text: # This file is part of the MapProxy project.
  # Copyright (C) 2011 Omniscale <http://omniscale.de>
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #    http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  """
  HTTP client that directly calls CGI executable.
  """
  
  import errno
  import os
  import re
  import subprocess
  import time
  
  from mapproxy.source import SourceError
  from mapproxy.image import ImageSource
  from mapproxy.client.http import HTTPClientError
  from mapproxy.client.log import log_request
  from mapproxy.compat.modules import urlparse
  from mapproxy.compat import BytesIO
  
  
  def split_cgi_response(data):
      headers = []
      prev_n = 0
      while True:
          next_n = data.find(b'\n', prev_n)
          if next_n < 0:
              break
          next_line_begin = data[next_n+1:next_n+3]
          headers.append(data[prev_n:next_n].rstrip(b'\r'))
          if next_line_begin[0:1] == b'\n':
              return headers_dict(headers), data[next_n+2:]
          elif next_line_begin == b'\r\n':
              return headers_dict(headers), data[next_n+3:]
          prev_n = next_n+1
      return {}, data
  
  def headers_dict(header_lines):
      headers = {}
      for line in header_lines:
          if b':' in line:
              key, value = line.split(b':', 1)
              value = value.strip()
          else:
              key = line
              value = None
          key = key.decode('latin-1')
          key = key[0].upper() + key[1:].lower()
          if value:
              value = value.decode('latin-1')
          headers[key] = value
      return headers
  
  class IOwithHeaders(object):
      def __init__(self, io, headers):
          self.io = io
          self.headers = headers
  
      def __getattr__(self, name):
          return getattr(self.io, name)
  
  class CGIClient(object):
      def __init__(self, script, no_headers=False, working_directory=None):
          self.script = script
          self.working_directory = working_directory
          self.no_headers = no_headers
  
      def open(self, url, data=None):
          assert data is None, 'POST requests not supported by CGIClient'
  
          parsed_url = urlparse.urlparse(url)
          environ = os.environ.copy()
          environ.update({
              'QUERY_STRING': parsed_url.query,
              'REQUEST_METHOD': 'GET',
              'GATEWAY_INTERFACE': 'CGI/1.1',
              'SERVER_ADDR': '127.0.0.1',
              'SERVER_NAME': 'localhost',
              'SERVER_PROTOCOL': 'HTTP/1.0',
              'SERVER_SOFTWARE': 'MapProxy',
          })
  
          start_time = time.time()
          try:
              p = subprocess.Popen([self.script], env=environ,
                  stdout=subprocess.PIPE,
                  cwd=self.working_directory or os.path.dirname(self.script)
              )
          except OSError as ex:
              if ex.errno == errno.ENOENT:
                  raise SourceError('CGI script not found (%s)' % (self.script,))
              elif ex.errno == errno.EACCES:
                  raise SourceError('No permission for CGI script (%s)' % (self.script,))
              else:
                  raise
  
          stdout = p.communicate()[0]
          ret = p.wait()
          if ret != 0:
              raise HTTPClientError('Error during CGI call (exit code: %d)'
                                                % (ret, ))
  
          if self.no_headers:
              content = stdout
              headers = dict()
          else:
              headers, content = split_cgi_response(stdout)
  
          status_match = re.match('(\d\d\d) ', headers.get('Status', ''))
          if status_match:
              status_code = status_match.group(1)
          else:
              status_code = '-'
          size = len(content)
          content = IOwithHeaders(BytesIO(content), headers)
  
          log_request('%s:%s' % (self.script, parsed_url.query),
              status_code, size=size, method='CGI', duration=time.time()-start_time)
          return content
  
      def open_image(self, url, data=None):
          resp = self.open(url, data=data)
          if 'Content-type' in resp.headers:
              if not resp.headers['Content-type'].lower().startswith('image'):
                  raise HTTPClientError('response is not an image: (%s)' % (resp.read()))
          return ImageSource(resp)
  
  