1 # ==================================================================================
2 # Copyright (c) 2019 Nokia
3 # Copyright (c) 2018-2019 AT&T Intellectual Property.
5 # Licensed under the Apache License, Version 2.0 (the "License");
6 # you may not use this file except in compliance with the License.
7 # You may obtain a copy of the License at
9 # http://www.apache.org/licenses/LICENSE-2.0
11 # Unless required by applicable law or agreed to in writing, software
12 # distributed under the License is distributed on an "AS IS" BASIS,
13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 # See the License for the specific language governing permissions and
15 # limitations under the License.
16 # ==================================================================================
19 from ctypes import RTLD_GLOBAL, Structure, c_int, POINTER, c_char, c_char_p, c_void_p, memmove, cast
20 from ctypes import CDLL
21 from ctypes import create_string_buffer
22 from rmr.exceptions import BadBufferAllocation
24 # https://docs.python.org/3.7/library/ctypes.html
25 # https://stackoverflow.com/questions/2327344/ctypes-loading-a-c-shared-library-that-has-dependencies/30845750#30845750
26 # make sure you do a set -x LD_LIBRARY_PATH /usr/local/lib/;
28 # even though we don't use these directly, they contain symbols we need
29 _ = CDLL("libnng.so", mode=RTLD_GLOBAL)
30 rmr_c_lib = CDLL("librmr_nng.so", mode=RTLD_GLOBAL)
33 # Internal Helpers (not a part of public api)
36 _rmr_const = rmr_c_lib.rmr_get_consts
37 _rmr_const.argtypes = []
38 _rmr_const.restype = c_char_p
41 def _get_constants(cache={}):
43 Get or build needed constants from rmr
44 TODO: are there constants that end user applications need?
49 js = _rmr_const() # read json string
50 cache = json.loads(str(js.decode())) # create constants value object as a hash
54 def _get_mapping_dict(cache={}):
56 Get or build the state mapping dict
58 RMR_OK 0 state is good
59 RMR_ERR_BADARG 1 argument passd to function was unusable
60 RMR_ERR_NOENDPT 2 send/call could not find an endpoint based on msg type
61 RMR_ERR_EMPTY 3 msg received had no payload; attempt to send an empty message
62 RMR_ERR_NOHDR 4 message didn't contain a valid header
63 RMR_ERR_SENDFAILED 5 send failed; errno has nano reason
64 RMR_ERR_CALLFAILED 6 unable to send call() message
65 RMR_ERR_NOWHOPEN 7 no wormholes are open
66 RMR_ERR_WHID 8 wormhole id was invalid
67 RMR_ERR_OVERFLOW 9 operation would have busted through a buffer/field size
68 RMR_ERR_RETRY 10 request (send/call/rts) failed, but caller should retry (EAGAIN for wrappers)
69 RMR_ERR_RCVFAILED 11 receive failed (hard error)
70 RMR_ERR_TIMEOUT 12 message processing call timed out
71 RMR_ERR_UNSET 13 the message hasn't been populated with a transport buffer
72 RMR_ERR_TRUNC 14 received message likely truncated
73 RMR_ERR_INITFAILED 15 initialization of something (probably message) failed
79 rmr_consts = _get_constants()
80 for key in rmr_consts: # build the state mapping dict
81 if key[:7] in ["RMR_ERR", "RMR_OK"]:
82 en = int(rmr_consts[key])
88 def _state_to_status(stateno):
90 Convert a msg state to status
93 sdict = _get_mapping_dict()
94 return sdict.get(stateno, "UNKNOWN STATE")
97 _RCONST = _get_constants()
105 # These constants are directly usable by importers of this library
106 # TODO: Are there others that will be useful?
108 RMR_MAX_RCV_BYTES = _RCONST["RMR_MAX_RCV_BYTES"]
109 RMRFL_MTCALL = _RCONST.get("RMRFL_MTCALL", 0x02) # initialization flags
110 RMRFL_NONE = _RCONST.get("RMRFL_NONE", 0x0)
111 RMR_OK = _RCONST["RMR_OK"] # useful state constants
112 RMR_ERR_TIMEOUT = _RCONST["RMR_ERR_TIMEOUT"]
113 RMR_ERR_RETRY = _RCONST["RMR_ERR_RETRY"]
116 class rmr_mbuf_t(Structure):
118 Reimplementation of rmr_mbuf_t which is in an unaccessible header file (src/common/include/rmr.h)
121 | int state; // state of processing
122 | int mtype; // message type
123 | int len; // length of data in the payload (send or received)
124 | unsigned char* payload; // transported data
125 | unsigned char* xaction; // pointer to fixed length transaction id bytes
126 | int sub_id; // subscription id
127 | int tp_state; // transport state (a.k.a errno)
129 | these things are off limits to the user application
131 | void* tp_buf; // underlying transport allocated pointer (e.g. nng message)
132 | void* header; // internal message header (whole buffer: header+payload)
133 | unsigned char* id; // if we need an ID in the message separate from the xaction id
134 | int flags; // various MFL (private) flags as needed
135 | int alloc_len; // the length of the allocated space (hdr+payload)
138 We do not include the fields we are not supposed to mess with
140 RE PAYLOADs type below, see the documentation for c_char_p:
141 class ctypes.c_char_p
142 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.
152 ), # according to th following the python bytes are already unsinged https://bytes.com/topic/python/answers/695078-ctypes-unsigned-char
153 ("xaction", POINTER(c_char)),
159 # argtypes and restype are important: https://stackoverflow.com/questions/24377845/ctype-why-specify-argtypes
162 _rmr_init = rmr_c_lib.rmr_init
163 _rmr_init.argtypes = [c_char_p, c_int, c_int]
164 _rmr_init.restype = c_void_p
167 def rmr_init(uproto_port, max_msg_size, flags):
169 Refer to rmr C documentation for rmr_init
170 extern void* rmr_init(char* uproto_port, int max_msg_size, int flags)
172 return _rmr_init(uproto_port, max_msg_size, flags)
175 _rmr_ready = rmr_c_lib.rmr_ready
176 _rmr_ready.argtypes = [c_void_p]
177 _rmr_ready.restype = c_int
182 Refer to rmr C documentation for rmr_ready
183 extern int rmr_ready(void* vctx)
185 return _rmr_ready(vctx)
188 _rmr_close = rmr_c_lib.rmr_close
189 _rmr_close.argtypes = [c_void_p]
194 Refer to rmr C documentation for rmr_close
195 extern void rmr_close(void* vctx)
197 return _rmr_close(vctx)
200 _rmr_set_stimeout = rmr_c_lib.rmr_set_stimeout
201 _rmr_set_stimeout.argtypes = [c_void_p, c_int]
202 _rmr_set_stimeout.restype = c_int
205 def rmr_set_stimeout(vctx, time):
207 Refer to the rmr C documentation for rmr_set_stimeout
208 extern int rmr_set_stimeout(void* vctx, int time)
210 return _rmr_set_stimeout(vctx, time)
213 _rmr_alloc_msg = rmr_c_lib.rmr_alloc_msg
214 _rmr_alloc_msg.argtypes = [c_void_p, c_int]
215 _rmr_alloc_msg.restype = POINTER(rmr_mbuf_t)
218 def rmr_alloc_msg(vctx, size):
220 Refer to the rmr C documentation for rmr_alloc_msg
221 extern rmr_mbuf_t* rmr_alloc_msg(void* vctx, int size)
223 sbuf = _rmr_alloc_msg(vctx, size)
227 raise BadBufferAllocation
231 _rmr_free_msg = rmr_c_lib.rmr_free_msg
232 _rmr_free_msg.argtypes = [c_void_p]
233 _rmr_free_msg.restype = None
236 def rmr_free_msg(mbuf):
238 Refer to the rmr C documentation for rmr_free_msg
239 extern void rmr_free_msg( rmr_mbuf_t* mbuf )
245 _rmr_payload_size = rmr_c_lib.rmr_payload_size
246 _rmr_payload_size.argtypes = [POINTER(rmr_mbuf_t)]
247 _rmr_payload_size.restype = c_int
250 def rmr_payload_size(ptr_mbuf):
252 Refer to the rmr C documentation for rmr_payload_size
253 extern int rmr_payload_size(rmr_mbuf_t* msg)
255 return _rmr_payload_size(ptr_mbuf)
259 The following functions all seem to have the same interface
262 _rmr_send_msg = rmr_c_lib.rmr_send_msg
263 _rmr_send_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
264 _rmr_send_msg.restype = POINTER(rmr_mbuf_t)
267 def rmr_send_msg(vctx, ptr_mbuf):
269 Refer to the rmr C documentation for rmr_send_msg
270 extern rmr_mbuf_t* rmr_send_msg(void* vctx, rmr_mbuf_t* msg)
272 return _rmr_send_msg(vctx, ptr_mbuf)
275 # TODO: the old message (Send param) is actually optional, but I don't know how to specify that in Ctypes.
276 _rmr_rcv_msg = rmr_c_lib.rmr_rcv_msg
277 _rmr_rcv_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
278 _rmr_rcv_msg.restype = POINTER(rmr_mbuf_t)
281 def rmr_rcv_msg(vctx, ptr_mbuf):
283 Refer to the rmr C documentation for rmr_rcv_msg
284 extern rmr_mbuf_t* rmr_rcv_msg(void* vctx, rmr_mbuf_t* old_msg)
286 return _rmr_rcv_msg(vctx, ptr_mbuf)
289 _rmr_torcv_msg = rmr_c_lib.rmr_torcv_msg
290 _rmr_torcv_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t), c_int]
291 _rmr_torcv_msg.restype = POINTER(rmr_mbuf_t)
294 def rmr_torcv_msg(vctx, ptr_mbuf, ms_to):
296 Refer to the rmr C documentation for rmr_torcv_msg
297 extern rmr_mbuf_t* rmr_torcv_msg(void* vctx, rmr_mbuf_t* old_msg, int ms_to)
299 return _rmr_torcv_msg(vctx, ptr_mbuf, ms_to)
302 _rmr_rts_msg = rmr_c_lib.rmr_rts_msg
303 _rmr_rts_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
304 _rmr_rts_msg.restype = POINTER(rmr_mbuf_t)
307 def rmr_rts_msg(vctx, ptr_mbuf):
309 Refer to the rmr C documentation for rmr_rts_msg
310 extern rmr_mbuf_t* rmr_rts_msg(void* vctx, rmr_mbuf_t* msg)
312 return _rmr_rts_msg(vctx, ptr_mbuf)
315 _rmr_call = rmr_c_lib.rmr_call
316 _rmr_call.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
317 _rmr_call.restype = POINTER(rmr_mbuf_t)
320 def rmr_call(vctx, ptr_mbuf):
322 Refer to the rmr C documentation for rmr_call
323 extern rmr_mbuf_t* rmr_call(void* vctx, rmr_mbuf_t* msg)
325 return _rmr_call(vctx, ptr_mbuf)
328 _rmr_bytes2meid = rmr_c_lib.rmr_bytes2meid
329 _rmr_bytes2meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p, c_int]
330 _rmr_bytes2meid.restype = c_int
333 def rmr_bytes2meid(ptr_mbuf, src, length):
335 Refer to the rmr C documentation for rmr_bytes2meid
336 extern int rmr_bytes2meid(rmr_mbuf_t* mbuf, unsigned char const* src, int len);
338 return _rmr_bytes2meid(ptr_mbuf, src, length)
341 # this is an alias to rmr_bytes2meid using familiar set/get terminoloigy
342 rmr_set_meid = rmr_bytes2meid
344 # CAUTION: Some of the C functions expect a mutable buffer to copy the bytes into;
345 # if there is a get_* function below, use it to set up and return the
348 # extern unsigned char* rmr_get_meid(rmr_mbuf_t* mbuf, unsigned char* dest);
349 # 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.
350 # Rather, rmr_get_meid does this for you, and just returns the string.
351 _rmr_get_meid = rmr_c_lib.rmr_get_meid
352 _rmr_get_meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p]
353 _rmr_get_meid.restype = c_char_p
356 def rmr_get_meid(ptr_mbuf):
358 Get the managed equipment ID (meid) from the message header.
362 ptr_mbuf: ctypes c_void_p
363 Pointer to an rmr message buffer
370 sz = _get_constants().get("RMR_MAX_MEID", 64) # size for buffer to fill
371 buf = create_string_buffer(sz)
372 _rmr_get_meid(ptr_mbuf, buf)
373 return buf.value.decode() # decode turns into a string
376 _rmr_get_src = rmr_c_lib.rmr_get_src
377 _rmr_get_src.argtypes = [POINTER(rmr_mbuf_t), c_char_p]
378 _rmr_get_src.restype = c_char_p
381 def rmr_get_src(ptr_mbuf, dest):
383 Refer to the rmr C documentation for rmr_get_src
384 extern unsigned char* rmr_get_src(rmr_mbuf_t* mbuf, unsigned char* dest);
386 return _rmr_get_src(ptr_mbuf, dest)
389 # Methods that exist ONLY in rmr-python, and are not wrapped methods
390 # In hindsight, I wish i put these in a seperate module, but leaving this here to prevent api breakage.
393 def get_payload(ptr_mbuf):
395 Given a rmr_buf_t*, get it's binary payload as a bytes object
399 ptr_mbuf: ctypes c_void_p
400 Pointer to an rmr message buffer
407 # Logic came from the answer here: https://stackoverflow.com/questions/55103298/python-ctypes-read-pointerc-char-in-python
408 sz = ptr_mbuf.contents.len
409 CharArr = c_char * sz
410 return CharArr(*ptr_mbuf.contents.payload[:sz]).raw
413 def get_xaction(ptr_mbuf):
415 given a rmr_buf_t*, get it's transaction id
419 ptr_mbuf: ctypes c_void_p
420 Pointer to an rmr message buffer
427 val = cast(ptr_mbuf.contents.xaction, c_char_p).value
428 sz = _get_constants().get("RMR_MAX_XID", 0)
432 def message_summary(ptr_mbuf):
434 Returns a dict that contains the fields of a message
438 ptr_mbuf: ctypes c_void_p
439 Pointer to an rmr message buffer
447 "payload": get_payload(ptr_mbuf) if ptr_mbuf.contents.state == RMR_OK else None,
448 "payload length": ptr_mbuf.contents.len,
449 "message type": ptr_mbuf.contents.mtype,
450 "subscription id": ptr_mbuf.contents.sub_id,
451 "transaction id": get_xaction(ptr_mbuf),
452 "message state": ptr_mbuf.contents.state,
453 "message status": _state_to_status(ptr_mbuf.contents.state),
454 "payload max size": rmr_payload_size(ptr_mbuf),
455 "meid": rmr_get_meid(ptr_mbuf),
456 "message source": get_src(ptr_mbuf),
457 "errno": ptr_mbuf.contents.tp_state,
461 def set_payload_and_length(byte_str, ptr_mbuf):
463 | Set an rmr payload and content length
464 | In place method, no return
469 the bytes to set the payload to
470 ptr_mbuf: ctypes c_void_p
471 Pointer to an rmr message buffer
473 memmove(ptr_mbuf.contents.payload, byte_str, len(byte_str))
474 ptr_mbuf.contents.len = len(byte_str)
477 def generate_and_set_transaction_id(ptr_mbuf):
479 | Generate a UUID and Set an rmr transaction id to it
480 | In place method, no return
484 ptr_mbuf: ctypes c_void_p
485 Pointer to an rmr message buffer
487 uu_id = uuid.uuid1().hex.encode("utf-8")
488 sz = _get_constants().get("RMR_MAX_XID", 0)
489 memmove(ptr_mbuf.contents.xaction, uu_id, sz)
492 def get_src(ptr_mbuf):
494 Get the message source (likely host:port)
498 ptr_mbuf: ctypes c_void_p
499 Pointer to an rmr message buffer
506 sz = _get_constants().get("RMR_MAX_SRC", 64) # size to fill
507 buf = create_string_buffer(sz)
508 rmr_get_src(ptr_mbuf, buf)
509 return buf.value.decode()