tumblrproxy.rb

get '/blog*' do
  begin
    path = params[:splat][0]
    source_url = URI.parse('http://asdf.tumblr.com' + path.gsub(/ /, '+'))
    source_content_type = ''
    source_body = open(source_url) do |f|
      source_content_type = f.content_type
      f.read
    end

if source_content_type == 'text/html'
    output_base = request.base_url + '/blog'
    output_body = source_body.gsub(/\b(href|src|rel)="\/\//, '\1="https:\/\/')
    output_body = output_body.gsub(/\b(href|src|rel)="\//, '\1="' + output_base + '/')
    output_body = output_body.gsub(/\b(href|src|rel)="http:\/\/asdf\.tumblr\.com/, '\1="/blog')
  else
    output_body = source_body
  end

  content_type source_content_type
  output_body
  rescue OpenURI::HTTPError
    erb :error
  end
end