A session wrapper for curb

curb_session.rb

require 'curb'

class Session
  
  # The internal Curl::Easy instance
  attr_reader :curb
  
  # The last response, or nil
  attr_reader :last
  
  def initialize
    @curb ||= Curl::Easy.new
    @curb.enable_cookies = true
    @last = nil
  end
  
  # Make a get request using the query and headers.  The query may be a query
  # string, a hash, or an array of arrays.  Yields curb to the block, if
  # given, before the request is made.
  #
  # Returns a Response.
  def get(url, query={}, headers={})
    unless query.kind_of?(String)
      query = query.collect do |key, value|
        "#{curb.escape(key.to_s)}=#{curb.escape(value.to_s)}"
      end.join('&')
    end
  
    curb.url = query.empty? ? url : "#{url}?#{build_query(query)}"
    curb.headers = headers
    yield(curb) if block_given?
  
    curb.http_get
    @last = Response.new(curb)
  end

  # Make a post request using the query and headers.  The query may be a query
  # string, a hash, or an array of arrays.  Yields curb and the post fields to
  # the block, if given, before submitting the request.
  #
  # If a query value is a File, then the file contents will be uploaded using
  # 'multipart/formdata'.  Otherwise the content type will be
  # 'application/x-www-form-urlencoded'.
  #
  # Returns a Response.
  def post(url, query={}, headers={})
    curb.url = url
    curb.headers = headers
    curb.multipart_form_post = false
    
    fields = []
    query.each do |key, value|
      case value
      when File
        curb.multipart_form_post = true
        
        # it is not very efficient to close the file and re-open it
        # for the post, but the block form does not appear to work
        #
        #   Curl::PostField.file(key, value.path) { value.read }
        fields << Curl::PostField.file(key, value.path)
        value.close
      else
        fields << Curl::PostField.content(key, value)
      end
    end
    yield(curb, fields) if block_given?
  
    curb.http_post(*fields)
    @last = Response.new(curb)
  end
  
  class Response
    def initialize(curb)
      @curb = curb
      reset
    end
    
    # Returns the status line of the response.
    def status_line
      @status_line || parse_header(false)
    end
    
    # Returns a hash of the headers.
    def headers
      @headers || parse_header(true)
    end
    
    # Returns the response body.
    def body
      @curb.body_str
    end
    
    # Returns the response code.
    def code
      @curb.response_code
    end
    
    # Returns a hash of cookies in the header.
    def cookies
      cookies = {}
      headers["Set-Cookie"].to_s.split(/;\s*/).each do |cookie|
        key, value = cookie.split("=", 2)
        cookies[key] = value
      end
      cookies
    end
    
    # Returns true if the response code == 302
    def redirect?
      code == 302
    end
    
    # Returns the redirect location.
    def redirect_location
      headers["Location"]
    end
    
    # Performs an HTTP get for the redirect_location and refreshes self to
    # reflect the new response.  The current state of self is overwritten.
    def follow_redirect!
      @curb.url = redirect_location
      @curb.http_get
      reset
      self
    end
    
    private
    
    # resets self so the status_line and headers will be re-parsed
    def reset # :nodoc:
      @status_line = nil
      @headers = nil
    end
    
    # parses the headers and status_line, returns headers if return_headers is
    # true and status_line otherwise
    def parse_header(return_headers) # :nodoc:
      lines = @curb.header_str.split(/\r\n/)
      @status_line = lines.shift
      @headers = {}

      lines.each do |line|
        key, value = line.split(/:\s*/, 2)
        @headers[key] = value
      end
      
      return_headers ? @headers : @status_line
    end
  end
end