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diff --git a/src/base64.c b/src/base64.c
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+/*
+ * Copyright 2014 Vincent Sanders <vince@netsurf-browser.org>
+ *
+ * This file is part of libnsutils.
+ *
+ * Licensed under the MIT License,
+ * http://www.opensource.org/licenses/mit-license.php
+ */
+
+/**
+ * \file
+ * Base64 encoding and decoding implementation.
+ *
+ * Implements RFC4648 (https://tools.ietf.org/html/rfc4648)
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include "nsutils/base64.h"
+
+static uint8_t decoding_table[256];
+static uint8_t encoding_table[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
+ 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
+ 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
+ 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
+ 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
+ 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
+ 'w', 'x', 'y', 'z', '0', '1', '2', '3',
+ '4', '5', '6', '7', '8', '9', '+', '/'};
+static unsigned int mod_table[] = {0, 2, 1};
+
+/* exported interface documented in nsutils/base64.h */
+nserror base64_encode_alloc(const uint8_t *input,
+ size_t input_length,
+ uint8_t **output,
+ size_t *output_length)
+{
+ uint8_t *encoded;
+ size_t encoded_len;
+ size_t i; /* input index */
+ size_t j; /* output index */
+
+ encoded_len = 4 * ((input_length + 2) / 3);
+
+ encoded = malloc(encoded_len);
+ if (encoded == NULL) {
+ return NSERROR_NOMEM;
+ }
+
+ for (i = 0, j = 0; i < input_length;) {
+
+ uint32_t octet_a = i < input_length ? input[i++] : 0;
+ uint32_t octet_b = i < input_length ? input[i++] : 0;
+ uint32_t octet_c = i < input_length ? input[i++] : 0;
+
+ uint32_t triple = (octet_a << 0x10) + (octet_b << 0x08) + octet_c;
+
+ encoded[j++] = encoding_table[(triple >> 3 * 6) & 0x3F];
+ encoded[j++] = encoding_table[(triple >> 2 * 6) & 0x3F];
+ encoded[j++] = encoding_table[(triple >> 1 * 6) & 0x3F];
+ encoded[j++] = encoding_table[(triple >> 0 * 6) & 0x3F];
+ }
+
+ for (i = 0; i < mod_table[input_length % 3]; i++) {
+ encoded[encoded_len - 1 - i] = '=';
+ }
+
+ *output = encoded;
+ *output_length = encoded_len;
+
+ return NSERROR_OK;
+}
+
+
+/* exported interface documented in nsutils/base64.h */
+nserror base64_decode_alloc(const uint8_t *input,
+ size_t input_length,
+ uint8_t **output,
+ size_t *output_length)
+{
+ static bool decode_initialised = false;
+ uint8_t *decoded;
+ size_t decoded_len;
+ size_t idx;
+ size_t opidx;
+ uint8_t sextet[4];
+ int sextet_idx;
+
+ if (!decode_initialised) {
+ memset(decoding_table, 0xff, sizeof(decoding_table));
+ for (idx = 0; idx < 64; idx++) {
+ decoding_table[encoding_table[idx]] = idx;
+ }
+ decoding_table['='] = 64;
+ decode_initialised = true;
+ }
+
+ decoded_len = ((input_length + 3) / 4) * 3;
+ if (input[input_length - 1] == '=') (decoded_len)--;
+ if (input[input_length - 2] == '=') (decoded_len)--;
+
+ decoded = malloc(decoded_len);
+ if (decoded == NULL) {
+ return NSERROR_NOMEM;
+ }
+
+ sextet_idx = 0;
+ idx = 0;
+ opidx = 0;
+ while (idx < input_length) {
+ sextet[sextet_idx] = decoding_table[input[idx++]];
+ if (sextet[sextet_idx] >= 64) {
+ /* not in encoding set */
+ if (sextet[sextet_idx] == 64) {
+ break; /* pad recived - input complete */
+ }
+ } else {
+ sextet_idx++;
+ if (sextet_idx == 4) {
+ if (opidx >= (decoded_len - 3)) {
+ break; /* insufficient output buffer space */
+ }
+ decoded[opidx++] = (sextet[0] << 2) | (sextet[1] >> 4);
+ decoded[opidx++] = (sextet[1] << 4) | (sextet[2] >> 2);
+ decoded[opidx++] = (sextet[2] << 6) | (sextet[3]);
+
+ sextet_idx = 0;
+ }
+ }
+ }
+
+ /* deal with any remaining recived bytes ensuring output buffer is not overrun */
+ switch (sextet_idx) {
+ case 1:
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[0] << 2);
+ }
+ break;
+
+ case 2:
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[0] << 2) | (sextet[1] >> 4);
+ }
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[1] << 4);
+ }
+ break;
+
+ case 3:
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[0] << 2) | (sextet[1] >> 4);
+ }
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[1] << 4) | (sextet[2] >> 2);
+ }
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[2] << 6);
+ }
+ break;
+
+ case 4:
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[0] << 2) | (sextet[1] >> 4);
+ }
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[1] << 4) | (sextet[2] >> 2);
+ }
+ if (opidx < decoded_len) {
+ decoded[opidx++] = (sextet[2] << 6) | (sextet[3]);
+ }
+ break;
+ }
+
+ *output = decoded;
+ *output_length = opidx;
+
+ return NSERROR_OK;
+}