/*

 * Copyright (C) 2017 OpenSIPS Project

 *

 * This file is part of opensips, a free SIP server.

 *

 * opensips is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version

 *

 * opensips is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include <string.h>

#include <errno.h>

#include <sys/types.h>

#include <sys/socket.h>

#include "ipc.h"

#include "dprint.h"

#include "profiling.h"

#include "mem/mem.h"

#include <fcntl.h>

#define IPC_HANDLER_NAME_MAX  32

typedef struct _ipc_handler {

  /* handler function */

  ipc_handler_f *func;

  /* same name/description, null terminated */

  char name[IPC_HANDLER_NAME_MAX+1];

} ipc_handler;

typedef struct _ipc_job {

  /* the ID (internal) of the process sending the job */

  unsigned short snd_proc;

  /* the job's handler type */

  ipc_handler_type handler_type;

  /* the payload of the job, just pointers */

  void *payload1;

  void *payload2;

} ipc_job;

static ipc_handler *ipc_handlers = NULL;

static unsigned int ipc_handlers_no = 0;

/* shared IPC support: dispatching a job to a random OpenSIPS worker */

static int ipc_shared_pipe[2];

/* IPC type used for RPC - a self registered type */

static ipc_handler_type ipc_rpc_type = 0;

/* FD (pipe) used for dispatching IPC jobs between all processes (1 to any) */

int ipc_shared_fd_read;

int init_ipc(void)

{

  int optval;

  /* create the pipe for dispatching the timer jobs */

  if (pipe(ipc_shared_pipe) != 0) {

    LM_ERR("failed to create ipc pipe (%s)!\n", strerror(errno));

    return -1;

  }

  /* make reading fd non-blocking */

  optval = fcntl(ipc_shared_pipe[0], F_GETFL);

  if (optval == -1) {

    LM_ERR("fcntl failed: (%d) %s\n", errno, strerror(errno));

    return -1;

  }

  if (fcntl(ipc_shared_pipe[0], F_SETFL, optval|O_NONBLOCK) == -1) {

    LM_ERR("set non-blocking failed: (%d) %s\n", errno, strerror(errno));

    return -1;

  }

  ipc_shared_fd_read = ipc_shared_pipe[0];

  /* self-register the IPC type for RPC */

  ipc_rpc_type = ipc_register_handler( NULL, "RPC");

  if (ipc_bad_handler_type(ipc_rpc_type)) {

    LM_ERR("failed to self register RPC type\n");

    return -1;

  }

  /* we are all set */

  return 0;

}

int create_ipc_pipes( int proc_no )

{

  int optval, i;

  for( i=0 ; i<proc_no ; i++ ) {

    if (pipe(pt[i].ipc_pipe_holder)<0) {

      LM_ERR("failed to create IPC pipe for process %d, err %d/%s\n",

        i, errno, strerror(errno));

      return -1;

    }

    /* make writing fd non-blocking */

    optval = fcntl( pt[i].ipc_pipe_holder[1], F_GETFL);

    if (optval == -1) {

      LM_ERR("fcntl failed: (%d) %s\n", errno, strerror(errno));

      return -1;

    }

    if (fcntl(pt[i].ipc_pipe_holder[1], F_SETFL, optval|O_NONBLOCK) == -1){

      LM_ERR("set non-blocking write failed: (%d) %s\n",

        errno, strerror(errno));

      return -1;

    }

    if (pipe(pt[i].ipc_sync_pipe_holder)<0) {

      LM_ERR("failed to create IPC sync pipe for process %d, "

        "err %d/%s\n", i, errno, strerror(errno));

      return -1;

    }

    /* make writing fd non-blocking */

    optval = fcntl( pt[i].ipc_sync_pipe_holder[1], F_GETFL);

    if (optval == -1) {

      LM_ERR("fcntl failed: (%d) %s\n", errno, strerror(errno));

      return -1;

    }

    if (fcntl(pt[i].ipc_sync_pipe_holder[1], F_SETFL, optval|O_NONBLOCK) == -1){

      LM_ERR("set non-blocking write failed: (%d) %s\n",

        errno, strerror(errno));

      return -1;

    }

  }

  return 0;

}

ipc_handler_type ipc_register_handler( ipc_handler_f *hdl, char *name)

{

  ipc_handler *new;

  /* allocate an n+1 new buffer to accomodate the new handler */

  new = (ipc_handler*)

    pkg_malloc( (ipc_handlers_no+1)*sizeof(ipc_handler) );

  if (new==NULL) {

    LM_ERR("failed to alloctes IPC handler array for size %d\n",

      ipc_handlers_no+1);

    return -1;

  }

  /* copy previous records, if any */

  if (ipc_handlers) {

    memcpy( new, ipc_handlers, ipc_handlers_no*sizeof(ipc_handler) );

    pkg_free( ipc_handlers );

  }

  /* copy handler function */

  new[ipc_handlers_no].func = hdl;

  /* copy the name, trunkate it needed, but keep it null terminated */

  strncpy( new[ipc_handlers_no].name , name, IPC_HANDLER_NAME_MAX);

  new[ipc_handlers_no].name[IPC_HANDLER_NAME_MAX] = 0;

  ipc_handlers = new;

  LM_DBG("IPC type %d [%s] registered with handler %p\n",

    ipc_handlers_no, ipc_handlers[ipc_handlers_no].name, hdl );

  return ipc_handlers_no++;

}

static inline int __ipc_send_job(int fd, int dst_proc, ipc_handler_type type,

                        void *payload1, void *payload2)

{

  ipc_job job;

  int n;

  // FIXME - we should check if the destination process really listens

  // for read, otherwise we may end up filling in the pipe and block

  memset(&job, 0, sizeof job);

  job.snd_proc = (short)process_no;

  job.handler_type = type;

  job.payload1 = payload1;

  job.payload2 = payload2;

again:

  /* The per-proc IPC write fds are sent to non-blocking (to be sure we

   * do not escalate into a global blocking if a single process got stuck.

   * In such care the EAGAIN or EWOULDBLOCK will be thrown and we will

   * handle as generic error, nothing special to do.

   */

  n = write(fd, &job, sizeof(job) );

  if (n<0) {

    if (errno==EAGAIN || errno==EWOULDBLOCK)

      LM_CRIT("blocking detected while sending job type %d[%s] on %d "

        " to proc id %d/%d [%s]\n", type, ipc_handlers[type].name, fd,

        dst_proc, (dst_proc==-1)?-1:pt[dst_proc].pid ,

        (dst_proc==-1)?"n/a":pt[dst_proc].desc);

    else if (errno==EINTR)

      goto again;

    else

      LM_ERR("sending job type %d[%s] on %d failed: %s\n",

        type, ipc_handlers[type].name, fd, strerror(errno));

    return -1;

  }

  return 0;

}

int ipc_send_job(int dst_proc, ipc_handler_type type, void *payload)

{

  return __ipc_send_job(IPC_FD_WRITE(dst_proc), dst_proc,

    type, payload, NULL);

}

int ipc_dispatch_job(ipc_handler_type type, void *payload)

{

  return __ipc_send_job(ipc_shared_pipe[1], -1, type, payload, NULL);

}

int ipc_send_rpc(int dst_proc, ipc_rpc_f *rpc, void *param)

{

  /* wait for the write IPC FD to be available, for a maximum 200ms */

  busy_wait_for(IPC_FD_WRITE(dst_proc) >= 0, 200000, 10);

  return __ipc_send_job(IPC_FD_WRITE(dst_proc), dst_proc,

    ipc_rpc_type, rpc, param);

}

int ipc_send_rpc_all(ipc_rpc_f *rpc, void *param)

{

  int p, count = 0;

  for (p = 1; p < counted_max_processes; p++) {

    if (pt[p].flags & OSS_PROC_NO_IPC)

      continue;

    if (p == process_no) {

      /* run line the cmd for the proc itself */

      rpc(process_no, param);

      count++;

    } else {

      if (ipc_send_rpc(p, rpc, param) >= 0)

        count++;

    }

  }

  return count;

}

int ipc_dispatch_rpc( ipc_rpc_f *rpc, void *param)

{

  return __ipc_send_job(ipc_shared_pipe[1], -1, ipc_rpc_type, rpc, param);

}

int ipc_send_sync_reply(int dst_proc, void *param)

{

  int n;

again:

  n = write(IPC_FD_SYNC_WRITE(dst_proc), &param, sizeof(param));

  if (n<0) {

    if (errno==EINTR)

      goto again;

    LM_ERR("sending sync rpc %d[%s]\n", errno, strerror(errno));

    return -1;

  }

  return 0;

}

int ipc_recv_sync_reply(void **param)

{

  void *ret;

  int n;

again:

  n = read(IPC_FD_SYNC_READ_SELF, &ret, sizeof(ret));

  if (n < sizeof(*ret)) {

    if (errno == EINTR)

      goto again;

    /* if we got here, it's definitely an error, because the socket is

     * blocking, so we can't read partial messages */

    LM_ERR("read failed:[%d] %s\n", errno, strerror(errno));

    return -1;

  }

  *param = ret;

  return 0;

}

int ipc_running_rpc_job;

void ipc_handle_job(int fd)

{

  ipc_job job;

  int n;

  /* read one IPC job from the pipe; even if the read is blocking,

   * we are here triggered from the reactor, on a READ event, so 

   * we shouldn;t ever block */

  n = read(fd, &job, sizeof(job) );

  if (n==-1) {

    if (errno==EAGAIN || errno==EINTR || errno==EWOULDBLOCK )

      return;

    LM_ERR("read failed:[%d] %s\n", errno, strerror(errno));

    return;

  }

  /* suppress the E_CORE_LOG event for the below log while handling

   * the event itself */

  suppress_proc_log_event();

  LM_DBG("received job type %d[%s] from process %d\n",

    job.handler_type, ipc_handlers[job.handler_type].name, job.snd_proc);

  reset_proc_log_event();

  profiling_proc_enter( LEVEL_SIP, ipc_handlers[job.handler_type].name, 0 );

  /* custom handling for RPC type */

  if (job.handler_type==ipc_rpc_type) {

    ipc_running_rpc_job = 1;

    ((ipc_rpc_f*)job.payload1)( job.snd_proc, job.payload2);

    ipc_running_rpc_job = 0;

  } else {

    /* generic registered type */

    ipc_handlers[job.handler_type].func( job.snd_proc, job.payload1);

  }

  profiling_proc_exit( LEVEL_SIP, ipc_handlers[job.handler_type].name, 0 );

  return;

}

void ipc_handle_all_pending_jobs(int fd)

{

  char buf;

  while ( recv(fd, &buf, 1, MSG_DONTWAIT|MSG_PEEK)==1 )

    ipc_handle_job(fd);

}