/*
* Sketchy HTTP client
* (C) 2013,2016 Jack Lloyd
*     2017 René Korthaus, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/http_util.h>
#include <botan/parsing.h>
#include <botan/hex.h>
#include <botan/internal/os_utils.h>
#include <botan/internal/socket.h>
#include <botan/internal/stl_util.h>
#include <sstream>

namespace Botan {

namespace HTTP {

namespace {

/*
* Connect to a host, write some bytes, then read until the server
* closes the socket.
*/
std::string http_transact(const std::string& hostname,
                          const std::string& message,
                          std::chrono::milliseconds timeout)
   {
   std::unique_ptr<OS::Socket> socket;

   const std::chrono::system_clock::time_point start_time = std::chrono::system_clock::now();

   try
      {
      socket = OS::open_socket(hostname, "http", timeout);
      if(!socket)
         throw Exception("No socket support enabled in build");
      }
   catch(std::exception& e)
      {
      throw HTTP_Error("HTTP connection to " + hostname + " failed: " + e.what());
      }

   // Blocks until entire message has been written
   socket->write(cast_char_ptr_to_uint8(message.data()),
                 message.size());

   if(std::chrono::system_clock::now() - start_time > timeout)
      throw HTTP_Error("Timeout during writing message body");

   std::ostringstream oss;
   std::vector<uint8_t> buf(BOTAN_DEFAULT_BUFFER_SIZE);
   while(true)
      {
      const size_t got = socket->read(buf.data(), buf.size());
      if(got == 0) // EOF
         break;

      if(std::chrono::system_clock::now() - start_time > timeout)
         throw HTTP_Error("Timeout while reading message body");

      oss.write(cast_uint8_ptr_to_char(buf.data()),
                static_cast<std::streamsize>(got));
      }

   return oss.str();
   }

}

std::string url_encode(const std::string& in)
   {
   std::ostringstream out;

   for(auto c : in)
      {
      if(c >= 'A' && c <= 'Z')
         out << c;
      else if(c >= 'a' && c <= 'z')
         out << c;
      else if(c >= '0' && c <= '9')
         out << c;
      else if(c == '-' || c == '_' || c == '.' || c == '~')
         out << c;
      else
         out << '%' << hex_encode(cast_char_ptr_to_uint8(&c), 1);
      }

   return out.str();
   }

std::ostream& operator<<(std::ostream& o, const Response& resp)
   {
   o << "HTTP " << resp.status_code() << " " << resp.status_message() << "\n";
   for(auto h : resp.headers())
      o << "Header '" << h.first << "' = '" << h.second << "'\n";
   o << "Body " << std::to_string(resp.body().size()) << " bytes:\n";
   o.write(cast_uint8_ptr_to_char(resp.body().data()), resp.body().size());
   return o;
   }

Response http_sync(http_exch_fn http_transact,
                   const std::string& verb,
                   const std::string& url,
                   const std::string& content_type,
                   const std::vector<uint8_t>& body,
                   size_t allowable_redirects)
   {
   if(url.empty())
      throw HTTP_Error("URL empty");

   const auto protocol_host_sep = url.find("://");
   if(protocol_host_sep == std::string::npos)
      throw HTTP_Error("Invalid URL '" + url + "'");

   const auto host_loc_sep = url.find('/', protocol_host_sep + 3);

   std::string hostname, loc;

   if(host_loc_sep == std::string::npos)
      {
      hostname = url.substr(protocol_host_sep + 3, std::string::npos);
      loc = "/";
      }
   else
      {
      hostname = url.substr(protocol_host_sep + 3, host_loc_sep-protocol_host_sep-3);
      loc = url.substr(host_loc_sep, std::string::npos);
      }

   std::ostringstream outbuf;

   outbuf << verb << " " << loc << " HTTP/1.0\r\n";
   outbuf << "Host: " << hostname << "\r\n";

   if(verb == "GET")
      {
      outbuf << "Accept: */*\r\n";
      outbuf << "Cache-Control: no-cache\r\n";
      }
   else if(verb == "POST")
      outbuf << "Content-Length: " << body.size() << "\r\n";

   if(!content_type.empty())
      outbuf << "Content-Type: " << content_type << "\r\n";
   outbuf << "Connection: close\r\n\r\n";
   outbuf.write(cast_uint8_ptr_to_char(body.data()), body.size());

   std::istringstream io(http_transact(hostname, outbuf.str()));

   std::string line1;
   std::getline(io, line1);
   if(!io || line1.empty())
      throw HTTP_Error("No response");

   std::stringstream response_stream(line1);
   std::string http_version;
   unsigned int status_code;
   std::string status_message;

   response_stream >> http_version >> status_code;

   std::getline(response_stream, status_message);

   if(!response_stream || http_version.substr(0,5) != "HTTP/")
      throw HTTP_Error("Not an HTTP response");

   std::map<std::string, std::string> headers;
   std::string header_line;
   while (std::getline(io, header_line) && header_line != "\r")
      {
      auto sep = header_line.find(": ");
      if(sep == std::string::npos || sep > header_line.size() - 2)
         throw HTTP_Error("Invalid HTTP header " + header_line);
      const std::string key = header_line.substr(0, sep);

      if(sep + 2 < header_line.size() - 1)
         {
         const std::string val = header_line.substr(sep + 2, (header_line.size() - 1) - (sep + 2));
         headers[key] = val;
         }
      }

   if(status_code == 301 && headers.count("Location"))
      {
      if(allowable_redirects == 0)
         throw HTTP_Error("HTTP redirection count exceeded");
      return GET_sync(headers["Location"], allowable_redirects - 1);
      }

   std::vector<uint8_t> resp_body;
   std::vector<uint8_t> buf(4096);
   while(io.good())
      {
      io.read(cast_uint8_ptr_to_char(buf.data()), buf.size());
      resp_body.insert(resp_body.end(), buf.data(), &buf[io.gcount()]);
      }

   const std::string header_size = search_map(headers, std::string("Content-Length"));

   if(!header_size.empty())
      {
      if(resp_body.size() != to_u32bit(header_size))
         throw HTTP_Error("Content-Length disagreement, header says " +
                          header_size + " got " + std::to_string(resp_body.size()));
      }

   return Response(status_code, status_message, resp_body, headers);
   }

Response http_sync(const std::string& verb,
                   const std::string& url,
                   const std::string& content_type,
                   const std::vector<uint8_t>& body,
                   size_t allowable_redirects,
                   std::chrono::milliseconds timeout)
   {
   auto transact_with_timeout =
      [timeout](const std::string& hostname, const std::string& service)
      {
      return http_transact(hostname, service, timeout);
      };

   return http_sync(
      transact_with_timeout,
      verb,
      url,
      content_type,
      body,
      allowable_redirects);
   }

Response GET_sync(const std::string& url,
                  size_t allowable_redirects,
                  std::chrono::milliseconds timeout)
   {
   return http_sync("GET", url, "", std::vector<uint8_t>(), allowable_redirects, timeout);
   }

Response POST_sync(const std::string& url,
                   const std::string& content_type,
                   const std::vector<uint8_t>& body,
                   size_t allowable_redirects,
                   std::chrono::milliseconds timeout)
   {
   return http_sync("POST", url, content_type, body, allowable_redirects, timeout);
   }

}

}