Merge pull request #6572 from y-zeng/base64_decode

Add base64 decoder

2 files changed, 298 insertions, 0 deletions

diff --git a/src/core/ext/transport/chttp2/transport/bin_decoder.c b/src/core/ext/transport/chttp2/transport/bin_decoder.c
new file mode 100644
index 0000000000..2d90b01cd8
--- /dev/null
+++ b/src/core/ext/transport/chttp2/transport/bin_decoder.c
@@ -0,0 +1,232 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * 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.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * 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 "src/core/ext/transport/chttp2/transport/bin_decoder.h"
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include "src/core/lib/support/string.h"
+
+static uint8_t decode_table[] = {
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 62,   0x40, 0x40, 0x40, 63,
+    52,   53,   54,   55,   56,   57,   58,   59,   60,   61,   0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0,    1,    2,    3,    4,    5,    6,
+    7,    8,    9,    10,   11,   12,   13,   14,   15,   16,   17,   18,
+    19,   20,   21,   22,   23,   24,   25,   0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 26,   27,   28,   29,   30,   31,   32,   33,   34,   35,   36,
+    37,   38,   39,   40,   41,   42,   43,   44,   45,   46,   47,   48,
+    49,   50,   51,   0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+    0x40, 0x40, 0x40, 0x40};
+
+static const uint8_t tail_xtra[4] = {0, 0, 1, 2};
+
+static bool input_is_valid(uint8_t *input_ptr, size_t length) {
+  size_t i;
+
+  for (i = 0; i < length; ++i) {
+    if ((decode_table[input_ptr[i]] & 0xC0) != 0) {
+      gpr_log(GPR_ERROR,
+              "Base64 decoding failed, invalid character '%c' in base64 "
+              "input.\n",
+              (char)(*input_ptr));
+      return false;
+    }
+  }
+  return true;
+}
+
+#define COMPOSE_OUTPUT_BYTE_0(input_ptr)        \
+  (uint8_t)((decode_table[input_ptr[0]] << 2) | \
+            (decode_table[input_ptr[1]] >> 4))
+
+#define COMPOSE_OUTPUT_BYTE_1(input_ptr)        \
+  (uint8_t)((decode_table[input_ptr[1]] << 4) | \
+            (decode_table[input_ptr[2]] >> 2))
+
+#define COMPOSE_OUTPUT_BYTE_2(input_ptr) \
+  (uint8_t)((decode_table[input_ptr[2]] << 6) | decode_table[input_ptr[3]])
+
+bool grpc_base64_decode_partial(struct grpc_base64_decode_context *ctx) {
+  size_t input_tail;
+
+  if (ctx->input_cur > ctx->input_end || ctx->output_cur > ctx->output_end) {
+    return false;
+  }
+
+  // Process a block of 4 input characters and 3 output bytes
+  while (ctx->input_end >= ctx->input_cur + 4 &&
+         ctx->output_end >= ctx->output_cur + 3) {
+    if (!input_is_valid(ctx->input_cur, 4)) return false;
+    ctx->output_cur[0] = COMPOSE_OUTPUT_BYTE_0(ctx->input_cur);
+    ctx->output_cur[1] = COMPOSE_OUTPUT_BYTE_1(ctx->input_cur);
+    ctx->output_cur[2] = COMPOSE_OUTPUT_BYTE_2(ctx->input_cur);
+    ctx->output_cur += 3;
+    ctx->input_cur += 4;
+  }
+
+  // Process the tail of input data
+  input_tail = (size_t)(ctx->input_end - ctx->input_cur);
+  if (input_tail == 4) {
+    // Process the input data with pad chars
+    if (ctx->input_cur[3] == '=') {
+      if (ctx->input_cur[2] == '=' && ctx->output_end >= ctx->output_cur + 1) {
+        if (!input_is_valid(ctx->input_cur, 2)) return false;
+        *(ctx->output_cur++) = COMPOSE_OUTPUT_BYTE_0(ctx->input_cur);
+        ctx->input_cur += 4;
+      } else if (ctx->output_end >= ctx->output_cur + 2) {
+        if (!input_is_valid(ctx->input_cur, 3)) return false;
+        *(ctx->output_cur++) = COMPOSE_OUTPUT_BYTE_0(ctx->input_cur);
+        *(ctx->output_cur++) = COMPOSE_OUTPUT_BYTE_1(ctx->input_cur);
+        ;
+        ctx->input_cur += 4;
+      }
+    }
+
+  } else if (ctx->contains_tail && input_tail > 1) {
+    // Process the input data without pad chars, but constains_tail is set
+    if (ctx->output_end >= ctx->output_cur + tail_xtra[input_tail]) {
+      if (!input_is_valid(ctx->input_cur, input_tail)) return false;
+      switch (input_tail) {
+        case 3:
+          ctx->output_cur[1] = COMPOSE_OUTPUT_BYTE_1(ctx->input_cur);
+        case 2:
+          ctx->output_cur[0] = COMPOSE_OUTPUT_BYTE_0(ctx->input_cur);
+      }
+      ctx->output_cur += tail_xtra[input_tail];
+      ctx->input_cur += input_tail;
+    }
+  }
+
+  return true;
+}
+
+gpr_slice grpc_chttp2_base64_decode(gpr_slice input) {
+  size_t input_length = GPR_SLICE_LENGTH(input);
+  size_t output_length = input_length / 4 * 3;
+  struct grpc_base64_decode_context ctx;
+  gpr_slice output;
+
+  if (input_length % 4 != 0) {
+    gpr_log(GPR_ERROR,
+            "Base64 decoding failed, input of "
+            "grpc_chttp2_base64_decode has a length of %d, which is not a "
+            "multiple of 4.\n",
+            (int)input_length);
+    return gpr_empty_slice();
+  }
+
+  if (input_length > 0) {
+    uint8_t *input_end = GPR_SLICE_END_PTR(input);
+    if (*(--input_end) == '=') {
+      output_length--;
+      if (*(--input_end) == '=') {
+        output_length--;
+      }
+    }
+  }
+  output = gpr_slice_malloc(output_length);
+
+  ctx.input_cur = GPR_SLICE_START_PTR(input);
+  ctx.input_end = GPR_SLICE_END_PTR(input);
+  ctx.output_cur = GPR_SLICE_START_PTR(output);
+  ctx.output_end = GPR_SLICE_END_PTR(output);
+  ctx.contains_tail = false;
+
+  if (!grpc_base64_decode_partial(&ctx)) {
+    char *s = gpr_dump_slice(input, GPR_DUMP_ASCII);
+    gpr_log(GPR_ERROR, "Base64 decoding failed, input string:\n%s\n", s);
+    gpr_free(s);
+    gpr_slice_unref(output);
+    return gpr_empty_slice();
+  }
+  GPR_ASSERT(ctx.output_cur == GPR_SLICE_END_PTR(output));
+  GPR_ASSERT(ctx.input_cur == GPR_SLICE_END_PTR(input));
+  return output;
+}
+
+gpr_slice grpc_chttp2_base64_decode_with_length(gpr_slice input,
+                                                size_t output_length) {
+  size_t input_length = GPR_SLICE_LENGTH(input);
+  gpr_slice output = gpr_slice_malloc(output_length);
+  struct grpc_base64_decode_context ctx;
+
+  // The length of a base64 string cannot be 4 * n + 1
+  if (input_length % 4 == 1) {
+    gpr_log(GPR_ERROR,
+            "Base64 decoding failed, input of "
+            "grpc_chttp2_base64_decode_with_length has a length of %d, which "
+            "has a tail of 1 byte.\n",
+            (int)input_length);
+    gpr_slice_unref(output);
+    return gpr_empty_slice();
+  }
+
+  if (output_length > input_length / 4 * 3 + tail_xtra[input_length % 4]) {
+    gpr_log(GPR_ERROR,
+            "Base64 decoding failed, output_length %d is longer "
+            "than the max possible output length %d.\n",
+            (int)output_length,
+            (int)(input_length / 4 * 3 + tail_xtra[input_length % 4]));
+    gpr_slice_unref(output);
+    return gpr_empty_slice();
+  }
+
+  ctx.input_cur = GPR_SLICE_START_PTR(input);
+  ctx.input_end = GPR_SLICE_END_PTR(input);
+  ctx.output_cur = GPR_SLICE_START_PTR(output);
+  ctx.output_end = GPR_SLICE_END_PTR(output);
+  ctx.contains_tail = true;
+
+  if (!grpc_base64_decode_partial(&ctx)) {
+    char *s = gpr_dump_slice(input, GPR_DUMP_ASCII);
+    gpr_log(GPR_ERROR, "Base64 decoding failed, input string:\n%s\n", s);
+    gpr_free(s);
+    gpr_slice_unref(output);
+    return gpr_empty_slice();
+  }
+  GPR_ASSERT(ctx.output_cur == GPR_SLICE_END_PTR(output));
+  GPR_ASSERT(ctx.input_cur <= GPR_SLICE_END_PTR(input));
+  return output;
+}
diff --git a/src/core/ext/transport/chttp2/transport/bin_decoder.h b/src/core/ext/transport/chttp2/transport/bin_decoder.h
new file mode 100644
index 0000000000..b9d40c9b74
--- /dev/null
+++ b/src/core/ext/transport/chttp2/transport/bin_decoder.h
@@ -0,0 +1,66 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * 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.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_BIN_DECODER_H
+#define GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_BIN_DECODER_H
+
+#include <grpc/support/slice.h>
+#include <stdbool.h>
+
+struct grpc_base64_decode_context {
+  /* input/output: */
+  uint8_t *input_cur;
+  uint8_t *input_end;
+  uint8_t *output_cur;
+  uint8_t *output_end;
+  /* Indicate if the decoder should handle the tail of input data*/
+  bool contains_tail;
+};
+
+/* base64 decode a grpc_base64_decode_context util either input_end is reached
+   or output_end is reached. When input_end is reached, (input_end - input_cur)
+   is less than 4. When output_end is reached, (output_end - output_cur) is less
+   than 3. Returns false if decoding is failed. */
+bool grpc_base64_decode_partial(struct grpc_base64_decode_context *ctx);
+
+/* base64 decode a slice with pad chars. Returns a new slice, does not take
+   ownership of the input. Returns an empty slice if decoding is failed. */
+gpr_slice grpc_chttp2_base64_decode(gpr_slice input);
+
+/* base64 decode a slice without pad chars, data length is needed. Returns a new
+   slice, does not take ownership of the input. Returns an empty slice if
+   decoding is failed. */
+gpr_slice grpc_chttp2_base64_decode_with_length(gpr_slice input,
+                                                size_t output_length);
+
+#endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_BIN_DECODER_H */