#!/usr/bin/python2.7
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
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#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
# Copyright (c) 2010, 2016, Oracle and/or its affiliates. All rights reserved.
#
#
# userland-fetch - a file download utility
#
#  A simple program similiar to wget(1), but handles local file copy, ignores
#  directories, and verifies file hashes.
#

import errno
import os
import sys
import shutil
import subprocess
from urllib import splittype
from urllib2 import urlopen
import hashlib

def printIOError(e, txt):
	""" Function to decode and print IOError type exception """
	print "I/O Error: " + txt + ": "
	try:
		(code, message) = e
		print str(message) + " (" + str(code) + ")"
	except:
		print str(e)

def validate_signature(path, signature):
	"""Given paths to a file and a detached PGP signature, verify that
	the signature is valid for the file.  Current configuration allows for
	unrecognized keys to be downloaded as necessary."""

	# Find the root of the repo so that we can point GnuPG at the right
	# configuration and keyring.
	proc = subprocess.Popen(["hg", "root"], stdout=subprocess.PIPE)
	proc.wait()
	if proc.returncode != 0:
		return False
	out, err = proc.communicate()
	gpgdir = os.path.join(out.strip(), "tools", ".gnupg")

        # Skip the permissions warning: none of the information here is private,
        # so not having to worry about getting mercurial keeping the directory
        # unreadable is just simplest.
	try:
		proc = subprocess.Popen(["gpg2", "--verify",
		    "--no-permission-warning", "--homedir", gpgdir, signature,
		    path], stdin=open("/dev/null"),
		    stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
	except OSError as e:
		# If the executable simply couldn't be found, just skip the
		# validation.
		if e.errno == errno.ENOENT:
			return False
		raise

        proc.wait()
        if proc.returncode != 0:
		# Only print GnuPG's output when there was a problem.
                print proc.stdout.read()
                return False
        return True

def validate(file, hash):
	"""Given a file-like object and a hash string, verify that the hash
	matches the file contents."""

	try:
		algorithm, hashvalue = hash.split(':')
	except:
		algorithm = "sha256"

	# force migration away from sha1
	if algorithm == "sha1":
		algorithm = "sha256"
	try:
		m = hashlib.new(algorithm)
	except ValueError:
		return False

	while True:
		try:
			block = file.read()
		except IOError, err:
			print str(err),
			break

		m.update(block)
		if block == '':
			break

	return "%s:%s" % (algorithm, m.hexdigest())

def validate_container(filename, hash):
	"""Given a file path and a hash string, verify that the hash matches the
	file contents."""

	try:
		file = open(filename, 'r')
	except IOError as e:
		printIOError(e, "Can't open file " + filename)
		return False
	return validate(file, hash)


def validate_payload(filename, hash):
	"""Given a file path and a hash string, verify that the hash matches the
	payload (uncompressed content) of the file."""

	import re
	import gzip
	import bz2

	expr_bz = re.compile('.+\.bz2$', re.IGNORECASE)
	expr_gz = re.compile('.+\.gz$', re.IGNORECASE)
	expr_tgz = re.compile('.+\.tgz$', re.IGNORECASE)

	try:
		if expr_bz.match(filename):
			file = bz2.BZ2File(filename, 'r')
		elif expr_gz.match(filename):
			file = gzip.GzipFile(filename, 'r')
		elif expr_tgz.match(filename):
			file = gzip.GzipFile(filename, 'r')
		else:
			return False
	except IOError as e:
		printIOError(e, "Can't open archive " + filename)
		return False
	return validate(file, hash)


def download(url, timeout, filename=None, quiet=False):
	"""Download the content at the given URL to the given filename
	(defaulting to the basename of the URL if not given.  If 'quiet' is
	True, throw away any error messages.  Returns the name of the file to
	which the content was donloaded."""

	src = None

	try:
		src = urlopen(url=url, timeout=timeout)
	except IOError as e:
		if not quiet:
			printIOError(e, "Can't open url " + url)
		return None

	# 3xx, 4xx and 5xx (f|ht)tp codes designate unsuccessfull action
	if 3 <= int(src.getcode()/100) <= 5:
		if not quiet:
			print "Error code: " + str(src.getcode())
		return None

	if filename == None:
		filename = src.geturl().split('/')[-1]

	try:
		dst = open(filename, 'wb');
	except IOError as e:
		if not quiet:
			printIOError(e, "Can't open file " + filename + " for writing")
		src.close()
		return None

	while True:
		block = src.read()
		if block == '':
			break;
		dst.write(block)

	src.close()
	dst.close()

	# return the name of the file that we downloaded the data to.
	return filename

def download_paths(search, filename, url):
	"""Returns a list of URLs where the file 'filename' might be found,
	using 'url', 'search', and $DOWNLOAD_SEARCH_PATH as places to look.

	If 'filename' is None, then the list will simply contain 'url'.
	"""

	urls = list()

	if filename != None:
		tmp = os.getenv('DOWNLOAD_SEARCH_PATH')
		if tmp:
			search += tmp.split(' ')

		file = os.path.basename(filename)

		urls = [ base + '/' + file for base in search ]

		# filename should always be first
		if filename in urls:
			urls.remove(filename)
		urls.insert(0, filename)

	# command line url is a fallback, so it's last
	if url != None and url not in urls:
		urls.append(url)

	return urls

def download_from_paths(search_list, file_arg, url, timeout_arg, link_arg, quiet=False):
	"""Attempts to download a file from a number of possible locations.
	Generates a list of paths where the file ends up on the local
	filesystem.  This is a generator because while a download might be
	successful, the signature or hash may not validate, and the caller may
	want to try again from the next location.  The 'link_arg' argument is a
	boolean which, when True, specifies that if the source is not a remote
	URL and not already found where it should be, to make a symlink to the
	source rather than copying it.
	"""
	for url in download_paths(search_list, file_arg, url):
		if not quiet:
			print "Source %s..." % url,

		scheme, path = splittype(url)
		name = file_arg

		if scheme in [ None, 'file' ]:
			if os.path.exists(path) == False:
				if not quiet:
					print "not found, skipping file copy"
				continue
			elif name and name != path:
				if link_arg == False:
					if not quiet:
						print "\n    copying..."
					shutil.copy2(path, name)
				else:
					if not quiet:
						print "\n    linking..."
					os.symlink(path, name)
		elif scheme in [ 'http', 'https', 'ftp' ]:
			if not quiet:
				print "\n    downloading...",
			name = download(url, timeout_arg, file_arg, quiet)
			if name == None:
				if not quiet:
					print "failed"
				continue

		yield name

def usage():
	print "Usage: %s [-f|--file (file)] [-l|--link] [-h|--hash (hash)] " \
          "[-s|--search (search-dir)] [-S|--sigurl (signature-url)] " \
	  "[-t|--timeout (timeout)] --url (url)" % \
          (sys.argv[0].split('/')[-1])
	sys.exit(1)

def main():
	import getopt

	# FLUSH STDOUT
	sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)

	file_arg = None
	link_arg = False
	hash_arg = None
	url_arg = None
	sig_arg = None
	timeout_arg = 300
	search_list = list()

	try:
                opts, args = getopt.getopt(sys.argv[1:], "f:h:ls:S:t:u:",
			["file=", "link", "hash=", "search=", "sigurl=",
			"timeout=", "url="])
	except getopt.GetoptError, err:
		print str(err)
		usage()

	for opt, arg in opts:
		if opt in [ "-f", "--file" ]:
			file_arg = arg
		elif opt in [ "-l", "--link" ]:
			link_arg = True
		elif opt in [ "-h", "--hash" ]:
			hash_arg = arg
		elif opt in [ "-s", "--search" ]:
			search_list.append(arg)
		elif opt in [ "-S", "--sigurl" ]:
			sig_arg = arg
		elif opt in [ "-t", "--timeout" ]:
			try:
				timeout_arg = int(arg)
			except ValueError:
				print "Invalid argument for %s, should be a " \
				    "number, but is %s" % (opt, arg)
				sys.exit(1)
			if timeout_arg < 0:
				print "Invalid argument for %s, should be a " \
				    "positive number, but is %s" % (opt, arg)
				sys.exit(1)
		elif opt in [ "-u", "--url" ]:
			url_arg = arg
		else:
			assert False, "unknown option"

	for name in download_from_paths(search_list, file_arg, url_arg,
	    timeout_arg, link_arg):
		print "\n    validating signature...",

		sig_valid = False
		if not sig_arg:
			print "skipping (no signature URL)"
		else:
			# Put the signature file in the same directory as the
			# file we're downloading.
			sig_file = os.path.join(
			    os.path.dirname(file_arg),
			    os.path.basename(sig_arg))
			# Validate with the first signature we find.
			for sig_file in download_from_paths(search_list, sig_file,
			    sig_arg, timeout_arg, link_arg, True):
				if sig_file:
					if validate_signature(name, sig_file):
						print "ok"
						sig_valid = True
					else:
						print "failed"
					break
				else:
					continue
			else:
				print "failed (couldn't fetch signature)"

		print "    validating hash...",
		realhash = validate_container(name, hash_arg)

		if not hash_arg:
			print "skipping (no hash)"
			print "hash is: %s" % realhash
		elif realhash == hash_arg:
			print "ok"
		else:
			payloadhash = validate_payload(name, hash_arg)
			if payloadhash == hash_arg:
				print "ok"
			else:
				# If the signature validated, then we assume
				# that the expected hash is just a typo, but we
				# warn just in case.
				if sig_valid:
					print "invalid hash! Did you forget " \
					    "to update it?"
				else:
					print "corruption detected"

				print "    expected: %s" % hash_arg
				print "    actual:   %s" % realhash
				print "    payload:  %s" % payloadhash

				# If the hash is invalid, but the signature
				# validation succeeded, rename the archive (so
				# the user doesn't have to re-download it) and
				# fail.  Otherwise, try to remove the file and
				# try again.
				if sig_valid:
					newname = name + ".invalid-hash"
					try:
						os.rename(name, newname)
					except OSError:
						pass
					else:
						print "archive saved as %s; " \
						    "if it isn't corrupt, " \
						    "rename to %s" % (newname,
						    name)
					sys.exit(1)
				else:
					try:
						os.remove(name)
					except OSError:
						pass

					continue

		sys.exit(0)
	sys.exit(1)

if __name__ == "__main__":
	main()