1 # vim: expandtab ts=4 sw=4:
2 # ==================================================================================
3 # Copyright (c) 2019 Nokia
4 # Copyright (c) 2018-2019 AT&T Intellectual Property.
6 # Licensed under the Apache License, Version 2.0 (the "License");
7 # you may not use this file except in compliance with the License.
8 # You may obtain a copy of the License at
10 # http://www.apache.org/licenses/LICENSE-2.0
12 # Unless required by applicable law or agreed to in writing, software
13 # distributed under the License is distributed on an "AS IS" BASIS,
14 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 # See the License for the specific language governing permissions and
16 # limitations under the License.
17 # ==================================================================================
20 from ctypes import RTLD_GLOBAL, Structure, c_int, POINTER, c_char, c_char_p, c_void_p, memmove, cast
21 from ctypes import CDLL
22 from ctypes import create_string_buffer
23 from rmr.exceptions import BadBufferAllocation
25 # https://docs.python.org/3.7/library/ctypes.html
26 # https://stackoverflow.com/questions/2327344/ctypes-loading-a-c-shared-library-that-has-dependencies/30845750#30845750
27 # make sure you do a set -x LD_LIBRARY_PATH /usr/local/lib/;
29 # even though we don't use these directly, they contain symbols we need
30 _ = CDLL("libnng.so", mode=RTLD_GLOBAL)
31 rmr_c_lib = CDLL("librmr_nng.so", mode=RTLD_GLOBAL)
34 # Internal Helpers (not a part of public api)
37 _rmr_const = rmr_c_lib.rmr_get_consts
38 _rmr_const.argtypes = []
39 _rmr_const.restype = c_char_p
42 def _get_constants(cache={}):
44 Get or build needed constants from rmr
45 TODO: are there constants that end user applications need?
50 js = _rmr_const() # read json string
51 cache = json.loads(str(js.decode())) # create constants value object as a hash
55 def _get_mapping_dict(cache={}):
57 Get or build the state mapping dict
59 RMR_OK 0 state is good
60 RMR_ERR_BADARG 1 argument passd to function was unusable
61 RMR_ERR_NOENDPT 2 send/call could not find an endpoint based on msg type
62 RMR_ERR_EMPTY 3 msg received had no payload; attempt to send an empty message
63 RMR_ERR_NOHDR 4 message didn't contain a valid header
64 RMR_ERR_SENDFAILED 5 send failed; errno has nano reason
65 RMR_ERR_CALLFAILED 6 unable to send call() message
66 RMR_ERR_NOWHOPEN 7 no wormholes are open
67 RMR_ERR_WHID 8 wormhole id was invalid
68 RMR_ERR_OVERFLOW 9 operation would have busted through a buffer/field size
69 RMR_ERR_RETRY 10 request (send/call/rts) failed, but caller should retry (EAGAIN for wrappers)
70 RMR_ERR_RCVFAILED 11 receive failed (hard error)
71 RMR_ERR_TIMEOUT 12 message processing call timed out
72 RMR_ERR_UNSET 13 the message hasn't been populated with a transport buffer
73 RMR_ERR_TRUNC 14 received message likely truncated
74 RMR_ERR_INITFAILED 15 initialization of something (probably message) failed
80 rmr_consts = _get_constants()
81 for key in rmr_consts: # build the state mapping dict
82 if key[:7] in ["RMR_ERR", "RMR_OK"]:
83 en = int(rmr_consts[key])
89 def _state_to_status(stateno):
91 Convert a msg state to status
94 sdict = _get_mapping_dict()
95 return sdict.get(stateno, "UNKNOWN STATE")
98 _RCONST = _get_constants()
106 # These constants are directly usable by importers of this library
107 # TODO: Are there others that will be useful?
109 RMR_MAX_RCV_BYTES = _RCONST["RMR_MAX_RCV_BYTES"]
110 RMRFL_MTCALL = _RCONST.get("RMRFL_MTCALL", 0x02) # initialization flags
111 RMRFL_NONE = _RCONST.get("RMRFL_NONE", 0x0)
112 RMR_OK = _RCONST["RMR_OK"] # useful state constants
113 RMR_ERR_TIMEOUT = _RCONST["RMR_ERR_TIMEOUT"]
114 RMR_ERR_RETRY = _RCONST["RMR_ERR_RETRY"]
117 class rmr_mbuf_t(Structure):
119 Reimplementation of rmr_mbuf_t which is in an unaccessible header file (src/common/include/rmr.h)
122 | int state; // state of processing
123 | int mtype; // message type
124 | int len; // length of data in the payload (send or received)
125 | unsigned char* payload; // transported data
126 | unsigned char* xaction; // pointer to fixed length transaction id bytes
127 | int sub_id; // subscription id
128 | int tp_state; // transport state (a.k.a errno)
130 | these things are off limits to the user application
132 | void* tp_buf; // underlying transport allocated pointer (e.g. nng message)
133 | void* header; // internal message header (whole buffer: header+payload)
134 | unsigned char* id; // if we need an ID in the message separate from the xaction id
135 | int flags; // various MFL (private) flags as needed
136 | int alloc_len; // the length of the allocated space (hdr+payload)
139 We do not include the fields we are not supposed to mess with
141 RE PAYLOADs type below, see the documentation for c_char_p:
142 class ctypes.c_char_p
143 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.
153 ), # according to th following the python bytes are already unsinged https://bytes.com/topic/python/answers/695078-ctypes-unsigned-char
154 ("xaction", POINTER(c_char)),
160 # argtypes and restype are important: https://stackoverflow.com/questions/24377845/ctype-why-specify-argtypes
163 _rmr_init = rmr_c_lib.rmr_init
164 _rmr_init.argtypes = [c_char_p, c_int, c_int]
165 _rmr_init.restype = c_void_p
168 def rmr_init(uproto_port, max_msg_size, flags):
170 Refer to rmr C documentation for rmr_init
171 extern void* rmr_init(char* uproto_port, int max_msg_size, int flags)
173 return _rmr_init(uproto_port, max_msg_size, flags)
176 _rmr_ready = rmr_c_lib.rmr_ready
177 _rmr_ready.argtypes = [c_void_p]
178 _rmr_ready.restype = c_int
183 Refer to rmr C documentation for rmr_ready
184 extern int rmr_ready(void* vctx)
186 return _rmr_ready(vctx)
189 _rmr_close = rmr_c_lib.rmr_close
190 _rmr_close.argtypes = [c_void_p]
195 Refer to rmr C documentation for rmr_close
196 extern void rmr_close(void* vctx)
198 return _rmr_close(vctx)
201 _rmr_set_stimeout = rmr_c_lib.rmr_set_stimeout
202 _rmr_set_stimeout.argtypes = [c_void_p, c_int]
203 _rmr_set_stimeout.restype = c_int
206 def rmr_set_stimeout(vctx, time):
208 Refer to the rmr C documentation for rmr_set_stimeout
209 extern int rmr_set_stimeout(void* vctx, int time)
211 return _rmr_set_stimeout(vctx, time)
214 _rmr_alloc_msg = rmr_c_lib.rmr_alloc_msg
215 _rmr_alloc_msg.argtypes = [c_void_p, c_int]
216 _rmr_alloc_msg.restype = POINTER(rmr_mbuf_t)
219 def rmr_alloc_msg(vctx, size, payload=None, gen_transaction_id=False, mtype=None, meid=None, sub_id=None):
221 Refer to the rmr C documentation for rmr_alloc_msg
222 extern rmr_mbuf_t* rmr_alloc_msg(void* vctx, int size)
224 if payload is not None, attempts to set the payload
225 if gen_transaction_id is True, it generates and sets a transaction id
226 if mtype is not None, sets the sbuf's message type
227 if meid is not None, sets the sbuf's meid
230 sbuf = _rmr_alloc_msg(vctx, size)
232 # make sure the alloc worked
235 # set specified fields
237 set_payload_and_length(payload, sbuf)
239 if gen_transaction_id:
240 generate_and_set_transaction_id(sbuf)
243 sbuf.contents.mtype = mtype
246 rmr_set_meid(sbuf, meid)
249 sbuf.contents.sub_id = sub_id
254 raise BadBufferAllocation
257 _rmr_realloc_payload = rmr_c_lib.rmr_realloc_payload
258 _rmr_realloc_payload.argtypes = [POINTER(rmr_mbuf_t), c_int, c_int, c_int] # new_len, copy, clone
259 _rmr_realloc_payload.restype = POINTER(rmr_mbuf_t)
262 def rmr_realloc_payload(ptr_mbuf, new_len, copy=False, clone=False):
264 Refer to the rmr C documentation for rmr_realloc_payload().
265 extern rmr_mbuf_t* rmr_realloc_payload(rmr_mbuf_t*, int, int, int)
267 return _rmr_realloc_payload(ptr_mbuf, new_len, copy, clone)
270 _rmr_free_msg = rmr_c_lib.rmr_free_msg
271 _rmr_free_msg.argtypes = [c_void_p]
272 _rmr_free_msg.restype = None
275 def rmr_free_msg(mbuf):
277 Refer to the rmr C documentation for rmr_free_msg
278 extern void rmr_free_msg(rmr_mbuf_t* mbuf )
284 _rmr_payload_size = rmr_c_lib.rmr_payload_size
285 _rmr_payload_size.argtypes = [POINTER(rmr_mbuf_t)]
286 _rmr_payload_size.restype = c_int
289 def rmr_payload_size(ptr_mbuf):
291 Refer to the rmr C documentation for rmr_payload_size
292 extern int rmr_payload_size(rmr_mbuf_t* msg)
294 return _rmr_payload_size(ptr_mbuf)
298 The following functions all seem to have the same interface
301 _rmr_send_msg = rmr_c_lib.rmr_send_msg
302 _rmr_send_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
303 _rmr_send_msg.restype = POINTER(rmr_mbuf_t)
306 def rmr_send_msg(vctx, ptr_mbuf):
308 Refer to the rmr C documentation for rmr_send_msg
309 extern rmr_mbuf_t* rmr_send_msg(void* vctx, rmr_mbuf_t* msg)
311 return _rmr_send_msg(vctx, ptr_mbuf)
314 # TODO: the old message (Send param) is actually optional, but I don't know how to specify that in Ctypes.
315 _rmr_rcv_msg = rmr_c_lib.rmr_rcv_msg
316 _rmr_rcv_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
317 _rmr_rcv_msg.restype = POINTER(rmr_mbuf_t)
320 def rmr_rcv_msg(vctx, ptr_mbuf):
322 Refer to the rmr C documentation for rmr_rcv_msg
323 extern rmr_mbuf_t* rmr_rcv_msg(void* vctx, rmr_mbuf_t* old_msg)
325 return _rmr_rcv_msg(vctx, ptr_mbuf)
328 _rmr_torcv_msg = rmr_c_lib.rmr_torcv_msg
329 _rmr_torcv_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t), c_int]
330 _rmr_torcv_msg.restype = POINTER(rmr_mbuf_t)
333 def rmr_torcv_msg(vctx, ptr_mbuf, ms_to):
335 Refer to the rmr C documentation for rmr_torcv_msg
336 extern rmr_mbuf_t* rmr_torcv_msg(void* vctx, rmr_mbuf_t* old_msg, int ms_to)
338 return _rmr_torcv_msg(vctx, ptr_mbuf, ms_to)
341 _rmr_rts_msg = rmr_c_lib.rmr_rts_msg
342 _rmr_rts_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
343 _rmr_rts_msg.restype = POINTER(rmr_mbuf_t)
346 def rmr_rts_msg(vctx, ptr_mbuf):
348 Refer to the rmr C documentation for rmr_rts_msg
349 extern rmr_mbuf_t* rmr_rts_msg(void* vctx, rmr_mbuf_t* msg)
351 return _rmr_rts_msg(vctx, ptr_mbuf)
354 _rmr_call = rmr_c_lib.rmr_call
355 _rmr_call.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
356 _rmr_call.restype = POINTER(rmr_mbuf_t)
359 def rmr_call(vctx, ptr_mbuf):
361 Refer to the rmr C documentation for rmr_call
362 extern rmr_mbuf_t* rmr_call(void* vctx, rmr_mbuf_t* msg)
364 return _rmr_call(vctx, ptr_mbuf)
367 _rmr_bytes2meid = rmr_c_lib.rmr_bytes2meid
368 _rmr_bytes2meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p, c_int]
369 _rmr_bytes2meid.restype = c_int
372 def rmr_set_meid(ptr_mbuf, byte_str):
374 Refer to the rmr C documentation for rmr_bytes2meid
375 extern int rmr_bytes2meid(rmr_mbuf_t* mbuf, unsigned char const* src, int len);
377 return _rmr_bytes2meid(ptr_mbuf, byte_str, len(byte_str))
380 # CAUTION: Some of the C functions expect a mutable buffer to copy the bytes into;
381 # if there is a get_* function below, use it to set up and return the
384 # extern unsigned char* rmr_get_meid(rmr_mbuf_t* mbuf, unsigned char* dest);
385 # 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.
386 # Rather, rmr_get_meid does this for you, and just returns the string.
387 _rmr_get_meid = rmr_c_lib.rmr_get_meid
388 _rmr_get_meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p]
389 _rmr_get_meid.restype = c_char_p
392 def rmr_get_meid(ptr_mbuf):
394 Get the managed equipment ID (meid) from the message header.
398 ptr_mbuf: ctypes c_void_p
399 Pointer to an rmr message buffer
406 sz = _get_constants().get("RMR_MAX_MEID", 64) # size for buffer to fill
407 buf = create_string_buffer(sz)
408 _rmr_get_meid(ptr_mbuf, buf)
412 _rmr_get_src = rmr_c_lib.rmr_get_src
413 _rmr_get_src.argtypes = [POINTER(rmr_mbuf_t), c_char_p]
414 _rmr_get_src.restype = c_char_p
417 def rmr_get_src(ptr_mbuf, dest):
419 Refer to the rmr C documentation for rmr_get_src
420 extern unsigned char* rmr_get_src(rmr_mbuf_t* mbuf, unsigned char* dest);
422 return _rmr_get_src(ptr_mbuf, dest)
425 # Methods that exist ONLY in rmr-python, and are not wrapped methods
426 # In hindsight, I wish i put these in a seperate module, but leaving this here to prevent api breakage.
429 def get_payload(ptr_mbuf):
431 Given a rmr_buf_t*, get it's binary payload as a bytes object
435 ptr_mbuf: ctypes c_void_p
436 Pointer to an rmr message buffer
443 # Logic came from the answer here: https://stackoverflow.com/questions/55103298/python-ctypes-read-pointerc-char-in-python
444 sz = ptr_mbuf.contents.len
445 CharArr = c_char * sz
446 return CharArr(*ptr_mbuf.contents.payload[:sz]).raw
449 def get_xaction(ptr_mbuf):
451 given a rmr_buf_t*, get it's transaction id
455 ptr_mbuf: ctypes c_void_p
456 Pointer to an rmr message buffer
463 val = cast(ptr_mbuf.contents.xaction, c_char_p).value
464 sz = _get_constants().get("RMR_MAX_XID", 0)
468 def message_summary(ptr_mbuf):
470 Returns a dict that contains the fields of a message
474 ptr_mbuf: ctypes c_void_p
475 Pointer to an rmr message buffer
483 "payload": get_payload(ptr_mbuf) if ptr_mbuf.contents.state == RMR_OK else None,
484 "payload length": ptr_mbuf.contents.len,
485 "message type": ptr_mbuf.contents.mtype,
486 "subscription id": ptr_mbuf.contents.sub_id,
487 "transaction id": get_xaction(ptr_mbuf),
488 "message state": ptr_mbuf.contents.state,
489 "message status": _state_to_status(ptr_mbuf.contents.state),
490 "payload max size": rmr_payload_size(ptr_mbuf),
491 "meid": rmr_get_meid(ptr_mbuf),
492 "message source": get_src(ptr_mbuf),
493 "errno": ptr_mbuf.contents.tp_state,
497 def set_payload_and_length(byte_str, ptr_mbuf):
499 | Set an rmr payload and content length
500 | In place method, no return
505 the bytes to set the payload to
506 ptr_mbuf: ctypes c_void_p
507 Pointer to an rmr message buffer
509 if rmr_payload_size(ptr_mbuf) < len(byte_str): # existing message payload too small
510 ptr_mbuf = rmr_realloc_payload(ptr_mbuf, len(byte_str), True)
512 memmove(ptr_mbuf.contents.payload, byte_str, len(byte_str))
513 ptr_mbuf.contents.len = len(byte_str)
516 def generate_and_set_transaction_id(ptr_mbuf):
518 | Generate a UUID and Set an rmr transaction id to it
519 | In place method, no return
523 ptr_mbuf: ctypes c_void_p
524 Pointer to an rmr message buffer
526 uu_id = uuid.uuid1().hex.encode("utf-8")
527 sz = _get_constants().get("RMR_MAX_XID", 0)
528 memmove(ptr_mbuf.contents.xaction, uu_id, sz)
531 def get_src(ptr_mbuf):
533 Get the message source (likely host:port)
537 ptr_mbuf: ctypes c_void_p
538 Pointer to an rmr message buffer
545 sz = _get_constants().get("RMR_MAX_SRC", 64) # size to fill
546 buf = create_string_buffer(sz)
547 rmr_get_src(ptr_mbuf, buf)
548 return buf.value.decode()