def get_by_label(self, label, label_idx=None):
"""
Get an OF list by label. If a label index is supplied, use that to index
into the label and return a single OF instead.
:param str label: The label to fetch. E.g. ``UP_HOFS``.
:param int label_idx:
(Optional) an index of an OF in the specified label.
:returns:
A list of OFs (or if `label_idx` was specified, a single OF).
:raises:
:any:`SCIONKeyError`: if the label is unknown.
:any:`SCIONIndexError`: if the specified label index is out of range
"""
try:
group = self._labels[label]
except KeyError:
raise SCIONKeyError("Opaque field label (%s) unknown" %
label) from None
if label_idx is None:
return group
try:
return group[label_idx]
except IndexError:
raise SCIONIndexError(
"Opaque field label index (%d) for label %s out of range" %
(label_idx, label)) from None
def __getitem__(self, idx):
if idx == 0:
return self.isd_as()
elif idx == 1:
return self.p.ifID
raise SCIONIndexError(
"Invalid index used on PathInterface object: %d" % idx)
def __getitem__(self, idx): # pragma: no cover
if idx == 0:
return self._isd
elif idx == 1:
return self._as
else:
raise SCIONIndexError("Invalid index used on %s object: %s" % (
(self.NAME, idx)))
def set_current_index(self, index):
"""
Sets the current index in the chain.
"""
if index <= 1 or index > self._length - 1:
raise SCIONIndexError("Index must be in [2, %d] but was %d.",
self._length - 1, index)
self._next_ele_ptr = index - 1
def get_label_by_idx(self, idx):
"""
Returns the label to which idx points to.
:param int idx: The index for which we want to know the label.
:returns: The label 'idx' points to.
:raises:
:any:`SCIONIndexError`: if the index is out of range.
"""
if idx < 0:
raise SCIONIndexError(
"Index for requested label is negative (%d)" % idx)
offset = idx
for label in self._order:
group = self._labels[label]
if offset < len(group):
return label
offset -= len(group)
raise SCIONIndexError("Index (%d) for requested label is out of range "
"(max %d)" % (idx, len(self) - 1)) from None
def get_by_idx(self, idx):
"""
Get an OF by index. The index follows the order supplied when the
:class:`OpaqueFieldList` object was created.
:param int idx: The index to fetch.
:returns: The OF at that index.
:rtype: :class:`OpaqueField`
:raises:
SCIONIndexError: if the index is negative, or too large.
"""
if idx < 0:
raise SCIONIndexError("Requested OF index (%d) is negative" % idx)
offset = idx
for label in self._order:
group = self._labels[label]
if offset < len(group):
return group[offset]
offset -= len(group)
raise SCIONIndexError("Requested OF index (%d) is out of range (max %d)"
% (idx, len(self) - 1))
def get(self, n=None, bounds=True):
"""
Return next elements from data.
If `n` is not specified, return all remaining elements of data.
If `n` is 1, return the next element of data (as an int).
If `n` is > 1, return the next `n` elements of data (as bytes).
:param n: How many elements to return (see above)
:param bool bounds: Perform bounds checking on access if True
"""
dlen = len(self._data)
if n and bounds and (self._offset + n) > dlen:
raise SCIONIndexError("%s: Attempted to access beyond end of raw "
"data (len=%d, offset=%d, request=%d)" %
(self._desc, dlen, self._offset, n))
if n is None:
return self._data[self._offset:]
elif n == 1:
return self._data[self._offset]
else:
return self._data[self._offset:self._offset + n]
