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# vim: expandtab ts=4 sw=4:
# ==================================================================================
# Copyright (c) 2019-2020 Nokia
# Copyright (c) 2018-2020 AT&T Intellectual Property.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==================================================================================
import uuid
import json
from ctypes import RTLD_GLOBAL, Structure, c_int, POINTER, c_char, c_char_p, c_void_p, memmove, cast
from ctypes import CDLL
from ctypes import create_string_buffer
from ricxappframe.rmr.exceptions import BadBufferAllocation, MeidSizeOutOfRange, InitFailed
# https://docs.python.org/3.7/library/ctypes.html
# https://stackoverflow.com/questions/2327344/ctypes-loading-a-c-shared-library-that-has-dependencies/30845750#30845750
# make sure you do a set -x LD_LIBRARY_PATH /usr/local/lib/;
# even though we don't use these directly, they contain symbols we need
rmr_c_lib = CDLL("librmr_si.so", mode=RTLD_GLOBAL)
# Internal Helpers (not a part of public api)
_rmr_const = rmr_c_lib.rmr_get_consts
_rmr_const.argtypes = []
_rmr_const.restype = c_char_p
def _get_constants(cache={}):
"""
Get or build needed constants from rmr
TODO: are there constants that end user applications need?
"""
if cache:
return cache
js = _rmr_const() # read json string
cache = json.loads(str(js.decode())) # create constants value object as a hash
return cache
def _get_mapping_dict(cache={}):
"""
Get or build the state mapping dict
RMR_OK 0 state is good
RMR_ERR_BADARG 1 argument passd to function was unusable
RMR_ERR_NOENDPT 2 send/call could not find an endpoint based on msg type
RMR_ERR_EMPTY 3 msg received had no payload; attempt to send an empty message
RMR_ERR_NOHDR 4 message didn't contain a valid header
RMR_ERR_SENDFAILED 5 send failed; errno has nano reason
RMR_ERR_CALLFAILED 6 unable to send call() message
RMR_ERR_NOWHOPEN 7 no wormholes are open
RMR_ERR_WHID 8 wormhole id was invalid
RMR_ERR_OVERFLOW 9 operation would have busted through a buffer/field size
RMR_ERR_RETRY 10 request (send/call/rts) failed, but caller should retry (EAGAIN for wrappers)
RMR_ERR_RCVFAILED 11 receive failed (hard error)
RMR_ERR_TIMEOUT 12 message processing call timed out
RMR_ERR_UNSET 13 the message hasn't been populated with a transport buffer
RMR_ERR_TRUNC 14 received message likely truncated
RMR_ERR_INITFAILED 15 initialization of something (probably message) failed
"""
if cache:
return cache
rmr_consts = _get_constants()
for key in rmr_consts: # build the state mapping dict
if key[:7] in ["RMR_ERR", "RMR_OK"]:
en = int(rmr_consts[key])
cache[en] = key
return cache
def _state_to_status(stateno):
"""
Convert a msg state to status
"""
sdict = _get_mapping_dict()
return sdict.get(stateno, "UNKNOWN STATE")
_RCONST = _get_constants()
##############
# PUBLIC API
##############
# These constants are directly usable by importers of this library
# TODO: Are there others that will be useful?
RMR_MAX_RCV_BYTES = _RCONST["RMR_MAX_RCV_BYTES"]
RMRFL_MTCALL = _RCONST.get("RMRFL_MTCALL", 0x02) # initialization flags
RMRFL_NONE = _RCONST.get("RMRFL_NONE", 0x0)
RMR_OK = _RCONST["RMR_OK"] # useful state constants
RMR_ERR_TIMEOUT = _RCONST["RMR_ERR_TIMEOUT"]
RMR_ERR_RETRY = _RCONST["RMR_ERR_RETRY"]
class rmr_mbuf_t(Structure):
"""
Reimplementation of rmr_mbuf_t which is in an unaccessible header file (src/common/include/rmr.h)
| typedef struct {
| int state; // state of processing
| int mtype; // message type
| int len; // length of data in the payload (send or received)
| unsigned char* payload; // transported data
| unsigned char* xaction; // pointer to fixed length transaction id bytes
| int sub_id; // subscription id
| int tp_state; // transport state (a.k.a errno)
|
| these things are off limits to the user application
|
| void* tp_buf; // underlying transport allocated pointer (e.g. nng message)
| void* header; // internal message header (whole buffer: header+payload)
| unsigned char* id; // if we need an ID in the message separate from the xaction id
| int flags; // various MFL (private) flags as needed
| int alloc_len; // the length of the allocated space (hdr+payload)
| } rmr_mbuf_t;
We do not include the fields we are not supposed to mess with
RE PAYLOADs type below, see the documentation for c_char_p:
class ctypes.c_char_p
Represents the C char * datatype when it points to a zero-terminated string. For a general character pointer that may also point to binary data, POINTER(c_char) must be used. The constructor accepts an integer address, or a bytes object.
"""
_fields_ = [
("state", c_int),
("mtype", c_int),
("len", c_int),
(
"payload",
POINTER(c_char),
), # according to th following the python bytes are already unsinged https://bytes.com/topic/python/answers/695078-ctypes-unsigned-char
("xaction", POINTER(c_char)),
("sub_id", c_int),
("tp_state", c_int),
]
# argtypes and restype are important: https://stackoverflow.com/questions/24377845/ctype-why-specify-argtypes
_rmr_init = rmr_c_lib.rmr_init
_rmr_init.argtypes = [c_char_p, c_int, c_int]
_rmr_init.restype = c_void_p
def rmr_init(uproto_port, max_msg_size, flags):
"""
Refer to rmr C documentation for rmr_init
extern void* rmr_init(char* uproto_port, int max_msg_size, int flags)
This python function checks that the context is not None and raises
an excption if it is.
"""
mrc = _rmr_init(uproto_port, max_msg_size, flags)
if mrc is None:
raise InitFailed()
return mrc
_rmr_ready = rmr_c_lib.rmr_ready
_rmr_ready.argtypes = [c_void_p]
_rmr_ready.restype = c_int
def rmr_ready(vctx):
"""
Refer to rmr C documentation for rmr_ready
extern int rmr_ready(void* vctx)
"""
return _rmr_ready(vctx)
_rmr_close = rmr_c_lib.rmr_close
_rmr_close.argtypes = [c_void_p]
def rmr_close(vctx):
"""
Refer to rmr C documentation for rmr_close
extern void rmr_close(void* vctx)
"""
return _rmr_close(vctx)
_rmr_set_stimeout = rmr_c_lib.rmr_set_stimeout
_rmr_set_stimeout.argtypes = [c_void_p, c_int]
_rmr_set_stimeout.restype = c_int
def rmr_set_stimeout(vctx, time):
"""
Refer to the rmr C documentation for rmr_set_stimeout
extern int rmr_set_stimeout(void* vctx, int time)
"""
return _rmr_set_stimeout(vctx, time)
_rmr_alloc_msg = rmr_c_lib.rmr_alloc_msg
_rmr_alloc_msg.argtypes = [c_void_p, c_int]
_rmr_alloc_msg.restype = POINTER(rmr_mbuf_t)
def rmr_alloc_msg(
vctx, size, payload=None, gen_transaction_id=False, mtype=None, meid=None, sub_id=None, fixed_transaction_id=None
):
"""
Refer to the rmr C documentation for rmr_alloc_msg
extern rmr_mbuf_t* rmr_alloc_msg(void* vctx, int size)
TODO: on next API break, clean up transaction_id ugliness. Kept for now to preserve API.
if payload is not None, attempts to set the payload
if gen_transaction_id is True, it generates and sets a transaction id. Note, fixed_transaction_id supersedes this option
if mtype is not None, sets the sbuf's message type
if meid is not None, sets the sbuf's meid
if sub_id is not None, sets the sbud's subscription id
if fixed_transaction_id is set, it deterministically sets the transaction_id. This overrides the option gen_transation_id
"""
sbuf = _rmr_alloc_msg(vctx, size)
try:
# make sure the alloc worked
sbuf.contents
# set specified fields
if payload:
set_payload_and_length(payload, sbuf)
if fixed_transaction_id:
set_transaction_id(sbuf, fixed_transaction_id)
elif gen_transaction_id:
generate_and_set_transaction_id(sbuf)
if mtype:
sbuf.contents.mtype = mtype
if meid:
rmr_set_meid(sbuf, meid)
if sub_id:
sbuf.contents.sub_id = sub_id
return sbuf
except ValueError:
raise BadBufferAllocation
_rmr_realloc_payload = rmr_c_lib.rmr_realloc_payload
_rmr_realloc_payload.argtypes = [POINTER(rmr_mbuf_t), c_int, c_int, c_int] # new_len, copy, clone
_rmr_realloc_payload.restype = POINTER(rmr_mbuf_t)
def rmr_realloc_payload(ptr_mbuf, new_len, copy=False, clone=False):
"""
Refer to the rmr C documentation for rmr_realloc_payload().
extern rmr_mbuf_t* rmr_realloc_payload(rmr_mbuf_t*, int, int, int)
"""
return _rmr_realloc_payload(ptr_mbuf, new_len, copy, clone)
_rmr_free_msg = rmr_c_lib.rmr_free_msg
_rmr_free_msg.argtypes = [c_void_p]
_rmr_free_msg.restype = None
def rmr_free_msg(mbuf):
"""
Refer to the rmr C documentation for rmr_free_msg
extern void rmr_free_msg(rmr_mbuf_t* mbuf )
"""
if mbuf is not None:
_rmr_free_msg(mbuf)
_rmr_payload_size = rmr_c_lib.rmr_payload_size
_rmr_payload_size.argtypes = [POINTER(rmr_mbuf_t)]
_rmr_payload_size.restype = c_int
def rmr_payload_size(ptr_mbuf):
"""
Refer to the rmr C documentation for rmr_payload_size
extern int rmr_payload_size(rmr_mbuf_t* msg)
"""
return _rmr_payload_size(ptr_mbuf)
"""
The following functions all seem to have the same interface
"""
_rmr_send_msg = rmr_c_lib.rmr_send_msg
_rmr_send_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
_rmr_send_msg.restype = POINTER(rmr_mbuf_t)
def rmr_send_msg(vctx, ptr_mbuf):
"""
Refer to the rmr C documentation for rmr_send_msg
extern rmr_mbuf_t* rmr_send_msg(void* vctx, rmr_mbuf_t* msg)
"""
return _rmr_send_msg(vctx, ptr_mbuf)
# TODO: the old message (Send param) is actually optional, but I don't know how to specify that in Ctypes.
_rmr_rcv_msg = rmr_c_lib.rmr_rcv_msg
_rmr_rcv_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
_rmr_rcv_msg.restype = POINTER(rmr_mbuf_t)
def rmr_rcv_msg(vctx, ptr_mbuf):
"""
Refer to the rmr C documentation for rmr_rcv_msg
extern rmr_mbuf_t* rmr_rcv_msg(void* vctx, rmr_mbuf_t* old_msg)
"""
return _rmr_rcv_msg(vctx, ptr_mbuf)
_rmr_torcv_msg = rmr_c_lib.rmr_torcv_msg
_rmr_torcv_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t), c_int]
_rmr_torcv_msg.restype = POINTER(rmr_mbuf_t)
def rmr_torcv_msg(vctx, ptr_mbuf, ms_to):
"""
Refer to the rmr C documentation for rmr_torcv_msg
extern rmr_mbuf_t* rmr_torcv_msg(void* vctx, rmr_mbuf_t* old_msg, int ms_to)
"""
return _rmr_torcv_msg(vctx, ptr_mbuf, ms_to)
_rmr_rts_msg = rmr_c_lib.rmr_rts_msg
_rmr_rts_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
_rmr_rts_msg.restype = POINTER(rmr_mbuf_t)
def rmr_rts_msg(vctx, ptr_mbuf, payload=None, mtype=None):
"""
Refer to the rmr C documentation for rmr_rts_msg
extern rmr_mbuf_t* rmr_rts_msg(void* vctx, rmr_mbuf_t* msg)
additional features beyond c-rmr:
if payload is not None, attempts to set the payload
if mtype is not None, sets the sbuf's message type
"""
if payload:
set_payload_and_length(payload, ptr_mbuf)
if mtype:
ptr_mbuf.contents.mtype = mtype
return _rmr_rts_msg(vctx, ptr_mbuf)
_rmr_call = rmr_c_lib.rmr_call
_rmr_call.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
_rmr_call.restype = POINTER(rmr_mbuf_t)
def rmr_call(vctx, ptr_mbuf):
"""
Refer to the rmr C documentation for rmr_call
extern rmr_mbuf_t* rmr_call(void* vctx, rmr_mbuf_t* msg)
"""
return _rmr_call(vctx, ptr_mbuf)
_rmr_bytes2meid = rmr_c_lib.rmr_bytes2meid
_rmr_bytes2meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p, c_int]
_rmr_bytes2meid.restype = c_int
def rmr_set_meid(ptr_mbuf, byte_str):
"""
Refer to the rmr C documentation for rmr_bytes2meid
extern int rmr_bytes2meid(rmr_mbuf_t* mbuf, unsigned char const* src, int len);
Caution: the meid length supported in an RMR message is 32 bytes, but C applications
expect this to be a nil terminated string and thus only 31 bytes are actually available.
Raises: exceptions.MeidSizeOutOfRang
"""
max = _get_constants().get("RMR_MAX_MEID", 32)
if len(byte_str) >= max:
raise MeidSizeOutOfRange
return _rmr_bytes2meid(ptr_mbuf, byte_str, len(byte_str))
# CAUTION: Some of the C functions expect a mutable buffer to copy the bytes into;
# if there is a get_* function below, use it to set up and return the
# buffer properly.
# extern unsigned char* rmr_get_meid(rmr_mbuf_t* mbuf, unsigned char* dest);
# we don't provide direct access to this function (unless it is asked for) because it is not really useful to provide your own buffer.
# Rather, rmr_get_meid does this for you, and just returns the string.
_rmr_get_meid = rmr_c_lib.rmr_get_meid
_rmr_get_meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p]
_rmr_get_meid.restype = c_char_p
def rmr_get_meid(ptr_mbuf):
"""
Get the managed equipment ID (meid) from the message header.
Parameters
----------
ptr_mbuf: ctypes c_void_p
Pointer to an rmr message buffer
Returns
-------
string:
meid
"""
sz = _get_constants().get("RMR_MAX_MEID", 32) # size for buffer to fill
buf = create_string_buffer(sz)
_rmr_get_meid(ptr_mbuf, buf)
return buf.value
_rmr_get_src = rmr_c_lib.rmr_get_src
_rmr_get_src.argtypes = [POINTER(rmr_mbuf_t), c_char_p]
_rmr_get_src.restype = c_char_p
def rmr_get_src(ptr_mbuf, dest):
"""
Refer to the rmr C documentation for rmr_get_src
extern unsigned char* rmr_get_src(rmr_mbuf_t* mbuf, unsigned char* dest);
"""
return _rmr_get_src(ptr_mbuf, dest)
# Methods that exist ONLY in rmr-python, and are not wrapped methods
# In hindsight, I wish i put these in a seperate module, but leaving this here to prevent api breakage.
def get_payload(ptr_mbuf):
"""
Given a rmr_buf_t*, get it's binary payload as a bytes object
Parameters
----------
ptr_mbuf: ctypes c_void_p
Pointer to an rmr message buffer
Returns
-------
bytes:
the message payload
"""
# Logic came from the answer here: https://stackoverflow.com/questions/55103298/python-ctypes-read-pointerc-char-in-python
sz = ptr_mbuf.contents.len
CharArr = c_char * sz
return CharArr(*ptr_mbuf.contents.payload[:sz]).raw
def get_xaction(ptr_mbuf):
"""
given a rmr_buf_t*, get it's transaction id
Parameters
----------
ptr_mbuf: ctypes c_void_p
Pointer to an rmr message buffer
Returns
-------
bytes:
the transaction id
"""
val = cast(ptr_mbuf.contents.xaction, c_char_p).value
sz = _get_constants().get("RMR_MAX_XID", 0)
return val[:sz]
def message_summary(ptr_mbuf):
"""
Returns a dict that contains the fields of a message
Parameters
----------
ptr_mbuf: ctypes c_void_p
Pointer to an rmr message buffer
Returns
-------
dict:
dict message summary
"""
return {
"payload": get_payload(ptr_mbuf) if ptr_mbuf.contents.state == RMR_OK else None,
"payload length": ptr_mbuf.contents.len,
"message type": ptr_mbuf.contents.mtype,
"subscription id": ptr_mbuf.contents.sub_id,
"transaction id": get_xaction(ptr_mbuf),
"message state": ptr_mbuf.contents.state,
"message status": _state_to_status(ptr_mbuf.contents.state),
"payload max size": rmr_payload_size(ptr_mbuf),
"meid": rmr_get_meid(ptr_mbuf),
"message source": get_src(ptr_mbuf),
"errno": ptr_mbuf.contents.tp_state,
}
def set_payload_and_length(byte_str, ptr_mbuf):
"""
| Set an rmr payload and content length
| In place method, no return
Parameters
----------
byte_str: bytes
the bytes to set the payload to
ptr_mbuf: ctypes c_void_p
Pointer to an rmr message buffer
"""
if rmr_payload_size(ptr_mbuf) < len(byte_str): # existing message payload too small
ptr_mbuf = rmr_realloc_payload(ptr_mbuf, len(byte_str), True)
memmove(ptr_mbuf.contents.payload, byte_str, len(byte_str))
ptr_mbuf.contents.len = len(byte_str)
def generate_and_set_transaction_id(ptr_mbuf):
"""
Generate a UUID and Set an rmr transaction id to it
Parameters
----------
ptr_mbuf: ctypes c_void_p
Pointer to an rmr message buffer
"""
set_transaction_id(ptr_mbuf, uuid.uuid1().hex.encode("utf-8"))
def set_transaction_id(ptr_mbuf, tid_bytes):
"""
Set an rmr transaction id
TODO: on next API break, merge these two functions. Not done now to preserve API.
Parameters
----------
ptr_mbuf: ctypes c_void_p
Pointer to an rmr message buffer
tid_bytes: bytes
bytes of the desired transaction id
"""
sz = _get_constants().get("RMR_MAX_XID", 0)
memmove(ptr_mbuf.contents.xaction, tid_bytes, sz)
def get_src(ptr_mbuf):
"""
Get the message source (likely host:port)
Parameters
----------
ptr_mbuf: ctypes c_void_p
Pointer to an rmr message buffer
Returns
-------
string:
message source
"""
sz = _get_constants().get("RMR_MAX_SRC", 64) # size to fill
buf = create_string_buffer(sz)
rmr_get_src(ptr_mbuf, buf)
return buf.value.decode()