From ef35f9327eb4a749727aac7bb1d8225ac7bdf625 Mon Sep 17 00:00:00 2001
From: Dan Williams <dcbw@redhat.com>
Date: Mon, 12 Jun 2006 22:51:06 +0000
Subject: Forgot to add the Group.py file

---
diff --git a/sugar/presence/Group.py b/sugar/presence/Group.py
new file mode 100644
index 0000000..a0527d3
--- /dev/null
+++ b/sugar/presence/Group.py
@@ -0,0 +1,80 @@
+import Service
+import sha
+import binascii
+import time
+
+
+def is_group_service_type(stype):
+	"""Return True if the service type matches a group
+	service type, or False if it does not."""
+	if stype.endswith("_group_olpc._tcp") or stype.endswith("_group_olpc._udp"):
+		return True
+	return False
+
+
+def _stringify_sha(sha_hash):
+	"""Convert binary sha1 hash data into printable characters."""
+	print_sha = ""
+	for char in sha_hash:
+		print_sha = print_sha + binascii.b2a_hex(char)
+	return print_sha
+
+def _sha_data(data):
+	"""sha1 hash some bytes."""
+	sha_hash = sha.new()
+	sha_hash.update(data)
+	return sha_hash.digest()
+
+
+__GROUP_NAME_TAG = "Name"
+__GROUP_RESOURCE_TAG = "Resource"
+
+def new_group_service(group_name, resource):
+	"""Create a new service suitable for defining a new group."""
+	if type(group_name) != type("") or not len(group_name):
+		raise ValueError("group name must be a valid string.")
+	if type(resource) != type("") or not len(resource):
+		raise ValueError("group resource must be a valid string.")
+
+	# Create a randomized service type
+	data_string = "%s%s%s%s" % (time.time(), random.randint(10000, 100000), \
+			group_name, resource)
+	hash_string = _stringify_sha(_sha_data(data_string))
+	stype = "_%s_group_olpc._udp" % hash_string
+
+	properties = {__GROUP_NAME_TAG: group_name, __GROUP_RESOURCE_TAG: resource }
+	owner_nick = ""
+	port = random.randint(5000, 65000)
+	# Use random currently unassigned multicast address
+	address = "232.%d.%d.%d" % (random.randint(0, 254), random.randint(1, 254),
+			random.randint(1, 254))
+	service = Service.Service(owner_nick, stype, "local", address=address,
+			port=port, properties=properties)
+	return service
+
+
+class Group(object):
+	"""Represents a collection of buddies all interested in the same resource."""
+	def __init__(self, service):
+		if not isinstance(service, Service.Service):
+			raise ValueError("service argument was not a Service object.")
+		if not service.is_group_service():
+			raise ValueError("provided serivce was not a group service.")
+		name = service.get_one_property(__GROUP_NAME_TAG)
+		if name == None:
+			raise ValueError("provided service did not provide a group name.")
+		self._name = name
+		resource = service.get_one_property(__GROUP_RESOURCE_TAG)
+		if resource == None:
+			raise ValueError("provided service did not provide a group resource.")
+		self._resource = resource
+		self._service = service
+
+	def get_name(self):
+		return self._name
+
+	def get_service(self):
+		return self._service
+
+	def get_resource(self):
+		return self._resource
--
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