Percent encoding routines

2 files changed, 168 insertions, 0 deletions

diff --git a/src/core/lib/support/percent_encoding.c b/src/core/lib/support/percent_encoding.c
new file mode 100644
index 0000000000..5da763c9a5
--- /dev/null
+++ b/src/core/lib/support/percent_encoding.c
@@ -0,0 +1,124 @@
+/*
+ *
+ * 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/lib/support/percent_encoding.h"
+
+#include <grpc/support/log.h>
+
+static bool is_unreserved_character(uint8_t c) {
+  return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') ||
+         (c >= '0' && c <= '9') || c == '-' || c == '_' || c == '.' || c == '~';
+}
+
+gpr_slice gpr_percent_encode_slice(gpr_slice slice) {
+  static const uint8_t hex[] = "0123456789ABCDEF";
+
+  // first pass: count the number of bytes needed to output this string
+  size_t output_length = 0;
+  const uint8_t *slice_start = GPR_SLICE_START_PTR(slice);
+  const uint8_t *slice_end = GPR_SLICE_END_PTR(slice);
+  const uint8_t *p;
+  bool any_reserved_bytes = false;
+  for (p = slice_start; p < slice_end; p++) {
+    bool unres = is_unreserved_character(*p);
+    output_length += unres ? 1 : 3;
+    any_reserved_bytes |= !unres;
+  }
+  // no unreserved bytes: return the string unmodified
+  if (!any_reserved_bytes) {
+    return gpr_slice_ref(slice);
+  }
+  // second pass: actually encode
+  gpr_slice out = gpr_slice_malloc(output_length);
+  uint8_t *q = GPR_SLICE_START_PTR(out);
+  for (p = slice_start; p < slice_end; p++) {
+    if (is_unreserved_character(*p)) {
+      *q++ = *p;
+    } else {
+      *q++ = '%';
+      *q++ = hex[*p >> 4];
+      *q++ = hex[*p & 15];
+    }
+  }
+  GPR_ASSERT(q == GPR_SLICE_END_PTR(out));
+  return out;
+}
+
+static bool valid_hex(const uint8_t *p, const uint8_t *end) {
+  if (p == end) return false;
+  return (*p >= '0' && *p <= '9') || (*p >= 'a' && *p <= 'f') ||
+         (*p >= 'A' && *p <= 'F');
+}
+
+static uint8_t dehex(uint8_t c) {
+  if (c >= '0' && c <= '9') return c - '0';
+  if (c >= 'A' && c <= 'F') return c - 'A' + 10;
+  if (c >= 'a' && c <= 'f') return c - 'a' + 10;
+  GPR_UNREACHABLE_CODE(return 255);
+}
+
+bool gpr_percent_decode_slice(gpr_slice slice_in, gpr_slice *slice_out) {
+  const uint8_t *p = GPR_SLICE_START_PTR(slice_in);
+  const uint8_t *in_end = GPR_SLICE_END_PTR(slice_in);
+  size_t out_length = 0;
+  bool any_percent_encoded_stuff = false;
+  while (p != in_end) {
+    if (*p == '%') {
+      if (!valid_hex(++p, in_end)) return false;
+      if (!valid_hex(++p, in_end)) return false;
+      p++;
+      any_percent_encoded_stuff = true;
+      out_length++;
+    } else {
+      p++;
+      out_length++;
+    }
+  }
+  if (!any_percent_encoded_stuff) {
+    *slice_out = gpr_slice_ref(slice_in);
+    return true;
+  }
+  p = GPR_SLICE_START_PTR(slice_in);
+  *slice_out = gpr_slice_malloc(out_length);
+  uint8_t *q = GPR_SLICE_START_PTR(*slice_out);
+  while (p != in_end) {
+    if (*p == '%') {
+      *q++ = (uint8_t)(dehex(p[1]) << 4) | (dehex(p[2]));
+      p += 3;
+    } else {
+      *q++ = *p++;
+    }
+  }
+  GPR_ASSERT(q == GPR_SLICE_END_PTR(*slice_out));
+  return true;
+}
diff --git a/src/core/lib/support/percent_encoding.h b/src/core/lib/support/percent_encoding.h
new file mode 100644
index 0000000000..df59cbd606
--- /dev/null
+++ b/src/core/lib/support/percent_encoding.h
@@ -0,0 +1,44 @@
+/*
+ *
+ * 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 PRECENT_H
+#define PRECENT_H
+
+#include <stdbool.h>
+
+#include <grpc/support/slice.h>
+
+gpr_slice gpr_percent_encode_slice(gpr_slice slice);
+bool gpr_percent_decode_slice(gpr_slice slice_in, gpr_slice *slice_out);
+
+#endif /* PRECENT_H */