#!/usr/local/bin/python

import os,sys

from BaseHTTPServer import BaseHTTPRequestHandler
from ZSI import *
from M2Crypto import SSL
from M2Crypto.SSL.SSLServer import SSLServer
import M2Crypto.httpslib

import re
import random
import string
import subprocess
import tempfile

from fedd_services import *
from fedd_util import *

class fedd_proj:
    """
    The implementation of access control based on mapping users to projects.

    Users can be mapped to existing projects or have projects created
    dynamically.  This implements both direct requests and proxies.
    """
    # Attributes that can be parsed from the configuration file
    bool_attrs = ("dynamic_projects", "project_priority")
    emulab_attrs = ("boss", "ops", "domain", "fileserver", "eventserver")
    id_attrs = ("testbed", "cert_file", "trusted_certs", "proxy",
	    "proxy_trusted_certs", "cert_pwd")

    class access_project:
	"""
	A project description used to grant access to this testbed.

	The description includes a name and a list of node types to which the
	project will be granted access.
	"""
	def __init__(self, name, nt):
	    self.name = name
	    self.node_types = list(nt)

	def __repr__(self):
	    if len(self.node_types) > 0:
		return "access_proj('%s', ['%s'])" % \
			(self.name, str("','").join(self.node_types))
	    else:
		return "access_proj('%s', [])" % self.name


    class parse_error(RuntimeError):
	"""Raised if the configuration file is unparsable"""
	pass

    def __init__(self, config=None):
	"""
	Initializer.  Parses a configuration if one is given.
	"""

	# Create instance attributes from the static lists
	for a in fedd_proj.bool_attrs:
	    setattr(self, a, False)

	for a in fedd_proj.emulab_attrs + fedd_proj.id_attrs:
	    setattr(self, a, None)

	# Other attributes
	self.attrs = {}
	self.access = {}
	self.fedid_category = {}
	self.fedid_default = "user"
	self.restricted = []
	self.wap = '/usr/testbed/sbin/wap'
	self.newproj = '/usr/testbed/sbin/newproj'
	self.mkproj = '/usr/testbed/sbin/mkproj'
	self.grantnodetype = '/usr/testbed/sbin/grantnodetype'

	# Read the configuration
	if config != None: 
	    self.read_config(config)

    def dump_state(self):
	"""
	Dump the state read from a configuration file.  Mostly for debugging.
	"""
	for a in fedd_proj.bool_attrs:
	    print "%s: %s" % (a, getattr(self, a ))
	for a in fedd_proj.emulab_attrs + fedd_proj.id_attrs:
	    print "%s: %s" % (a, getattr(self, a))
	for k, v in self.attrs.iteritems():
	    print "%s %s" % (k, v)
	print "Access DB:"
	for k, v in self.access.iteritems():
	    print "%s %s" % (k, v)
	print "Trust DB:"
	for k, v in self.fedid_category.iteritems():
	    print "%s %s" % (k, v)
	print "Restricted: %s" % str(',').join(sorted(self.restricted))

    def get_id(self, id):
	"""
	Utility to get an object from the polymorphic IDType.
	
	Only fedids and usernames are currently understood.  If neither is
	present None is returned.  If both are present (which is a bug) the
	fedid is returned.
	"""
	if id == None: 
	    return None
	elif getattr(id, "get_element_fedid", None) != None:
	    return fedid(id.get_element_fedid())
	elif getattr(id, "get_element_username", None) != None:
	    return id.get_element_username()
	else:
	    return None

    def get_users(self, obj):
	"""
	Return a list of the IDs of the users in obj (accessed using get_id)
	"""
	if obj.get_element_user() != None:
	    return [ self.get_id(u.get_element_userID()) \
		    for u in obj.get_element_user() \
			if u.get_element_userID() != None]
	else:
	    return None

    def random_string(self, s, n=3):
	"""Append n random ASCII characters to s and return the string"""
	rv = s
	for i in range(0,n):
	    rv += random.choice(string.ascii_letters)
	return rv

    def write_attr_xml(self, file, root, lines):
	"""
	Write an emulab config file for a dynamic project.

	Format is <root><attribute name=lines[0]>lines[1]</attribute></root>
	"""
	# Convert a pair to an attribute line
	out_attr = lambda a,v : \
		'<attribute name="%s"><value>%s</value></attribute>' % (a, v)

	f = os.fdopen(file, "w")
	f.write("<%s>\n" % root)
	f.write("\n".join([out_attr(*l) for l in lines]))
	f.write("</%s>\n" % root)
	f.close()


    def dynamic_project(self, found, ssh):
	"""Create a dynamic project with ssh access"""
	user_fields = [
		("name", "Federation User %s" % found[1]),
		("email", "%s-fed@isi.deterlab.net" % found[1]),
		("password", self.random_string("", 8)),
		("login", found[1]),
		("address", "4676 Admiralty"),
		("city", "Marina del Rey"),
		("state", "CA"),
		("zip", "90292"),
		("country", "USA"),
		("phone", "310-448-9190"),
		("title", "None"),
		("affiliation", "USC/ISI")
	]

	proj_fields = [
		("name", found[0].name),
		("short description", "dynamic federated project"),
		("URL", "http://www.isi.edu/~faber"),
		("funders", "USC/USU"),
		("long description", "Federation access control"),
		("public", "1"),
		("num_pcs", "100"),
		("linkedtous", "1")
	]

	# tempfiles for the parameter files
	uf, userfile = tempfile.mkstemp(prefix="usr", suffix=".xml",
		dir="/tmp")
	pf, projfile = tempfile.mkstemp(prefix="proj", suffix=".xml",
		dir="/tmp")

	# A few more dynamic fields
	for s in ssh:
	    user_fields.append(("pubkey", s))
	proj_fields.append(("newuser_xml", userfile))

	# Write out the files
	self.write_attr_xml(uf, "user", user_fields)
	self.write_attr_xml(pf, "project", proj_fields)

	# Generate the commands (only grantnodetype's are dynamic)
	cmds = [
		(self.wap, self.newproj, projfile),
		(self.wap, self.mkproj, found[0].name)
		]
	for nt in found[0].node_types:
	    cmds.append((self.wap, self.grantnodetype, '-p', found[0].name, nt))

	# Create the projects
	rc = 0
	for cmd in cmds:
	    if self.dynamic_projects:
		try:
		    rc = subprocess.call(cmd)
		except OSerror, e:
		    raise Fault(Fault.Server, 
			    "Dynamic project subprocess creation error "+ \
				    "[%s] (%s)" %  (cmd[1], e.strerror))
	    else:
		print >>sys.stdout, str(" ").join(cmd)

	    if rc != 0: 
		raise Fault(Fault.Server,
			"Dynamic project subprocess error " +\
				"[%s] (%d)" % (cmd[1], rc))
	# Clean up tempfiles
	os.unlink(userfile)
	os.unlink(projfile)

    def proxy_request(self, dt, req):
	"""
	Send req on to the real destination in dt and return the response

	Req is just the requestType object.  This function re-wraps it.  It
	also rethrows any faults.
	"""
	tc = self.proxy_trusted_certs or self.trusted_certs

	# No retry loop here.  Proxy servers must correctly authenticate
	# themselves without help
	try:
	    ctx = fedd_ssl_context(self.cert_file, tc, password=self.cert_pwd)
	except SSL.SSLError:
	    raise Fault(Fault.Server, "Server certificates misconfigured")

	loc = feddServiceLocator();
	port = loc.getfeddPortType(dt,
		transport=M2Crypto.httpslib.HTTPSConnection, 
		transdict={ 'ssl_context' : ctx })

	# Reconstruct the full request message
	msg = RequestAccessRequestMessage()
	msg.set_element_RequestAccessRequestBody(req)

	try:
	    resp = port.RequestAccess(msg)
	except ZSI.FaultException, e:
	    raise e.fault
	return resp

    def permute_wildcards(self, a, p):
	"""Return a copy of a with various fields wildcarded.

	The bits of p control the wildcards.  A set bit is a wildcard
	replacement with the lowest bit being user then project then testbed.
	"""
	if p & 1: user = ["<any>"]
	else: user = a[2]
	if p & 2: proj = "<any>"
	else: proj = a[1]
	if p & 4: tb = "<any>"
	else: tb = a[0]

	return (tb, proj, user)

    def find_access(self, search):
	"""
	Search the access DB for a match on this tuple.  Return the matching
	access tuple and the user that matched.
	
	NB, if the initial tuple fails to match we start inserting wildcards in
	an order determined by self.project_priority.  Try the list of users in
	order (when wildcarded, there's only one user in the list).
	"""
	if self.project_priority: perm = (0, 1, 2, 3, 4, 5, 6, 7)
	else: perm = (0, 2, 1, 3, 4, 6, 5, 7)

	for p in perm: 
	    s = self.permute_wildcards(search, p)
	    # s[2] is None on an anonymous, unwildcarded request
	    if s[2] != None:
		for u in s[2]:
		    if self.access.has_key((s[0], s[1], u)):
			return (self.access[(s[0], s[1], u)], u)
	    else:
		if self.access.has_key(s):
		    return (self.access[s], None)
	return None

    def lookup_access(self, req, fid):
	"""
	Determine the allowed access for this request.  Return the access and
	which fields are dynamic.

	The fedid is needed to construct the request
	"""
	tb = None
	project = None
	user = None

	principal_type = self.fedid_category.get(fid, self.fedid_default)

	if principal_type == "testbed": tb = fid

	p = req.get_element_project()
	if p != None:
	    if p.get_element_name() != None: 
		project = self.get_id(p.get_element_name())
	    user = self.get_users(p)
	else:
	    user = self.get_users(req)

	# Now filter by prinicpal type
	if principal_type == "user":
	    if user != None:
		fedids = [ u for u in user if isinstance(u, type(fid))]
		if len(fedids) > 1:
		    raise Fault(Fault.Client,
			    "User asserting multiple fedids")
		elif len(fedids) == 1 and fedids[0] != fid:
		    raise Fault(Fault.Client, 
			    "User asserting different fedid")
	    project = None
	    tb = None
	elif principal_type == "project":
	    if isinstance(project, type(fid)) and fid != project:
		raise Fault(Fault.Client,
			"Project asserting different fedid")
	    tb = None

	# Ready to look up access
	print "Lookup %s %s %s: " % (tb, project, user)
	found, user_match = self.find_access((tb, project, user))
	print "Found: ", found
	
	if found == None: raise Fault(Fault.Server, "Access denied")

	# resolve <dynamic> and <same> in found
	dyn_proj = False
	dyn_user = False

	if found[0].name == "<same>":
	    if project != None:
		found[0].name = project
	    else : 
		raise Fault(Fault.Server, 
			"Project matched <same> when no project given")
	elif found[0].name == "<dynamic>":
	    found[0].name = self.random_string("project", 3)
	    dyn_proj = True

	if found[1] == "<same>":
	    if user_match == "<any>":
		if user != None: found = (found[0], user[0])
		else: raise Fault(Fault.Server,
			"Matched <same> on anonymous request")
	    else:
		found = (found[0], user_match)
	elif found[1] == "<dynamic>":
	    found = (found[0], self.random_string("user", 4))
	    dyn_user = True
	
	return found, (dyn_user, dyn_proj)

    def build_response(self, resp, alloc_id, ap, ssh):
	"""
	Create the SOAP response.

	Build the dictionary description of the response and use
	fedd_utils.pack_soap to create the soap message.  NB that alloc_id is
	a fedd_services_types.IDType_Holder pulled from the incoming message
	"""
	# Because alloc_id is already a fedd_services_types.IDType_Holder,
	# there's no need to repack it
	msg = { 
		'allocID': alloc_id,
		'emulab': { 
		    'domain': self.domain,
		    'boss': self.boss,
		    'ops': self.ops,
		    'fileServer': self.fileserver,
		    'eventServer': self.eventserver,
		    'project': {
			'name': pack_id(ap[0].name),
			'user': [ {
			    'userID': pack_id(ap[1]),
			    'access' : [ { 'sshPubkey': x } for x in ssh ],
			    }
			]
		    }
		},
	    }
	if len(self.attrs) > 0:
	    msg['emulab']['fedAttr'] = \
		[ { 'attribute': x, 'value' : y } \
			for x,y in self.attrs.iteritems()]

	resp.set_element_RequestAccessResponseBody(
		pack_soap(resp, "RequestAccessResponseBody", msg))

    def soap_RequestAccess(self, ps, fid):
	req = ps.Parse(RequestAccessRequestMessage.typecode)
	resp = RequestAccessResponseMessage()


	if req == None: raise Fault(Fault.Client, "No request??")
	req = req.get_element_RequestAccessRequestBody()
	if req == None: raise Fault(Fault.Client, "No request body??")


	dt = req.get_element_destinationTestbed()

	if dt != None: dt = dt.get_element_uri()
	
	if dt == None or dt == self.testbed:
	    # Request for this fedd
	    found, dyn = self.lookup_access(req, fid)

	    # Check for access to restricted nodes
	    if req.get_element_resources() != None and \
		    req.get_element_resources().get_element_node() != None:

		resources = req.get_element_resources()
		inaccessible = [ t for n in resources.get_element_node()\
				if n.get_element_hardware() != None \
				    for t in n.get_element_hardware()
					if t in self.restricted and \
						t not in found[0].node_types]
		if len(inaccessible) > 0:
		    raise Fault(Fault.Server, 
			    "Access denied (nodetypes %s)" % \
			    str(', ').join(inaccessible))

	    ssh = [ x.get_element_sshPubkey() \
		    for x in req.get_element_access() \
			if x.get_element_sshPubkey() != None]

	    if len(ssh) > 0: 
		if dyn[1]: self.dynamic_project(found, ssh)
		else: pass    # SSH key additions
	    else:
		raise Fault(Fault.Client, "SSH access parameters required")

	    self.build_response(resp, req.get_element_allocID(), found, ssh)
	    return resp
	else:
	    # Proxy the request
	    return self.proxy_request(dt, req)


    def read_trust(self, trust):
	"""
	Read a trust file that splits fedids into testbeds, users or projects

	Format is:

	[type]
	fedid
	fedid
	default: type
	"""
	lineno = 0;
	cat = None
	cat_re = re.compile("\[(user|testbed|project)\]$", re.IGNORECASE)
	fedid_re = re.compile("[" + string.hexdigits + "]+$")
	default_re = re.compile("default:\s*(user|testbed|project)$", 
		re.IGNORECASE)

	f = open(trust, "r")
	for line in f:
	    lineno += 1
	    line = line.strip()
	    if len(line) == 0 or line.startswith("#"):
		continue
	    # Category line
	    m = cat_re.match(line)
	    if m != None:
		cat = m.group(1).lower()
		continue
	    # Fedid line
	    m = fedid_re.match(line)
	    if m != None:
		if cat != None:
		    self.fedid_category[fedid(hexstr=m.string)] = cat
		else:
		    raise fedd_proj.parse_error(\
			    "Bad fedid in trust file (%s) line: %d" % \
			    (trust, lineno))
		continue
	    # default line
	    m = default_re.match(line)
	    if m != None:
		self.fedid_default = m.group(1).lower()
		continue
	    # Nothing matched - bad line, raise exception
	    f.close()
	    raise fedd_proj.parse_error(\
		    "Unparsable line in trustfile %s line %d" % (trust, lineno))
	f.close()

    def read_config(self, config):
	"""
	Read a configuration file and set internal parameters.

	The format is more complex than one might hope.  The basic format is
	attribute value pairs separated by colons(:) on a signle line.  The
	attributes in bool_attrs, emulab_attrs and id_attrs can all be set
	directly using the name: value syntax.  E.g. 
	boss: hostname
	sets self.boss to hostname.  In addition, there are access lines of the
	form (tb, proj, user) -> (aproj, auser) that map the first tuple of
	names to the second for access purposes.  Names in the key (left side)
	can include "<NONE> or <ANY>" to act as wildcards or to require the
	fields to be empty.  Similarly aproj or auser can be <SAME> or
	<DYNAMIC> indicating that either the matching key is to be used or a
	dynamic user or project will be created.  These names can also be
	federated IDs (fedid's) if prefixed with fedid:.  Finally, the aproj
	can be followed with a colon-separated list of node types to which that
	project has access (or will have access if dynamic).
	Testbed attributes outside the forms above can be given using the
	format attribute: name value: value.  The name is a single word and the
	value continues to the end of the line.  Empty lines and lines startin
	with a # are ignored.

	Parsing errors result in a parse_error exception being raised.
	"""
	lineno=0
	name_expr = "["+string.ascii_letters + string.digits + "\.\-_]+"
	fedid_expr = "fedid:[" + string.hexdigits + "]+"
	key_name = "(<ANY>|<NONE>|"+fedid_expr + "|"+ name_expr + ")"
	access_proj = "(<DYNAMIC>(?::" + name_expr +")*|"+ \
		"<SAME>" + "(?::" + name_expr + ")*|" + \
		fedid_expr + "(?::" + name_expr + ")*|" + \
		name_expr + "(?::" + name_expr + ")*)"
	access_name = "(<DYNAMIC>|<SAME>|" + fedid_expr + "|"+ name_expr + ")"

	bool_re = re.compile('(' + '|'.join(fedd_proj.bool_attrs) + 
		'):\s+(true|false)', re.IGNORECASE)
	string_re = re.compile( "(" + \
		'|'.join(fedd_proj.emulab_attrs + fedd_proj.id_attrs) + \
		'):\s*(.*)', re.IGNORECASE)
	attr_re = re.compile('attribute:\s*([\._\-a-z0-9]+)\s+value:\s*(.*)',
		re.IGNORECASE)
	access_re = re.compile('\('+key_name+'\s*,\s*'+key_name+'\s*,\s*'+
		key_name+'\s*\)\s*->\s*\('+access_proj + '\s*,\s*' + 
		access_name + '\s*\)', re.IGNORECASE)
	trustfile_re = re.compile("trustfile:\s*(.*)", re.IGNORECASE)
	restricted_re = re.compile("restricted:\s*(.*)", re.IGNORECASE)

	def parse_name(n):
	    if n.startswith('fedid:'): return fedid(n[len('fedid:'):])
	    else: return n

	f = open(config, "r");
	for line in f:
	    lineno += 1
	    line = line.strip();
	    if len(line) == 0 or line.startswith('#'):
		continue

	    # Boolean attribute line
	    m = bool_re.match(line);
	    if m != None:
		attr, val = m.group(1,2)
		setattr(self, attr.lower(), bool(val.lower() == "true"))
		continue

	    # String attribute line
	    m = string_re.match(line)
	    if m != None:
		attr, val = m.group(1,2)
		setattr(self, attr.lower(), val)
		continue

	    # Extended (attribute: x value: y) attribute line
	    m = attr_re.match(line)
	    if m != None:
		attr, val = m.group(1,2)
		self.attrs[attr] = val
		continue

	    # Access line (t, p, u) -> (ap, au) line
	    m = access_re.match(line)
	    if m != None:
		access_key = tuple([ parse_name(x) for x in m.group(1,2,3)])
		aps = m.group(4).split(":");
		if aps[0] == 'fedid:':
		    del aps[0]
		    aps[0] = fedid(hexstr=aps[0])

		au = m.group(5)
		if au.startswith("fedid:"):
		    au = fedid(hexstr=aus[len("fedid:"):])

		access_val = (fedd_proj.access_project(aps[0], aps[1:]), au)

		self.access[access_key] = access_val
		continue

	    # Trustfile inclusion
	    m = trustfile_re.match(line)
	    if m != None:
		self.read_trust(m.group(1))
		continue
	    # Restricted node types

	    m = restricted_re.match(line)
	    if m != None:
		self.restricted.append(m.group(1))
		continue

	    # Nothing matched to here: unknown line - raise exception
	    f.close()
	    raise fedd_proj.parse_error("Unknown statement at line %d of %s" % \
		    (lineno, config))
	f.close()

def new_feddservice(configfile):
    return fedd_proj(configfile)