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      1 /*
      2  * Base64 encoding/decoding (RFC1341)
      3  * Copyright (c) 2005-2011, Jouni Malinen <j (at) w1.fi>
      4  *
      5  * This software may be distributed under the terms of the BSD license.
      6  * See README for more details.
      7  */
      8 
      9 #include "includes.h"
     10 
     11 #include "os.h"
     12 #include "base64.h"
     13 
     14 static const unsigned char base64_table[65] =
     15 	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
     16 
     17 /**
     18  * base64_encode - Base64 encode
     19  * @src: Data to be encoded
     20  * @len: Length of the data to be encoded
     21  * @out_len: Pointer to output length variable, or %NULL if not used
     22  * Returns: Allocated buffer of out_len bytes of encoded data,
     23  * or %NULL on failure
     24  *
     25  * Caller is responsible for freeing the returned buffer. Returned buffer is
     26  * nul terminated to make it easier to use as a C string. The nul terminator is
     27  * not included in out_len.
     28  */
     29 unsigned char * base64_encode(const unsigned char *src, size_t len,
     30 			      size_t *out_len)
     31 {
     32 	unsigned char *out, *pos;
     33 	const unsigned char *end, *in;
     34 	size_t olen;
     35 	int line_len;
     36 
     37 	olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
     38 	olen += olen / 72; /* line feeds */
     39 	olen++; /* nul termination */
     40 	if (olen < len)
     41 		return NULL; /* integer overflow */
     42 	out = os_malloc(olen);
     43 	if (out == NULL)
     44 		return NULL;
     45 
     46 	end = src + len;
     47 	in = src;
     48 	pos = out;
     49 	line_len = 0;
     50 	while (end - in >= 3) {
     51 		*pos++ = base64_table[in[0] >> 2];
     52 		*pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
     53 		*pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
     54 		*pos++ = base64_table[in[2] & 0x3f];
     55 		in += 3;
     56 		line_len += 4;
     57 		if (line_len >= 72) {
     58 			*pos++ = '\n';
     59 			line_len = 0;
     60 		}
     61 	}
     62 
     63 	if (end - in) {
     64 		*pos++ = base64_table[in[0] >> 2];
     65 		if (end - in == 1) {
     66 			*pos++ = base64_table[(in[0] & 0x03) << 4];
     67 			*pos++ = '=';
     68 		} else {
     69 			*pos++ = base64_table[((in[0] & 0x03) << 4) |
     70 					      (in[1] >> 4)];
     71 			*pos++ = base64_table[(in[1] & 0x0f) << 2];
     72 		}
     73 		*pos++ = '=';
     74 		line_len += 4;
     75 	}
     76 
     77 	if (line_len)
     78 		*pos++ = '\n';
     79 
     80 	*pos = '\0';
     81 	if (out_len)
     82 		*out_len = pos - out;
     83 	return out;
     84 }
     85 
     86 
     87 /**
     88  * base64_decode - Base64 decode
     89  * @src: Data to be decoded
     90  * @len: Length of the data to be decoded
     91  * @out_len: Pointer to output length variable
     92  * Returns: Allocated buffer of out_len bytes of decoded data,
     93  * or %NULL on failure
     94  *
     95  * Caller is responsible for freeing the returned buffer.
     96  */
     97 unsigned char * base64_decode(const unsigned char *src, size_t len,
     98 			      size_t *out_len)
     99 {
    100 	unsigned char dtable[256], *out, *pos, block[4], tmp;
    101 	size_t i, count, olen;
    102 	int pad = 0;
    103 
    104 	os_memset(dtable, 0x80, 256);
    105 	for (i = 0; i < sizeof(base64_table) - 1; i++)
    106 		dtable[base64_table[i]] = (unsigned char) i;
    107 	dtable['='] = 0;
    108 
    109 	count = 0;
    110 	for (i = 0; i < len; i++) {
    111 		if (dtable[src[i]] != 0x80)
    112 			count++;
    113 	}
    114 
    115 	if (count == 0 || count % 4)
    116 		return NULL;
    117 
    118 	olen = count / 4 * 3;
    119 	pos = out = os_malloc(olen);
    120 	if (out == NULL)
    121 		return NULL;
    122 
    123 	count = 0;
    124 	for (i = 0; i < len; i++) {
    125 		tmp = dtable[src[i]];
    126 		if (tmp == 0x80)
    127 			continue;
    128 
    129 		if (src[i] == '=')
    130 			pad++;
    131 		block[count] = tmp;
    132 		count++;
    133 		if (count == 4) {
    134 			*pos++ = (block[0] << 2) | (block[1] >> 4);
    135 			*pos++ = (block[1] << 4) | (block[2] >> 2);
    136 			*pos++ = (block[2] << 6) | block[3];
    137 			count = 0;
    138 			if (pad) {
    139 				if (pad == 1)
    140 					pos--;
    141 				else if (pad == 2)
    142 					pos -= 2;
    143 				else {
    144 					/* Invalid padding */
    145 					os_free(out);
    146 					return NULL;
    147 				}
    148 				break;
    149 			}
    150 		}
    151 	}
    152 
    153 	*out_len = pos - out;
    154 	return out;
    155 }
    156