JS: Add third party base32 library

2026-05-08 11:21:17 -05:00 · 2016-06-24 14:20:11 +08:00
parent 1507b8dd8f
commit 15ecbeaa2f
1 changed files with 125 additions and 0 deletions
@@ -0,0 +1,125 @@
+/*
+Copyright (c) 2011, Chris Umbel
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*/
+
+var charTable = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
+var byteTable = [
+    0xff, 0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+    0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
+    0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
+    0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
+    0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff,
+    0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
+    0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
+    0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
+    0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff
+];
+
+function quintetCount(buff) {
+    var quintets = Math.floor(buff.length / 5);
+    return buff.length % 5 == 0 ? quintets: quintets + 1;
+}
+
+exports.encode = function(plain) {
+    if(!Buffer.isBuffer(plain)){
+    	plain = new Buffer(plain);
+    }
+    var i = 0;
+    var j = 0;
+    var shiftIndex = 0;
+    var digit = 0;
+    var encoded = new Buffer(quintetCount(plain) * 8);
+
+    /* byte by byte isn't as pretty as quintet by quintet but tests a bit
+        faster. will have to revisit. */
+    while(i < plain.length) {
+        var current = plain[i];
+
+        if(shiftIndex > 3) {
+            digit = current & (0xff >> shiftIndex);
+            shiftIndex = (shiftIndex + 5) % 8;
+            digit = (digit << shiftIndex) | ((i + 1 < plain.length) ?
+                plain[i + 1] : 0) >> (8 - shiftIndex);
+            i++;
+        } else {
+            digit = (current >> (8 - (shiftIndex + 5))) & 0x1f;
+            shiftIndex = (shiftIndex + 5) % 8;
+            if(shiftIndex == 0) i++;
+        }
+
+        encoded[j] = charTable.charCodeAt(digit);
+        j++;
+    }
+
+    for(i = j; i < encoded.length; i++)
+        encoded[i] = 0x3d; //'='.charCodeAt(0)
+
+    return encoded;
+};
+
+exports.decode = function(encoded) {
+    var shiftIndex = 0;
+    var plainDigit = 0;
+    var plainChar;
+    var plainPos = 0;
+    if(!Buffer.isBuffer(encoded)){
+    	encoded = new Buffer(encoded);
+    }
+    var decoded = new Buffer(Math.ceil(encoded.length * 5 / 8));
+
+    /* byte by byte isn't as pretty as octet by octet but tests a bit
+        faster. will have to revisit. */
+    for(var i = 0; i < encoded.length; i++) {
+    	if(encoded[i] == 0x3d){ //'='
+    		break;
+    	}
+
+        var encodedByte = encoded[i] - 0x30;
+
+        if(encodedByte < byteTable.length) {
+            plainDigit = byteTable[encodedByte];
+
+            if(shiftIndex <= 3) {
+                shiftIndex = (shiftIndex + 5) % 8;
+
+                if(shiftIndex == 0) {
+                    plainChar |= plainDigit;
+                    decoded[plainPos] = plainChar;
+                    plainPos++;
+                    plainChar = 0;
+                } else {
+                    plainChar |= 0xff & (plainDigit << (8 - shiftIndex));
+                }
+            } else {
+                shiftIndex = (shiftIndex + 5) % 8;
+                plainChar |= 0xff & (plainDigit >>> shiftIndex);
+                decoded[plainPos] = plainChar;
+                plainPos++;
+
+                plainChar = 0xff & (plainDigit << (8 - shiftIndex));
+            }
+        } else {
+        	throw new Error('Invalid input - it is not base32 encoded string');
+        }
+    }
+    return decoded.slice(0, plainPos);
+};