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/********************************************************
* MIME.cpp *
* 05.04.00 *
* Keith Resar *
* *
* functions for decoding and encoding MIME in *
* in base64 *
********************************************************/
#include "MIME.h"
// the table to lookup our base64 en/decoding scheme
const string table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
unsigned int LookUp(const char base64Val) {
unsigned int counter;
for (counter=0; counter<table.length(); counter++) {
if (table[counter]==base64Val)
return(counter);
}
// wasn't a valid charcter, ignore
return(99);
}
int encode64(ifstream &file, string &encodedFile) {
// defs
char readIn;
char readInAltered;
int base64Val;
int n;
int bits2;
int bits4;
// mess around
n = 0;
encodedFile = "";
do {
file.get(readIn);
n++;
switch (n) {
case 1:
// we have no extra bits laying around.
// read in 8, must store 2.
readInAltered = readIn >> 2;
base64Val = readInAltered & 63;
bits2 = (readIn & 3) << 4;
break;
case 2:
// we have 2 bits laying around
// then we read in 8 bits.
// we want the higher 2 bits laying around,
// and the lower 4 bits we just read.
// store our extra 4 bits
readInAltered = readIn >> 4;
base64Val = (readInAltered | bits2) & 63;
bits4 = (readIn << 2) & 63;
break;
case 3:
// we have 4 bits laying around.
// then we read in 8 bits.
// we want the lower 4 we saved and
// 2 of the bits we read in.
// save the upper 6 bits we read in
readInAltered = readIn >> 6;
base64Val = (readInAltered | bits4) & 63;
encodedFile += table.c_str()[base64Val];
base64Val = readIn & 63;
n = 0;
break;
}
// store what we've got
encodedFile += table.c_str()[base64Val];
} while (file);
// make sure we have a multiple of 4 chars
switch (n) {
case 1:
encodedFile += "==";
break;
case 2:
encodedFile += "=";
break;
}
// return the encoded string
//cout << "encoded file: " << encodedFile << endl;
return(0);
}
void check(unsigned int convertedVal, ifstream &fileIn, int loc, int counter) {
char c;
fileIn.get(c);
if ((unsigned int)c!=convertedVal) {
cout << "was: " << c << "\tnow: " << convertedVal
<< "\tat: " << loc << "\tcounter: " << counter << endl;
}
}
int decode64(string &encodedText, ofstream &fileOut) {
// defs
unsigned int convertedVal;
unsigned int partialVal;
int n;
unsigned int bits2;
unsigned int bits4;
unsigned int bits6;
unsigned int counter;
unsigned int lookedUp;
//char c;
//fileIn.get(c);
// mess around
n = 0;
unsigned int encodedTextLength = encodedText.length();
for (counter=0; counter<encodedTextLength && encodedText[counter]!='=';
counter++) {
lookedUp = LookUp(encodedText[counter]);
if (lookedUp<70) {
n++;
switch (n) {
case 1:
// we have no extra bits laying around.
// only have 6 bits, so just save them until
// we have a read with enough bits
bits6 = lookedUp << 2;
break;
case 2:
// we have 6 bits stored.
// our next char has 6 bits.
// write out 8 of these bits,
// store 4 of these bits
partialVal = (lookedUp & 48) >> 4;
convertedVal = bits6 + partialVal;
bits4 = lookedUp << 4;
fileOut.put((unsigned char)convertedVal);
break;
case 3:
// we have 4 bits stored
// our next char has 6 bits
// write out 8 of these bits,
// store 2 of these bits
partialVal = (lookedUp & 60) >> 2;
convertedVal = bits4 + partialVal;
bits2 = lookedUp << 6;
fileOut.put((unsigned char)convertedVal);
break;
case 4:
// we have 2 bits stored
// our nextchar has 6 bits
// write out all 8 bits
convertedVal = lookedUp + bits2;
n = 0;
fileOut.put((unsigned char)convertedVal);
break;
}
}
}
// return the encoded string
return(0);
}
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