"""
Convert between bytestreams and higher-level AMQP types.
2007-11-05 Barry Pederson <bp@barryp.org>
"""
# Copyright (C) 2007 Barry Pederson <bp@barryp.org>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
from __future__ import absolute_import
import calendar
import sys
from datetime import datetime
from decimal import Decimal
from io import BytesIO
from struct import pack, unpack
from .exceptions import FrameSyntaxError
from .five import int_types, long_t, string, string_t, items
IS_PY3K = sys.version_info[0] >= 3
if IS_PY3K:
def byte(n):
return bytes([n])
else:
byte = chr
ILLEGAL_TABLE_TYPE_WITH_KEY = """\
Table type {0!r} for key {1!r} not handled by amqp. [value: {2!r}]
"""
ILLEGAL_TABLE_TYPE = """\
Table type {0!r} not handled by amqp. [value: {1!r}]
"""
class AMQPReader(object):
"""Read higher-level AMQP types from a bytestream."""
def __init__(self, source):
"""Source should be either a file-like object with a read() method, or
a plain (non-unicode) string."""
if isinstance(source, bytes):
self.input = BytesIO(source)
elif hasattr(source, 'read'):
self.input = source
else:
raise ValueError(
'AMQPReader needs a file-like object or plain string')
self.bitcount = self.bits = 0
def close(self):
self.input.close()
def read(self, n):
"""Read n bytes."""
self.bitcount = self.bits = 0
return self.input.read(n)
def read_bit(self):
"""Read a single boolean value."""
if not self.bitcount:
self.bits = ord(self.input.read(1))
self.bitcount = 8
result = (self.bits & 1) == 1
self.bits >>= 1
self.bitcount -= 1
return result
def read_octet(self):
"""Read one byte, return as an integer"""
self.bitcount = self.bits = 0
return unpack('B', self.input.read(1))[0]
def read_short(self):
"""Read an unsigned 16-bit integer"""
self.bitcount = self.bits = 0
return unpack('>H', self.input.read(2))[0]
def read_long(self):
"""Read an unsigned 32-bit integer"""
self.bitcount = self.bits = 0
return unpack('>I', self.input.read(4))[0]
def read_longlong(self):
"""Read an unsigned 64-bit integer"""
self.bitcount = self.bits = 0
return unpack('>Q', self.input.read(8))[0]
def read_float(self):
"""Read float value."""
self.bitcount = self.bits = 0
return unpack('>d', self.input.read(8))[0]
def read_shortstr(self):
"""Read a short string that's stored in up to 255 bytes.
The encoding isn't specified in the AMQP spec, so
assume it's utf-8
"""
self.bitcount = self.bits = 0
slen = unpack('B', self.input.read(1))[0]
return self.input.read(slen).decode('utf-8')
def read_longstr(self):
"""Read a string that's up to 2**32 bytes.
The encoding isn't specified in the AMQP spec, so
assume it's utf-8
"""
self.bitcount = self.bits = 0
slen = unpack('>I', self.input.read(4))[0]
return self.input.read(slen).decode('utf-8')
def read_table(self):
"""Read an AMQP table, and return as a Python dictionary."""
self.bitcount = self.bits = 0
tlen = unpack('>I', self.input.read(4))[0]
table_data = AMQPReader(self.input.read(tlen))
result = {}
while table_data.input.tell() < tlen:
name = table_data.read_shortstr()
val = table_data.read_item()
result[name] = val
return result
def read_item(self):
ftype = ord(self.input.read(1))
# 'S': long string
if ftype == 83:
val = self.read_longstr()
# 's': short string
elif ftype == 115:
val = self.read_shortstr()
# 'b': short-short int
elif ftype == 98:
val, = unpack('>B', self.input.read(1))
# 'B': short-short unsigned int
elif ftype == 66:
val, = unpack('>b', self.input.read(1))
# 'U': short int
elif ftype == 85:
val, = unpack('>h', self.input.read(2))
# 'u': short unsigned int
elif ftype == 117:
val, = unpack('>H', self.input.read(2))
# 'I': long int
elif ftype == 73:
val, = unpack('>i', self.input.read(4))
# 'i': long unsigned int
elif ftype == 105: # 'l'
val, = unpack('>I', self.input.read(4))
# 'L': long long int
elif ftype == 76:
val, = unpack('>q', self.input.read(8))
# 'l': long long unsigned int
elif ftype == 108:
val, = unpack('>Q', self.input.read(8))
# 'f': float
elif ftype == 102:
val, = unpack('>f', self.input.read(4))
# 'd': double
elif ftype == 100:
val = self.read_float()
# 'D': decimal
elif ftype == 68:
d = self.read_octet()
n, = unpack('>i', self.input.read(4))
val = Decimal(n) / Decimal(10 ** d)
# 'F': table
elif ftype == 70:
val = self.read_table() # recurse
# 'A': array
elif ftype == 65:
val = self.read_array()
# 't' (bool)
elif ftype == 116:
val = self.read_bit()
# 'T': timestamp
elif ftype == 84:
val = self.read_timestamp()
# 'V': void
elif ftype == 86:
val = None
else:
raise FrameSyntaxError(
'Unknown value in table: {0!r} ({1!r})'.format(
ftype, type(ftype)))
return val
def read_array(self):
array_length = unpack('>I', self.input.read(4))[0]
array_data = AMQPReader(self.input.read(array_length))
result = []
while array_data.input.tell() < array_length:
val = array_data.read_item()
result.append(val)
return result
def read_timestamp(self):
"""Read and AMQP timestamp, which is a 64-bit integer representing
seconds since the Unix epoch in 1-second resolution.
Return as a Python datetime.datetime object,
expressed as localtime.
"""
return datetime.utcfromtimestamp(self.read_longlong())
class AMQPWriter(object):
"""Convert higher-level AMQP types to bytestreams."""
def __init__(self, dest=None):
"""dest may be a file-type object (with a write() method). If None
then a BytesIO is created, and the contents can be accessed with
this class's getvalue() method."""
self.out = BytesIO() if dest is None else dest
self.bits = []
self.bitcount = 0
def _flushbits(self):
if self.bits:
out = self.out
for b in self.bits:
out.write(pack('B', b))
self.bits = []
self.bitcount = 0
def close(self):
"""Pass through if possible to any file-like destinations."""
try:
self.out.close()
except AttributeError:
pass
def flush(self):
"""Pass through if possible to any file-like destinations."""
try:
self.out.flush()
except AttributeError:
pass
def getvalue(self):
"""Get what's been encoded so far if we're working with a BytesIO."""
self._flushbits()
return self.out.getvalue()
def write(self, s):
"""Write a plain Python string with no special encoding in Python 2.x,
or bytes in Python 3.x"""
self._flushbits()
self.out.write(s)
def write_bit(self, b):
"""Write a boolean value."""
b = 1 if b else 0
shift = self.bitcount % 8
if shift == 0:
self.bits.append(0)
self.bits[-1] |= (b << shift)
self.bitcount += 1
def write_octet(self, n):
"""Write an integer as an unsigned 8-bit value."""
if n < 0 or n > 255:
raise FrameSyntaxError(
'Octet {0!r} out of range 0..255'.format(n))
self._flushbits()
self.out.write(pack('B', n))
def write_short(self, n):
"""Write an integer as an unsigned 16-bit value."""
if n < 0 or n > 65535:
raise FrameSyntaxError(
'Octet {0!r} out of range 0..65535'.format(n))
self._flushbits()
self.out.write(pack('>H', int(n)))
def write_long(self, n):
"""Write an integer as an unsigned2 32-bit value."""
if n < 0 or n >= 4294967296:
raise FrameSyntaxError(
'Octet {0!r} out of range 0..2**31-1'.format(n))
self._flushbits()
self.out.write(pack('>I', n))
def write_longlong(self, n):
"""Write an integer as an unsigned 64-bit value."""
if n < 0 or n >= 18446744073709551616:
raise FrameSyntaxError(
'Octet {0!r} out of range 0..2**64-1'.format(n))
self._flushbits()
self.out.write(pack('>Q', n))
def write_shortstr(self, s):
"""Write a string up to 255 bytes long (after any encoding).
If passed a unicode string, encode with UTF-8.
"""
self._flushbits()
if isinstance(s, string):
s = s.encode('utf-8')
if len(s) > 255:
raise FrameSyntaxError(
'Shortstring overflow ({0} > 255)'.format(len(s)))
self.write_octet(len(s))
self.out.write(s)
def write_longstr(self, s):
"""Write a string up to 2**32 bytes long after encoding.
If passed a unicode string, encode as UTF-8.
"""
self._flushbits()
if isinstance(s, string):
s = s.encode('utf-8')
self.write_long(len(s))
self.out.write(s)
def write_table(self, d):
"""Write out a Python dictionary made of up string keys, and values
that are strings, signed integers, Decimal, datetime.datetime, or
sub-dictionaries following the same constraints."""
self._flushbits()
table_data = AMQPWriter()
for k, v in items(d):
table_data.write_shortstr(k)
table_data.write_item(v, k)
table_data = table_data.getvalue()
self.write_long(len(table_data))
self.out.write(table_data)
def write_item(self, v, k=None):
if isinstance(v, (string_t, bytes)):
if isinstance(v, string):
v = v.encode('utf-8')
self.write(b'S')
self.write_longstr(v)
elif isinstance(v, bool):
self.write(pack('>cB', b't', int(v)))
elif isinstance(v, float):
self.write(pack('>cd', b'd', v))
elif isinstance(v, int_types):
self.write(pack('>ci', b'I', v))
elif isinstance(v, Decimal):
self.write(b'D')
sign, digits, exponent = v.as_tuple()
v = 0
for d in digits:
v = (v * 10) + d
if sign:
v = -v
self.write_octet(-exponent)
self.write(pack('>i', v))
elif isinstance(v, datetime):
self.write(b'T')
self.write_timestamp(v)
elif isinstance(v, dict):
self.write(b'F')
self.write_table(v)
elif isinstance(v, (list, tuple)):
self.write(b'A')
self.write_array(v)
elif v is None:
self.write(b'V')
else:
err = (ILLEGAL_TABLE_TYPE_WITH_KEY.format(type(v), k, v) if k
else ILLEGAL_TABLE_TYPE.format(type(v), v))
raise FrameSyntaxError(err)
def write_array(self, a):
array_data = AMQPWriter()
for v in a:
array_data.write_item(v)
array_data = array_data.getvalue()
self.write_long(len(array_data))
self.out.write(array_data)
def write_timestamp(self, v):
"""Write out a Python datetime.datetime object as a 64-bit integer
representing seconds since the Unix epoch."""
self.out.write(pack('>Q', long_t(calendar.timegm(v.utctimetuple()))))
class GenericContent(object):
"""Abstract base class for AMQP content.
Subclasses should override the PROPERTIES attribute.
"""
PROPERTIES = [('dummy', 'shortstr')]
def __init__(self, **props):
"""Save the properties appropriate to this AMQP content type
in a 'properties' dictionary."""
d = {}
for propname, _ in self.PROPERTIES:
if propname in props:
d[propname] = props[propname]
# FIXME: should we ignore unknown properties?
self.properties = d
def __eq__(self, other):
"""Check if this object has the same properties as another
content object."""
try:
return self.properties == other.properties
except AttributeError:
return NotImplemented
def __getattr__(self, name):
"""Look for additional properties in the 'properties'
dictionary, and if present - the 'delivery_info'
dictionary."""
if name == '__setstate__':
# Allows pickling/unpickling to work
raise AttributeError('__setstate__')
if name in self.properties:
return self.properties[name]
if 'delivery_info' in self.__dict__ \
and name in self.delivery_info:
return self.delivery_info[name]
raise AttributeError(name)
def _load_properties(self, raw_bytes):
"""Given the raw bytes containing the property-flags and property-list
from a content-frame-header, parse and insert into a dictionary
stored in this object as an attribute named 'properties'."""
r = AMQPReader(raw_bytes)
#
# Read 16-bit shorts until we get one with a low bit set to zero
#
flags = []
while 1:
flag_bits = r.read_short()
flags.append(flag_bits)
if flag_bits & 1 == 0:
break
shift = 0
d = {}
for key, proptype in self.PROPERTIES:
if shift == 0:
if not flags:
break
flag_bits, flags = flags[0], flags[1:]
shift = 15
if flag_bits & (1 << shift):
d[key] = getattr(r, 'read_' + proptype)()
shift -= 1
self.properties = d
def _serialize_properties(self):
"""serialize the 'properties' attribute (a dictionary) into
the raw bytes making up a set of property flags and a
property list, suitable for putting into a content frame header."""
shift = 15
flag_bits = 0
flags = []
raw_bytes = AMQPWriter()
for key, proptype in self.PROPERTIES:
val = self.properties.get(key, None)
if val is not None:
if shift == 0:
flags.append(flag_bits)
flag_bits = 0
shift = 15
flag_bits |= (1 << shift)
if proptype != 'bit':
getattr(raw_bytes, 'write_' + proptype)(val)
shift -= 1
flags.append(flag_bits)
result = AMQPWriter()
for flag_bits in flags:
result.write_short(flag_bits)
result.write(raw_bytes.getvalue())
return result.getvalue()