Downloads updates to Elite Dangerous by imitating the patcher.

ed-downloader.py

import gzip
import hashlib
import os
import StringIO
import sys
import urllib
import getpass

from xml.etree import ElementTree

def generateDirectories(path):
  dir = os.path.dirname(path)
  
  if not os.path.isdir(dir):
    os.makedirs(dir)

def getPatchManifest(manifestURL):
  compressedManifest = StringIO.StringIO(urllib.urlopen(manifestURL).read())
  decompressedManifest = gzip.GzipFile(fileobj=compressedManifest)
  parsedManifest = ElementTree.fromstring(decompressedManifest.read())
  
  return parsedManifest

def alreadyHaveAsset(downloadPath, assetHash):
  if os.path.isfile(downloadPath):
    # Asset exists on disk, but need to check version
    sha1 = hashlib.sha1()
    sha1.update(open(downloadPath, "rb").read())
    localHash = sha1.hexdigest()
    
    return localHash == assetHash
  else:
    # Asset doesn't exist on disk
    return False

def reportFileProgress(blockNumber, blockSize, fileSize):
  blockSize /= 1048576.0 # Bytes -> Megabytes
  fileSize /= 1048576.0 # Bytes -> Megabytes
  
  currentSize = blockNumber * blockSize
  percentComplete = min(100.0 * currentSize/fileSize, 100.00)
  
  print "\r\t%.2f MB / %.2f MB (%.2f%%)" % (currentSize, fileSize, percentComplete),

def getAsset(assetNumber, assetCount, assetRelPath, assetURL, downloadPath):
  print "Downloading file %d of %d: %s" % (assetNumber, assetCount, assetRelPath)
  
  downloaded = False
  currentTry = 1
  maxTries = 5
  
  while not downloaded and currentTry <= maxTries:
    try:
      urllib.urlretrieve(assetURL, downloadPath, reportFileProgress)
      downloaded = True
    except IOError:
      print 
      print "Failed to download, retry %d of %d" % (currentTry, maxTries)
      currentTry += 1
  
  print 

def downloadAssets(manifest, downloadDir):
  assetCount = len(manifest)

  # Get assets
  for assetNumber, asset in enumerate(manifest.getchildren()):
    assetURL = asset.find("Download").text
    assetSize = float(asset.find("Size").text) / 1048576.0 # Bytes -> Megabytes
    assetHash = asset.find("Hash").text
    assetRelPath = asset.find("Path").text
    downloadPath = os.path.join(downloadDir, assetRelPath)
    
    generateDirectories(downloadPath)
    
    if alreadyHaveAsset(downloadPath, assetHash):
      print "Skipping file %d of %d: %s" % (assetNumber+1, assetCount, assetRelPath)
    else:
      getAsset(assetNumber+1, assetCount, assetRelPath, assetURL, downloadPath)

if __name__ == "__main__":
  # Found via Wireshark.
  manifestURL = "http://cdn.zaonce.net/elitedangerous/win/manifests/RetailUpdate_1.1.02_Final+%282015.02.11.57320%29.xml.gz"
  
  possibleDownloadDirs = [
		  "C:\\Users\\%s\\AppData\\Local\\Frontier_Developments\\Products\\FORC-FDEV-D-1010" % getpass.getuser(),
		  "C:\\Program Files (x86)\Frontier\\EDLaunch\\Products\\FORC-FDEV-D-1010",
		  "C:\\Program Files\\Frontier\\EDLaunch\\Products\\FORC-FDEV-D-1010"
		  ]

  print "Looking for ED download directory in the following paths:\n" + "\n".join(possibleDownloadDirs)
  
  downloadDirs = [ d for d in possibleDownloadDirs if os.path.isdir(downloadDir) ]

  if len(downloadDirs) == 0:
    print "Couldn't find ED download directory."
  else
    print "Downloading client files to %s..." % downloadDirs[0]
    manifest = getPatchManifest(manifestURL)
    downloadAssets(manifest, downloadDirs[0])