Added new source file openvpn/http/urlencode.hpp to deal with

URL validation, encoding, and decoding.

openvpn/http/urlencode.hpp

@@ -0,0 +1,98 @@
+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2015 OpenVPN Technologies, Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    This program is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef OPENVPN_HTTP_URLENCODE_H
+#define OPENVPN_HTTP_URLENCODE_H
+
+#include <string>
+#include <vector>
+
+#include <openvpn/common/exception.hpp>
+#include <openvpn/common/split.hpp>
+#include <openvpn/common/hexstr.hpp>
+#include <openvpn/common/unicode.hpp>
+
+namespace openvpn {
+  namespace URL {
+    OPENVPN_EXCEPTION(url_error);
+
+    inline std::string decode(const std::string& encoded)
+    {
+      enum State {
+	TEXT,
+	PERCENT,
+	DIGIT
+      };
+
+      int value = 0;
+      State state = TEXT;
+      std::string ret;
+
+      for (auto &c : encoded)
+	{
+	  switch (state)
+	    {
+	    case TEXT:
+	      {
+		if (c == '%')
+		  state = PERCENT;
+		else
+		  ret += c;
+		break;
+	      }
+	    case PERCENT:
+	      {
+		const int v = parse_hex_char(c);
+		if (v < 0)
+		  throw url_error(std::string("decode error after %: ") + encoded);
+		value = v;
+		state = DIGIT;
+		break;
+	      }
+	    case DIGIT:
+	      {
+		const int v = parse_hex_char(c);
+		if (v < 0)
+		  throw url_error(std::string("decode error after %: ") + encoded);
+		ret += static_cast<unsigned char>((value * 16) + v);
+		state = TEXT;
+	      }
+	    }
+	}
+      if (state != TEXT)
+	throw url_error(std::string("decode error: %-encoding item not closed out: ") + encoded);
+      if (!Unicode::is_valid_utf8(ret))
+	throw url_error(std::string("not UTF-8: ") + encoded);
+      return ret;
+    }
+
+    inline std::vector<std::string> decode_path(const std::string& path)
+    {
+      std::vector<std::string> list;
+      Split::by_char_void<decltype(list), NullLex, Split::NullLimit>(list, path, '/');
+      for (auto &i : list)
+	i = decode(i);
+      return list;
+    }
+  }
+}
+
+#endif