Correct potenital locking issue in msg allocation

[ric-plt/lib/rmr.git] / src / rmr / si / src / rmr_si.c

// vim: ts=4 sw=4 noet :
/*
==================================================================================
        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.
==================================================================================
*/

/*
        Mnemonic:       rmr_si.c
        Abstract:       This is the compile point for the si version of the rmr
                                library (formarly known as uta, so internal function names
                                are likely still uta_*)

                                With the exception of the symtab portion of the library,
                                RMr is built with a single compile so as to "hide" the
                                internal functions as statics.  Because they interdepend
                                on each other, and CMake has issues with generating two
                                different wormhole objects from a single source, we just
                                pull it all together with a centralised comple using
                                includes.

                                Future:  the API functions at this point can be separated
                                into a common source module.

        Author:         E. Scott Daniels
        Date:           1 February 2019
*/

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <errno.h>
#include <string.h>
#include <errno.h>
#include <pthread.h>
#include <unistd.h>
#include <time.h>
#include <arpa/inet.h>
#include <semaphore.h>
#include <pthread.h>

#include "si95/socket_if.h"
#include "si95/siproto.h"

#define SI95_BUILD      1                       // we drop some common functions for si

#include "rmr.h"                                // things the users see
#include "rmr_agnostic.h"               // agnostic things (must be included before private)
#include "rmr_si_private.h"             // things that we need too
#include "rmr_symtab.h"
#include "rmr_logging.h"

#include "ring_static.c"                        // message ring support
#include "rt_generic_static.c"          // route table things not transport specific
#include "rtable_si_static.c"           // route table things -- transport specific
#include "rtc_static.c"                         // route table collector (thread code)
#include "tools_static.c"
#include "sr_si_static.c"                       // send/receive static functions
#include "wormholes.c"                          // wormhole api externals and related static functions (must be LAST!)
#include "mt_call_static.c"
#include "mt_call_si_static.c"


//------------------------------------------------------------------------------


/*
        Clean up a context.
*/
static void free_ctx( uta_ctx_t* ctx ) {
        if( ctx ) {
                if( ctx->rtg_addr ){
                        free( ctx->rtg_addr );
                }
                uta_ring_free( ctx->mring );
                uta_ring_free( ctx->zcb_mring );
                if( ctx->chutes ){
                        free( ctx->chutes );
                }
                if( ctx->fd2ep ){
                        rmr_sym_free( ctx->fd2ep );
                }
                if( ctx->my_name ){
                        free( ctx->my_name );
                }
                if( ctx->my_ip ){
                        free( ctx->my_ip );
                }
                if( ctx->rtable ){
                        rmr_sym_free( ctx->rtable->hash );
                        free( ctx->rtable );
                }
                if ( ctx->ephash ){
                        free( ctx->ephash );
                }
                free( ctx );
        }
}

// --------------- public functions --------------------------------------------------------------------------

/*
        Returns the size of the payload (bytes) that the msg buffer references.
        Len in a message is the number of bytes which were received, or should
        be transmitted, however, it is possible that the mbuf was allocated
        with a larger payload space than the payload length indicates; this
        function returns the absolute maximum space that the user has available
        in the payload. On error (bad msg buffer) -1 is returned and errno should
        indicate the rason.

        The allocated len stored in the msg is:
                transport header length +
                message header +
                user requested payload

        The msg header is a combination of the fixed RMR header and the variable
        trace data and d2 fields which may vary for each message.
*/
extern int rmr_payload_size( rmr_mbuf_t* msg ) {
        if( msg == NULL || msg->header == NULL ) {
                errno = EINVAL;
                return -1;
        }

        errno = 0;
        return msg->alloc_len - RMR_HDR_LEN( msg->header ) - TP_HDR_LEN;        // allocated transport size less the header and other data bits
}

/*
        Allocates a send message as a zerocopy message allowing the underlying message protocol
        to send the buffer without copy.
*/
extern rmr_mbuf_t* rmr_alloc_msg( void* vctx, int size ) {
        uta_ctx_t*      ctx;
        rmr_mbuf_t*     m;

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                return NULL;
        }

        m = alloc_zcmsg( ctx, NULL, size, 0, DEF_TR_LEN );                              // alloc with default trace data
        return  m;
}


/*
        Allocates a send message as a zerocopy message allowing the underlying message protocol
        to send the buffer without copy. In addition, a trace data field of tr_size will be
        added and the supplied data coppied to the buffer before returning the message to
        the caller.
*/
extern rmr_mbuf_t* rmr_tralloc_msg( void* vctx, int size, int tr_size, unsigned const char* data ) {
        uta_ctx_t*      ctx;
        rmr_mbuf_t*     m;
        int state;

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                return NULL;
        }

        m = alloc_zcmsg( ctx, NULL, size, 0, tr_size );                         // alloc with specific tr size
        if( m != NULL ) {
                state = rmr_set_trace( m, data, tr_size );                              // roll their data in
                if( state != tr_size ) {
                        m->state = RMR_ERR_INITFAILED;
                }
        }

        return  m;
}

/*
        This provides an external path to the realloc static function as it's called by an
        outward facing mbuf api function. Used to reallocate a message with a different
        trace data size.
*/
extern rmr_mbuf_t* rmr_realloc_msg( rmr_mbuf_t* msg, int new_tr_size ) {
        return realloc_msg( msg, new_tr_size );
}


/*
        Return the message to the available pool, or free it outright.
*/
extern void rmr_free_msg( rmr_mbuf_t* mbuf ) {
        if( mbuf == NULL ) {
                return;
        }

        if( mbuf->flags & MFL_HUGE ||                                                   // don't cache oversized messages
                ! mbuf->ring ||                                                                         // cant cache if no ring
                ! uta_ring_insert( mbuf->ring, mbuf ) ) {                       // or ring is full

                if( mbuf->tp_buf ) {
                        free( mbuf->tp_buf );
                        mbuf->tp_buf = NULL;            // just in case user tries to reuse this mbuf; this will be an NPE
                }

                mbuf->cookie = 0;                       // should signal a bad mbuf (if not reallocated)
                free( mbuf );
        }
}

/*
        This is a wrapper to the real timeout send. We must wrap it now to ensure that
        the call flag and call-id are reset
*/
extern rmr_mbuf_t* rmr_mtosend_msg( void* vctx, rmr_mbuf_t* msg, int max_to ) {
        char* d1;                                                                                                                       // point at the call-id in the header

        if( msg != NULL ) {
                ((uta_mhdr_t *) msg->header)->flags &= ~HFL_CALL_MSG;                   // must ensure call flag is off

                d1 = DATA1_ADDR( msg->header );
                d1[D1_CALLID_IDX] = NO_CALL_ID;                                                                 // must blot out so it doesn't queue on a chute at the other end
        }

        return mtosend_msg( vctx, msg, max_to );
}

/*
        Send with default max timeout as is set in the context.
        See rmr_mtosend_msg() for more details on the parameters.
        See rmr_stimeout() for info on setting the default timeout.
*/
extern rmr_mbuf_t* rmr_send_msg( void* vctx, rmr_mbuf_t* msg ) {
        char* d1;                                                                                                               // point at the call-id in the header

        if( msg != NULL ) {
                ((uta_mhdr_t *) msg->header)->flags &= ~HFL_CALL_MSG;                   // must ensure call flag is off

                d1 = DATA1_ADDR( msg->header );
                d1[D1_CALLID_IDX] = NO_CALL_ID;                                                                         // must blot out so it doesn't queue on a chute at the other end
        }

        return rmr_mtosend_msg( vctx, msg,  -1 );                                                       // retries < 0  uses default from ctx
}

/*
        Return to sender allows a message to be sent back to the endpoint where it originated.

        With SI95 it was thought that the return to sender would be along the same open conneciton
        and thus no table lookup would be needed to open a 'reverse direction' path. However, for
        applications sending at high message rates, returning responses on the same connection
        causes major strife. Thus the decision was made to use the same method as NNG and just
        open a second connection for reverse path.

        We will attempt to use the name in the received message to look up the endpoint. If
        that failes, then we will write on the connection that the message arrived on as a
        falback.

        On success (state is RMR_OK, the caller may use the buffer for another receive operation),
        and on error it can be passed back to this function to retry the send if desired. On error,
        errno will liklely have the failure reason set by the nng send processing.  The following
        are possible values for the state in the message buffer:

        Message states returned:
                RMR_ERR_BADARG - argument (context or msg) was nil or invalid
                RMR_ERR_NOHDR  - message did not have a header
                RMR_ERR_NOENDPT- an endpoint to send the message to could not be determined
                RMR_ERR_SENDFAILED - send failed; errno has nano error code
                RMR_ERR_RETRY   - the reqest failed but should be retried (EAGAIN)

        A nil message as the return value is rare, and generally indicates some kind of horrible
        failure. The value of errno might give a clue as to what is wrong.

        CAUTION:
                Like send_msg(), this is non-blocking and will return the msg if there is an error.
                The caller must check for this and handle it properly.
*/
extern rmr_mbuf_t*  rmr_rts_msg( void* vctx, rmr_mbuf_t* msg ) {
        int                     nn_sock;                        // endpoint socket for send
        uta_ctx_t*      ctx;
        char*           hold_src;                       // we need the original source if send fails
        char*           hold_ip;                        // also must hold original ip
        int                     sock_ok = 0;            // true if we found a valid endpoint socket
        endpoint_t*     ep = NULL;                      // end point to track counts

        if( (ctx = (uta_ctx_t *) vctx) == NULL || msg == NULL ) {               // bad stuff, bail fast
                errno = EINVAL;                                                                                         // if msg is null, this is their clue
                if( msg != NULL ) {
                        msg->state = RMR_ERR_BADARG;
                        msg->tp_state = errno;
                }
                return msg;
        }

        errno = 0;                                                                                                              // at this point any bad state is in msg returned
        if( msg->header == NULL ) {
                rmr_vlog( RMR_VL_ERR, "rmr_send_msg: message had no header\n" );
                msg->state = RMR_ERR_NOHDR;
                msg->tp_state = errno;
                return msg;
        }

        ((uta_mhdr_t *) msg->header)->flags &= ~HFL_CALL_MSG;                   // must ensure call flag is off

        sock_ok = uta_epsock_byname( ctx, (char *) ((uta_mhdr_t *)msg->header)->src, &nn_sock, &ep );   // always try src first
        if( ! sock_ok ) {
                if( (nn_sock = msg->rts_fd) < 0 ) {
                        if( HDR_VERSION( msg->header ) > 2 ) {                                                  // with ver2 the ip is there, try if src name not known
                                sock_ok = uta_epsock_byname( ctx, (char *) ((uta_mhdr_t *)msg->header)->srcip, &nn_sock, &ep  );
                        }
                        if( ! sock_ok ) {
                                msg->state = RMR_ERR_NOENDPT;
                                return msg;
                        }
                }
        }


        msg->state = RMR_OK;                                                                                                                            // ensure it is clear before send
        hold_src = strdup( (char *) ((uta_mhdr_t *)msg->header)->src );                                         // the dest where we're returning the message to
        hold_ip = strdup( (char *) ((uta_mhdr_t *)msg->header)->srcip );                                        // both the src host and src ip
        zt_buf_fill( (char *) ((uta_mhdr_t *)msg->header)->src, ctx->my_name, RMR_MAX_SRC );    // must overlay the source to be ours
        msg = send_msg( ctx, msg, nn_sock, -1 );
        if( msg ) {
                if( ep != NULL ) {
                        switch( msg->state ) {
                                case RMR_OK:
                                        ep->scounts[EPSC_GOOD]++;
                                        break;

                                case RMR_ERR_RETRY:
                                        ep->scounts[EPSC_TRANS]++;
                                        break;

                                default:
                                        // FIX ME uta_fd_failed( nn_sock );                     // we don't have an ep so this requires a look up/search to mark it failed
                                        ep->scounts[EPSC_FAIL]++;
                                        break;
                        }
                }
                zt_buf_fill( (char *) ((uta_mhdr_t *)msg->header)->src, hold_src, RMR_MAX_SRC );        // always replace original source & ip so rts can be called again
                zt_buf_fill( (char *) ((uta_mhdr_t *)msg->header)->srcip, hold_ip, RMR_MAX_SRC );
                msg->flags |= MFL_ADDSRC;                                                                                                               // if msg given to send() it must add source
        }

        free( hold_src );
        free( hold_ip );
        return msg;
}

/*
        If multi-threading call is turned on, this invokes that mechanism with the special call
        id of 1 and a max wait of 1 second.  If multi threaded call is not on, then the original
        behavour (described below) is carried out.  This is safe to use when mt is enabled, but
        the user app is invoking rmr_call() from only one thread, and the caller doesn't need
        a flexible timeout.

        On timeout this function will return a nil pointer. If the original message could not
        be sent without blocking, it will be returned with the RMR_ERR_RETRY set as the status.

        Original behavour:
        Call sends the message based on message routing using the message type, and waits for a
        response message to arrive with the same transaction id that was in the outgoing message.
        If, while wiating for the expected response,  messages are received which do not have the
        desired transaction ID, they are queued. Calls to uta_rcv_msg() will dequeue them in the
        order that they were received.

        Normally, a message struct pointer is returned and msg->state must be checked for RMR_OK
        to ensure that no error was encountered. If the state is UTA_BADARG, then the message
        may be resent (likely the context pointer was nil).  If the message is sent, but no
        response is received, a nil message is returned with errno set to indicate the likley
        issue:
                ETIMEDOUT -- too many messages were queued before reciving the expected response
                ENOBUFS -- the queued message ring is full, messages were dropped
                EINVAL  -- A parameter was not valid
                EAGAIN  -- the underlying message system wsa interrupted or the device was busy;
                                        user should call this function with the message again.

*/
extern rmr_mbuf_t* rmr_call( void* vctx, rmr_mbuf_t* msg ) {
        uta_ctx_t*              ctx;

        if( (ctx = (uta_ctx_t *) vctx) == NULL || msg == NULL ) {               // bad stuff, bail fast
                if( msg != NULL ) {
                        msg->state = RMR_ERR_BADARG;
                }
                return msg;
        }

    return mt_call( vctx, msg, 1, 1000, NULL );         // use the reserved call-id of 1 and wait up to 1 sec
}

/*
        The outward facing receive function. When invoked it will pop the oldest message
        from the receive ring, if any are queued, and return it. If the ring is empty
        then the receive function is invoked to wait for the next message to arrive (blocking).

        If old_msg is provided, it will be populated (avoiding lots of free/alloc cycles). If
        nil, a new one will be allocated. However, the caller should NOT expect to get the same
        struct back (if a queued message is returned the message struct will be different).
*/
extern rmr_mbuf_t* rmr_rcv_msg( void* vctx, rmr_mbuf_t* old_msg ) {
        uta_ctx_t*      ctx;
        rmr_mbuf_t*     qm;                             // message that was queued on the ring

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                errno = EINVAL;
                if( old_msg != NULL ) {
                        old_msg->state = RMR_ERR_BADARG;
                        old_msg->tp_state = errno;
                }
                return old_msg;
        }
        errno = 0;

        return rmr_mt_rcv( ctx, old_msg, -1 );
}

/*
        This allows a timeout based receive for applications unable to implement epoll_wait()
        (e.g. wrappers).
*/
extern rmr_mbuf_t* rmr_torcv_msg( void* vctx, rmr_mbuf_t* old_msg, int ms_to ) {
        uta_ctx_t*      ctx;

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                errno = EINVAL;
                if( old_msg != NULL ) {
                        old_msg->state = RMR_ERR_BADARG;
                        old_msg->tp_state = errno;
                }
                return old_msg;
        }

        return rmr_mt_rcv( ctx, old_msg, ms_to );
}

/*
        DEPRECATED -- this function is not needed in the SI world, and when NNG goes away this will
                too.  This function likely will not behave as expected in SI, and we are pretty sure it
                isn't being used as there was an abort triggering reference to rmr_rcv() until now.

        This blocks until the message with the 'expect' ID is received. Messages which are received
        before the expected message are queued onto the message ring.  The function will return
        a nil message and set errno to ETIMEDOUT if allow2queue messages are received before the
        expected message is received. If the queued message ring fills a nil pointer is returned
        and errno is set to ENOBUFS.

        Generally this will be invoked only by the call() function as it waits for a response, but
        it is exposed to the user application as three is no reason not to.
*/
extern rmr_mbuf_t* rmr_rcv_specific( void* vctx, rmr_mbuf_t* msg, char* expect, int allow2queue ) {
        uta_ctx_t*      ctx;
        int     queued = 0;                             // number we pushed into the ring
        int     exp_len = 0;                    // length of expected ID

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                errno = EINVAL;
                if( msg != NULL ) {
                        msg->state = RMR_ERR_BADARG;
                        msg->tp_state = errno;
                }
                return msg;
        }

        errno = 0;

        if( expect == NULL || ! *expect ) {                             // nothing expected if nil or empty string, just receive
                return rmr_rcv_msg( ctx, msg );
        }

        exp_len = strlen( expect );
        if( exp_len > RMR_MAX_XID ) {
                exp_len = RMR_MAX_XID;
        }
        if( DEBUG ) rmr_vlog( RMR_VL_DEBUG, " rcv_specific waiting for id=%s\n",  expect );

        while( queued < allow2queue ) {
                msg = rmr_rcv_msg( ctx, msg );                                  // hard wait for next
                if( msg != NULL ) {
                        if( DEBUG ) rmr_vlog( RMR_VL_DEBUG, " rcv_specific checking message; queued=%d allowed=%d state=%d\n",  queued, allow2queue, msg->state );
                        if( msg->state == RMR_OK ) {
                                if( memcmp( msg->xaction, expect, exp_len ) == 0 ) {                    // got it -- return it
                                        if( DEBUG ) rmr_vlog( RMR_VL_DEBUG, " rcv_specific matched (%s); %d messages were queued\n", msg->xaction, queued );
                                        return msg;
                                }

                                if( ! uta_ring_insert( ctx->mring, msg ) ) {                                    // just queue, error if ring is full
                                        if( DEBUG > 1 ) rmr_vlog( RMR_VL_DEBUG, " rcv_specific ring is full\n" );
                                        errno = ENOBUFS;
                                        return NULL;
                                }

                                if( DEBUG ) rmr_vlog( RMR_VL_DEBUG, " rcv_specific queued message type=%d\n", msg->mtype );
                                queued++;
                                msg = NULL;
                        }
                }
        }

        if( DEBUG ) rmr_vlog( RMR_VL_DEBUG, " rcv_specific timeout waiting for %s\n", expect );
        errno = ETIMEDOUT;
        return NULL;
}

/*
        Set send timeout. The value time is assumed to be milliseconds.  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 1K retries before returning,
        but _without_ issuing a sleep.  If timeout is > 1, then RMr will issue a sleep (1us)
        after every 1K send attempts until the "time" value is reached. Retries are abandoned
        if NNG returns anything other than EAGAIN or EINTER is returned.

        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.

        Returns -1 if the context was invalid; RMR_OK otherwise.
*/
extern int rmr_set_stimeout( void* vctx, int time ) {
        uta_ctx_t*      ctx;

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                return -1;
        }

        if( time < 0 ) {
                time = 0;
        }

        ctx->send_retries = time;
        return RMR_OK;
}

/*
        Set receive timeout -- not supported in nng implementation

        CAUTION:  this is not supported as they must be set differently (between create and open) in NNG.
*/
extern int rmr_set_rtimeout( void* vctx, int time ) {
        rmr_vlog( RMR_VL_WARN, "Current underlying transport mechanism (SI) does not support rcv timeout; not set\n" );
        return 0;
}


/*
        This is the actual init workhorse. The user visible function meerly ensures that the
        calling programme does NOT set any internal flags that are supported, and then
        invokes this.  Internal functions (the route table collector) which need additional
        open ports without starting additional route table collectors, will invoke this
        directly with the proper flag.

        CAUTION:   The max_ibm (max inbound message) size is the supplied user max plus the lengths
                                that we know about. The _user_ should ensure that the supplied length also
                                includes the trace data length maximum as they are in control of that.
*/
static void* init(  char* uproto_port, int def_msg_size, int flags ) {
        static  int announced = 0;
        uta_ctx_t*      ctx = NULL;
        char    bind_info[256];                         // bind info
        char*   proto = "tcp";                          // pointer into the proto/port string user supplied
        char*   port;                                           // pointer into the proto_port buffer at the port value
        char*   interface = NULL;                       // interface to bind to (from RMR_BIND_IF, 0.0.0.0 if not defined)
        char*   proto_port;
        char    wbuf[1024];                                     // work buffer
        char*   tok;                                            // pointer at token in a buffer
        char*   tok2;
        int             static_rtc = 0;                         // if rtg env var is < 1, then we set and don't listen on a port
        int             state;
        int             i;
        int             old_vlevel;

        old_vlevel = rmr_vlog_init();                   // initialise and get the current level

        if( ! announced ) {
                rmr_set_vlevel( RMR_VL_INFO );          // we WILL announce our version
                rmr_vlog( RMR_VL_INFO, "ric message routing library on SI95/g mv=%d flg=%02x (%s %s.%s.%s built: %s)\n",
                        RMR_MSG_VER, flags, QUOTE_DEF(GIT_ID), QUOTE_DEF(MAJOR_VER), QUOTE_DEF(MINOR_VER), QUOTE_DEF(PATCH_VER), __DATE__ );
                announced = 1;

                rmr_set_vlevel( old_vlevel );           // return logging to the desired state
                uta_dump_env();                                                 // spit out environment settings meaningful to us if in info mode
        }

        errno = 0;
        if( uproto_port == NULL ) {
                proto_port = strdup( DEF_COMM_PORT );
        } else {
                proto_port = strdup( uproto_port );             // so we can modify it
        }

        if ( proto_port == NULL ){
                errno = ENOMEM;
                return NULL;
        }

        if( (ctx = (uta_ctx_t *) malloc( sizeof( uta_ctx_t ) )) == NULL ) {
                errno = ENOMEM;
                goto err;
        }
        memset( ctx, 0, sizeof( uta_ctx_t ) );

        if( DEBUG ) rmr_vlog( RMR_VL_DEBUG, " rmr_init: allocating 266 rivers\n" );
        ctx->nrivers = 256;                                                             // number of input flows we'll manage
        ctx->rivers = (river_t *) malloc( sizeof( river_t ) * ctx->nrivers );
        memset( ctx->rivers, 0, sizeof( river_t ) * ctx->nrivers );
        for( i = 0; i < ctx->nrivers; i++ ) {
                ctx->rivers[i].state = RS_NEW;                          // force allocation of accumulator on first received packet
        }

        ctx->send_retries = 1;                                                  // default is not to sleep at all; RMr will retry about 10K times before returning
        ctx->d1_len = 4;                                                                // data1 space in header -- 4 bytes for now
        ctx->max_ibm = def_msg_size < 1024 ? 1024 : def_msg_size;                                       // larger than their request doesn't hurt
        ctx->max_ibm += sizeof( uta_mhdr_t ) + ctx->d1_len + ctx->d2_len + TP_HDR_LEN + 64;             // add in header size, transport hdr, and a bit of fudge

        ctx->mring = uta_mk_ring( 4096 );                               // message ring is always on for si
        ctx->zcb_mring = uta_mk_ring( 128 );                    // zero copy buffer mbuf ring to reduce malloc/free calls

        if( ! (flags & RMRFL_NOLOCK) ) {                                // user did not specifically ask that it be off; turn it on
                uta_ring_config( ctx->mring, RING_RLOCK );                      // concurrent rcv calls require read lock
                uta_ring_config( ctx->zcb_mring, RING_WLOCK );          // concurrent free calls from userland require write lock
                uta_ring_config( ctx->zcb_mring, RING_FRLOCK );         // concurrent message allocatieon calls from userland require read lock, but can be fast
        } else {
                rmr_vlog( RMR_VL_INFO, "receive ring locking disabled by user application\n" );
        }
        init_mtcall( ctx );                                                             // set up call chutes
        fd2ep_init( ctx );                                                              // initialise the fd to endpoint sym tab


        ctx->max_plen = RMR_MAX_RCV_BYTES;                              // max user payload lengh
        if( def_msg_size > 0 ) {
                ctx->max_plen = def_msg_size;
        }

        ctx->si_ctx = SIinitialise( SI_OPT_FG );                // FIX ME: si needs to streamline and drop fork/bg stuff
        if( ctx->si_ctx == NULL ) {
                rmr_vlog( RMR_VL_CRIT, "unable to initialise SI95 interface\n" );
                goto err;
        }

        if( (port = strchr( proto_port, ':' )) != NULL ) {
                if( port == proto_port ) {              // ":1234" supplied; leave proto to default and point port correctly
                        port++;
                } else {
                        *(port++) = 0;                  // term proto string and point at port string
                        proto = proto_port;             // user supplied proto so point at it rather than default
                }
        } else {
                port = proto_port;                      // assume something like "1234" was passed
        }

        if( (tok = getenv( ENV_RTG_PORT )) != NULL && atoi( tok ) < 0 ) {       // must check here -- if < 0 then we just start static file 'listener'
                static_rtc = 1;
        }

        if( (tok = getenv( ENV_SRC_ID )) != NULL ) {                                                    // env var overrides what we dig from system
                tok = strdup( tok );                                    // something we can destroy
                if( *tok == '[' ) {                                             // we allow an ipv6 address here
                        tok2 = strchr( tok, ']' ) + 1;          // we will chop the port (...]:port) if given
                } else {
                        tok2 = strchr( tok, ':' );                      // find :port if there so we can chop
                }
                if( tok2  && *tok2 ) {                                  // if it's not the end of string marker
                        *tok2 = 0;                                                      // make it so
                }

                snprintf( wbuf, RMR_MAX_SRC, "%s", tok );
                free( tok );
        } else {
                if( (gethostname( wbuf, sizeof( wbuf ) )) != 0 ) {
                        rmr_vlog( RMR_VL_CRIT, "rmr_init: cannot determine localhost name: %s\n", strerror( errno ) );
                        goto err;
                }
                if( (tok = strchr( wbuf, '.' )) != NULL ) {
                        *tok = 0;                                                                       // we don't keep domain portion
                }
        }

        ctx->my_name = (char *) malloc( sizeof( char ) * RMR_MAX_SRC );
        if( snprintf( ctx->my_name, RMR_MAX_SRC, "%s:%s", wbuf, port ) >= RMR_MAX_SRC ) {                       // our registered name is host:port
                rmr_vlog( RMR_VL_CRIT, "rmr_init: hostname + port must be less than %d characters; %s:%s is not\n", RMR_MAX_SRC, wbuf, port );
                errno = EINVAL;
                goto err;
        }

        if( (tok = getenv( ENV_NAME_ONLY )) != NULL ) {
                if( atoi( tok ) > 0 ) {
                        flags |= RMRFL_NAME_ONLY;                                       // don't allow IP addreess to go out in messages
                }
        }

        ctx->ip_list = mk_ip_list( port );                              // suss out all IP addresses we can find on the box, and bang on our port for RT comparisons
        if( flags & RMRFL_NAME_ONLY ) {
                ctx->my_ip = strdup( ctx->my_name );                    // user application or env var has specified that IP address is NOT sent out, use name
        } else {
                ctx->my_ip = get_default_ip( ctx->ip_list );    // and (guess) at what should be the default to put into messages as src
                if( ctx->my_ip == NULL ) {
                        rmr_vlog( RMR_VL_WARN, "rmr_init: default ip address could not be sussed out, using name\n" );
                        ctx->my_ip = strdup( ctx->my_name );            // if we cannot suss it out, use the name rather than a nil pointer
                }
        }
        if( DEBUG ) rmr_vlog( RMR_VL_DEBUG, " default ip address: %s\n", ctx->my_ip );

        if( (tok = getenv( ENV_WARNINGS )) != NULL ) {
                if( *tok == '1' ) {
                        ctx->flags |= CTXFL_WARN;                                       // turn on some warnings (not all, just ones that shouldn't impact performance)
                }
        }


        if( (interface = getenv( ENV_BIND_IF )) == NULL ) {
                interface = "0.0.0.0";
        }

        snprintf( bind_info, sizeof( bind_info ), "%s:%s", interface, port );           // FIXME -- si only supports 0.0.0.0 by default
        if( (state = SIlistener( ctx->si_ctx, TCP_DEVICE, bind_info )) < 0 ) {
                rmr_vlog( RMR_VL_CRIT, "rmr_init: unable to start si listener for %s: %s\n", bind_info, strerror( errno ) );
                goto err;
        }

                                                                                                // finish all flag setting before threads to keep helgrind quiet
        ctx->flags |= CFL_MTC_ENABLED;                          // for SI threaded receiver is the only way


        // ---------------- setup for route table collector before invoking ----------------------------------
        ctx->rtgate = (pthread_mutex_t *) malloc( sizeof( *ctx->rtgate ) );             // single mutex required to gate access to moving rtables
        if( ctx->rtgate != NULL ) {
                pthread_mutex_init( ctx->rtgate, NULL );
        }

        ctx->ephash = rmr_sym_alloc( 129 );                                     // host:port to ep symtab exists outside of any route table
        if( ctx->ephash == NULL ) {
                rmr_vlog( RMR_VL_CRIT, "rmr_init: unable to allocate ep hash\n" );
                errno = ENOMEM;
                goto err;
        }

        ctx->rtable = rt_clone_space( ctx, NULL, NULL, 0 );     // create an empty route table so that wormhole/rts calls can be used
        if( flags & RMRFL_NOTHREAD ) {                                          // no thread prevents the collector start for very special cases
                ctx->rtable_ready = 1;                                                  // route based sends will always fail, but rmr is ready for the non thread case
        } else {
                ctx->rtable_ready = 0;                                                  // no sends until a real route table is loaded in the rtc thread

                if( static_rtc ) {
                        rmr_vlog( RMR_VL_INFO, "rmr_init: file based route table only for context on port %s\n", uproto_port );
                        if( pthread_create( &ctx->rtc_th,  NULL, rtc_file, (void *) ctx ) ) {   // kick the rt collector thread as just file reader
                                rmr_vlog( RMR_VL_WARN, "rmr_init: unable to start static route table collector thread: %s", strerror( errno ) );
                        }
                } else {
                        rmr_vlog( RMR_VL_INFO, "rmr_init: dynamic route table for context on port %s\n", uproto_port );
                        if( pthread_create( &ctx->rtc_th,  NULL, rtc, (void *) ctx ) ) {        // kick the real rt collector thread
                                rmr_vlog( RMR_VL_WARN, "rmr_init: unable to start dynamic route table collector thread: %s", strerror( errno ) );
                        }
                }
        }

        if( pthread_create( &ctx->mtc_th,  NULL, mt_receive, (void *) ctx ) ) {         // so kick it
                rmr_vlog( RMR_VL_WARN, "rmr_init: unable to start multi-threaded receiver: %s", strerror( errno ) );
        }

        free( proto_port );
        return (void *) ctx;

err:
        free( proto_port );
        free_ctx( ctx );
        return NULL;
}

/*
        Initialise the message routing environment. Flags are one of the UTAFL_
        constants. Proto_port is a protocol:port string (e.g. tcp:1234). If default protocol
        (tcp) to be used, then :port is all that is needed.

        At the moment it seems that TCP really is the only viable protocol, but
        we'll allow flexibility.

        The return value is a void pointer which must be passed to most uta functions. On
        error, a nil pointer is returned and errno should be set.

        Flags:
                No user flags supported (needed) at the moment, but this provides for extension
                without drastically changing anything. The user should invoke with RMRFL_NONE to
                avoid any misbehavour as there are internal flags which are suported
*/
extern void* rmr_init( char* uproto_port, int def_msg_size, int flags ) {
        return init( uproto_port, def_msg_size, flags & UFL_MASK  );            // ensure any internal flags are off
}

/*
        This sets the default trace length which will be added to any message buffers
        allocated.  It can be set at any time, and if rmr_set_trace() is given a
        trace len that is different than the default allcoated in a message, the message
        will be resized.

        Returns 0 on failure and 1 on success. If failure, then errno will be set.
*/
extern int rmr_init_trace( void* vctx, int tr_len ) {
        uta_ctx_t* ctx;

        errno = 0;
        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                errno = EINVAL;
                return 0;
        }

        ctx->trace_data_len = tr_len;
        return 1;
}

/*
        Return true if routing table is initialised etc. and app can send/receive.
*/
extern int rmr_ready( void* vctx ) {
        uta_ctx_t *ctx;

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                return FALSE;
        }

        return ctx->rtable_ready;
}

/*
        This returns the message queue ring's filedescriptor which can be used for
        calls to epoll.  The user shouild NOT read, write, or close the fd.

        Returns the file descriptor or -1 on error.
*/
extern int rmr_get_rcvfd( void* vctx ) {
        uta_ctx_t* ctx;
        int state;

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                return -1;
        }

        return uta_ring_getpfd( ctx->mring );
}


/*
        Clean up things.

        There isn't an si_flush() per se, but we can pause, generate
        a context switch, which should allow the last sent buffer to
        flow. There isn't exactly an nng_term/close either, so there
        isn't much we can do.
*/
extern void rmr_close( void* vctx ) {
        uta_ctx_t *ctx;

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                return;
        }

        ctx->shutdown = 1;

        SItp_stats( ctx->si_ctx );                      // dump some interesting stats

        // FIX ME -- how to we turn off si; close all sessions etc?
        //SIclose( ctx->nn_sock );

}


// ----- multi-threaded call/receive support -------------------------------------------------

/*
        Blocks on the receive ring chute semaphore and then reads from the ring
        when it is tickled.  If max_wait is -1 then the function blocks until
        a message is ready on the ring. Else max_wait is assumed to be the number
        of millaseconds to wait before returning a timeout message.
*/
extern rmr_mbuf_t* rmr_mt_rcv( void* vctx, rmr_mbuf_t* mbuf, int max_wait ) {
        uta_ctx_t*      ctx;
        chute_t*        chute;
        struct timespec ts;                     // time info if we have a timeout
        long    new_ms;                         // adjusted mu-sec
        long    seconds = 0;            // max wait seconds
        long    nano_sec;                       // max wait xlated to nano seconds
        int             state;
        rmr_mbuf_t*     ombuf;                  // mbuf user passed; if we timeout we return state here

        if( (ctx = (uta_ctx_t *) vctx) == NULL ) {
                errno = EINVAL;
                if( mbuf ) {
                        mbuf->state = RMR_ERR_BADARG;
                        mbuf->tp_state = errno;
                }
                return mbuf;
        }

        ombuf = mbuf;           // if we timeout we must return original msg with status, so save it

        chute = &ctx->chutes[0];                                        // chute 0 used only for its semaphore

        if( max_wait == 0 ) {                                           // one shot poll; handle wihtout sem check as that is SLOW!
                if( (mbuf = (rmr_mbuf_t *) uta_ring_extract( ctx->mring )) != NULL ) {                  // pop if queued
                        clock_gettime( CLOCK_REALTIME, &ts );                   // pass current time as expriry time
                        sem_timedwait( &chute->barrier, &ts );                  // must pop the count (ring is locking so if we got a message we can pop)
                        if( ombuf ) {
                                rmr_free_msg( ombuf );                          // can't reuse, caller's must be trashed now
                        }
                } else {
                        mbuf = ombuf;                                           // return original if it was given with timeout status
                        if( ombuf != NULL ) {
                                mbuf->state = RMR_ERR_TIMEOUT;                  // preset if for failure
                                mbuf->len = 0;
                        }
                }

                if( mbuf != NULL ) {
                        mbuf->flags |= MFL_ADDSRC;               // turn on so if user app tries to send this buffer we reset src
                }

                return mbuf;
        }

        if( ombuf ) {
                ombuf->state = RMR_ERR_TIMEOUT;                 // preset if for failure
                ombuf->len = 0;
        }
        if( max_wait > 0 ) {
                clock_gettime( CLOCK_REALTIME, &ts );   // sem timeout based on clock, not a delta

                if( max_wait > 999 ) {
                        seconds = max_wait / 1000;
                        max_wait -= seconds * 1000;
                        ts.tv_sec += seconds;
                }
                if( max_wait > 0 ) {
                        nano_sec = max_wait * 1000000;
                        ts.tv_nsec += nano_sec;
                        if( ts.tv_nsec > 999999999 ) {
                                ts.tv_nsec -= 999999999;
                                ts.tv_sec++;
                        }
                }

                seconds = 1;                                                                                                    // use as flag later to invoked timed wait
        }

        errno = EINTR;
        state = -1;
        while( state < 0 && errno == EINTR ) {
                if( seconds ) {
                        state = sem_timedwait( &chute->barrier, &ts );                          // wait for msg or timeout
                } else {
                        state = sem_wait( &chute->barrier );
                }
        }

        if( state < 0 ) {
                mbuf = ombuf;                           // return caller's buffer if they passed one in
        } else {
                errno = 0;                                              // interrupted call state could be left; clear
                if( DEBUG ) rmr_vlog( RMR_VL_DEBUG, " mt_rcv extracting from normal ring\n" );
                if( (mbuf = (rmr_mbuf_t *) uta_ring_extract( ctx->mring )) != NULL ) {                  // pop if queued
                        mbuf->state = RMR_OK;
                        mbuf->flags |= MFL_ADDSRC;               // turn on so if user app tries to send this buffer we reset src

                        if( ombuf ) {
                                rmr_free_msg( ombuf );                                  // we cannot reuse as mbufs are queued on the ring
                        }
                } else {
                        errno = ETIMEDOUT;
                        mbuf = ombuf;                           // no buffer, return user's if there
                }
        }

        if( mbuf ) {
                mbuf->tp_state = errno;
        }
        return mbuf;
}




/*
        This is the work horse for the multi-threaded call() function. It supports
        both the rmr_mt_call() and the rmr_wormhole wh_call() functions. See the description
        for for rmr_mt_call() modulo the caveat below.

        If endpoint is given, then we assume that we're not doing normal route table
        routing and that we should send directly to that endpoint (probably worm
        hole).
*/
static rmr_mbuf_t* mt_call( void* vctx, rmr_mbuf_t* mbuf, int call_id, int max_wait, endpoint_t* ep ) {
        rmr_mbuf_t* ombuf;                      // original mbuf passed in
        uta_ctx_t*      ctx;
        uta_mhdr_t*     hdr;                    // header in the transport buffer
        chute_t*        chute;
        unsigned char*  d1;                     // d1 data in header
        struct timespec ts;                     // time info if we have a timeout
        long    new_ms;                         // adjusted mu-sec
        long    seconds = 0;            // max wait seconds
        long    nano_sec;                       // max wait xlated to nano seconds
        int             state;

        errno = EINVAL;
        if( (ctx = (uta_ctx_t *) vctx) == NULL || mbuf == NULL ) {
                if( mbuf ) {
                        mbuf->tp_state = errno;
                        mbuf->state = RMR_ERR_BADARG;
                }
                return mbuf;
        }

        if( ! (ctx->flags & CFL_MTC_ENABLED) ) {
                mbuf->state = RMR_ERR_NOTSUPP;
                mbuf->tp_state = errno;
                return mbuf;
        }

        ombuf = mbuf;                                                                                                   // save to return timeout status with

        chute = &ctx->chutes[call_id];
        if( chute->mbuf != NULL ) {                                                                             // probably a delayed message that wasn't dropped
                rmr_free_msg( chute->mbuf );
                chute->mbuf = NULL;
        }

        hdr = (uta_mhdr_t *) mbuf->header;
        hdr->flags |= HFL_CALL_MSG;                                                                             // must signal this sent with a call
        memcpy( chute->expect, mbuf->xaction, RMR_MAX_XID );                    // xaction that we will wait for
        d1 = DATA1_ADDR( hdr );
        d1[D1_CALLID_IDX] = (unsigned char) call_id;                                    // set the caller ID for the response
        mbuf->flags |= MFL_NOALLOC;                                                                             // send message without allocating a new one (expect nil from mtosend

        if( max_wait >= 0 ) {
                clock_gettime( CLOCK_REALTIME, &ts );

                if( max_wait > 999 ) {
                        seconds = max_wait / 1000;
                        max_wait -= seconds * 1000;
                        ts.tv_sec += seconds;
                }
                if( max_wait > 0 ) {
                        nano_sec = max_wait * 1000000;
                        ts.tv_nsec += nano_sec;
                        if( ts.tv_nsec > 999999999 ) {
                                ts.tv_nsec -= 999999999;
                                ts.tv_sec++;
                        }
                }

                seconds = 1;                                                                            // use as flag later to invoked timed wait
        }

        if( ep == NULL ) {                                                                              // normal routing
                mbuf = mtosend_msg( ctx, mbuf, 0 );                                     // use internal function so as not to strip call-id; should be nil on success!
        } else {
                mbuf = send_msg( ctx, mbuf, ep->nn_sock, -1 );
        }
        if( mbuf ) {
                if( mbuf->state != RMR_OK ) {
                        mbuf->tp_state = errno;
                        return mbuf;                                                                    // timeout or unable to connect or no endpoint are most likely issues
                }
        }

        state = 0;
        errno = 0;
        while( chute->mbuf == NULL && ! errno ) {
                if( seconds ) {
                        state = sem_timedwait( &chute->barrier, &ts );                          // wait for msg or timeout
                } else {
                        state = sem_wait( &chute->barrier );
                }

                if( state < 0 && errno == EINTR ) {                                                             // interrupted go back and wait; all other errors cause exit
                        errno = 0;
                }

                if( chute->mbuf != NULL ) {                                                                             // offload receiver thread and check xaction buffer here
                        if( memcmp( chute->expect, chute->mbuf->xaction, RMR_MAX_XID ) != 0 ) {
                                rmr_free_msg( chute->mbuf );
                                chute->mbuf = NULL;
                                errno = 0;
                        }
                }
        }

        if( state < 0 ) {
                return NULL;                                    // leave errno as set by sem wait call
        }

        mbuf = chute->mbuf;
        if( mbuf != NULL ) {
                mbuf->state = RMR_OK;
        }
        chute->mbuf = NULL;

        return mbuf;
}

/*
        Accept a message buffer and caller ID, send the message and then wait
        for the receiver to tickle the semaphore letting us know that a message
        has been received. The call_id is a value between 2 and 255, inclusive; if
        it's not in this range an error will be returned. Max wait is the amount
        of time in millaseconds that the call should block for. If 0 is given
        then no timeout is set.

        If the mt_call feature has not been initialised, then the attempt to use this
        funciton will fail with RMR_ERR_NOTSUPP

        If no matching message is received before the max_wait period expires, a
        nil pointer is returned, and errno is set to ETIMEOUT. If any other error
        occurs after the message has been sent, then a nil pointer is returned
        with errno set to some other value.

        This is now just an outward facing wrapper so we can support wormhole calls.
*/
extern rmr_mbuf_t* rmr_mt_call( void* vctx, rmr_mbuf_t* mbuf, int call_id, int max_wait ) {

        // must vet call_id here, all others vetted by workhorse mt_call() function
        if( call_id > MAX_CALL_ID || call_id < 2 ) {            // 0 and 1 are reserved; user app cannot supply them
                if( mbuf != NULL ) {
                        mbuf->state = RMR_ERR_BADARG;
                        mbuf->tp_state = EINVAL;
                }
                return mbuf;
        }

        return mt_call( vctx, mbuf, call_id, max_wait, NULL );
}


/*
        Given an existing message buffer, reallocate the payload portion to
        be at least new_len bytes.  The message header will remain such that
        the caller may use the rmr_rts_msg() function to return a payload
        to the sender.

        The mbuf passed in may or may not be reallocated and the caller must
        use the returned pointer and should NOT assume that it can use the
        pointer passed in with the exceptions based on the clone flag.

        If the clone flag is set, then a duplicated message, with larger payload
        size, is allocated and returned.  The old_msg pointer in this situation is
        still valid and must be explicitly freed by the application. If the clone
        message is not set (0), then any memory management of the old message is
        handled by the function.

        If the copy flag is set, the contents of the old message's payload is
        copied to the reallocated payload.  If the flag is not set, then the
        contents of the payload is undetermined.
*/
extern rmr_mbuf_t* rmr_realloc_payload( rmr_mbuf_t* old_msg, int new_len, int copy, int clone ) {
        if( old_msg == NULL ) {
                return NULL;
        }

        return realloc_payload( old_msg, new_len, copy, clone );        // message allocation is transport specific, so this is a passthrough
}

/*
        Enable low latency things in the transport (when supported).
*/
extern void rmr_set_low_latency( void* vctx ) {
        uta_ctx_t*      ctx;

        if( (ctx = (uta_ctx_t *) vctx) != NULL ) {
                if( ctx->si_ctx != NULL ) {
                        SIset_tflags( ctx->si_ctx, SI_TF_NODELAY );
                }
        }
}

/*
        Turn on fast acks.
*/
extern void rmr_set_fack( void* vctx ) {
        uta_ctx_t*      ctx;

        if( (ctx = (uta_ctx_t *) vctx) != NULL ) {
                if( ctx->si_ctx != NULL ) {
                        SIset_tflags( ctx->si_ctx, SI_TF_FASTACK );
                }
        }
}