/* file-png.c * * Routines for PNG (Portable Network Graphics) image file dissection * * Copyright 2006 Ronnie Sahlberg * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ /* See http://www.w3.org/TR/PNG for specification */ #include "config.h" #include #include #define MAKE_TYPE_VAL(a, b, c, d) ((a)<<24 | (b)<<16 | (c)<<8 | (d)) #define CHUNK_TYPE_IHDR MAKE_TYPE_VAL('I', 'H', 'D', 'R') #define CHUNK_TYPE_bKGD MAKE_TYPE_VAL('b', 'K', 'G', 'D') #define CHUNK_TYPE_gAMA MAKE_TYPE_VAL('g', 'A', 'M', 'A') #define CHUNK_TYPE_iCCP MAKE_TYPE_VAL('i', 'C', 'C', 'P') #define CHUNK_TYPE_cHRM MAKE_TYPE_VAL('c', 'H', 'R', 'M') #define CHUNK_TYPE_pHYs MAKE_TYPE_VAL('p', 'H', 'Y', 's') #define CHUNK_TYPE_iTXt MAKE_TYPE_VAL('i', 'T', 'X', 't') #define CHUNK_TYPE_tEXt MAKE_TYPE_VAL('t', 'E', 'X', 't') #define CHUNK_TYPE_sBIT MAKE_TYPE_VAL('s', 'B', 'I', 'T') #define CHUNK_TYPE_sRGB MAKE_TYPE_VAL('s', 'R', 'G', 'B') #define CHUNK_TYPE_tIME MAKE_TYPE_VAL('t', 'I', 'M', 'E') #define CHUNK_TYPE_IDAT MAKE_TYPE_VAL('I', 'D', 'A', 'T') #define CHUNK_TYPE_IEND MAKE_TYPE_VAL('I', 'E', 'N', 'D') #define CHUNK_TYPE_tRNS MAKE_TYPE_VAL('t', 'R', 'N', 'S') #define CHUNK_TYPE_PLTE MAKE_TYPE_VAL('P', 'L', 'T', 'E') static const value_string chunk_types[] = { { CHUNK_TYPE_IHDR, "Image Header" }, { CHUNK_TYPE_bKGD, "Background colour" }, { CHUNK_TYPE_gAMA, "Image gamma" }, { CHUNK_TYPE_iCCP, "Embedded ICC profile" }, { CHUNK_TYPE_cHRM, "Primary chromaticities and white point" }, { CHUNK_TYPE_pHYs, "Physical pixel dimensions" }, { CHUNK_TYPE_iTXt, "International textual data" }, { CHUNK_TYPE_tEXt, "Textual data" }, { CHUNK_TYPE_sBIT, "Significant bits" }, { CHUNK_TYPE_sRGB, "Standard RGB colour space" }, { CHUNK_TYPE_tIME, "Image last-modification time" }, { CHUNK_TYPE_IDAT, "Image data chunk" }, { CHUNK_TYPE_IEND, "Image Trailer" }, { CHUNK_TYPE_tRNS, "Transparency" }, { CHUNK_TYPE_PLTE, "Palette" }, { 0, NULL } }; void proto_register_png(void); void proto_reg_handoff_png(void); static const true_false_string png_chunk_anc = { "This is an ANCILLARY chunk", "This is a CRITICAL chunk" }; static const true_false_string png_chunk_priv = { "This is a PRIVATE chunk", "This is a PUBLIC chunk" }; static const true_false_string png_chunk_stc = { "This chunk is SAFE TO COPY", "This chunk is NOT safe to copy" }; static const value_string colour_type_vals[] = { { 0, "Greyscale"}, { 2, "Truecolour"}, { 3, "Indexed-colour"}, { 4, "Greyscale with alpha"}, { 6, "Truecolour with alpha"}, { 0, NULL } }; static const value_string compression_method_vals[] = { { 0, "Deflate"}, { 0, NULL } }; static const value_string filter_method_vals[] = { { 0, "Adaptive"}, { 0, NULL } }; static const value_string interlace_method_vals[] = { { 0, "No interlace"}, { 1, "Adam7"}, { 0, NULL } }; static const value_string srgb_intent_vals[] = { { 0, "Perceptual" }, { 1, "Relative colorimetric" }, { 2, "Saturation" }, { 3, "Absolute colorimetric" }, { 0, NULL } }; static const value_string phys_unit_vals[] = { { 0, "Unit is unknown"}, { 1, "Unit is METRE"}, { 0, NULL } }; static int proto_png = -1; static int hf_png_bkgd_blue = -1; static int hf_png_bkgd_green = -1; static int hf_png_bkgd_greyscale = -1; static int hf_png_bkgd_palette_index = -1; static int hf_png_bkgd_red = -1; static int hf_png_chrm_blue_x = -1; static int hf_png_chrm_blue_y = -1; static int hf_png_chrm_green_x = -1; static int hf_png_chrm_green_y = -1; static int hf_png_chrm_red_x = -1; static int hf_png_chrm_red_y = -1; static int hf_png_chrm_white_x = -1; static int hf_png_chrm_white_y = -1; static int hf_png_chunk_crc = -1; static int hf_png_chunk_data = -1; static int hf_png_chunk_flag_anc = -1; static int hf_png_chunk_flag_priv = -1; static int hf_png_chunk_flag_stc = -1; static int hf_png_chunk_len = -1; static int hf_png_chunk_type_str = -1; static int hf_png_gama_gamma = -1; static int hf_png_ihdr_bitdepth = -1; static int hf_png_ihdr_colour_type = -1; static int hf_png_ihdr_compression_method = -1; static int hf_png_ihdr_filter_method = -1; static int hf_png_ihdr_height = -1; static int hf_png_ihdr_interlace_method = -1; static int hf_png_ihdr_width = -1; static int hf_png_phys_horiz = -1; static int hf_png_phys_unit = -1; static int hf_png_phys_vert = -1; static int hf_png_signature = -1; static int hf_png_srgb_intent = -1; static int hf_png_text_keyword = -1; static int hf_png_text_string = -1; static int hf_png_time_day = -1; static int hf_png_time_hour = -1; static int hf_png_time_minute = -1; static int hf_png_time_month = -1; static int hf_png_time_second = -1; static int hf_png_time_year = -1; static gint ett_png = -1; static gint ett_png_chunk = -1; static expert_field ei_png_chunk_too_large = EI_INIT; 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, hf_png_ihdr_width, tvb, 0, 4, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_ihdr_height, tvb, 4, 4, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_ihdr_bitdepth, tvb, 8, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_ihdr_colour_type, tvb, 9, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_ihdr_compression_method, tvb, 10, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_ihdr_filter_method, tvb, 11, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_ihdr_interlace_method, tvb, 12, 1, ENC_BIG_ENDIAN); } static void dissect_png_srgb(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree) { proto_tree_add_item(tree, hf_png_srgb_intent, tvb, 0, 1, ENC_BIG_ENDIAN); } static void dissect_png_text(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree) { gint offset=0, nul_offset; nul_offset = tvb_find_guint8(tvb, offset, tvb_captured_length_remaining(tvb, offset), 0); /* nul_offset == 0 means empty keyword, this is not allowed by the png standard */ if (nul_offset<=0) { /* XXX exception */ return; } proto_tree_add_item(tree, hf_png_text_keyword, tvb, offset, nul_offset, ENC_ISO_8859_1|ENC_NA); offset = nul_offset+1; /* length of the key word + 0 character */ proto_tree_add_item(tree, hf_png_text_string, tvb, offset, tvb_captured_length_remaining(tvb, offset), ENC_ISO_8859_1|ENC_NA); } static void dissect_png_time(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree) { proto_tree_add_item(tree, hf_png_time_year, tvb, 0, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_time_month, tvb, 2, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_time_day, tvb, 3, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_time_hour, tvb, 4, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_time_minute, tvb, 5, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_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, hf_png_phys_horiz, tvb, 0, 4, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_phys_vert, tvb, 4, 4, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_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, hf_png_bkgd_palette_index, tvb, 0, 1, ENC_BIG_ENDIAN); break; case 2: /* colour type 0, 4 */ proto_tree_add_item(tree, hf_png_bkgd_greyscale, tvb, 0, 2, ENC_BIG_ENDIAN); break; case 6: /* colour type 2, 6 */ proto_tree_add_item(tree, hf_png_bkgd_red, tvb, 0, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_bkgd_green, tvb, 2, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_png_bkgd_blue, tvb, 4, 2, ENC_BIG_ENDIAN); break; } } static void dissect_png_chrm(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree) { float wx, wy, rx, ry, gx, gy, bx, by; gint offset = 0; wx = tvb_get_ntohl(tvb, offset) / 100000.0f; proto_tree_add_float(tree, hf_png_chrm_white_x, tvb, offset, 4, wx); offset += 4; wy = tvb_get_ntohl(tvb, offset) / 100000.0f; proto_tree_add_float(tree, hf_png_chrm_white_y, tvb, offset, 4, wy); offset += 4; rx = tvb_get_ntohl(tvb, offset) / 100000.0f; proto_tree_add_float(tree, hf_png_chrm_red_x, tvb, offset, 4, rx); offset += 4; ry = tvb_get_ntohl(tvb, offset) / 100000.0f; proto_tree_add_float(tree, hf_png_chrm_red_y, tvb, offset, 4, ry); offset += 4; gx = tvb_get_ntohl(tvb, offset) / 100000.0f; proto_tree_add_float(tree, hf_png_chrm_green_x, tvb, offset, 4, gx); offset += 4; gy = tvb_get_ntohl(tvb, offset) / 100000.0f; proto_tree_add_float(tree, hf_png_chrm_green_y, tvb, offset, 4, gy); offset += 4; bx = tvb_get_ntohl(tvb, offset) / 100000.0f; proto_tree_add_float(tree, hf_png_chrm_blue_x, tvb, offset, 4, bx); offset += 4; by = tvb_get_ntohl(tvb, offset) / 100000.0f; proto_tree_add_float(tree, hf_png_chrm_blue_y, tvb, offset, 4, by); } static void dissect_png_gama(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree) { float gamma; gamma = tvb_get_ntohl(tvb, 0) / 100000.0f; proto_tree_add_float(tree, hf_png_gama_gamma, tvb, 0, 4, gamma); } static gint dissect_png(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data _U_) { proto_tree *tree; proto_item *ti; gint 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_captured_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, proto_png, tvb, offset, -1, ENC_NA); tree=proto_item_add_subtree(ti, ett_png); proto_tree_add_item(tree, hf_png_signature, tvb, offset, 8, ENC_NA); offset+=8; while(tvb_reported_length_remaining(tvb, offset) > 0){ guint32 len_field; proto_item *len_it; proto_tree *chunk_tree; guint32 type; guint8 *type_str; tvbuff_t *chunk_tvb; len_field = tvb_get_ntohl(tvb, offset); type = tvb_get_ntohl(tvb, offset+4); type_str = tvb_get_string_enc(pinfo->pool, tvb, offset+4, 4, ENC_ASCII|ENC_NA); /* 4 byte len field, 4 byte chunk type, 4 byte CRC */ chunk_tree = proto_tree_add_subtree_format(tree, tvb, offset, 4+4+len_field+4, ett_png_chunk, NULL, "%s (%s)", val_to_str_const(type, chunk_types, "unknown"), type_str); len_it = proto_tree_add_item(chunk_tree, hf_png_chunk_len, tvb, offset, 4, ENC_BIG_ENDIAN); offset+=4; if (len_field > G_MAXINT) { expert_add_info(pinfo, len_it, &ei_png_chunk_too_large); return offset; } proto_tree_add_item(chunk_tree, hf_png_chunk_type_str, tvb, offset, 4, ENC_ASCII); proto_tree_add_item(chunk_tree, hf_png_chunk_flag_anc, tvb, offset, 4, ENC_BIG_ENDIAN); proto_tree_add_item(chunk_tree, hf_png_chunk_flag_priv, tvb, offset, 4, ENC_BIG_ENDIAN); proto_tree_add_item(chunk_tree, hf_png_chunk_flag_stc, tvb, offset, 4, ENC_BIG_ENDIAN); offset+=4; chunk_tvb=tvb_new_subset_length(tvb, offset, len_field); switch (type) { case CHUNK_TYPE_IHDR: dissect_png_ihdr(chunk_tvb, pinfo, chunk_tree); break; case CHUNK_TYPE_bKGD: dissect_png_bkgd(chunk_tvb, pinfo, chunk_tree); break; case CHUNK_TYPE_cHRM: dissect_png_chrm(chunk_tvb, pinfo, chunk_tree); break; case CHUNK_TYPE_gAMA: dissect_png_gama(chunk_tvb, pinfo, chunk_tree); break; case CHUNK_TYPE_pHYs: dissect_png_phys(chunk_tvb, pinfo, chunk_tree); break; case CHUNK_TYPE_sRGB: dissect_png_srgb(chunk_tvb, pinfo, chunk_tree); break; case CHUNK_TYPE_tEXt: dissect_png_text(chunk_tvb, pinfo, chunk_tree); break; case CHUNK_TYPE_tIME: dissect_png_time(chunk_tvb, pinfo, chunk_tree); break; default: if (len_field>0) { proto_tree_add_item(chunk_tree, hf_png_chunk_data, tvb, offset, len_field, ENC_NA); } break; } offset += len_field; proto_tree_add_item(chunk_tree, hf_png_chunk_crc, tvb, offset, 4, ENC_BIG_ENDIAN); offset+=4; } return offset; } void proto_register_png(void) { static hf_register_info hf[] = { { &hf_png_signature, { "PNG Signature", "png.signature", FT_BYTES, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chunk_data, { "Data", "png.chunk.data", FT_NONE, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chunk_type_str, { "Chunk", "png.chunk.type", FT_STRING, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chunk_len, { "Len", "png.chunk.len", FT_UINT32, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_chunk_crc, { "CRC", "png.chunk.crc", FT_UINT32, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_png_chunk_flag_anc, { "Ancillary", "png.chunk.flag.ancillary", FT_BOOLEAN, 32, TFS(&png_chunk_anc), 0x20000000, NULL, HFILL } }, { &hf_png_chunk_flag_priv, { "Private", "png.chunk.flag.private", FT_BOOLEAN, 32, TFS(&png_chunk_priv), 0x00200000, NULL, HFILL } }, { &hf_png_chunk_flag_stc, { "Safe To Copy", "png.chunk.flag.stc", FT_BOOLEAN, 32, TFS(&png_chunk_stc), 0x00000020, NULL, HFILL } }, { &hf_png_ihdr_width, { "Width", "png.ihdr.width", FT_UINT32, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_ihdr_height, { "Height", "png.ihdr.height", FT_UINT32, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_ihdr_bitdepth, { "Bit Depth", "png.ihdr.bitdepth", FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_ihdr_colour_type, { "Colour Type", "png.ihdr.colour_type", FT_UINT8, BASE_DEC, VALS(colour_type_vals), 0, NULL, HFILL } }, { &hf_png_ihdr_compression_method, { "Compression Method", "png.ihdr.compression_method", FT_UINT8, BASE_DEC, VALS(compression_method_vals), 0, NULL, HFILL } }, { &hf_png_ihdr_filter_method, { "Filter Method", "png.ihdr.filter_method", FT_UINT8, BASE_DEC, VALS(filter_method_vals), 0, NULL, HFILL } }, { &hf_png_ihdr_interlace_method, { "Interlace Method", "png.ihdr.interlace_method", FT_UINT8, BASE_DEC, VALS(interlace_method_vals), 0, NULL, HFILL } }, { &hf_png_srgb_intent, { "Intent", "png.srgb.intent", FT_UINT8, BASE_DEC, VALS(srgb_intent_vals), 0, NULL, HFILL } }, { &hf_png_text_keyword, { "Keyword", "png.text.keyword", FT_STRING, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_text_string, { "String", "png.text.string", FT_STRING, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_time_year, { "Year", "png.time.year", FT_UINT16, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_time_month, { "Month", "png.time.month", FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_time_day, { "Day", "png.time.day", FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_time_hour, { "Hour", "png.time.hour", FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_time_minute, { "Minute", "png.time.minute", FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_time_second, { "Second", "png.time.second", FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_phys_horiz, { "Horizontal pixels per unit", "png.phys.horiz", FT_UINT32, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_phys_vert, { "Vertical pixels per unit", "png.phys.vert", FT_UINT32, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_phys_unit, { "Unit", "png.phys.unit", FT_UINT8, BASE_DEC, VALS(phys_unit_vals), 0, NULL, HFILL } }, { &hf_png_bkgd_palette_index, { "Palette Index", "png.bkgd.palette_index", FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } }, { &hf_png_bkgd_greyscale, { "Greyscale", "png.bkgd.greyscale", FT_UINT16, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_png_bkgd_red, { "Red", "png.bkgd.red", FT_UINT16, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_png_bkgd_green, { "Green", "png.bkgd.green", FT_UINT16, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_png_bkgd_blue, { "Blue", "png.bkgd.blue", FT_UINT16, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_png_chrm_white_x, { "White X", "png.chrm.white.x", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chrm_white_y, { "White Y", "png.chrm.white.y", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chrm_red_x, { "Red X", "png.chrm.red.x", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chrm_red_y, { "Red Y", "png.chrm.red.y", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chrm_green_x, { "Green X", "png.chrm.green.x", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chrm_green_y, { "Green Y", "png.chrm.green.y", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chrm_blue_x, { "Blue X", "png.chrm.blue.x", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_chrm_blue_y, { "Blue Y", "png.chrm.blue.y", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, { &hf_png_gama_gamma, { "Gamma", "png.gama.gamma", FT_FLOAT, BASE_NONE, NULL, 0, NULL, HFILL } }, }; static gint *ett[] = { &ett_png, &ett_png_chunk, }; static ei_register_info ei[] = { { &ei_png_chunk_too_large, { "png.chunk_too_large", PI_PROTOCOL, PI_WARN, "chunk size too large, dissection of this chunk is not supported", EXPFILL }} }; expert_module_t *expert_png; proto_png = proto_register_protocol("Portable Network Graphics","PNG","png"); proto_register_field_array(proto_png, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); expert_png = expert_register_protocol(proto_png); expert_register_field_array(expert_png, ei, array_length(ei)); png_handle = 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; } void proto_reg_handoff_png(void) { dissector_add_string("media_type", "image/png", png_handle); heur_dissector_add("http", dissect_png_heur, "PNG file in HTTP", "png_http", proto_png, HEURISTIC_ENABLE); heur_dissector_add("wtap_file", dissect_png_heur, "PNG file in HTTP", "png_wtap", proto_png, HEURISTIC_ENABLE); } /* * Editor modelines - https://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: */