Feature Request: native Base64 decoder function

RouterOS Scripting
1

Sometimes we get an access token in a response that we need to Base64 decode before using in a subsequent request.

For now, I am using these functions (fixed up for ROS7 from an older example I found out there somewhere)…

:global int2chr do={
:local symbolsHex {"\00";"\01";"\02";"\03";"\04";"\05";"\06";"\07";"\08";"\09";"\0A";"\0B";"\0C";"\0D";"\0E";"\0F";"\10";"\11";"\12";"\13";"\14";"\15";"\16";"\17";"\18";"\19";"\1A";"\1B";"\1C";"\1D";"\1E";"\1F";"\20";"\21";"\22";"\23";"\24";"\25";"\26";"\27";"\28";"\29";"\2A";"\2B";"\2C";"\2D";"\2E";"\2F";"\30";"\31";"\32";"\33";"\34";"\35";"\36";"\37";"\38";"\39";"\3A";"\3B";"\3C";"\3D";"\3E";"\3F";"\40";"\41";"\42";"\43";"\44";"\45";"\46";"\47";"\48";"\49";"\4A";"\4B";"\4C";"\4D";"\4E";"\4F";"\50";"\51";"\52";"\53";"\54";"\55";"\56";"\57";"\58";"\59";"\5A";"\5B";"\5C";"\5D";"\5E";"\5F";"\60";"\61";"\62";"\63";"\64";"\65";"\66";"\67";"\68";"\69";"\6A";"\6B";"\6C";"\6D";"\6E";"\6F";"\70";"\71";"\72";"\73";"\74";"\75";"\76";"\77";"\78";"\79";"\7A";"\7B";"\7C";"\7D";"\7E";"\7F";"\80";"\81";"\82";"\83";"\84";"\85";"\86";"\87";"\88";"\89";"\8A";"\8B";"\8C";"\8D";"\8E";"\8F";"\90";"\91";"\92";"\93";"\94";"\95";"\96";"\97";"\98";"\99";"\9A";"\9B";"\9C";"\9D";"\9E";"\9F";"\A0";"\A1";"\A2";"\A3";"\A4";"\A5";"\A6";"\A7";"\A8";"\A9";"\AA";"\AB";"\AC";"\AD";"\AE";"\AF";"\B0";"\B1";"\B2";"\B3";"\B4";"\B5";"\B6";"\B7";"\B8";"\B9";"\BA";"\BB";"\BC";"\BD";"\BE";"\BF";"\C0";"\C1";"\C2";"\C3";"\C4";"\C5";"\C6";"\C7";"\C8";"\C9";"\CA";"\CB";"\CC";"\CD";"\CE";"\CF";"\D0";"\D1";"\D2";"\D3";"\D4";"\D5";"\D6";"\D7";"\D8";"\D9";"\DA";"\DB";"\DC";"\DD";"\DE";"\DF";"\E0";"\E1";"\E2";"\E3";"\E4";"\E5";"\E6";"\E7";"\E8";"\E9";"\EA";"\EB";"\EC";"\ED";"\EE";"\EF";"\F0";"\F1";"\F2";"\F3";"\F4";"\F5";"\F6";"\F7";"\F8";"\F9";"\FA";"\FB";"\FC";"\FD";"\FE";"\FF"};
:return ($symbolsHex->[:tonum $1])
}

:global base64decode do={
:global int2chr
:local encoded $1;
:local decoded ""
:local b64 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

:for pos from=0 to=([:len $encoded]-1) step=4 do={
:local part [:pick $encoded $pos ($pos+4)]

:local n 0
:local idx 0

:for step from=0 to=4 step=1 do={
:local c [:pick $part $step ($step+1)]
:set idx [:find $b64 $c 0]
:set $n ($n + ($idx << (18-$step*6)))
}

:for shift from=16 to=0 step=-8 do={
:local asciicode (($n >> $shift) & 255)
:set $decoded ($decoded . [$int2chr $asciicode])
}
}

:return $decoded
}

However, that’s a bit long-winded. Native support would obviously be much, much nicer.

Thanks!

2

You should check out the new “:convert” operator in V7. For example, to get base64 string from the alphabet:

:put [:convert from=raw to=base64 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"]



QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODkrLw==

And reverse works too:

:put [:convert from=base64 to=raw "QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODkrLw=="]



ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/

There is even a “byte-array” pseudo-type, so if you want an array on the ASCII int values from a base64-encoded string, that too is possible:

:put [:convert from=base64 to=byte-array "QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVphYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3h5ejAxMjM0NTY3ODkrLw=="]



65;66;67;68;69;70;71;72;73;74;75;76;77;78;79;80;81;82;83;84;85;86;87;88;89;90;97;98;99;100;101;102;103;104;105;106;107;108;109;110;111;112;113;114;115;116;117;11
8;119;120;121;122;48;49;50;51;52;53;54;55;56;57;43;47

which is the same ABCD…xyz…789+/, as num type in array of those ascii codes.

The “raw” in to=raw or from=raw just mean “RouterOS string” for purposes here.

3

That’s tons better. Thanks, @Amm0!