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
23 # https://docs.python.org/3.7/library/ctypes.html
24 # https://stackoverflow.com/questions/2327344/ctypes-loading-a-c-shared-library-that-has-dependencies/30845750#30845750
25 # make sure you do a set -x LD_LIBRARY_PATH /usr/local/lib/;
27 # even though we don't use these directly, they contain symbols we need
28 _ = CDLL("libnng.so", mode=RTLD_GLOBAL)
29 rmr_c_lib = CDLL("librmr_nng.so", mode=RTLD_GLOBAL)
32 _rmr_const = rmr_c_lib.rmr_get_consts
33 _rmr_const.argtypes = []
34 _rmr_const.restype = c_char_p
37 def _get_constants(cache={}):
39 Get or build needed constants from rmr
40 TODO: are there constants that end user applications need?
45 js = _rmr_const() # read json string
46 cache = json.loads(str(js.decode())) # create constants value object as a hash
50 def _get_mapping_dict(cache={}):
52 Get or build the state mapping dict
54 #define RMR_OK 0 // state is good
55 #define RMR_ERR_BADARG 1 // argument passd to function was unusable
56 #define RMR_ERR_NOENDPT 2 // send/call could not find an endpoint based on msg type
57 #define RMR_ERR_EMPTY 3 // msg received had no payload; attempt to send an empty message
58 #define RMR_ERR_NOHDR 4 // message didn't contain a valid header
59 #define RMR_ERR_SENDFAILED 5 // send failed; errno has nano reason
60 #define RMR_ERR_CALLFAILED 6 // unable to send call() message
61 #define RMR_ERR_NOWHOPEN 7 // no wormholes are open
62 #define RMR_ERR_WHID 8 // wormhole id was invalid
63 #define RMR_ERR_OVERFLOW 9 // operation would have busted through a buffer/field size
64 #define RMR_ERR_RETRY 10 // request (send/call/rts) failed, but caller should retry (EAGAIN for wrappers)
65 #define RMR_ERR_RCVFAILED 11 // receive failed (hard error)
66 #define RMR_ERR_TIMEOUT 12 // message processing call timed out
67 #define RMR_ERR_UNSET 13 // the message hasn't been populated with a transport buffer
68 #define RMR_ERR_TRUNC 14 // received message likely truncated
69 #define RMR_ERR_INITFAILED 15 // initialisation of something (probably message) failed
75 rmr_consts = _get_constants()
76 for key in rmr_consts: # build the state mapping dict
77 if key[:7] in ["RMR_ERR", "RMR_OK"]:
78 en = int(rmr_consts[key])
84 def _state_to_status(stateno):
86 Convert a msg state to status
91 the state of the rmr message buffer
96 the cooresponding message state
98 sdict = _get_mapping_dict()
99 return sdict.get(stateno, "UNKNOWN STATE")
106 # These constants are directly usable by importers of this library
107 # TODO: Are there others that will be useful?
108 RMR_MAX_RCV_BYTES = _get_constants()["RMR_MAX_RCV_BYTES"]
111 class rmr_mbuf_t(Structure):
113 Reimplementation of rmr_mbuf_t which is in an unaccessible header file (src/common/include/rmr.h)
116 int state; // state of processing
117 int mtype; // message type
118 int len; // length of data in the payload (send or received)
119 unsigned char* payload; // transported data
120 unsigned char* xaction; // pointer to fixed length transaction id bytes
121 int sub_id; // subscription id
122 int tp_state; // transport state (a.k.a errno)
123 // these things are off limits to the user application
124 void* tp_buf; // underlying transport allocated pointer (e.g. nng message)
125 void* header; // internal message header (whole buffer: header+payload)
126 unsigned char* id; // if we need an ID in the message separate from the xaction id
127 int flags; // various MFL_ (private) flags as needed
128 int alloc_len; // the length of the allocated space (hdr+payload)
131 We do not include the fields we are not supposed to mess with
133 RE PAYLOADs type below, see the documentation for c_char_p:
134 class ctypes.c_char_p
135 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.
146 ), # according to th following the python bytes are already unsinged https://bytes.com/topic/python/answers/695078-ctypes-unsigned-char
147 ("xaction", POINTER(c_char)),
153 # argtypes and restype are important: https://stackoverflow.com/questions/24377845/ctype-why-specify-argtypes
156 # extern void* rmr_init(char* uproto_port, int max_msg_size, int flags)
157 rmr_init = rmr_c_lib.rmr_init
158 rmr_init.argtypes = [c_char_p, c_int, c_int]
159 rmr_init.restype = c_void_p
162 # extern void rmr_close(void* vctx)
163 rmr_close = rmr_c_lib.rmr_close
164 rmr_close.argtypes = [c_void_p]
165 # I don't think there's a restype needed here. THe return is simply "return" in the c lib
167 # extern int rmr_ready(void* vctx)
168 rmr_ready = rmr_c_lib.rmr_ready
169 rmr_ready.argtypes = [c_void_p]
170 rmr_ready.restype = c_int
172 # extern int rmr_set_stimeout(void* vctx, int time)
173 # RE "int time", from the C docs:
174 # Set send timeout. The value time is assumed to be microseconds. The timeout is the
175 # rough maximum amount of time that RMr will block on a send attempt when the underlying
176 # mechnism indicates eagain or etimeedout. All other error conditions are reported
177 # without this delay. Setting a timeout of 0 causes no retries to be attempted in
178 # RMr code. Setting a timeout of 1 causes RMr to spin up to 10K retries before returning,
179 # but without issuing a sleep. If timeout is > 1, then RMr will issue a sleep (1us)
180 # after every 10K send attempts until the time value is reached. Retries are abandoned
181 # if NNG returns anything other than NNG_AGAIN or NNG_TIMEDOUT.
183 # The default, if this function is not used, is 1; meaning that RMr will retry, but will
184 # not enter a sleep. In all cases the caller should check the status in the message returned
186 rmr_set_stimeout = rmr_c_lib.rmr_set_rtimeout
187 rmr_set_stimeout.argtypes = [c_void_p, c_int]
188 rmr_set_stimeout.restype = c_int
190 # extern rmr_mbuf_t* rmr_alloc_msg(void* vctx, int size)
191 rmr_alloc_msg = rmr_c_lib.rmr_alloc_msg
192 rmr_alloc_msg.argtypes = [c_void_p, c_int]
193 rmr_alloc_msg.restype = POINTER(rmr_mbuf_t)
195 # extern int rmr_payload_size(rmr_mbuf_t* msg)
196 rmr_payload_size = rmr_c_lib.rmr_payload_size
197 rmr_payload_size.argtypes = [POINTER(rmr_mbuf_t)]
198 rmr_payload_size.restype = c_int
202 The following functions all seem to have the same interface
205 # extern rmr_mbuf_t* rmr_send_msg(void* vctx, rmr_mbuf_t* msg)
206 rmr_send_msg = rmr_c_lib.rmr_send_msg
207 rmr_send_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
208 rmr_send_msg.restype = POINTER(rmr_mbuf_t)
210 # extern rmr_mbuf_t* rmr_rcv_msg(void* vctx, rmr_mbuf_t* old_msg)
211 # TODO: the old message (Send param) is actually optional, but I don't know how to specify that in Ctypes.
212 rmr_rcv_msg = rmr_c_lib.rmr_rcv_msg
213 rmr_rcv_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
214 rmr_rcv_msg.restype = POINTER(rmr_mbuf_t)
216 # extern rmr_mbuf_t* rmr_torcv_msg(void* vctx, rmr_mbuf_t* old_msg, int ms_to)
217 # the version of receive for nng that has a timeout (give up after X ms)
218 rmr_torcv_msg = rmr_c_lib.rmr_torcv_msg
219 rmr_torcv_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t), c_int]
220 rmr_torcv_msg.restype = POINTER(rmr_mbuf_t)
222 # extern rmr_mbuf_t* rmr_rts_msg(void* vctx, rmr_mbuf_t* msg)
223 rmr_rts_msg = rmr_c_lib.rmr_rts_msg
224 rmr_rts_msg.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
225 rmr_rts_msg.restype = POINTER(rmr_mbuf_t)
227 # extern rmr_mbuf_t* rmr_call(void* vctx, rmr_mbuf_t* msg)
228 rmr_call = rmr_c_lib.rmr_call
229 rmr_call.argtypes = [c_void_p, POINTER(rmr_mbuf_t)]
230 rmr_call.restype = POINTER(rmr_mbuf_t)
233 # Header field interface
235 # extern int rmr_bytes2meid(rmr_mbuf_t* mbuf, unsigned char const* src, int len);
236 rmr_bytes2meid = rmr_c_lib.rmr_bytes2meid
237 rmr_bytes2meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p, c_int]
238 rmr_bytes2meid.restype = c_int
241 # CAUTION: Some of the C functions expect a mutable buffer to copy the bytes into;
242 # if there is a get_* function below, use it to set up and return the
245 # extern unsigned char* rmr_get_meid(rmr_mbuf_t* mbuf, unsigned char* dest);
246 rmr_get_meid = rmr_c_lib.rmr_get_meid
247 rmr_get_meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p]
248 rmr_get_meid.restype = c_char_p
250 # extern unsigned char* rmr_get_src(rmr_mbuf_t* mbuf, unsigned char* dest);
251 rmr_get_src = rmr_c_lib.rmr_get_src
252 rmr_get_src.argtypes = [POINTER(rmr_mbuf_t), c_char_p]
253 rmr_get_src.restype = c_char_p
259 def get_payload(ptr_to_rmr_buf_t):
261 given a rmr_buf_t*, get it's binary payload as a bytes object
262 this magical function came from the answer here: https://stackoverflow.com/questions/55103298/python-ctypes-read-pointerc-char-in-python
264 sz = ptr_to_rmr_buf_t.contents.len
265 CharArr = c_char * sz
266 return CharArr(*ptr_to_rmr_buf_t.contents.payload[:sz]).raw
269 def get_xaction(ptr_to_rmr_buf_t):
271 given a rmr_buf_t*, get it's transaction id
273 val = cast(ptr_to_rmr_buf_t.contents.xaction, c_char_p).value
274 sz = _get_constants().get("RMR_MAX_XID", 0)
278 def message_summary(ptr_to_rmr_buf_t):
280 Used for debugging mostly: returns a dict that contains the fields of a message
282 if ptr_to_rmr_buf_t.contents.len > RMR_MAX_RCV_BYTES:
283 return "Malformed message: message length is greater than the maximum possible"
285 meid = get_meid(ptr_to_rmr_buf_t)
286 if meid == "\000" * _get_constants().get("RMR_MAX_MEID", 32): # special case all nils
290 "payload": get_payload(ptr_to_rmr_buf_t),
291 "payload length": ptr_to_rmr_buf_t.contents.len,
292 "message type": ptr_to_rmr_buf_t.contents.mtype,
293 "subscription id": ptr_to_rmr_buf_t.contents.sub_id,
294 "transaction id": get_xaction(ptr_to_rmr_buf_t),
295 "message state": ptr_to_rmr_buf_t.contents.state,
296 "message status": _state_to_status(ptr_to_rmr_buf_t.contents.state),
297 "payload max size": rmr_payload_size(ptr_to_rmr_buf_t),
299 "message source": get_src(ptr_to_rmr_buf_t),
300 "errno": ptr_to_rmr_buf_t.contents.tp_state,
304 def set_payload_and_length(byte_str, ptr_to_rmr_buf_t):
306 use memmove to set the rmr_buf_t payload and content length
308 memmove(ptr_to_rmr_buf_t.contents.payload, byte_str, len(byte_str))
309 ptr_to_rmr_buf_t.contents.len = len(byte_str)
312 def generate_and_set_transaction_id(ptr_to_rmr_buf_t):
314 use memmove to set the rmr_buf_t xaction
316 uu_id = uuid.uuid1().hex.encode("utf-8")
317 sz = _get_constants().get("RMR_MAX_XID", 0)
318 memmove(ptr_to_rmr_buf_t.contents.xaction, uu_id, sz)
323 Suss out the managed equipment ID (meid) from the message header.
324 This is a 32 byte field and RMr returns all 32 bytes which if the
325 sender did not set will be garbage.
327 sz = _get_constants().get("RMR_MAX_MEID", 64) # size for buffer to fill
328 buf = create_string_buffer(sz)
329 rmr_get_meid(mbuf, buf)
330 return buf.raw.decode()
335 Suss out the message source information (likely host:port).
337 sz = _get_constants().get("RMR_MAX_SRC", 64) # size to fill
338 buf = create_string_buffer(sz)
339 rmr_get_src(mbuf, buf)
340 return buf.value.decode()