base64: Add decoder

5 files changed, 410 insertions, 0 deletions

diff --git a/cpukit/base64/base64-decode.c b/cpukit/base64/base64-decode.c
new file mode 100644
index 0000000000..5739266528
--- /dev/null
+++ b/cpukit/base64/base64-decode.c
@@ -0,0 +1,165 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/**
+ * @file
+ *
+ * @ingroup RTEMSImplBase64
+ *
+ * @brief This source file contains the implementation of
+ *   _Base64_Decode_initialize() and _Base64_Decode().
+ */
+
+/*
+ * Copyright (C) 2023 embedded brains GmbH & Co. KG
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <rtems/base64.h>
+
+#define SPACE 253
+
+#define PAD 254
+
+#define INVALID 255
+
+const uint8_t _Base64_Decoding[128] = {
+    ['A'] = 0,       ['B'] = 1,       ['C'] = 2,       ['D'] = 3,
+    ['E'] = 4,       ['F'] = 5,       ['G'] = 6,       ['H'] = 7,
+    ['I'] = 8,       ['J'] = 9,       ['K'] = 10,      ['L'] = 11,
+    ['M'] = 12,      ['N'] = 13,      ['O'] = 14,      ['P'] = 15,
+    ['Q'] = 16,      ['R'] = 17,      ['S'] = 18,      ['T'] = 19,
+    ['U'] = 20,      ['V'] = 21,      ['W'] = 22,      ['X'] = 23,
+    ['Y'] = 24,      ['Z'] = 25,      ['a'] = 26,      ['b'] = 27,
+    ['c'] = 28,      ['d'] = 29,      ['e'] = 30,      ['f'] = 31,
+    ['g'] = 32,      ['h'] = 33,      ['i'] = 34,      ['j'] = 35,
+    ['k'] = 36,      ['l'] = 37,      ['m'] = 38,      ['n'] = 39,
+    ['o'] = 40,      ['p'] = 41,      ['q'] = 42,      ['r'] = 43,
+    ['s'] = 44,      ['t'] = 45,      ['u'] = 46,      ['v'] = 47,
+    ['w'] = 48,      ['x'] = 49,      ['y'] = 50,      ['z'] = 51,
+    ['0'] = 52,      ['1'] = 53,      ['2'] = 54,      ['3'] = 55,
+    ['4'] = 56,      ['5'] = 57,      ['6'] = 58,      ['7'] = 59,
+    ['8'] = 60,      ['9'] = 61,      ['+'] = 62,      ['-'] = 62,
+    ['/'] = 63,      ['_'] = 63,      ['='] = PAD,     [' '] = SPACE,
+    ['\t'] = SPACE,  ['\n'] = SPACE,  ['\v'] = SPACE,  ['\f'] = SPACE,
+    ['\r'] = SPACE,  [0] = INVALID,   [1] = INVALID,   [2] = INVALID,
+    [3] = INVALID,   [4] = INVALID,   [5] = INVALID,   [6] = INVALID,
+    [7] = INVALID,   [8] = INVALID,   [14] = INVALID,  [15] = INVALID,
+    [16] = INVALID,  [17] = INVALID,  [18] = INVALID,  [19] = INVALID,
+    [20] = INVALID,  [21] = INVALID,  [22] = INVALID,  [23] = INVALID,
+    [24] = INVALID,  [25] = INVALID,  [26] = INVALID,  [27] = INVALID,
+    [28] = INVALID,  [29] = INVALID,  [30] = INVALID,  [31] = INVALID,
+    [33] = INVALID,  [34] = INVALID,  [35] = INVALID,  [36] = INVALID,
+    [37] = INVALID,  [38] = INVALID,  [39] = INVALID,  [40] = INVALID,
+    [41] = INVALID,  [42] = INVALID,  [44] = INVALID,  [46] = INVALID,
+    [58] = INVALID,  [59] = INVALID,  [60] = INVALID,  [62] = INVALID,
+    [63] = INVALID,  [64] = INVALID,  [91] = INVALID,  [92] = INVALID,
+    [93] = INVALID,  [94] = INVALID,  [96] = INVALID,  [123] = INVALID,
+    [124] = INVALID, [125] = INVALID, [126] = INVALID, [127] = INVALID};
+
+void _Base64_Decode_initialize(Base64_Decode_control* self,
+                               uint8_t* target,
+                               size_t target_size) {
+  self->state = BASE64_DECODE_STATE_0;
+  self->target = target;
+  self->target_end = target + target_size;
+}
+
+Base64_Decode_status _Base64_Decode(Base64_Decode_control* self, char ch) {
+  uint8_t decoded_ch;
+  uint8_t next_ch;
+  uint8_t* target;
+  const uint8_t* target_end;
+  Base64_Decode_state next_state;
+
+  if ((unsigned char)ch >= 128) {
+    return BASE64_DECODE_INVALID_INPUT;
+  }
+
+  decoded_ch = _Base64_Decoding[(unsigned char)ch];
+
+  if (decoded_ch == SPACE) {
+    return BASE64_DECODE_SUCCESS;
+  }
+
+  target = self->target;
+
+  if (decoded_ch == PAD) {
+    self->target_end = target;
+    return BASE64_DECODE_SUCCESS;
+  }
+
+  if (decoded_ch == INVALID) {
+    return BASE64_DECODE_INVALID_INPUT;
+  }
+
+  target_end = self->target_end;
+
+  if (target == target_end) {
+    return BASE64_DECODE_OVERFLOW;
+  }
+
+  switch (self->state) {
+    case BASE64_DECODE_STATE_0:
+      *target = decoded_ch << 2;
+      next_state = BASE64_DECODE_STATE_1;
+      break;
+
+    case BASE64_DECODE_STATE_1:
+      *target |= decoded_ch >> 4;
+      next_ch = (decoded_ch & 0x0fU) << 4;
+      ++target;
+
+      if (target != target_end) {
+        *target = next_ch;
+      } else if (next_ch != 0) {
+        return BASE64_DECODE_OVERFLOW;
+      }
+
+      next_state = BASE64_DECODE_STATE_2;
+      break;
+
+    case BASE64_DECODE_STATE_2:
+      *target |= decoded_ch >> 2;
+      next_ch = (decoded_ch & 0x03U) << 6;
+      ++target;
+
+      if (target != target_end) {
+        *target = next_ch;
+      } else if (next_ch != 0) {
+        return BASE64_DECODE_OVERFLOW;
+      }
+
+      next_state = BASE64_DECODE_STATE_3;
+      break;
+
+    default: /* BASE64_DECODE_STATE_3 */
+      *target |= decoded_ch;
+      ++target;
+      next_state = BASE64_DECODE_STATE_0;
+      break;
+  }
+
+  self->state = next_state;
+  self->target = target;
+  return BASE64_DECODE_SUCCESS;
+}
diff --git a/cpukit/include/rtems/base64.h b/cpukit/include/rtems/base64.h
index b9d88f7818..58e48a8c33 100644
--- a/cpukit/include/rtems/base64.h
+++ b/cpukit/include/rtems/base64.h
@@ -126,6 +126,69 @@ int _Base64url_Encode(
   int          wordlen
 );
 
+/**
+ * @brief Represents the base64 and base64url decoder state.
+ */
+typedef enum {
+  BASE64_DECODE_STATE_0,
+  BASE64_DECODE_STATE_1,
+  BASE64_DECODE_STATE_2,
+  BASE64_DECODE_STATE_3
+} Base64_Decode_state;
+
+/**
+ * @brief Contains the base64 and base64url decoder control.
+ */
+typedef struct {
+  Base64_Decode_state state;
+  uint8_t            *target;
+  const uint8_t      *target_end;
+} Base64_Decode_control;
+
+/**
+ * @brief Maps a 7-bit character to the associated 6-bit integer as defined by
+ *   the base64 or base64url encoding or a special value.
+ */
+extern const uint8_t _Base64_Decoding[ 128 ];
+
+/**
+ * @brief Initializes the base64 decoder.
+ *
+ * @param[out] self is the base64 decoder control to initialize.
+ *
+ * @param[out] target is the base address of the target area for decoding.
+ *
+ * @param target_size is the size in bytes of the target area for decoding.
+ */
+void _Base64_Decode_initialize(
+  Base64_Decode_control *self,
+  uint8_t               *target,
+  size_t                 target_size
+);
+
+/**
+ * @brief Represents the base64 and base64url decoder status.
+ */
+typedef enum {
+  BASE64_DECODE_SUCCESS,
+  BASE64_DECODE_OVERFLOW,
+  BASE64_DECODE_INVALID_INPUT
+} Base64_Decode_status;
+
+/**
+ * @brief Decodes the character.
+ *
+ * The decoder accepts base64 and base64url encodings.  White space is ignored.
+ *
+ * @param[in, out] self is the base64 decoder control.
+ *
+ * @param ch is the character to decode.
+ */
+Base64_Decode_status _Base64_Decode(
+  Base64_Decode_control *self,
+  char                   ch
+);
+
 /** @} */
 
 #ifdef __cplusplus
diff --git a/spec/build/cpukit/librtemscpu.yml b/spec/build/cpukit/librtemscpu.yml
index 24b63af8de..45960099e8 100644
--- a/spec/build/cpukit/librtemscpu.yml
+++ b/spec/build/cpukit/librtemscpu.yml
@@ -529,6 +529,7 @@ source:
 - cpukit/compression/xz/xz_dec_lzma2.c
 - cpukit/compression/xz/xz_dec_stream.c
 - cpukit/base64/base64-encode.c
+- cpukit/base64/base64-decode.c
 - cpukit/dev/flash/flashdev.c
 - cpukit/dev/i2c/eeprom.c
 - cpukit/dev/i2c/fpga-i2c-slave.c
diff --git a/spec/build/testsuites/unit/unit-no-clock-0.yml b/spec/build/testsuites/unit/unit-no-clock-0.yml
index 5d15bf52b7..d61c570183 100644
--- a/spec/build/testsuites/unit/unit-no-clock-0.yml
+++ b/spec/build/testsuites/unit/unit-no-clock-0.yml
@@ -11,6 +11,7 @@ includes: []
 ldflags: []
 links: []
 source:
+- testsuites/unit/tc-base64-decode.c
 - testsuites/unit/tc-compiler-builtins.c
 - testsuites/unit/tc-config.c
 - testsuites/unit/tc-misaligned-builtin-memcpy.c
diff --git a/testsuites/unit/tc-base64-decode.c b/testsuites/unit/tc-base64-decode.c
new file mode 100644
index 0000000000..dd9d50b069
--- /dev/null
+++ b/testsuites/unit/tc-base64-decode.c
@@ -0,0 +1,180 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/*
+ * Copyright (C) 2023 embedded brains GmbH & Co. KG
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <rtems/base64.h>
+
+#include <rtems/test.h>
+
+typedef struct {
+  Base64_Decode_control base;
+  uint8_t buf[64];
+} test_control;
+
+static int test_run(test_control* self, const char* payload) {
+  size_t len = strlen(payload);
+
+  for (size_t i = 0; i < len; ++i) {
+    int rv = _Base64_Decode(&self->base, payload[i]);
+
+    if (rv != 0) {
+      return rv;
+    }
+  }
+
+  return 0;
+}
+
+static int test_payload(test_control* self, const char* payload) {
+  memset(self->buf, 0xff, sizeof(self->buf));
+  _Base64_Decode_initialize(&self->base, &self->buf[0], sizeof(self->buf));
+  return test_run(self, payload);
+}
+
+T_TEST_CASE(IOBase64Decode) {
+  int rv;
+  test_control instance;
+  test_control* self = &instance;
+
+  rv = test_payload(self, "POOL");
+  T_eq_int(rv, BASE64_DECODE_SUCCESS);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_0);
+  T_eq_ptr(self->base.target, &self->buf[3]);
+  const uint8_t expected1[] = {0x3c, 0xe3, 0x8b, 0xff};
+  T_eq_mem(&self->buf[0], expected1, sizeof(expected1));
+
+  rv = test_payload(self, "ABCDEFGH");
+  T_eq_int(rv, BASE64_DECODE_SUCCESS);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_0);
+  T_eq_ptr(self->base.target, &self->buf[6]);
+  const uint8_t expected2[] = {0x00, 0x10, 0x83, 0x10, 0x51, 0x87, 0xff};
+  T_eq_mem(&self->buf[0], expected2, sizeof(expected2));
+
+  /* Non-base64 character results in an error */
+  rv = test_payload(self, "PO*OL");
+  T_eq_int(rv, BASE64_DECODE_INVALID_INPUT);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_2);
+  T_eq_ptr(self->base.target, &self->buf[1]);
+  const uint8_t expected3[] = {0x3c};
+  T_eq_mem(&self->buf[0], expected3, sizeof(expected3));
+
+  /* Other non-base64 character results in an error */
+  rv = test_payload(self, "PO\x80OL");
+  T_eq_int(rv, BASE64_DECODE_INVALID_INPUT);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_2);
+  T_eq_ptr(self->base.target, &self->buf[1]);
+  T_eq_mem(&self->buf[0], expected3, sizeof(expected3));
+
+  /* Space characters should be ignored */
+  rv = test_payload(self, "P OOL");
+  T_eq_int(rv, BASE64_DECODE_SUCCESS);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_0);
+  T_eq_ptr(self->base.target, &self->buf[3]);
+  const uint8_t expected4[] = {0x3c, 0xe3, 0x8b, 0xff};
+  T_eq_mem(&self->buf[0], expected4, sizeof(expected4));
+
+  /* Handle pad characters */
+  rv = test_payload(self, "POOL==");
+  T_eq_int(rv, BASE64_DECODE_SUCCESS);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_0);
+  T_eq_ptr(self->base.target, &self->buf[3]);
+  T_eq_ptr(self->base.target, self->base.target_end);
+  const uint8_t expected5[] = {0x3c, 0xe3, 0x8b, 0xff};
+  T_eq_mem(&self->buf[0], expected5, sizeof(expected5));
+
+  /* If characters come after pad characters, an error results */
+  rv = test_payload(self, "POOL==xy");
+  T_eq_int(rv, BASE64_DECODE_OVERFLOW);
+  T_eq_int(self->base.state, BASE64_DECODE_SUCCESS);
+  T_eq_ptr(self->base.target, &self->buf[3]);
+  T_eq_ptr(self->base.target, self->base.target_end);
+  const uint8_t expected6[] = {0x3c, 0xe3, 0x8b, 0xff};
+  T_eq_mem(&self->buf[0], expected6, sizeof(expected6));
+
+  rv = test_payload(self, "POOLPOOL");
+  T_eq_int(rv, BASE64_DECODE_SUCCESS);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_0);
+  T_eq_ptr(self->base.target, &self->buf[6]);
+  const uint8_t expected7[] = {0x3c, 0xe3, 0x8b, 0x3c, 0xe3, 0x8b, 0xff};
+  T_eq_mem(&self->buf[0], expected7, sizeof(expected7));
+
+  /*
+   * Test valid payload with series of target sizes. All target sizes
+   * less than three are invalid for the given payload and will result
+   * in an error.
+   */
+  const uint8_t expected9[] = {0x3c, 0xe3, 0x8b, 0xff};
+
+  for (size_t i = 0; i < 4; ++i) {
+    memset(&self->buf[0], 0xff, sizeof(self->buf));
+    _Base64_Decode_initialize(&self->base, &self->buf[0], i);
+    rv = test_run(self, "POOL");
+
+    if (i < 3) {
+      T_eq_int(rv, BASE64_DECODE_OVERFLOW);
+      T_eq_int(self->base.state, i);
+      T_ne_ptr(self->base.target, &self->buf[3]);
+      T_ne_mem(&self->buf[0], expected9, sizeof(expected9));
+    } else {
+      T_eq_int(rv, BASE64_DECODE_SUCCESS);
+      T_eq_int(self->base.state, BASE64_DECODE_STATE_0);
+      T_eq_ptr(self->base.target, &self->buf[3]);
+      T_eq_mem(&self->buf[0], expected9, sizeof(expected9));
+    }
+  }
+
+  /* No overflow in state 1 */
+  memset(&self->buf[0], 0xff, sizeof(self->buf));
+  _Base64_Decode_initialize(&self->base, &self->buf[0], 1);
+  rv = test_run(self, "AA");
+  T_eq_int(rv, BASE64_DECODE_SUCCESS);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_2);
+  T_eq_ptr(self->base.target, &self->buf[1]);
+  const uint8_t expected10[] = {0x00, 0xff};
+  T_eq_mem(&self->buf[0], expected10, sizeof(expected10));
+
+  /* No overflow in state 2 */
+  memset(&self->buf[0], 0xff, sizeof(self->buf));
+  _Base64_Decode_initialize(&self->base, &self->buf[0], 2);
+  rv = test_run(self, "AAA");
+  T_eq_int(rv, BASE64_DECODE_SUCCESS);
+  T_eq_int(self->base.state, BASE64_DECODE_STATE_3);
+  T_eq_ptr(self->base.target, &self->buf[2]);
+  const uint8_t expected11[] = {0x00, 0x00, 0xff};
+  T_eq_mem(&self->buf[0], expected11, sizeof(expected11));
+}
+
+T_TEST_CASE(IOBase64DecodeInitialize) {
+  Base64_Decode_control instance;
+  Base64_Decode_control* self = &instance;
+  uint8_t buf[1];
+
+  memset(self, 0xff, sizeof(*self));
+  _Base64_Decode_initialize(self, buf, sizeof(buf));
+  T_eq_int(self->state, BASE64_DECODE_STATE_0);
+  T_eq_ptr(self->target, &buf[0]);
+  T_eq_ptr(self->target_end, &buf[1]);
+}