 591         { &hf_png_chrm_blue_x,
 592             { "Blue X", "png.chrm.blue.x",
 593               FT_FLOAT, BASE_NONE, NULL, 0,
 594               NULL, HFILL }
 595         },
 596         { &hf_png_chrm_blue_y,
 597             { "Blue Y", "png.chrm.blue.y",
 598               FT_FLOAT, BASE_NONE, NULL, 0,
 599               NULL, HFILL }
 600         },
 601         { &hf_png_gama_gamma,
 602             { "Gamma", "png.gama.gamma",
 603               FT_FLOAT, BASE_NONE, NULL, 0,
 604               NULL, HFILL }
 605         },
 606     };
 607
 608     static int *ett[] =
 609     {
 610         &ett_png,
 611         &ett_png_chunk,
 612     };
 613
 614     static ei_register_info ei[] = {
 615         { &ei_png_chunk_too_large,
 616             { "png.chunk_too_large", PI_PROTOCOL, PI_WARN,
 617                 "chunk size too large, dissection of this chunk is not supported", EXPFILL }}
 618     };
 619     expert_module_t *expert_png;
 620
 621     proto_png = proto_register_protocol("Portable Network Graphics","PNG","png");
 622     proto_register_field_array(proto_png, hf, array_length(hf));
 623     proto_register_subtree_array(ett, array_length(ett));
 624
 625     expert_png = expert_register_protocol(proto_png);
 626     expert_register_field_array(expert_png, ei, array_length(ei));
 627
 628     png_handle = register_dissector("png", dissect_png, proto_png);
 629 }
 630
 631 static bool dissect_png_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
 632 {
 633     return dissect_png(tvb, pinfo, tree, data) > 0;
 634 }
 635
 636 void
 637 proto_reg_handoff_png(void)
 638 {
 639     dissector_add_string("media_type", "image/png", png_handle);
 640     heur_dissector_add("http", dissect_png_heur, "PNG file in HTTP", "png_http", proto_png, HEURISTIC_ENABLE);
 641     heur_dissector_add("wtap_file", dissect_png_heur, "PNG file in HTTP", "png_wtap", proto_png, HEURISTIC_ENABLE);
 642 }
 643
 644 /*
 645  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 646  *
 647  * Local variables:
 648  * c-basic-offset: 4
 649  * tab-width: 8
 650  * indent-tabs-mode: nil
 651  * End:
 652  *
 653  * vi: set shiftwidth=4 tabstop=8 expandtab:
 654  * :indentSize=4:tabSize=8:noTabs=true:
 655  */