nodejs canvas Slowbuffer to string - node.js

I use node-canvas;
....
var content = canvas.toBuffer();
var length=content.length;
console.log(content);
result:
<SlowBuffer 89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52 00 00 00 30 00 00 00 30 08 06 00 00 00 57 02 f9 87 00 00 00 06 62 4b 47 44 00 ff 00 ff 00 ff a0 bd a7 93 ...>
And
var buf=new SlowBuffer(length);
buf.write(content.toString());
console.log(buf);
result:
<Buffer ff d8 ff e0 00 10 4a 46 49 46 00 01 01 01 00 28 00 28 00 00 ff db 00 43 00 08 06 06 07 06 05 08 07 07 07 09 09 08 0a 0c 14 0d 0c 0b 0b 0c 19 12 13 0f 14 ...>
They are not equal:( ,so when I store it into redis ,I can't get it back;


Depending on the format you want, you can use the following methods:
buf.toJSON() // Straight to JSON format
buf.toString('utf8') ; // UTF8 format
Read on for more alternatives: https://nodejs.org/api/buffer.html#buffer_buf_tostring_encoding_start_end


You can't just call Buffer.toString and assume that everything will be all right, since the default encoding is utf8. If you want to encode binary data, you need base64 encoding.

Related

How to change specific byte in packet using scapy?

I want to modify icmp.unused value in scapy. But no matter what value I set for it, the value of icmp.unused is still 0. I know which byte in my packet is responsible for its value. So I want to modify the byte directly. hexstr and hexdump don't work. The end of the packet is messed up. How to do this?
hex_packet = scapy.hexstr(packet)
print(type(hex_packet))
list_packet = list(hex_packet)
list_packet[38] = '\x05'
list_packet[39] = '\x14'
hex_packet = ''.join(list_packet)
packet_hex = scapy.Ether(scapy.import_hexcap())
08 00 27 78 FE 4B 52 54 00 12 35 00 080 45 00 00 38 00 01 00 00 40 01 31 6D C0 A8 64 01 C0 A8 64 05 03 04 41 5E 00 00 05 14 45 00 00 1C 00 01 00 00 40 11 31 74 C0 A8 64 05 C0 A8 64 06 FC F1 00 35 00 08 B9 5A ..'x.KRT..5...E..8....#.1m..d...d...A^....E.......#.1t..d...d....5...Z

std::map (Enum / CString) is triggering a memory leak in my app - why?

I have looked at similar discussions (std::map causing memory leaks?) about this issue but according to the debug build of my app this is triggering a memory leak:
void CMeetingScheduleAssistantApp::SetLocale(LanguageMSA eLang)
{
// See: https://www.microsoft.com/resources/msdn/goglobal/default.mspx#ISO2
map<LanguageMSA, CString> mapLocales;
mapLocales.emplace(LanguageMSA::Afrikaans, _T("af"));
mapLocales.emplace(LanguageMSA::Albanian, _T("sqi"));
mapLocales.emplace(LanguageMSA::Arabic, _T("ara"));
mapLocales.emplace(LanguageMSA::Aukan, _T("drk"));
mapLocales.emplace(LanguageMSA::Bulgarian, _T("bgr"));
mapLocales.emplace(LanguageMSA::ChineseSimplified, _T("chs"));
mapLocales.emplace(LanguageMSA::Croatian, _T("hrv"));
mapLocales.emplace(LanguageMSA::Czech, _T("csy"));
mapLocales.emplace(LanguageMSA::Danish, _T("dan"));
mapLocales.emplace(LanguageMSA::Dutch, _T("nld"));
mapLocales.emplace(LanguageMSA::English, _T("eng"));
mapLocales.emplace(LanguageMSA::Estonian, _T("et"));
mapLocales.emplace(LanguageMSA::Finnish, _T("fin"));
mapLocales.emplace(LanguageMSA::French, _T("fra"));
mapLocales.emplace(LanguageMSA::German, _T("deu"));
mapLocales.emplace(LanguageMSA::Greek, _T("ell"));
mapLocales.emplace(LanguageMSA::Gujarati, _T("guj"));
mapLocales.emplace(LanguageMSA::Hindi, _T("hin"));
mapLocales.emplace(LanguageMSA::Hungarian, _T("hu-HU"));
mapLocales.emplace(LanguageMSA::Indonesian, _T("ind"));
mapLocales.emplace(LanguageMSA::Italian, _T("ita"));
mapLocales.emplace(LanguageMSA::Japanese, _T("jpn"));
mapLocales.emplace(LanguageMSA::Lingala, _T("ln-CG"));
mapLocales.emplace(LanguageMSA::Maltese, _T("mt-MT"));
mapLocales.emplace(LanguageMSA::Polish, _T("plk"));
mapLocales.emplace(LanguageMSA::PortugueseBrazil, _T("ptb"));
mapLocales.emplace(LanguageMSA::PortuguesePortugal, _T("pt-PT"));
mapLocales.emplace(LanguageMSA::Punjabi, _T("pa"));
mapLocales.emplace(LanguageMSA::Romanian, _T("rom"));
mapLocales.emplace(LanguageMSA::Russian, _T("rus"));
mapLocales.emplace(LanguageMSA::Saramaccan, _T("fra")); // Special case (uses French)
mapLocales.emplace(LanguageMSA::Setswana, _T("tn-ZA"));
mapLocales.emplace(LanguageMSA::Slovenian, _T("slv"));
mapLocales.emplace(LanguageMSA::Spanish, _T("esp"));
mapLocales.emplace(LanguageMSA::Swahili, _T("swk"));
mapLocales.emplace(LanguageMSA::Swedish, _T("sve"));
mapLocales.emplace(LanguageMSA::Tagalog, _T("fil-PH"));
mapLocales.emplace(LanguageMSA::Tamil, _T("tai"));
mapLocales.emplace(LanguageMSA::Tsonga, _T("tso"));
mapLocales.emplace(LanguageMSA::Turkish, _T("trk"));
mapLocales.emplace(LanguageMSA::Ukrainian, _T("ukr"));
mapLocales.emplace(LanguageMSA::Vietnamese, _T("vit"));
mapLocales.emplace(LanguageMSA::Zulu, _T("zu-ZA"));
CString strLocale = _T("eng"); // Default (also used by some "partial" translations
if (mapLocales.find(eLang) != mapLocales.end())
strLocale = mapLocales[eLang];
_tsetlocale(LC_ALL, strLocale);
}
Please advise if there is anything I need to do to stop this memory leak being listed when the debug version closes. Or is it a red herring in this case?
LanguageMSA is an enum class:
enum class LanguageMSA
{
English = 0,
German,
Spanish,
Italian,
Polish,
French,
PortugueseBrazil,
Dutch,
Swedish,
Slovenian,
Czech,
Finnish,
Danish,
Ukrainian,
Russian,
Tagalog,
HaitianCreole,
Afrikaans,
Albanian,
ChineseSimplified,
Croatian,
Turkish,
Twi,
Swahili, // AJT v11.3.4
Estonian, // AJT v12.0.5
Romanian, // AJT v12.0.8
Greek, // AJT v13.0.0
Bulgarian, // AJT v13.0.2
Malagasy, // AJT v14.0.4‏
Arabic, // AJT v16.0.0
Indonesian, // AJT v16.0.2
Hindi, // AJT v16.0.7
Tamil, // AJT v16.1.0
Vietnamese, // AJT v16.1.1
Zulu, // AJT v16.1.6
Gun, // AJT v17.0.9
Lingala, // AJT v17.0.9
PortuguesePortugal, // AJT v17.1.0
Punjabi, // AJT v17.1.3
Maltese, // AJT v17.2.3
Hungarian, // AJT v17.2.6
Saramaccan, // AJT v18.0.0
Amharic, // AJT v18.0.6
Japanese, // AJT v18.0.6
Setswana, // AJT v18.0.8
Sranantongo,// AJT v18.1.4
Aukan, // AJT v18.1.6
Armenian, // AJT v18.2.1
Gujarati, // AJT v19.0.9
Sesotho, // AJT v20.0.3
Cebuano, // AJT v20.1.2
Tsonga, // AJT v20.1.5
PidginWestAfrica, // AJT v20.3.0
// Maintain a count of language enums
Count
} ;
Memory leak dump:
Detected memory leaks!
Dumping objects ->
{104257} normal block at 0x0000028AC8015830, 40 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 07 00 00 00 07 00 00 00
{104255} normal block at 0x0000028AC8015210, 40 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 07 00 00 00 07 00 00 00
{104253} normal block at 0x0000028AC706A920, 168 bytes long.
Data: < (R ÈŠ > 05 00 00 00 00 00 00 00 28 52 01 C8 8A 02 00 00
{104244} normal block at 0x0000028AE311F820, 34 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 04 00 00 00 04 00 00 00
{104242} normal block at 0x0000028AE311EEC0, 34 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 04 00 00 00 04 00 00 00
{104241} normal block at 0x0000028AC706A0B0, 168 bytes long.
Data: < Øî ㊠> 04 00 00 00 00 00 00 00 D8 EE 11 E3 8A 02 00 00
{104232} normal block at 0x0000028AC80152F0, 38 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 06 00 00 00 06 00 00 00
{104230} normal block at 0x0000028AC6CF9690, 54 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0E 00 00 00 0E 00 00 00
{104229} normal block at 0x0000028AC7069C00, 168 bytes long.
Data: < ¨–ÏÆŠ > 03 00 00 00 00 00 00 00 A8 96 CF C6 8A 02 00 00
{104220} normal block at 0x0000028AC8015DE0, 42 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 08 00 00 00 08 00 00 00
{104218} normal block at 0x0000028AC6CF8F10, 58 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 10 00 00 00 10 00 00 00
{104217} normal block at 0x0000028AC706B280, 168 bytes long.
Data: < ( ÏÆŠ > 02 00 00 00 00 00 00 00 28 8F CF C6 8A 02 00 00
{104208} normal block at 0x0000028AC80151A0, 46 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0A 00 00 00 0A 00 00 00
{104206} normal block at 0x0000028AC80164E0, 46 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0A 00 00 00 0A 00 00 00
{104204} normal block at 0x0000028AC706B910, 168 bytes long.
Data: < ød ÈŠ > 01 00 00 00 00 00 00 00 F8 64 01 C8 8A 02 00 00
{104195} normal block at 0x0000028AC8016A20, 52 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0D 00 00 00 0D 00 00 00
{104193} normal block at 0x0000028AC8014560, 52 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0D 00 00 00 0D 00 00 00
{104191} normal block at 0x0000028AC706A830, 168 bytes long.
Data: < xE ÈŠ > 00 00 00 00 00 00 00 00 78 45 01 C8 8A 02 00 00
{103563} normal block at 0x0000028AC80157C0, 40 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 07 00 00 00 07 00 00 00
{103561} normal block at 0x0000028AC8013B50, 40 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 07 00 00 00 07 00 00 00
{103559} normal block at 0x0000028AC706B820, 168 bytes long.
Data: < h; ÈŠ > 05 00 00 00 00 00 00 00 68 3B 01 C8 8A 02 00 00
{103550} normal block at 0x0000028AC7090340, 34 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 04 00 00 00 04 00 00 00
{103548} normal block at 0x0000028AC7090DC0, 34 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 04 00 00 00 04 00 00 00
{103547} normal block at 0x0000028AC706B730, 168 bytes long.
Data: < Ø ÇŠ > 04 00 00 00 00 00 00 00 D8 0D 09 C7 8A 02 00 00
{103538} normal block at 0x0000028AC8016BE0, 38 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 06 00 00 00 06 00 00 00
{103536} normal block at 0x0000028AC6CF8E90, 54 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0E 00 00 00 0E 00 00 00
{103535} normal block at 0x0000028AC706A290, 168 bytes long.
Data: < ¨ŽÏÆŠ > 03 00 00 00 00 00 00 00 A8 8E CF C6 8A 02 00 00
{103526} normal block at 0x0000028AC80169B0, 42 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 08 00 00 00 08 00 00 00
{103524} normal block at 0x0000028AC6CF8D10, 58 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 10 00 00 00 10 00 00 00
{103523} normal block at 0x0000028AC706A380, 168 bytes long.
Data: < ( ÏÆŠ > 02 00 00 00 00 00 00 00 28 8D CF C6 8A 02 00 00
{103514} normal block at 0x0000028AC8015F30, 46 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0A 00 00 00 0A 00 00 00
{103512} normal block at 0x0000028AC8013FB0, 46 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0A 00 00 00 0A 00 00 00
{103510} normal block at 0x0000028AC706A650, 168 bytes long.
Data: < È? ÈŠ > 01 00 00 00 00 00 00 00 C8 3F 01 C8 8A 02 00 00
{103501} normal block at 0x0000028AC8013CA0, 52 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0D 00 00 00 0D 00 00 00
{103499} normal block at 0x0000028AC8013760, 52 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0D 00 00 00 0D 00 00 00
{103497} normal block at 0x0000028AC706BA00, 168 bytes long.
Data: < x7 ÈŠ > 00 00 00 00 00 00 00 00 78 37 01 C8 8A 02 00 00
{101036} normal block at 0x0000028AC8013990, 40 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 07 00 00 00 07 00 00 00
{101034} normal block at 0x0000028AC8014640, 40 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 07 00 00 00 07 00 00 00
{101032} normal block at 0x0000028AC706B190, 168 bytes long.
Data: < XF ÈŠ > 05 00 00 00 00 00 00 00 58 46 01 C8 8A 02 00 00
{101023} normal block at 0x0000028AE311F700, 34 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 04 00 00 00 04 00 00 00
{101021} normal block at 0x0000028AE311E5C0, 34 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 04 00 00 00 04 00 00 00
{101020} normal block at 0x0000028AC706A740, 168 bytes long.
Data: < Øå ㊠> 04 00 00 00 00 00 00 00 D8 E5 11 E3 8A 02 00 00
{101011} normal block at 0x0000028AC8013680, 38 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 06 00 00 00 06 00 00 00
{101009} normal block at 0x0000028AC6CDEA80, 54 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0E 00 00 00 0E 00 00 00
{101008} normal block at 0x0000028AC706A560, 168 bytes long.
Data: < êÍÆŠ > 03 00 00 00 00 00 00 00 98 EA CD C6 8A 02 00 00
{100999} normal block at 0x0000028AC8015050, 42 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 08 00 00 00 08 00 00 00
{100997} normal block at 0x0000028AC6CDF900, 58 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 10 00 00 00 10 00 00 00
{100996} normal block at 0x0000028AC706ADD0, 168 bytes long.
Data: < ùÍÆŠ > 02 00 00 00 00 00 00 00 18 F9 CD C6 8A 02 00 00
{100987} normal block at 0x0000028AC80135A0, 46 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0A 00 00 00 0A 00 00 00
{100985} normal block at 0x0000028AC8014FE0, 46 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0A 00 00 00 0A 00 00 00
{100983} normal block at 0x0000028AC706B0A0, 168 bytes long.
Data: < øO ÈŠ > 01 00 00 00 00 00 00 00 F8 4F 01 C8 8A 02 00 00
{100974} normal block at 0x0000028AC80145D0, 52 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0D 00 00 00 0D 00 00 00
{100972} normal block at 0x0000028AC8014480, 52 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0D 00 00 00 0D 00 00 00
{100970} normal block at 0x0000028AC706B460, 168 bytes long.
Data: < D ÈŠ > 00 00 00 00 00 00 00 00 98 44 01 C8 8A 02 00 00
{12591} normal block at 0x0000028AC64B5970, 40 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 07 00 00 00 07 00 00 00
{12589} normal block at 0x0000028AC64B5740, 40 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 07 00 00 00 07 00 00 00
{12587} normal block at 0x0000028AC7F8D9D0, 168 bytes long.
Data: < XWKÆŠ > 05 00 00 00 00 00 00 00 58 57 4B C6 8A 02 00 00
{12578} normal block at 0x0000028AC7F06DB0, 34 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 04 00 00 00 04 00 00 00
{12576} normal block at 0x0000028AC7F07830, 34 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 04 00 00 00 04 00 00 00
{12575} normal block at 0x0000028AC7F8D8E0, 168 bytes long.
Data: < HxðÇŠ > 04 00 00 00 00 00 00 00 48 78 F0 C7 8A 02 00 00
{12566} normal block at 0x0000028AC64B5890, 38 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 06 00 00 00 06 00 00 00
{12564} normal block at 0x0000028AC6496AE0, 54 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0E 00 00 00 0E 00 00 00
{12563} normal block at 0x0000028AC7F8D7F0, 168 bytes long.
Data: < øjIÆŠ > 03 00 00 00 00 00 00 00 F8 6A 49 C6 8A 02 00 00
{12554} normal block at 0x0000028AC64B5820, 42 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 08 00 00 00 08 00 00 00
{12552} normal block at 0x0000028AC64965E0, 58 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 10 00 00 00 10 00 00 00
{12551} normal block at 0x0000028AC7F8E240, 168 bytes long.
Data: < øeIÆŠ > 02 00 00 00 00 00 00 00 F8 65 49 C6 8A 02 00 00
{12542} normal block at 0x0000028AC64B4E10, 46 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0A 00 00 00 0A 00 00 00
{12540} normal block at 0x0000028AC64B53C0, 46 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0A 00 00 00 0A 00 00 00
{12538} normal block at 0x0000028AC7F8D610, 168 bytes long.
Data: < ØSKÆŠ > 01 00 00 00 00 00 00 00 D8 53 4B C6 8A 02 00 00
{12529} normal block at 0x0000028AC64B4D30, 52 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0D 00 00 00 0D 00 00 00
{12527} normal block at 0x0000028AC64B4C50, 52 bytes long.
Data: < 3#^ö > 00 33 23 5E F6 7F 00 00 0D 00 00 00 0D 00 00 00
{12525} normal block at 0x0000028AC7EE7740, 168 bytes long.
Data: < hLKÆŠ > 00 00 00 00 00 00 00 00 68 4C 4B C6 8A 02 00 00
Object dump complete.

How would I "decode" the packet data from a pcap in NodeJS?

I'm wanting to make a PCap Analyzer script where it can detect what traffic is what from a pcap file.
The general idea is: HTTP(x10), DNS(x5), HTTPS(x20)
Now as you can see the majority of traffic is HTTPS based I want to be able to pull that from the pcap packet data to pass to another section of my analyzer script.
I don't have a clue nor any idea of what NPMs or anything that I can use, I have looked into pcap-parser which is a 9+ Yr old NPM this package , and only provides packet.data, packet.header.
I'm just completely losing all hope on making this script as I've tried ever potential resource even went into researching a potential API system to upload the pcap and bring the info I wish to obtain with no avail.
Example of packet.header
{
timestampSeconds: 1606145597,
timestampMicroseconds: 444357,
capturedLength: 60,
originalLength: 60
}
Example of packet.data (Buffer)
<Buffer 01 00 5e 7f ff fa 34 29 8f 99 09 70 08 00 45 00 00 a5 a4 76 00 00 04 11 10 f3 0a c8 06 1d ef ff ff fa ed 0c 07 6c 00 91 17 56 4d 2d 53 45 41 52 43 48 ... 129 more bytes>
<Buffer ff ff ff ff ff ff 34 29 8f 99 09 6e 08 06 00 01 08 00 06 04 00 01 34 29 8f 99 09 6e 0a c8 06 e6 00 00 00 00 00 00 0a c8 06 de 00 00 00 00 00 00 00 00 ... 10 more bytes>
<Buffer e0 55 3d 5e 95 a0 40 ec 99 d3 06 fd 08 00 45 00 05 6b a7 ed 40 00 80 06 00 00 0a 91 a6 ce 34 ef cf 64 e9 9f 01 bb a2 30 72 ed d9 06 6d cc 80 18 02 00 ... 1351 more bytes>
<Buffer 40 ec 99 d3 06 fd e0 55 3d 5e 95 a0 08 00 45 00 00 34 72 2d 40 00 70 06 e2 e3 34 ef cf 64 0a 91 a6 ce 01 bb e9 9f d9 06 6d cc a2 30 14 19 80 10 1b 25 ... 16 more bytes>
<Buffer e0 55 3d 5e 95 a0 40 ec 99 d3 06 fd 08 00 45 00 00 34 05 b4 40 00 80 06 00 00 0a 91 a6 ce 17 d9 8a 6c e9 a8 01 bb f0 0d cc ed 00 00 00 00 80 02 fa f0 ... 16 more bytes>

Socat corrupt image file

I use 'socat TCP4-LISTEN:8080,fork EXEC:./bashttpd' for http server. when try to receive image file from client socat remove some byte and corrupt my image.
correct:
01b0 0a 89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 ..PNG........IHD
01c0 52 00 00 07 80 00 00 04 38 08 02 00 00 00 67 b1 R.......8.....g.
01d0 56 14 00 00 00 09 70 48 59 73 00 00 11 b0 00 00 V.
incorrect:(socat -> read line -> xxh)
00000000: 89 50 4e 47 0d 0a .PNG..
00000000: 1a 0a ..
00000000: 0d 49 48 44 52 07 80 04 38 08 02 67 b1 56 14 09 .IHDR...8..g.V
how to solve this problem?
thanks

Experiencing weird behaviour with Buffer.compare / Buffer.from

I'm trying to modify buffers, however when modifying them I wish them to be in utf-8 so I attempt to do this via myBuffer.toString('utf8') however if I make no changes and attempt to convert it back via Buffer.from(myBuffer, 'utf8'), I am presented with a completely new buffer on occasions.
These occasions seem to be when parsing an image file, instead of a html file.
My next step was to accept a bug or erroneous behaviour by comparing the two buffers using the following code:
//myBuffer is the buffer is wish to attempt to modify
let testParse = Buffer.from(myBuffer.toString('utf8'), 'utf8');
let editable = Buffer.compare(myBuffer, testParse);
console.log(myBuffer);
console.log(testParse);
console.log(editable);
The following snippet however refuses to work and editable is always -1 here is an example output:
<Buffer 89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52 00 00 01 10 00 00 00 5c 08 02 00 00 00 29 85 7d e1 00 00 15 31 49 44 41 54 78 01 ed 5d 05 94 db c8 b2 ... >
<Buffer ef bf bd 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52 00 00 01 10 00 00 00 5c 08 02 00 00 00 29 ef bf bd 7d ef bf bd 00 00 15 31 49 44 41 54 78 01 ef ... >
-1
As you can see the buffers are completely different however returns -1
another example where the buffers are both equal:
<Buffer 3c 21 64 6f 63 74 79 70 65 20 68 74 6d 6c 3e 3c 68 74 6d 6c 20 69 74 65 6d 73 63 6f 70 65 3d 22 22 20 69 74 65 6d 74 79 70 65 3d 22 68 74 74 70 3a 2f ... >
<Buffer 3c 21 64 6f 63 74 79 70 65 20 68 74 6d 6c 3e 3c 68 74 6d 6c 20 69 74 65 6d 73 63 6f 70 65 3d 22 22 20 69 74 65 6d 74 79 70 65 3d 22 68 74 74 70 3a 2f ... >
-1
As you can see both buffers are equal and -1 is still returned.
So my question is, what am I doing wrong so that the buffers cannot be compared properly? Any suggestions/criticism are welcome.

You have to compare in the same encoding :
//:Buffer Comparison
const fs = require('fs')
fs.readFile(__dirname+"/test.jpg",(e,buffer)=>{
let testParse = Buffer.from(buffer.toString('utf8'), 'utf8');
let editable = Buffer.compare(buffer, testParse);
console.log("----: wrong method :----")
console.log(buffer);
console.log(testParse);
console.log(editable);
// You have to compare them in the same encoding :
console.log("----: right method :----")
let goodParse = Buffer.from(buffer.toString('utf8'));
let editable2 = goodParse.compare(Buffer.from(buffer.toString('utf8')));
console.log(buffer);
console.log(goodParse);
console.log(editable2);
})
As you can see, we load an image as a buffer, then it is parsed into utf8, so if you modify it, and then want to compare it to the original buffer. Since the modified was parsed to utf8 the original must also be parsed to utf8 in the moment of the comparison.
I hope you understand that explanation.
Console output:
----: wrong method :----
<Buffer ff d8 ff e0 00 10 4a 46 49 46 00 01 01 00 00 01 00 01 00 00 ff db 00 43 00 08 06 06 07 06 05 08 07 07 07 09 09 08 0a 0c 14 0d 0c 0b 0b 0c 19 12 13 0f ... >
<Buffer ef bf bd ef bf bd ef bf bd ef bf bd 00 10 4a 46 49 46 00 01 01 00 00 01 00 01 00 00 ef bf bd ef bf bd 00 43 00 08 06 06 07 06 05 08 07 07 07 09 09 08 ... >
1
----: right method :----
<Buffer ff d8 ff e0 00 10 4a 46 49 46 00 01 01 00 00 01 00 01 00 00 ff db 00 43 00 08 06 06 07 06 05 08 07 07 07 09 09 08 0a 0c 14 0d 0c 0b 0b 0c 19 12 13 0f ... >
<Buffer ef bf bd ef bf bd ef bf bd ef bf bd 00 10 4a 46 49 46 00 01 01 00 00 01 00 01 00 00 ef bf bd ef bf bd 00 43 00 08 06 06 07 06 05 08 07 07 07 09 09 08 ... >
0

Resources