# ================================================================================== # Copyright (c) 2019 Nokia # Copyright (c) 2018-2019 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 # 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 _ = CDLL("libnng.so", mode=RTLD_GLOBAL) rmr_c_lib = CDLL("librmr_nng.so", mode=RTLD_GLOBAL) _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 #define RMR_OK 0 // state is good #define RMR_ERR_BADARG 1 // argument passd to function was unusable #define RMR_ERR_NOENDPT 2 // send/call could not find an endpoint based on msg type #define RMR_ERR_EMPTY 3 // msg received had no payload; attempt to send an empty message #define RMR_ERR_NOHDR 4 // message didn't contain a valid header #define RMR_ERR_SENDFAILED 5 // send failed; errno has nano reason #define RMR_ERR_CALLFAILED 6 // unable to send call() message #define RMR_ERR_NOWHOPEN 7 // no wormholes are open #define RMR_ERR_WHID 8 // wormhole id was invalid #define RMR_ERR_OVERFLOW 9 // operation would have busted through a buffer/field size #define RMR_ERR_RETRY 10 // request (send/call/rts) failed, but caller should retry (EAGAIN for wrappers) #define RMR_ERR_RCVFAILED 11 // receive failed (hard error) #define RMR_ERR_TIMEOUT 12 // message processing call timed out #define RMR_ERR_UNSET 13 // the message hasn't been populated with a transport buffer #define RMR_ERR_TRUNC 14 // received message likely truncated #define RMR_ERR_INITFAILED 15 // initialisation 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): """ convery a msg state to status """ sdict = _get_mapping_dict() return sdict.get(stateno, "UNKNOWN STATE") ############## # PUBLIC API ############## # These constants are directly usable by importers of this library # TODO: Are there others that will be useful? RMR_MAX_RCV_BYTES = _get_constants()["RMR_MAX_RCV_BYTES"] 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 # extern void* rmr_init(char* uproto_port, int max_msg_size, int flags) rmr_init = rmr_c_lib.rmr_init rmr_init.argtypes = [c_char_p, c_int, c_int] rmr_init.restype = c_void_p # extern void rmr_close(void* vctx) rmr_close = rmr_c_lib.rmr_close rmr_close.argtypes = [c_void_p] # I don't think there's a restype needed here. THe return is simply "return" in the c lib # extern int rmr_ready(void* vctx) rmr_ready = rmr_c_lib.rmr_ready rmr_ready.argtypes = [c_void_p] rmr_ready.restype = c_int # extern int rmr_set_stimeout(void* vctx, int time) # RE "int time", from the C docs: # Set send timeout. The value time is assumed to be microseconds. The timeout is the # rough maximum amount of time that RMr will block on a send attempt when the underlying # mechnism indicates eagain or etimeedout. All other error conditions are reported # without this delay. Setting a timeout of 0 causes no retries to be attempted in # RMr code. Setting a timeout of 1 causes RMr to spin up to 10K retries before returning, # but without issuing a sleep. If timeout is > 1, then RMr will issue a sleep (1us) # after every 10K send attempts until the time value is reached. Retries are abandoned # if NNG returns anything other than NNG_AGAIN or NNG_TIMEDOUT. # # The default, if this function is not used, is 1; meaning that RMr will retry, but will # not enter a sleep. In all cases the caller should check the status in the message returned # after a send call. rmr_set_stimeout = rmr_c_lib.rmr_set_rtimeout rmr_set_stimeout.argtypes = [c_void_p, c_int] rmr_set_stimeout.restype = c_int # extern rmr_mbuf_t* rmr_alloc_msg(void* vctx, int size) 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) # extern int rmr_payload_size(rmr_mbuf_t* msg) rmr_payload_size = rmr_c_lib.rmr_payload_size rmr_payload_size.argtypes = [POINTER(rmr_mbuf_t)] rmr_payload_size.restype = c_int """ The following functions all seem to have the same interface """ # extern rmr_mbuf_t* rmr_send_msg(void* vctx, rmr_mbuf_t* msg) 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) # extern rmr_mbuf_t* rmr_rcv_msg(void* vctx, rmr_mbuf_t* old_msg) # 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) # extern rmr_mbuf_t* rmr_torcv_msg(void* vctx, rmr_mbuf_t* old_msg, int ms_to) # the version of receive for nng that has a timeout (give up after X ms) 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) # extern rmr_mbuf_t* rmr_rts_msg(void* vctx, rmr_mbuf_t* msg) 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) # extern rmr_mbuf_t* rmr_call(void* vctx, rmr_mbuf_t* msg) rmr_call = rmr_c_lib.rmr_call rmr_call.argtypes = [c_void_p, POINTER(rmr_mbuf_t)] rmr_call.restype = POINTER(rmr_mbuf_t) # Header field interface # extern int rmr_bytes2meid(rmr_mbuf_t* mbuf, unsigned char const* src, int len); rmr_bytes2meid = rmr_c_lib.rmr_bytes2meid rmr_bytes2meid.argtypes = [POINTER(rmr_mbuf_t), c_char_p, c_int] rmr_bytes2meid.restype = c_int # 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); 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 # extern unsigned char* rmr_get_src(rmr_mbuf_t* mbuf, unsigned char* dest); 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 # GET Methods def get_payload(ptr_to_rmr_buf_t): """ given a rmr_buf_t*, get it's binary payload as a bytes object this magical function came from the answer here: https://stackoverflow.com/questions/55103298/python-ctypes-read-pointerc-char-in-python """ sz = ptr_to_rmr_buf_t.contents.len CharArr = c_char * sz return CharArr(*ptr_to_rmr_buf_t.contents.payload[:sz]).raw def get_xaction(ptr_to_rmr_buf_t): """ given a rmr_buf_t*, get it's transaction id """ val = cast(ptr_to_rmr_buf_t.contents.xaction, c_char_p).value sz = _get_constants().get("RMR_MAX_XID", 0) return val[:sz] def message_summary(ptr_to_rmr_buf_t): """ Used for debugging mostly: returns a dict that contains the fields of a message """ if ptr_to_rmr_buf_t.contents.len > RMR_MAX_RCV_BYTES: return "Malformed message: message length is greater than the maximum possible" meid = get_meid(ptr_to_rmr_buf_t) if meid == "\000" * _get_constants().get("RMR_MAX_MEID", 32): # special case all nils meid = None return { "payload": get_payload(ptr_to_rmr_buf_t), "payload length": ptr_to_rmr_buf_t.contents.len, "message type": ptr_to_rmr_buf_t.contents.mtype, "subscription id": ptr_to_rmr_buf_t.contents.sub_id, "transaction id": get_xaction(ptr_to_rmr_buf_t), "message state": ptr_to_rmr_buf_t.contents.state, "message status": _state_to_status(ptr_to_rmr_buf_t.contents.state), "payload max size": rmr_payload_size(ptr_to_rmr_buf_t), "meid": meid, "message source": get_src(ptr_to_rmr_buf_t), "errno": ptr_to_rmr_buf_t.contents.tp_state, } def set_payload_and_length(byte_str, ptr_to_rmr_buf_t): """ use memmove to set the rmr_buf_t payload and content length """ memmove(ptr_to_rmr_buf_t.contents.payload, byte_str, len(byte_str)) ptr_to_rmr_buf_t.contents.len = len(byte_str) def generate_and_set_transaction_id(ptr_to_rmr_buf_t): """ use memmove to set the rmr_buf_t xaction """ uu_id = uuid.uuid1().hex.encode("utf-8") sz = _get_constants().get("RMR_MAX_XID", 0) memmove(ptr_to_rmr_buf_t.contents.xaction, uu_id, sz) def get_meid(mbuf): """ Suss out the managed equipment ID (meid) from the message header. This is a 32 byte field and RMr returns all 32 bytes which if the sender did not set will be garbage. """ sz = _get_constants().get("RMR_MAX_MEID", 64) # size for buffer to fill buf = create_string_buffer(sz) rmr_get_meid(mbuf, buf) return buf.raw.decode() def get_src(mbuf): """ Suss out the message source information (likely host:port). """ sz = _get_constants().get("RMR_MAX_SRC", 64) # size to fill buf = create_string_buffer(sz) rmr_get_src(mbuf, buf) return buf.value.decode()