# encoding: utf-8
#--
#   Copyright (C) 2012 Gitorious AS and/or its subsidiary(-ies)
#   Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies)
#
#   This program is free software: you can redistribute it and/or modify
#   it under the terms of the GNU Affero General Public License as published by
#   the Free Software Foundation, either version 3 of the License, or
#   (at your option) any later version.
#
#   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.  If not, see <http://www.gnu.org/licenses/>.
#++
require "gitorious"

# Middleware that handles HTTP cloning
#
# - Rip out the repo path and rest from the URI
# - Return a X-Sendfile header in the response containing the full
#   path to the object requested
# - This will be picked up by Apache (given mod-x_sendfile is
#   installed) and then delivered to the client
module Gitorious
  class GitHttpCloner
    TRUSTED_PROXIES = /^127\.0\.0\.1$|^(10|172\.(1[6-9]|2[0-9]|30|31)|192\.168)\./i
    NOT_FOUND_RESPONSE = [404, { "Content-Type" => "text/html" },[]]
    NOT_ALLOWED_RESPONSE = [403, { "Content-Type" => "text/html" }, []]

    def self.call(env)
      match = /(.*\.git)(.*)/.match(env["PATH_INFO"])
      return NOT_FOUND_RESPONSE if match.nil?
      return NOT_ALLOWED_RESPONSE if Gitorious.git_http.nil?
      path = match[1]
      rest = match[2]

      begin
        repo = Repository.find_by_path(path)
        return NOT_ALLOWED_RESPONSE if !can_read?(nil, repo)
        return NOT_FOUND_RESPONSE unless repo
        repo.cloned_from(remote_ip(env), nil, nil, "http") if rest == "/HEAD"
        headers = {
          "Content-Type" => "application/octet-stream",
          "X-Robots-Tag" => "noindex,nofollow"
        }.merge(sendfile_headers(repo, rest))
        env["rack.session.options"] = {}
        return [200, headers, []]
      rescue ActiveRecord::RecordNotFound
        # Repo not found
        return NOT_FOUND_RESPONSE
      end
    end

    def self.sendfile_headers(repo, rest)
      if Gitorious.frontend_server == "nginx"
        { "X-Accel-Redirect" => File.join("/git-http", repo.real_gitdir, rest) }
      else
        { "X-Sendfile" => File.join(repo.full_repository_path, rest) }
      end
    end

    protected
    def self.can_read?(user, repository)
      return true if !Gitorious.private_repositories?
      Gitorious::Authorization::DatabaseAuthorization.new.can_read_repository?(user, repository)
    end

    # Borrowed from ActionController::Request. Extract proxy addresses
    # and stuff (except our own) Does not do ip spoofing checks
    def self.remote_ip(env)
      remote_addr_list = env["REMOTE_ADDR"] && env["REMOTE_ADDR"].scan(/[^,\s]+/)
      unless remote_addr_list.blank?
        not_trusted_addrs = remote_addr_list.reject {|addr| addr =~ TRUSTED_PROXIES}
        return not_trusted_addrs.first unless not_trusted_addrs.empty?
      end

      remote_ips = env["HTTP_X_FORWARDED_FOR"] && env["HTTP_X_FORWARDED_FOR"].split(",")

      if env.include? "HTTP_CLIENT_IP"
        return env["HTTP_CLIENT_IP"]
      end

      if remote_ips
        while remote_ips.size > 1 && TRUSTED_PROXIES =~ remote_ips.last.strip
          remote_ips.pop
        end
        return remote_ips.last.strip
      end

      env["REMOTE_ADDR"]
    end
  end
end