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import dataclasses
import secrets
from unittest import TestCase
import pylibsrtp
from pylibsrtp import Error, Policy, Session
RTP = (
b"\x80\x08\x00\x00" # version, packet type, sequence number
b"\x00\x00\x00\x00" # timestamp
b"\x00\x00\x30\x39" # ssrc: 12345
) + (b"\xd4" * 160)
RTCP = (
b"\x80\xc8\x00\x06\xf3\xcb\x20\x01\x83\xab\x03\xa1\xeb\x02\x0b\x3a"
b"\x00\x00\x94\x20\x00\x00\x00\x9e\x00\x00\x9b\x88"
)
@dataclasses.dataclass
class Profile:
key_length: int
protected_rtp_length: int
protected_rtcp_length: int
srtp_profile: int
# AES-GCM may not be supported depending on how libsrtp2 was built.
SRTP_PROFILES = [
Profile(
key_length=30,
protected_rtp_length=182,
protected_rtcp_length=42,
srtp_profile=Policy.SRTP_PROFILE_AES128_CM_SHA1_80,
),
Profile(
key_length=30,
protected_rtp_length=176,
protected_rtcp_length=42,
srtp_profile=Policy.SRTP_PROFILE_AES128_CM_SHA1_32,
),
]
try:
Policy(srtp_profile=Policy.SRTP_PROFILE_AEAD_AES_128_GCM)
except Error:
pass
else:
SRTP_PROFILES += [
Profile(
key_length=28,
protected_rtp_length=188,
protected_rtcp_length=48,
srtp_profile=Policy.SRTP_PROFILE_AEAD_AES_128_GCM,
),
Profile(
key_length=44,
protected_rtp_length=188,
protected_rtcp_length=48,
srtp_profile=Policy.SRTP_PROFILE_AEAD_AES_256_GCM,
),
]
class PolicyTest(TestCase):
def test_allow_repeat_tx(self):
policy = Policy()
self.assertEqual(policy.allow_repeat_tx, False)
policy.allow_repeat_tx = True
self.assertEqual(policy.allow_repeat_tx, True)
policy.allow_repeat_tx = False
self.assertEqual(policy.allow_repeat_tx, False)
policy.allow_repeat_tx = 1
self.assertEqual(policy.allow_repeat_tx, True)
policy.allow_repeat_tx = 0
self.assertEqual(policy.allow_repeat_tx, False)
def test_key(self):
key = secrets.token_bytes(30)
policy = Policy()
self.assertEqual(policy.key, None)
policy.key = key
self.assertEqual(policy.key, key)
policy.key = None
self.assertEqual(policy.key, None)
# Key is not bytes.
with self.assertRaises(TypeError) as cm:
policy.key = 1234
self.assertEqual(policy.key, None)
self.assertEqual(str(cm.exception), "key must be bytes")
# Key is too short.
with self.assertRaises(ValueError) as cm:
policy.key = b"0"
self.assertEqual(policy.key, None)
self.assertEqual(str(cm.exception), "key must contain at least 30 bytes")
def test_srtp_policy(self):
# Default profile.
policy = Policy()
self.assertEqual(policy.srtp_profile, Policy.SRTP_PROFILE_AES128_CM_SHA1_80)
# Valid user-specified profiles.
for profile in SRTP_PROFILES:
with self.subTest(profile=profile):
policy = Policy(srtp_profile=profile.srtp_profile)
self.assertEqual(policy.srtp_profile, profile.srtp_profile)
# Invalid profile.
with self.assertRaises(Error) as cm:
Policy(srtp_profile=0)
self.assertEqual(str(cm.exception), "unsupported parameter")
def test_ssrc_type(self):
policy = Policy()
self.assertEqual(policy.ssrc_type, Policy.SSRC_UNDEFINED)
policy.ssrc_type = Policy.SSRC_ANY_INBOUND
self.assertEqual(policy.ssrc_type, Policy.SSRC_ANY_INBOUND)
def test_ssrc_value(self):
policy = Policy()
self.assertEqual(policy.ssrc_value, 0)
policy.ssrc_value = 12345
self.assertEqual(policy.ssrc_value, 12345)
def test_window_size(self):
policy = Policy()
self.assertEqual(policy.window_size, 0)
policy.window_size = 1024
self.assertEqual(policy.window_size, 1024)
class SessionTest(TestCase):
def test_no_key(self):
policy = Policy(ssrc_type=Policy.SSRC_ANY_OUTBOUND)
with self.assertRaises(Error) as cm:
Session(policy=policy)
self.assertEqual(str(cm.exception), "unsupported parameter")
def test_add_remove_stream(self):
for profile in SRTP_PROFILES:
with self.subTest(profile=profile):
key = secrets.token_bytes(profile.key_length)
# protect RTP
tx_session = Session(
policy=Policy(
key=key,
srtp_profile=profile.srtp_profile,
ssrc_type=Policy.SSRC_SPECIFIC,
ssrc_value=12345,
)
)
protected = tx_session.protect(RTP)
self.assertEqual(len(protected), profile.protected_rtp_length)
# add stream and unprotect RTP
rx_session = Session()
rx_session.add_stream(
Policy(
key=key,
srtp_profile=profile.srtp_profile,
ssrc_type=Policy.SSRC_SPECIFIC,
ssrc_value=12345,
)
)
unprotected = rx_session.unprotect(protected)
self.assertEqual(unprotected, RTP)
# remove stream
rx_session.remove_stream(12345)
# try removing stream again
with self.assertRaises(Error) as cm:
rx_session.remove_stream(12345)
self.assertEqual(str(cm.exception), "no appropriate context found")
def test_rtp_any_ssrc(self):
for profile in SRTP_PROFILES:
with self.subTest(profile=profile):
key = secrets.token_bytes(profile.key_length)
# protect RTP
tx_session = Session(
policy=Policy(
key=key,
srtp_profile=profile.srtp_profile,
ssrc_type=Policy.SSRC_ANY_OUTBOUND,
)
)
protected = tx_session.protect(RTP)
self.assertEqual(len(protected), profile.protected_rtp_length)
# bad type
with self.assertRaises(TypeError) as cm:
tx_session.protect(4567)
self.assertEqual(str(cm.exception), "packet must be bytes")
# bad length
with self.assertRaises(ValueError) as cm:
tx_session.protect(b"0" * (1501 - pylibsrtp.SRTP_MAX_TRAILER_LEN))
self.assertEqual(str(cm.exception), "packet is too long")
# unprotect RTP
rx_session = Session(
policy=Policy(
key=key,
srtp_profile=profile.srtp_profile,
ssrc_type=Policy.SSRC_ANY_INBOUND,
)
)
unprotected = rx_session.unprotect(protected)
self.assertEqual(unprotected, RTP)
def test_rtcp_any_ssrc(self):
for profile in SRTP_PROFILES:
with self.subTest(profile=profile):
key = secrets.token_bytes(profile.key_length)
# protect RCTP
tx_session = Session(
policy=Policy(
key=key,
srtp_profile=profile.srtp_profile,
ssrc_type=Policy.SSRC_ANY_OUTBOUND,
)
)
protected = tx_session.protect_rtcp(RTCP)
self.assertEqual(len(protected), profile.protected_rtcp_length)
# bad type
with self.assertRaises(TypeError) as cm:
tx_session.protect_rtcp(4567)
self.assertEqual(str(cm.exception), "packet must be bytes")
# bad length
with self.assertRaises(ValueError) as cm:
tx_session.protect_rtcp(
b"0" * (1501 - pylibsrtp.SRTP_MAX_SRTCP_TRAILER_LEN)
)
self.assertEqual(str(cm.exception), "packet is too long")
# unprotect RTCP
rx_session = Session(
policy=Policy(
key=key,
srtp_profile=profile.srtp_profile,
ssrc_type=Policy.SSRC_ANY_INBOUND,
)
)
unprotected = rx_session.unprotect_rtcp(protected)
self.assertEqual(unprotected, RTCP)
def test_rtp_specific_ssrc(self):
for profile in SRTP_PROFILES:
with self.subTest(profile=profile):
key = secrets.token_bytes(profile.key_length)
# protect RTP
tx_session = Session(
policy=Policy(
key=key,
srtp_profile=profile.srtp_profile,
ssrc_type=Policy.SSRC_SPECIFIC,
ssrc_value=12345,
)
)
protected = tx_session.protect(RTP)
self.assertEqual(len(protected), profile.protected_rtp_length)
# unprotect RTP
rx_session = Session(
policy=Policy(
key=key,
srtp_profile=profile.srtp_profile,
ssrc_type=Policy.SSRC_SPECIFIC,
ssrc_value=12345,
)
)
unprotected = rx_session.unprotect(protected)
self.assertEqual(unprotected, RTP)
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