Initial nsutils library with base64 implementation an tests

2 files changed, 184 insertions, 0 deletions

diff --git a/src/Makefile b/src/Makefile
new file mode 100644
index 0000000..c5e0cbe
--- /dev/null
+++ b/src/Makefile
@@ -0,0 +1,3 @@
+DIR_SOURCES := base64.c
+
+include $(NSBUILD)/Makefile.subdir
diff --git a/src/base64.c b/src/base64.c
new file mode 100644
index 0000000..b2e020b
--- /dev/null
+++ b/src/base64.c
@@ -0,0 +1,181 @@
+/*
+ * 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;
+}