base64.cc

#include <cctype>
#include <cstring>
#include <cstdlib>
#include <v8.h>
#include <node.h>
#include <node_buffer.h>

using namespace v8;
using namespace node;

static Handle<Value>
VException(const char *msg) {
    HandleScope scope;
    return ThrowException(Exception::Error(String::New(msg)));
}

static const char base64_chars[] = 
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/";

static char *
base64_encode(const unsigned char *input, int length)
{
    /* http://www.adp-gmbh.ch/cpp/common/base64.html */
    int i=0, j=0, s=0;
    unsigned char char_array_3[3], char_array_4[4];

    int b64len = (length+2 - ((length+2)%3))*4/3;
    char *b64str = new char[b64len + 1];

    while (length--) {
        char_array_3[i++] = *(input++);
        if (i == 3) {
            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;

            for (i = 0; i < 4; i++)
                b64str[s++] = base64_chars[char_array_4[i]];

            i = 0;
        }
    }
    if (i) {
        for (j = i; j < 3; j++)
            char_array_3[j] = '\0';

        char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
        char_array_4[3] = char_array_3[2] & 0x3f;

        for (j = 0; j < i + 1; j++)
            b64str[s++] = base64_chars[char_array_4[j]];

        while (i++ < 3)
            b64str[s++] = '=';
    }
    b64str[b64len] = '\0';

    return b64str;
}

static inline bool is_base64(unsigned char c) {
    return (isalnum(c) || (c == '+') || (c == '/'));
}

static unsigned char *
base64_decode(const char *input, int length, int *outlen)
{
    int i = 0;
    int j = 0;
    int r = 0;
    int idx = 0;
    unsigned char char_array_4[4], char_array_3[3];
    unsigned char *output = new unsigned char[length*3/4];

    while (length-- && input[idx] != '=') {
	//skip invalid or padding based chars
	if (!is_base64(input[idx])) {
	    idx++;
	    continue;
	}
        char_array_4[i++] = input[idx++];
        if (i == 4) {
            for (i = 0; i < 4; i++)
                char_array_4[i] = strchr(base64_chars, char_array_4[i]) - base64_chars;

            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

            for (i = 0; (i < 3); i++)
                output[r++] = char_array_3[i];
            i = 0;
        }
    }

    if (i) {
        for (j = i; j <4; j++)
            char_array_4[j] = 0;

        for (j = 0; j <4; j++)
            char_array_4[j] = strchr(base64_chars, char_array_4[j]) - base64_chars;

        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
        char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
        char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

        for (j = 0; (j < i - 1); j++)
            output[r++] = char_array_3[j];
    }

    *outlen = r;

    return output;
}

Handle<Value>
base64_encode_binding(const Arguments &args)
{
    HandleScope scope;
    char * str;
    
    if (args.Length() != 1)
        return VException("One argument required - buffer or string with data to encode");

    if (Buffer::HasInstance(args[0])) {
        v8::Handle<v8::Object> buffer = args[0]->ToObject();
        str = base64_encode(
            (unsigned char *) Buffer::Data(buffer),
            Buffer::Length(buffer)
        );
    }
    else if (args[0]->IsString()) {
        String::Utf8Value v8str (args[0]->ToString());
        str = base64_encode((unsigned char *) *v8str, v8str.length());
    }
    else
        return VException("Argument should be a buffer or a string");

    Local<String> ret = String::New(str);
    delete [] str;
    return scope.Close(ret);
}

Handle<Value>
base64_decode_binding(const Arguments &args)
{
    HandleScope scope;
    node::encoding encflag = BINARY;

    if (args.Length() < 1)
        return VException("One argument required - buffer or string with data to decode");

    int outlen;
    unsigned char *decoded;
    if (Buffer::HasInstance(args[0])) { // buffer
        v8::Handle<v8::Object> buffer = args[0]->ToObject();
        
        decoded = base64_decode(
            Buffer::Data(buffer),
            Buffer::Length(buffer),
            &outlen
        );
    }
    else { // string
        String::AsciiValue b64data(args[0]->ToString());
        decoded = base64_decode(*b64data, b64data.length(), &outlen);
    }

    if (args.Length() > 1 && args[1]->IsString()) { 
        String::AsciiValue flag(args[1]->ToString());
        if (strcmp("utf8", *flag) == 0) encflag = UTF8;
    }
    
    Local<Value> ret = Encode(decoded, outlen, encflag);
    
    delete [] decoded;
    return scope.Close(ret);
}

extern "C" void init (Handle<Object> target)
{
    HandleScope scope;
    target->Set(String::New("encode"), FunctionTemplate::New(base64_encode_binding)->GetFunction());
    target->Set(String::New("decode"), FunctionTemplate::New(base64_decode_binding)->GetFunction());
}
NODE_MODULE(base64, init)