sig_ss7.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2010 Digium, Inc.
 *
 * Richard Mudgett <rmudgett@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*!
 * \file
 * \brief SS7 signaling module.
 *
 * \author Matthew Fredrickson <creslin@digium.com>
 * \author Richard Mudgett <rmudgett@digium.com>
 *
 * See Also:
 * \arg \ref AstCREDITS
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#if defined(HAVE_SS7)

#include <signal.h>

#include "asterisk/pbx.h"
#include "asterisk/causes.h"
#include "asterisk/musiconhold.h"
#include "asterisk/cli.h"
#include "asterisk/transcap.h"

#include "sig_ss7.h"
#if defined(LIBSS7_ABI_COMPATIBILITY)
#error "Your installed libss7 is not compatible"
#endif

/* ------------------------------------------------------------------- */

static const char *sig_ss7_call_level2str(enum sig_ss7_call_level level)
{
   switch (level) {
   case SIG_SS7_CALL_LEVEL_IDLE:
      return "Idle";
   case SIG_SS7_CALL_LEVEL_ALLOCATED:
      return "Allocated";
   case SIG_SS7_CALL_LEVEL_CONTINUITY:
      return "Continuity";
   case SIG_SS7_CALL_LEVEL_SETUP:
      return "Setup";
   case SIG_SS7_CALL_LEVEL_PROCEEDING:
      return "Proceeding";
   case SIG_SS7_CALL_LEVEL_ALERTING:
      return "Alerting";
   case SIG_SS7_CALL_LEVEL_CONNECT:
      return "Connect";
   case SIG_SS7_CALL_LEVEL_GLARE:
      return "Glare";
   }
   return "Unknown";
}

static void sig_ss7_unlock_private(struct sig_ss7_chan *p)
{
   if (p->calls->unlock_private) {
      p->calls->unlock_private(p->chan_pvt);
   }
}

static void sig_ss7_lock_private(struct sig_ss7_chan *p)
{
   if (p->calls->lock_private) {
      p->calls->lock_private(p->chan_pvt);
   }
}

void sig_ss7_set_alarm(struct sig_ss7_chan *p, int in_alarm)
{
   p->inalarm = in_alarm;
   if (p->calls->set_alarm) {
      p->calls->set_alarm(p->chan_pvt, in_alarm);
   }
}

static void sig_ss7_set_dialing(struct sig_ss7_chan *p, int is_dialing)
{
   if (p->calls->set_dialing) {
      p->calls->set_dialing(p->chan_pvt, is_dialing);
   }
}

static void sig_ss7_set_digital(struct sig_ss7_chan *p, int is_digital)
{
   if (p->calls->set_digital) {
      p->calls->set_digital(p->chan_pvt, is_digital);
   }
}

static void sig_ss7_set_outgoing(struct sig_ss7_chan *p, int is_outgoing)
{
   p->outgoing = is_outgoing;
   if (p->calls->set_outgoing) {
      p->calls->set_outgoing(p->chan_pvt, is_outgoing);
   }
}

static void sig_ss7_set_inservice(struct sig_ss7_chan *p, int is_inservice)
{
   if (p->calls->set_inservice) {
      p->calls->set_inservice(p->chan_pvt, is_inservice);
   }
}

static void sig_ss7_set_locallyblocked(struct sig_ss7_chan *p, int is_blocked)
{
   p->locallyblocked = is_blocked;
   if (p->calls->set_locallyblocked) {
      p->calls->set_locallyblocked(p->chan_pvt, is_blocked);
   }
}

static void sig_ss7_set_remotelyblocked(struct sig_ss7_chan *p, int is_blocked)
{
   p->remotelyblocked = is_blocked;
   if (p->calls->set_remotelyblocked) {
      p->calls->set_remotelyblocked(p->chan_pvt, is_blocked);
   }
}

/*!
 * \internal
 * \brief Open the SS7 channel media path.
 * \since 1.8.12
 *
 * \param p Channel private control structure.
 *
 * \return Nothing
 */
static void sig_ss7_open_media(struct sig_ss7_chan *p)
{
   if (p->calls->open_media) {
      p->calls->open_media(p->chan_pvt);
   }
}

/*!
 * \internal
 * \brief Set the caller id information in the parent module.
 * \since 1.8
 *
 * \param p sig_ss7 channel structure.
 *
 * \return Nothing
 */
static void sig_ss7_set_caller_id(struct sig_ss7_chan *p)
{
   struct ast_party_caller caller;

   if (p->calls->set_callerid) {
      ast_party_caller_init(&caller);

      caller.id.name.str = p->cid_name;
      caller.id.name.presentation = p->callingpres;
      caller.id.name.valid = 1;

      caller.id.number.str = p->cid_num;
      caller.id.number.plan = p->cid_ton;
      caller.id.number.presentation = p->callingpres;
      caller.id.number.valid = 1;

      if (!ast_strlen_zero(p->cid_subaddr)) {
         caller.id.subaddress.valid = 1;
         //caller.id.subaddress.type = 0;/* nsap */
         //caller.id.subaddress.odd_even_indicator = 0;
         caller.id.subaddress.str = p->cid_subaddr;
      }

      caller.ani.number.str = p->cid_ani;
      //caller.ani.number.plan = p->xxx;
      //caller.ani.number.presentation = p->xxx;
      caller.ani.number.valid = 1;

      caller.ani2 = p->cid_ani2;
      p->calls->set_callerid(p->chan_pvt, &caller);
   }
}

/*!
 * \internal
 * \brief Set the Dialed Number Identifier.
 * \since 1.8
 *
 * \param p sig_ss7 channel structure.
 * \param dnid Dialed Number Identifier string.
 *
 * \return Nothing
 */
static void sig_ss7_set_dnid(struct sig_ss7_chan *p, const char *dnid)
{
   if (p->calls->set_dnid) {
      p->calls->set_dnid(p->chan_pvt, dnid);
   }
}

static int sig_ss7_play_tone(struct sig_ss7_chan *p, enum sig_ss7_tone tone)
{
   int res;

   if (p->calls->play_tone) {
      res = p->calls->play_tone(p->chan_pvt, tone);
   } else {
      res = -1;
   }
   return res;
}

static int sig_ss7_set_echocanceller(struct sig_ss7_chan *p, int enable)
{
   if (p->calls->set_echocanceller) {
      return p->calls->set_echocanceller(p->chan_pvt, enable);
   }
   return -1;
}

static void sig_ss7_loopback(struct sig_ss7_chan *p, int enable)
{
   if (p->loopedback != enable) {
      p->loopedback = enable;
      if (p->calls->set_loopback) {
         p->calls->set_loopback(p->chan_pvt, enable);
      }
   }
}

static struct ast_channel *sig_ss7_new_ast_channel(struct sig_ss7_chan *p, int state, int ulaw, int transfercapability, char *exten, const struct ast_channel *requestor)
{
   struct ast_channel *ast;

   if (p->calls->new_ast_channel) {
      ast = p->calls->new_ast_channel(p->chan_pvt, state, ulaw, exten, requestor);
   } else {
      return NULL;
   }
   if (!ast) {
      return NULL;
   }

   if (!p->owner) {
      p->owner = ast;
   }
   p->alreadyhungup = 0;
   ast->transfercapability = transfercapability;
   pbx_builtin_setvar_helper(ast, "TRANSFERCAPABILITY",
      ast_transfercapability2str(transfercapability));
   if (transfercapability & AST_TRANS_CAP_DIGITAL) {
      sig_ss7_set_digital(p, 1);
   }

   return ast;
}

static void sig_ss7_handle_link_exception(struct sig_ss7_linkset *linkset, int which)
{
   if (linkset->calls->handle_link_exception) {
      linkset->calls->handle_link_exception(linkset, which);
   }
}

/*!
 * \internal
 * \brief Obtain the sig_ss7 owner channel lock if the owner exists.
 * \since 1.8
 *
 * \param ss7 SS7 linkset control structure.
 * \param chanpos Channel position in the span.
 *
 * \note Assumes the ss7->lock is already obtained.
 * \note Assumes the sig_ss7_lock_private(ss7->pvts[chanpos]) is already obtained.
 *
 * \return Nothing
 */
static void sig_ss7_lock_owner(struct sig_ss7_linkset *ss7, int chanpos)
{
   for (;;) {
      if (!ss7->pvts[chanpos]->owner) {
         /* There is no owner lock to get. */
         break;
      }
      if (!ast_channel_trylock(ss7->pvts[chanpos]->owner)) {
         /* We got the lock */
         break;
      }

      /* Avoid deadlock */
      sig_ss7_unlock_private(ss7->pvts[chanpos]);
      DEADLOCK_AVOIDANCE(&ss7->lock);
      sig_ss7_lock_private(ss7->pvts[chanpos]);
   }
}

/*!
 * \internal
 * \brief Queue the given frame onto the owner channel.
 * \since 1.8
 *
 * \param ss7 SS7 linkset control structure.
 * \param chanpos Channel position in the span.
 * \param frame Frame to queue onto the owner channel.
 *
 * \note Assumes the ss7->lock is already obtained.
 * \note Assumes the sig_ss7_lock_private(ss7->pvts[chanpos]) is already obtained.
 *
 * \return Nothing
 */
static void sig_ss7_queue_frame(struct sig_ss7_linkset *ss7, int chanpos, struct ast_frame *frame)
{
   sig_ss7_lock_owner(ss7, chanpos);
   if (ss7->pvts[chanpos]->owner) {
      ast_queue_frame(ss7->pvts[chanpos]->owner, frame);
      ast_channel_unlock(ss7->pvts[chanpos]->owner);
   }
}

/*!
 * \internal
 * \brief Queue a control frame of the specified subclass onto the owner channel.
 * \since 1.8
 *
 * \param ss7 SS7 linkset control structure.
 * \param chanpos Channel position in the span.
 * \param subclass Control frame subclass to queue onto the owner channel.
 *
 * \note Assumes the ss7->lock is already obtained.
 * \note Assumes the sig_ss7_lock_private(ss7->pvts[chanpos]) is already obtained.
 *
 * \return Nothing
 */
static void sig_ss7_queue_control(struct sig_ss7_linkset *ss7, int chanpos, int subclass)
{
   struct ast_frame f = {AST_FRAME_CONTROL, };
   struct sig_ss7_chan *p = ss7->pvts[chanpos];

   if (p->calls->queue_control) {
      p->calls->queue_control(p->chan_pvt, subclass);
   }

   f.subclass.integer = subclass;
   sig_ss7_queue_frame(ss7, chanpos, &f);
}

/*!
 * \internal
 * \brief Find the channel position by CIC/DPC.
 *
 * \param linkset SS7 linkset control structure.
 * \param cic Circuit Identification Code
 * \param dpc Destination Point Code
 *
 * \retval chanpos on success.
 * \retval -1 on error.
 */
static int ss7_find_cic(struct sig_ss7_linkset *linkset, int cic, unsigned int dpc)
{
   int i;
   int winner = -1;
   for (i = 0; i < linkset->numchans; i++) {
      if (linkset->pvts[i] && (linkset->pvts[i]->dpc == dpc && linkset->pvts[i]->cic == cic)) {
         winner = i;
         break;
      }
   }
   return winner;
}

/*!
 * \internal
 * \brief Find the channel position by CIC/DPC and gripe if not found.
 *
 * \param linkset SS7 linkset control structure.
 * \param cic Circuit Identification Code
 * \param dpc Destination Point Code
 * \param msg_name Message type name that failed.
 *
 * \retval chanpos on success.
 * \retval -1 on error.
 */
static int ss7_find_cic_gripe(struct sig_ss7_linkset *linkset, int cic, unsigned int dpc, const char *msg_name)
{
   int chanpos;

   chanpos = ss7_find_cic(linkset, cic, dpc);
   if (chanpos < 0) {
      ast_log(LOG_WARNING, "Linkset %d: SS7 %s requested unconfigured CIC/DPC %d/%d.\n",
         linkset->span, msg_name, cic, dpc);
      return -1;
   }
   return chanpos;
}

static void ss7_handle_cqm(struct sig_ss7_linkset *linkset, int startcic, int endcic, unsigned int dpc)
{
   unsigned char status[32];
   struct sig_ss7_chan *p = NULL;
   int i, offset;

   for (i = 0; i < linkset->numchans; i++) {
      if (linkset->pvts[i] && (linkset->pvts[i]->dpc == dpc && ((linkset->pvts[i]->cic >= startcic) && (linkset->pvts[i]->cic <= endcic)))) {
         p = linkset->pvts[i];
         offset = p->cic - startcic;
         status[offset] = 0;
         if (p->locallyblocked)
            status[offset] |= (1 << 0) | (1 << 4);
         if (p->remotelyblocked)
            status[offset] |= (1 << 1) | (1 << 5);
         if (p->ss7call) {
            if (p->outgoing)
               status[offset] |= (1 << 3);
            else
               status[offset] |= (1 << 2);
         } else
            status[offset] |= 0x3 << 2;
      }
   }

   if (p)
      isup_cqr(linkset->ss7, startcic, endcic, dpc, status);
   else
      ast_log(LOG_WARNING, "Could not find any equipped circuits within CQM CICs\n");

}

static inline void ss7_hangup_cics(struct sig_ss7_linkset *linkset, int startcic, int endcic, unsigned int dpc)
{
   int i;

   for (i = 0; i < linkset->numchans; i++) {
      if (linkset->pvts[i] && (linkset->pvts[i]->dpc == dpc && ((linkset->pvts[i]->cic >= startcic) && (linkset->pvts[i]->cic <= endcic)))) {
         sig_ss7_lock_private(linkset->pvts[i]);
         sig_ss7_lock_owner(linkset, i);
         if (linkset->pvts[i]->owner) {
            ast_softhangup_nolock(linkset->pvts[i]->owner, AST_SOFTHANGUP_DEV);
            ast_channel_unlock(linkset->pvts[i]->owner);
         }
         sig_ss7_unlock_private(linkset->pvts[i]);
      }
   }
}

static inline void ss7_block_cics(struct sig_ss7_linkset *linkset, int startcic, int endcic, unsigned int dpc, unsigned char state[], int block)
{
   int i;

   /* XXX the use of state here seems questionable about matching up with the linkset channels */
   for (i = 0; i < linkset->numchans; i++) {
      if (linkset->pvts[i] && (linkset->pvts[i]->dpc == dpc && ((linkset->pvts[i]->cic >= startcic) && (linkset->pvts[i]->cic <= endcic)))) {
         if (state) {
            if (state[i])
               sig_ss7_set_remotelyblocked(linkset->pvts[i], block);
         } else
            sig_ss7_set_remotelyblocked(linkset->pvts[i], block);
      }
   }
}

static void ss7_inservice(struct sig_ss7_linkset *linkset, int startcic, int endcic, unsigned int dpc)
{
   int i;

   for (i = 0; i < linkset->numchans; i++) {
      if (linkset->pvts[i] && (linkset->pvts[i]->dpc == dpc && ((linkset->pvts[i]->cic >= startcic) && (linkset->pvts[i]->cic <= endcic))))
         sig_ss7_set_inservice(linkset->pvts[i], 1);
   }
}

static void ss7_reset_linkset(struct sig_ss7_linkset *linkset)
{
   int i, startcic = -1, endcic, dpc;

   if (linkset->numchans <= 0)
      return;

   startcic = linkset->pvts[0]->cic;
   /* DB: CIC's DPC fix */
   dpc = linkset->pvts[0]->dpc;

   for (i = 0; i < linkset->numchans; i++) {
      if (linkset->pvts[i+1] && linkset->pvts[i+1]->dpc == dpc && ((linkset->pvts[i+1]->cic - linkset->pvts[i]->cic) == 1) && (linkset->pvts[i]->cic - startcic < 31)) {
         continue;
      } else {
         endcic = linkset->pvts[i]->cic;
         ast_verbose("Resetting CICs %d to %d\n", startcic, endcic);
         isup_grs(linkset->ss7, startcic, endcic, dpc);

         /* DB: CIC's DPC fix */
         if (linkset->pvts[i+1]) {
            startcic = linkset->pvts[i+1]->cic;
            dpc = linkset->pvts[i+1]->dpc;
         }
      }
   }
}

/* This function is assumed to be called with the private channel lock and linkset lock held */
static void ss7_start_call(struct sig_ss7_chan *p, struct sig_ss7_linkset *linkset)
{
   struct ss7 *ss7 = linkset->ss7;
   int law;
   struct ast_channel *c;
   char tmp[256];

   if (!(linkset->flags & LINKSET_FLAG_EXPLICITACM)) {
      p->call_level = SIG_SS7_CALL_LEVEL_PROCEEDING;
      isup_acm(ss7, p->ss7call);
   } else {
      p->call_level = SIG_SS7_CALL_LEVEL_SETUP;
   }

   /* Companding law is determined by SS7 signaling type. */
   if (linkset->type == SS7_ITU) {
      law = SIG_SS7_ALAW;
   } else {
      law = SIG_SS7_ULAW;
   }

   /*
    * Release the SS7 lock while we create the channel so other
    * threads can send messages.  We must also release the private
    * lock to prevent deadlock while creating the channel.
    */
   ast_mutex_unlock(&linkset->lock);
   sig_ss7_unlock_private(p);
   c = sig_ss7_new_ast_channel(p, AST_STATE_RING, law, 0, p->exten, NULL);
   if (!c) {
      ast_log(LOG_WARNING, "Unable to start PBX on CIC %d\n", p->cic);
      ast_mutex_lock(&linkset->lock);
      sig_ss7_lock_private(p);
      isup_rel(linkset->ss7, p->ss7call, -1);
      p->call_level = SIG_SS7_CALL_LEVEL_IDLE;
      p->alreadyhungup = 1;
      return;
   }

   /* Hold the channel and private lock while we setup the channel. */
   ast_channel_lock(c);
   sig_ss7_lock_private(p);

   sig_ss7_set_echocanceller(p, 1);

   /*
    * It is reasonably safe to set the following
    * channel variables while the channel private
    * structure is locked.  The PBX has not been
    * started yet and it is unlikely that any other task
    * will do anything with the channel we have just
    * created.
    *
    * We only reference these variables in the context of the ss7_linkset function
    * when receiving either and IAM or a COT message.
    */
   if (!ast_strlen_zero(p->charge_number)) {
      pbx_builtin_setvar_helper(c, "SS7_CHARGE_NUMBER", p->charge_number);
      /* Clear this after we set it */
      p->charge_number[0] = 0;
   }
   if (!ast_strlen_zero(p->gen_add_number)) {
      pbx_builtin_setvar_helper(c, "SS7_GENERIC_ADDRESS", p->gen_add_number);
      /* Clear this after we set it */
      p->gen_add_number[0] = 0;
   }
   if (!ast_strlen_zero(p->jip_number)) {
      pbx_builtin_setvar_helper(c, "SS7_JIP", p->jip_number);
      /* Clear this after we set it */
      p->jip_number[0] = 0;
   }
   if (!ast_strlen_zero(p->gen_dig_number)) {
      pbx_builtin_setvar_helper(c, "SS7_GENERIC_DIGITS", p->gen_dig_number);
      /* Clear this after we set it */
      p->gen_dig_number[0] = 0;
   }
   if (!ast_strlen_zero(p->orig_called_num)) {
      pbx_builtin_setvar_helper(c, "SS7_ORIG_CALLED_NUM", p->orig_called_num);
      /* Clear this after we set it */
      p->orig_called_num[0] = 0;
   }

   snprintf(tmp, sizeof(tmp), "%d", p->gen_dig_type);
   pbx_builtin_setvar_helper(c, "SS7_GENERIC_DIGTYPE", tmp);
   /* Clear this after we set it */
   p->gen_dig_type = 0;

   snprintf(tmp, sizeof(tmp), "%d", p->gen_dig_scheme);
   pbx_builtin_setvar_helper(c, "SS7_GENERIC_DIGSCHEME", tmp);
   /* Clear this after we set it */
   p->gen_dig_scheme = 0;

   if (!ast_strlen_zero(p->lspi_ident)) {
      pbx_builtin_setvar_helper(c, "SS7_LSPI_IDENT", p->lspi_ident);
      /* Clear this after we set it */
      p->lspi_ident[0] = 0;
   }

   snprintf(tmp, sizeof(tmp), "%d", p->call_ref_ident);
   pbx_builtin_setvar_helper(c, "SS7_CALLREF_IDENT", tmp);
   /* Clear this after we set it */
   p->call_ref_ident = 0;

   snprintf(tmp, sizeof(tmp), "%d", p->call_ref_pc);
   pbx_builtin_setvar_helper(c, "SS7_CALLREF_PC", tmp);
   /* Clear this after we set it */
   p->call_ref_pc = 0;

   snprintf(tmp, sizeof(tmp), "%d", p->calling_party_cat);
   pbx_builtin_setvar_helper(c, "SS7_CALLING_PARTY_CATEGORY", tmp);
   /* Clear this after we set it */
   p->calling_party_cat = 0;

   if (!ast_strlen_zero(p->redirecting_num)) {
      pbx_builtin_setvar_helper(c, "SS7_REDIRECTING_NUMBER", p->redirecting_num);
      /* Clear this after we set it */
      p->redirecting_num[0] = 0;
   }
   if (!ast_strlen_zero(p->generic_name)) {
      pbx_builtin_setvar_helper(c, "SS7_GENERIC_NAME", p->generic_name);
      /* Clear this after we set it */
      p->generic_name[0] = 0;
   }

   sig_ss7_unlock_private(p);
   ast_channel_unlock(c);

   if (ast_pbx_start(c)) {
      ast_log(LOG_WARNING, "Unable to start PBX on %s (CIC %d)\n", c->name, p->cic);
      ast_hangup(c);
   } else {
      ast_verb(3, "Accepting call to '%s' on CIC %d\n", p->exten, p->cic);
   }

   /* Must return with linkset and private lock. */
   ast_mutex_lock(&linkset->lock);
   sig_ss7_lock_private(p);
}

static void ss7_apply_plan_to_number(char *buf, size_t size, const struct sig_ss7_linkset *ss7, const char *number, const unsigned nai)
{
   if (ast_strlen_zero(number)) { /* make sure a number exists so prefix isn't placed on an empty string */
      if (size) {
         *buf = '\0';
      }
      return;
   }
   switch (nai) {
   case SS7_NAI_INTERNATIONAL:
      snprintf(buf, size, "%s%s", ss7->internationalprefix, number);
      break;
   case SS7_NAI_NATIONAL:
      snprintf(buf, size, "%s%s", ss7->nationalprefix, number);
      break;
   case SS7_NAI_SUBSCRIBER:
      snprintf(buf, size, "%s%s", ss7->subscriberprefix, number);
      break;
   case SS7_NAI_UNKNOWN:
      snprintf(buf, size, "%s%s", ss7->unknownprefix, number);
      break;
   default:
      snprintf(buf, size, "%s", number);
      break;
   }
}

static int ss7_pres_scr2cid_pres(char presentation_ind, char screening_ind)
{
   return ((presentation_ind & 0x3) << 5) | (screening_ind & 0x3);
}

/* This is a thread per linkset that handles all received events from libss7. */
void *ss7_linkset(void *data)
{
   int res, i;
   struct timeval *next = NULL, tv;
   struct sig_ss7_linkset *linkset = (struct sig_ss7_linkset *) data;
   struct ss7 *ss7 = linkset->ss7;
   ss7_event *e = NULL;
   struct sig_ss7_chan *p;
   int chanpos;
   struct pollfd pollers[SIG_SS7_NUM_DCHANS];
   int nextms = 0;

   pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);

   ss7_set_debug(ss7, SIG_SS7_DEBUG_DEFAULT);
   ast_mutex_lock(&linkset->lock);
   ss7_start(ss7);
   ast_mutex_unlock(&linkset->lock);

   for (;;) {
      ast_mutex_lock(&linkset->lock);
      if ((next = ss7_schedule_next(ss7))) {
         tv = ast_tvnow();
         tv.tv_sec = next->tv_sec - tv.tv_sec;
         tv.tv_usec = next->tv_usec - tv.tv_usec;
         if (tv.tv_usec < 0) {
            tv.tv_usec += 1000000;
            tv.tv_sec -= 1;
         }
         if (tv.tv_sec < 0) {
            tv.tv_sec = 0;
            tv.tv_usec = 0;
         }
         nextms = tv.tv_sec * 1000;
         nextms += tv.tv_usec / 1000;
      }

      for (i = 0; i < linkset->numsigchans; i++) {
         pollers[i].fd = linkset->fds[i];
         pollers[i].events = ss7_pollflags(ss7, linkset->fds[i]);
         pollers[i].revents = 0;
      }
      ast_mutex_unlock(&linkset->lock);

      pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
      pthread_testcancel();
      res = poll(pollers, linkset->numsigchans, nextms);
      pthread_testcancel();
      pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);

      if ((res < 0) && (errno != EINTR)) {
         ast_log(LOG_ERROR, "poll(%s)\n", strerror(errno));
      } else if (!res) {
         ast_mutex_lock(&linkset->lock);
         ss7_schedule_run(ss7);
         ast_mutex_unlock(&linkset->lock);
         continue;
      }

      ast_mutex_lock(&linkset->lock);
      for (i = 0; i < linkset->numsigchans; i++) {
         if (pollers[i].revents & POLLPRI) {
            sig_ss7_handle_link_exception(linkset, i);
         }
         if (pollers[i].revents & POLLIN) {
            res = ss7_read(ss7, pollers[i].fd);
         }
         if (pollers[i].revents & POLLOUT) {
            res = ss7_write(ss7, pollers[i].fd);
            if (res < 0) {
               ast_debug(1, "Error in write %s\n", strerror(errno));
            }
         }
      }

      while ((e = ss7_check_event(ss7))) {
         if (linkset->debug) {
            ast_verbose("Linkset %d: Processing event: %s\n",
               linkset->span, ss7_event2str(e->e));
         }

         switch (e->e) {
         case SS7_EVENT_UP:
            if (linkset->state != LINKSET_STATE_UP) {
               ast_verbose("--- SS7 Up ---\n");
               ss7_reset_linkset(linkset);
            }
            linkset->state = LINKSET_STATE_UP;
            break;
         case SS7_EVENT_DOWN:
            ast_verbose("--- SS7 Down ---\n");
            linkset->state = LINKSET_STATE_DOWN;
            for (i = 0; i < linkset->numchans; i++) {
               p = linkset->pvts[i];
               if (p) {
                  sig_ss7_set_alarm(p, 1);
               }
            }
            break;
         case MTP2_LINK_UP:
            ast_verbose("MTP2 link up (SLC %d)\n", e->gen.data);
            break;
         case MTP2_LINK_DOWN:
            ast_log(LOG_WARNING, "MTP2 link down (SLC %d)\n", e->gen.data);
            break;
         case ISUP_EVENT_CPG:
            chanpos = ss7_find_cic_gripe(linkset, e->cpg.cic, e->cpg.opc, "CPG");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            sig_ss7_lock_private(p);
            switch (e->cpg.event) {
            case CPG_EVENT_ALERTING:
               if (p->call_level < SIG_SS7_CALL_LEVEL_ALERTING) {
                  p->call_level = SIG_SS7_CALL_LEVEL_ALERTING;
               }
               sig_ss7_lock_owner(linkset, chanpos);
               if (p->owner) {
                  ast_setstate(p->owner, AST_STATE_RINGING);
                  ast_channel_unlock(p->owner);
               }
               sig_ss7_queue_control(linkset, chanpos, AST_CONTROL_RINGING);
               break;
            case CPG_EVENT_PROGRESS:
            case CPG_EVENT_INBANDINFO:
               {
                  ast_debug(1, "Queuing frame PROGRESS on CIC %d\n", p->cic);
                  sig_ss7_queue_control(linkset, chanpos, AST_CONTROL_PROGRESS);
                  p->progress = 1;
                  sig_ss7_set_dialing(p, 0);
                  sig_ss7_open_media(p);
               }
               break;
            default:
               ast_debug(1, "Do not handle CPG with event type 0x%x\n", e->cpg.event);
               break;
            }

            sig_ss7_unlock_private(p);
            break;
         case ISUP_EVENT_RSC:
            ast_verbose("Resetting CIC %d\n", e->rsc.cic);
            chanpos = ss7_find_cic_gripe(linkset, e->rsc.cic, e->rsc.opc, "RSC");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            sig_ss7_lock_private(p);
            sig_ss7_set_inservice(p, 1);
            sig_ss7_set_remotelyblocked(p, 0);
            isup_set_call_dpc(e->rsc.call, p->dpc);
            sig_ss7_lock_owner(linkset, chanpos);
            p->ss7call = NULL;
            if (p->owner) {
               ast_softhangup_nolock(p->owner, AST_SOFTHANGUP_DEV);
               ast_channel_unlock(p->owner);
            }
            sig_ss7_unlock_private(p);
            isup_rlc(ss7, e->rsc.call);
            break;
         case ISUP_EVENT_GRS:
            ast_debug(1, "Got Reset for CICs %d to %d: Acknowledging\n", e->grs.startcic, e->grs.endcic);
            chanpos = ss7_find_cic_gripe(linkset, e->grs.startcic, e->grs.opc, "GRS");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            isup_gra(ss7, e->grs.startcic, e->grs.endcic, e->grs.opc);
            ss7_block_cics(linkset, e->grs.startcic, e->grs.endcic, e->grs.opc, NULL, 0);
            ss7_hangup_cics(linkset, e->grs.startcic, e->grs.endcic, e->grs.opc);
            break;
         case ISUP_EVENT_CQM:
            ast_debug(1, "Got Circuit group query message from CICs %d to %d\n", e->cqm.startcic, e->cqm.endcic);
            ss7_handle_cqm(linkset, e->cqm.startcic, e->cqm.endcic, e->cqm.opc);
            break;
         case ISUP_EVENT_GRA:
            ast_verbose("Got reset acknowledgement from CIC %d to %d.\n", e->gra.startcic, e->gra.endcic);
            ss7_inservice(linkset, e->gra.startcic, e->gra.endcic, e->gra.opc);
            ss7_block_cics(linkset, e->gra.startcic, e->gra.endcic, e->gra.opc, e->gra.status, 1);
            break;
         case ISUP_EVENT_IAM:
            ast_debug(1, "Got IAM for CIC %d and called number %s, calling number %s\n", e->iam.cic, e->iam.called_party_num, e->iam.calling_party_num);
            chanpos = ss7_find_cic_gripe(linkset, e->iam.cic, e->iam.opc, "IAM");
            if (chanpos < 0) {
               isup_rel(ss7, e->iam.call, -1);
               break;
            }
            p = linkset->pvts[chanpos];
            sig_ss7_lock_private(p);
            sig_ss7_lock_owner(linkset, chanpos);
            if (p->call_level != SIG_SS7_CALL_LEVEL_IDLE) {
               /*
                * Detected glare/dual-seizure
                *
                * Always abort both calls since we can't implement the dual
                * seizure procedures due to our channel assignment architecture
                * and the fact that we cannot tell libss7 to discard its call
                * structure to ignore the incoming IAM.
                */
               ast_debug(1,
                  "Linkset %d: SS7 IAM glare on CIC/DPC %d/%d.  Dropping both calls.\n",
                  linkset->span, e->iam.cic, e->iam.opc);
               if (p->call_level == SIG_SS7_CALL_LEVEL_ALLOCATED) {
                  /*
                   * We have not sent our IAM yet and we never will at this point.
                   */
                  p->alreadyhungup = 1;
                  isup_rel(ss7, e->iam.call, -1);
               }
               p->call_level = SIG_SS7_CALL_LEVEL_GLARE;
               if (p->owner) {
                  p->owner->hangupcause = AST_CAUSE_NORMAL_CLEARING;
                  ast_softhangup_nolock(p->owner, AST_SOFTHANGUP_DEV);
                  ast_channel_unlock(p->owner);
               }
               sig_ss7_unlock_private(p);
               break;
            }
            /*
             * The channel should not have an owner at this point since we
             * are in the process of creating an owner for it.
             */
            ast_assert(!p->owner);

            /* Mark channel as in use so no outgoing call will steal it. */
            p->call_level = SIG_SS7_CALL_LEVEL_ALLOCATED;
            p->ss7call = e->iam.call;

            isup_set_call_dpc(p->ss7call, p->dpc);

            if ((p->use_callerid) && (!ast_strlen_zero(e->iam.calling_party_num))) {
               ss7_apply_plan_to_number(p->cid_num, sizeof(p->cid_num), linkset, e->iam.calling_party_num, e->iam.calling_nai);
               p->callingpres = ss7_pres_scr2cid_pres(e->iam.presentation_ind, e->iam.screening_ind);
            } else
               p->cid_num[0] = 0;

            /* Set DNID */
            if (!ast_strlen_zero(e->iam.called_party_num)) {
               ss7_apply_plan_to_number(p->exten, sizeof(p->exten), linkset,
                  e->iam.called_party_num, e->iam.called_nai);
            } else {
               p->exten[0] = '\0';
            }
            sig_ss7_set_dnid(p, p->exten);

            if (p->immediate) {
               p->exten[0] = 's';
               p->exten[1] = '\0';
            } else if (!ast_strlen_zero(e->iam.called_party_num)) {
               char *st;
               ss7_apply_plan_to_number(p->exten, sizeof(p->exten), linkset, e->iam.called_party_num, e->iam.called_nai);
               st = strchr(p->exten, '#');
               if (st) {
                  *st = '\0';
               }
            } else {
               p->exten[0] = '\0';
            }

            p->cid_ani[0] = '\0';
            if ((p->use_callerid) && (!ast_strlen_zero(e->iam.generic_name)))
               ast_copy_string(p->cid_name, e->iam.generic_name, sizeof(p->cid_name));
            else
               p->cid_name[0] = '\0';

            p->cid_ani2 = e->iam.oli_ani2;
            p->cid_ton = 0;
            ast_copy_string(p->charge_number, e->iam.charge_number, sizeof(p->charge_number));
            ast_copy_string(p->gen_add_number, e->iam.gen_add_number, sizeof(p->gen_add_number));
            p->gen_add_type = e->iam.gen_add_type;
            p->gen_add_nai = e->iam.gen_add_nai;
            p->gen_add_pres_ind = e->iam.gen_add_pres_ind;
            p->gen_add_num_plan = e->iam.gen_add_num_plan;
            ast_copy_string(p->gen_dig_number, e->iam.gen_dig_number, sizeof(p->gen_dig_number));
            p->gen_dig_type = e->iam.gen_dig_type;
            p->gen_dig_scheme = e->iam.gen_dig_scheme;
            ast_copy_string(p->jip_number, e->iam.jip_number, sizeof(p->jip_number));
            ast_copy_string(p->orig_called_num, e->iam.orig_called_num, sizeof(p->orig_called_num));
            ast_copy_string(p->redirecting_num, e->iam.redirecting_num, sizeof(p->redirecting_num));
            ast_copy_string(p->generic_name, e->iam.generic_name, sizeof(p->generic_name));
            p->calling_party_cat = e->iam.calling_party_cat;

            sig_ss7_set_caller_id(p);

            if (ast_exists_extension(NULL, p->context, p->exten, 1, p->cid_num)) {
               if (e->iam.cot_check_required) {
                  p->call_level = SIG_SS7_CALL_LEVEL_CONTINUITY;
                  sig_ss7_loopback(p, 1);
               } else {
                  ss7_start_call(p, linkset);
               }
            } else {
               ast_debug(1, "Call on CIC for unconfigured extension %s\n", p->exten);
               p->alreadyhungup = 1;
               isup_rel(ss7, e->iam.call, AST_CAUSE_UNALLOCATED);
            }
            sig_ss7_unlock_private(p);
            break;
         case ISUP_EVENT_COT:
            chanpos = ss7_find_cic_gripe(linkset, e->cot.cic, e->cot.opc, "COT");
            if (chanpos < 0) {
               isup_rel(ss7, e->cot.call, -1);
               break;
            }
            p = linkset->pvts[chanpos];

            sig_ss7_lock_private(p);
            if (p->loopedback) {
               sig_ss7_loopback(p, 0);
               ss7_start_call(p, linkset);
            }
            sig_ss7_unlock_private(p);
            break;
         case ISUP_EVENT_CCR:
            ast_debug(1, "Got CCR request on CIC %d\n", e->ccr.cic);
            chanpos = ss7_find_cic_gripe(linkset, e->ccr.cic, e->ccr.opc, "CCR");
            if (chanpos < 0) {
               break;
            }

            p = linkset->pvts[chanpos];

            sig_ss7_lock_private(p);
            sig_ss7_loopback(p, 1);
            sig_ss7_unlock_private(p);

            isup_lpa(linkset->ss7, e->ccr.cic, p->dpc);
            break;
         case ISUP_EVENT_CVT:
            ast_debug(1, "Got CVT request on CIC %d\n", e->cvt.cic);
            chanpos = ss7_find_cic_gripe(linkset, e->cvt.cic, e->cvt.opc, "CVT");
            if (chanpos < 0) {
               break;
            }

            p = linkset->pvts[chanpos];

            sig_ss7_lock_private(p);
            sig_ss7_loopback(p, 1);
            sig_ss7_unlock_private(p);

            isup_cvr(linkset->ss7, e->cvt.cic, p->dpc);
            break;
         case ISUP_EVENT_REL:
            chanpos = ss7_find_cic_gripe(linkset, e->rel.cic, e->rel.opc, "REL");
            if (chanpos < 0) {
               /* Continue hanging up the call anyway. */
               isup_rlc(ss7, e->rel.call);
               break;
            }
            p = linkset->pvts[chanpos];
            sig_ss7_lock_private(p);
            sig_ss7_lock_owner(linkset, chanpos);
            if (p->owner) {
               p->owner->hangupcause = e->rel.cause;
               ast_softhangup_nolock(p->owner, AST_SOFTHANGUP_DEV);
               ast_channel_unlock(p->owner);
            }

            /* End the loopback if we have one */
            sig_ss7_loopback(p, 0);

            isup_rlc(ss7, e->rel.call);
            p->ss7call = NULL;

            sig_ss7_unlock_private(p);
            break;
         case ISUP_EVENT_ACM:
            chanpos = ss7_find_cic_gripe(linkset, e->acm.cic, e->acm.opc, "ACM");
            if (chanpos < 0) {
               isup_rel(ss7, e->acm.call, -1);
               break;
            }
            {
               p = linkset->pvts[chanpos];

               ast_debug(1, "Queueing frame from SS7_EVENT_ACM on CIC %d\n", p->cic);

               if (e->acm.call_ref_ident > 0) {
                  p->rlt = 1; /* Setting it but not using it here*/
               }

               sig_ss7_lock_private(p);
               sig_ss7_queue_control(linkset, chanpos, AST_CONTROL_PROCEEDING);
               if (p->call_level < SIG_SS7_CALL_LEVEL_PROCEEDING) {
                  p->call_level = SIG_SS7_CALL_LEVEL_PROCEEDING;
               }
               sig_ss7_set_dialing(p, 0);
               /* Send alerting if subscriber is free */
               if (e->acm.called_party_status_ind == 1) {
                  if (p->call_level < SIG_SS7_CALL_LEVEL_ALERTING) {
                     p->call_level = SIG_SS7_CALL_LEVEL_ALERTING;
                  }
                  sig_ss7_lock_owner(linkset, chanpos);
                  if (p->owner) {
                     ast_setstate(p->owner, AST_STATE_RINGING);
                     ast_channel_unlock(p->owner);
                  }
                  sig_ss7_queue_control(linkset, chanpos, AST_CONTROL_RINGING);
               }
               sig_ss7_unlock_private(p);
            }
            break;
         case ISUP_EVENT_CGB:
            chanpos = ss7_find_cic_gripe(linkset, e->cgb.startcic, e->cgb.opc, "CGB");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            ss7_block_cics(linkset, e->cgb.startcic, e->cgb.endcic, e->cgb.opc, e->cgb.status, 1);
            isup_cgba(linkset->ss7, e->cgb.startcic, e->cgb.endcic, e->cgb.opc, e->cgb.status, e->cgb.type);
            break;
         case ISUP_EVENT_CGU:
            chanpos = ss7_find_cic_gripe(linkset, e->cgu.startcic, e->cgu.opc, "CGU");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            ss7_block_cics(linkset, e->cgu.startcic, e->cgu.endcic, e->cgu.opc, e->cgu.status, 0);
            isup_cgua(linkset->ss7, e->cgu.startcic, e->cgu.endcic, e->cgu.opc, e->cgu.status, e->cgu.type);
            break;
         case ISUP_EVENT_UCIC:
            chanpos = ss7_find_cic_gripe(linkset, e->ucic.cic, e->ucic.opc, "UCIC");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            ast_debug(1, "Unequiped Circuit Id Code on CIC %d\n", e->ucic.cic);
            sig_ss7_lock_private(p);
            sig_ss7_set_remotelyblocked(p, 1);
            sig_ss7_set_inservice(p, 0);
            sig_ss7_unlock_private(p);/* doesn't require a SS7 acknowledgement */
            break;
         case ISUP_EVENT_BLO:
            chanpos = ss7_find_cic_gripe(linkset, e->blo.cic, e->blo.opc, "BLO");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            ast_debug(1, "Blocking CIC %d\n", e->blo.cic);
            sig_ss7_lock_private(p);
            sig_ss7_set_remotelyblocked(p, 1);
            sig_ss7_unlock_private(p);
            isup_bla(linkset->ss7, e->blo.cic, p->dpc);
            break;
         case ISUP_EVENT_BLA:
            chanpos = ss7_find_cic_gripe(linkset, e->bla.cic, e->bla.opc, "BLA");
            if (chanpos < 0) {
               break;
            }
            ast_debug(1, "Blocking CIC %d\n", e->bla.cic);
            p = linkset->pvts[chanpos];
            sig_ss7_lock_private(p);
            sig_ss7_set_locallyblocked(p, 1);
            sig_ss7_unlock_private(p);
            break;
         case ISUP_EVENT_UBL:
            chanpos = ss7_find_cic_gripe(linkset, e->ubl.cic, e->ubl.opc, "UBL");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            ast_debug(1, "Unblocking CIC %d\n", e->ubl.cic);
            sig_ss7_lock_private(p);
            sig_ss7_set_remotelyblocked(p, 0);
            sig_ss7_unlock_private(p);
            isup_uba(linkset->ss7, e->ubl.cic, p->dpc);
            break;
         case ISUP_EVENT_UBA:
            chanpos = ss7_find_cic_gripe(linkset, e->uba.cic, e->uba.opc, "UBA");
            if (chanpos < 0) {
               break;
            }
            p = linkset->pvts[chanpos];
            ast_debug(1, "Unblocking CIC %d\n", e->uba.cic);
            sig_ss7_lock_private(p);
            sig_ss7_set_locallyblocked(p, 0);
            sig_ss7_unlock_private(p);
            break;
         case ISUP_EVENT_CON:
         case ISUP_EVENT_ANM:
            if (e->e == ISUP_EVENT_CON) {
               chanpos = ss7_find_cic_gripe(linkset, e->con.cic, e->con.opc, "CON");
               if (chanpos < 0) {
                  isup_rel(ss7, e->con.call, -1);
                  break;
               }
            } else {
               chanpos = ss7_find_cic_gripe(linkset, e->anm.cic, e->anm.opc, "ANM");
               if (chanpos < 0) {
                  isup_rel(ss7, e->anm.call, -1);
                  break;
               }
            }

            {
               p = linkset->pvts[chanpos];
               sig_ss7_lock_private(p);
               if (p->call_level < SIG_SS7_CALL_LEVEL_CONNECT) {
                  p->call_level = SIG_SS7_CALL_LEVEL_CONNECT;
               }
               sig_ss7_queue_control(linkset, chanpos, AST_CONTROL_ANSWER);
               sig_ss7_set_dialing(p, 0);
               sig_ss7_open_media(p);
               sig_ss7_set_echocanceller(p, 1);
               sig_ss7_unlock_private(p);
            }
            break;
         case ISUP_EVENT_RLC:
            /* XXX Call ptr should be passed up from libss7! */
            chanpos = ss7_find_cic_gripe(linkset, e->rlc.cic, e->rlc.opc, "RLC");
            if (chanpos < 0) {
               break;
            }
            {
               p = linkset->pvts[chanpos];
               sig_ss7_lock_private(p);
               if (p->alreadyhungup) {
                  if (!p->owner) {
                     p->call_level = SIG_SS7_CALL_LEVEL_IDLE;
                  }
                  p->ss7call = NULL;
               }
               sig_ss7_unlock_private(p);
            }
            break;
         case ISUP_EVENT_FAA:
            /*!
             * \todo The handling of the SS7 FAA message is not good and I
             * don't know enough to handle it correctly.
             */
            chanpos = ss7_find_cic_gripe(linkset, e->faa.cic, e->faa.opc, "FAA");
            if (chanpos < 0) {
               isup_rel(linkset->ss7, e->faa.call, -1);
               break;
            }
            {
               /* XXX FAR and FAA used for something dealing with transfers? */
               p = linkset->pvts[chanpos];
               ast_debug(1, "FAA received on CIC %d\n", e->faa.cic);
               sig_ss7_lock_private(p);
               if (p->alreadyhungup){
                  if (!p->owner) {
                     p->call_level = SIG_SS7_CALL_LEVEL_IDLE;
                  }
                  /* XXX We seem to be leaking the isup call structure here. */
                  p->ss7call = NULL;
                  ast_log(LOG_NOTICE, "Received FAA and we haven't sent FAR.  Ignoring.\n");
               }
               sig_ss7_unlock_private(p);
            }
            break;
         default:
            ast_debug(1, "Unknown event %s\n", ss7_event2str(e->e));
            break;
         }
      }
      ast_mutex_unlock(&linkset->lock);
   }

   return 0;
}

static inline void ss7_rel(struct sig_ss7_linkset *ss7)
{
   ast_mutex_unlock(&ss7->lock);
}

static void ss7_grab(struct sig_ss7_chan *pvt, struct sig_ss7_linkset *ss7)
{
   /* Grab the lock first */
   while (ast_mutex_trylock(&ss7->lock)) {
      /* Avoid deadlock */
      sig_ss7_unlock_private(pvt);
      sched_yield();
      sig_ss7_lock_private(pvt);
   }
   /* Then break the poll */
   if (ss7->master != AST_PTHREADT_NULL) {
      pthread_kill(ss7->master, SIGURG);
   }
}

/*!
 * \brief Notify the SS7 layer that the link is in alarm.
 * \since 1.8
 *
 * \param linkset Controlling linkset for the channel.
 * \param which Link index of the signaling channel.
 *
 * \return Nothing
 */
void sig_ss7_link_alarm(struct sig_ss7_linkset *linkset, int which)
{
   linkset->linkstate[which] |= (LINKSTATE_DOWN | LINKSTATE_INALARM);
   linkset->linkstate[which] &= ~LINKSTATE_UP;
   ss7_link_alarm(linkset->ss7, linkset->fds[which]);
}

/*!
 * \brief Notify the SS7 layer that the link is no longer in alarm.
 * \since 1.8
 *
 * \param linkset Controlling linkset for the channel.
 * \param which Link index of the signaling channel.
 *
 * \return Nothing
 */
void sig_ss7_link_noalarm(struct sig_ss7_linkset *linkset, int which)
{
   linkset->linkstate[which] &= ~(LINKSTATE_INALARM | LINKSTATE_DOWN);
   linkset->linkstate[which] |= LINKSTATE_STARTING;
   ss7_link_noalarm(linkset->ss7, linkset->fds[which]);
}

/*!
 * \brief Setup and add a SS7 link channel.
 * \since 1.8
 *
 * \param linkset Controlling linkset for the channel.
 * \param which Link index of the signaling channel.
 * \param ss7type Switch type of the linkset
 * \param transport Signaling transport of channel.
 * \param inalarm Non-zero if the channel is in alarm.
 * \param networkindicator User configuration parameter.
 * \param pointcode User configuration parameter.
 * \param adjpointcode User configuration parameter.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
int sig_ss7_add_sigchan(struct sig_ss7_linkset *linkset, int which, int ss7type, int transport, int inalarm, int networkindicator, int pointcode, int adjpointcode)
{
   if (!linkset->ss7) {
      linkset->type = ss7type;
      linkset->ss7 = ss7_new(ss7type);
      if (!linkset->ss7) {
         ast_log(LOG_ERROR, "Can't create new SS7!\n");
         return -1;
      }
   }

   ss7_set_network_ind(linkset->ss7, networkindicator);
   ss7_set_pc(linkset->ss7, pointcode);

   if (ss7_add_link(linkset->ss7, transport, linkset->fds[which])) {
      ast_log(LOG_WARNING, "Could not add SS7 link!\n");
   }

   if (inalarm) {
      linkset->linkstate[which] = LINKSTATE_DOWN | LINKSTATE_INALARM;
      ss7_link_alarm(linkset->ss7, linkset->fds[which]);
   } else {
      linkset->linkstate[which] = LINKSTATE_DOWN;
      ss7_link_noalarm(linkset->ss7, linkset->fds[which]);
   }

   ss7_set_adjpc(linkset->ss7, linkset->fds[which], adjpointcode);

   return 0;
}

/*!
 * \internal
 * \brief Determine if a private channel structure is available.
 *
 * \param pvt Channel to determine if available.
 *
 * \return TRUE if the channel is available.
 */
static int sig_ss7_is_chan_available(struct sig_ss7_chan *pvt)
{
   if (!pvt->inalarm && !pvt->owner && !pvt->ss7call
      && pvt->call_level == SIG_SS7_CALL_LEVEL_IDLE
      && !pvt->locallyblocked && !pvt->remotelyblocked) {
      return 1;
   }
   return 0;
}

/*!
 * \brief Determine if the specified channel is available for an outgoing call.
 * \since 1.8
 *
 * \param p Signaling private structure pointer.
 *
 * \retval TRUE if the channel is available.
 */
int sig_ss7_available(struct sig_ss7_chan *p)
{
   int available;

   if (!p->ss7) {
      /* Something is wrong here.  A SS7 channel without the ss7 pointer? */
      return 0;
   }

   /* Only have to deal with the linkset lock. */
   ast_mutex_lock(&p->ss7->lock);
   available = sig_ss7_is_chan_available(p);
   if (available) {
      p->call_level = SIG_SS7_CALL_LEVEL_ALLOCATED;
   }
   ast_mutex_unlock(&p->ss7->lock);

   return available;
}

static unsigned char cid_pres2ss7pres(int cid_pres)
{
    return (cid_pres >> 5) & 0x03;
}

static unsigned char cid_pres2ss7screen(int cid_pres)
{
   return cid_pres & 0x03;
}

/*!
 * \brief Dial out using the specified SS7 channel.
 * \since 1.8
 *
 * \param p Signaling private structure pointer.
 * \param ast Asterisk channel structure pointer.
 * \param rdest Dialstring.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
int sig_ss7_call(struct sig_ss7_chan *p, struct ast_channel *ast, char *rdest)
{
   char ss7_called_nai;
   int called_nai_strip;
   char ss7_calling_nai;
   int calling_nai_strip;
   const char *charge_str = NULL;
   const char *gen_address = NULL;
   const char *gen_digits = NULL;
   const char *gen_dig_type = NULL;
   const char *gen_dig_scheme = NULL;
   const char *gen_name = NULL;
   const char *jip_digits = NULL;
   const char *lspi_ident = NULL;
   const char *rlt_flag = NULL;
   const char *call_ref_id = NULL;
   const char *call_ref_pc = NULL;
   const char *send_far = NULL;
   char *c;
   char *l;
   char dest[256];

   ast_copy_string(dest, rdest, sizeof(dest));

   c = strchr(dest, '/');
   if (c) {
      c++;
   } else {
      c = "";
   }
   if (strlen(c) < p->stripmsd) {
      ast_log(LOG_WARNING, "Number '%s' is shorter than stripmsd (%d)\n", c, p->stripmsd);
      return -1;
   }

   if (!p->hidecallerid) {
      l = ast->connected.id.number.valid ? ast->connected.id.number.str : NULL;
   } else {
      l = NULL;
   }

   ss7_grab(p, p->ss7);

   if (p->call_level != SIG_SS7_CALL_LEVEL_ALLOCATED) {
      /* Call collision before sending IAM.  Abort call. */
      ss7_rel(p->ss7);
      return -1;
   }

   p->ss7call = isup_new_call(p->ss7->ss7);
   if (!p->ss7call) {
      ss7_rel(p->ss7);
      ast_log(LOG_ERROR, "Unable to allocate new SS7 call!\n");
      return -1;
   }

   called_nai_strip = 0;
   ss7_called_nai = p->ss7->called_nai;
   if (ss7_called_nai == SS7_NAI_DYNAMIC) { /* compute dynamically */
      if (strncmp(c + p->stripmsd, p->ss7->internationalprefix, strlen(p->ss7->internationalprefix)) == 0) {
         called_nai_strip = strlen(p->ss7->internationalprefix);
         ss7_called_nai = SS7_NAI_INTERNATIONAL;
      } else if (strncmp(c + p->stripmsd, p->ss7->nationalprefix, strlen(p->ss7->nationalprefix)) == 0) {
         called_nai_strip = strlen(p->ss7->nationalprefix);
         ss7_called_nai = SS7_NAI_NATIONAL;
      } else {
         ss7_called_nai = SS7_NAI_SUBSCRIBER;
      }
   }
   isup_set_called(p->ss7call, c + p->stripmsd + called_nai_strip, ss7_called_nai, p->ss7->ss7);

   calling_nai_strip = 0;
   ss7_calling_nai = p->ss7->calling_nai;
   if ((l != NULL) && (ss7_calling_nai == SS7_NAI_DYNAMIC)) { /* compute dynamically */
      if (strncmp(l, p->ss7->internationalprefix, strlen(p->ss7->internationalprefix)) == 0) {
         calling_nai_strip = strlen(p->ss7->internationalprefix);
         ss7_calling_nai = SS7_NAI_INTERNATIONAL;
      } else if (strncmp(l, p->ss7->nationalprefix, strlen(p->ss7->nationalprefix)) == 0) {
         calling_nai_strip = strlen(p->ss7->nationalprefix);
         ss7_calling_nai = SS7_NAI_NATIONAL;
      } else {
         ss7_calling_nai = SS7_NAI_SUBSCRIBER;
      }
   }
   isup_set_calling(p->ss7call, l ? (l + calling_nai_strip) : NULL, ss7_calling_nai,
      p->use_callingpres ? cid_pres2ss7pres(ast->connected.id.number.presentation) : (l ? SS7_PRESENTATION_ALLOWED : SS7_PRESENTATION_RESTRICTED),
      p->use_callingpres ? cid_pres2ss7screen(ast->connected.id.number.presentation) : SS7_SCREENING_USER_PROVIDED);

   isup_set_oli(p->ss7call, ast->connected.ani2);
   isup_init_call(p->ss7->ss7, p->ss7call, p->cic, p->dpc);

   /* Set the charge number if it is set */
   charge_str = pbx_builtin_getvar_helper(ast, "SS7_CHARGE_NUMBER");
   if (charge_str)
      isup_set_charge(p->ss7call, charge_str, SS7_ANI_CALLING_PARTY_SUB_NUMBER, 0x10);

   gen_address = pbx_builtin_getvar_helper(ast, "SS7_GENERIC_ADDRESS");
   if (gen_address)
      isup_set_gen_address(p->ss7call, gen_address, p->gen_add_nai,p->gen_add_pres_ind, p->gen_add_num_plan,p->gen_add_type); /* need to add some types here for NAI,PRES,TYPE */

   gen_digits = pbx_builtin_getvar_helper(ast, "SS7_GENERIC_DIGITS");
   gen_dig_type = pbx_builtin_getvar_helper(ast, "SS7_GENERIC_DIGTYPE");
   gen_dig_scheme = pbx_builtin_getvar_helper(ast, "SS7_GENERIC_DIGSCHEME");
   if (gen_digits)
      isup_set_gen_digits(p->ss7call, gen_digits, atoi(gen_dig_type), atoi(gen_dig_scheme));

   gen_name = pbx_builtin_getvar_helper(ast, "SS7_GENERIC_NAME");
   if (gen_name)
      isup_set_generic_name(p->ss7call, gen_name, GEN_NAME_TYPE_CALLING_NAME, GEN_NAME_AVAIL_AVAILABLE, GEN_NAME_PRES_ALLOWED);

   jip_digits = pbx_builtin_getvar_helper(ast, "SS7_JIP");
   if (jip_digits)
      isup_set_jip_digits(p->ss7call, jip_digits);

   lspi_ident = pbx_builtin_getvar_helper(ast, "SS7_LSPI_IDENT");
   if (lspi_ident)
      isup_set_lspi(p->ss7call, lspi_ident, 0x18, 0x7, 0x00);

   rlt_flag = pbx_builtin_getvar_helper(ast, "SS7_RLT_ON");
   if ((rlt_flag) && ((strncmp("NO", rlt_flag, strlen(rlt_flag))) != 0 )) {
      isup_set_lspi(p->ss7call, rlt_flag, 0x18, 0x7, 0x00); /* Setting for Nortel DMS-250/500 */
   }

   call_ref_id = pbx_builtin_getvar_helper(ast, "SS7_CALLREF_IDENT");
   call_ref_pc = pbx_builtin_getvar_helper(ast, "SS7_CALLREF_PC");
   if (call_ref_id && call_ref_pc) {
      isup_set_callref(p->ss7call, atoi(call_ref_id),
             call_ref_pc ? atoi(call_ref_pc) : 0);
   }

   send_far = pbx_builtin_getvar_helper(ast, "SS7_SEND_FAR");
   if ((send_far) && ((strncmp("NO", send_far, strlen(send_far))) != 0 ))
      (isup_far(p->ss7->ss7, p->ss7call));

   p->call_level = SIG_SS7_CALL_LEVEL_SETUP;
   isup_iam(p->ss7->ss7, p->ss7call);
   sig_ss7_set_dialing(p, 1);
   ast_setstate(ast, AST_STATE_DIALING);
   ss7_rel(p->ss7);
   return 0;
}

/*!
 * \brief SS7 hangup channel.
 * \since 1.8
 *
 * \param p Signaling private structure pointer.
 * \param ast Asterisk channel structure pointer.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
int sig_ss7_hangup(struct sig_ss7_chan *p, struct ast_channel *ast)
{
   int res = 0;

   if (!ast->tech_pvt) {
      ast_log(LOG_WARNING, "Asked to hangup channel not connected\n");
      return 0;
   }

   p->owner = NULL;
   sig_ss7_set_dialing(p, 0);
   sig_ss7_set_outgoing(p, 0);
   p->progress = 0;
   p->rlt = 0;
   p->exten[0] = '\0';
   /* Perform low level hangup if no owner left */
   ss7_grab(p, p->ss7);
   p->call_level = SIG_SS7_CALL_LEVEL_IDLE;
   if (p->ss7call) {
      if (!p->alreadyhungup) {
         const char *cause = pbx_builtin_getvar_helper(ast,"SS7_CAUSE");
         int icause = ast->hangupcause ? ast->hangupcause : -1;

         if (cause) {
            if (atoi(cause)) {
               icause = atoi(cause);
            }
         }
         isup_rel(p->ss7->ss7, p->ss7call, icause);
         p->alreadyhungup = 1;
      }
   }
   ss7_rel(p->ss7);

   return res;
}

/*!
 * \brief SS7 answer channel.
 * \since 1.8
 *
 * \param p Signaling private structure pointer.
 * \param ast Asterisk channel structure pointer.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
int sig_ss7_answer(struct sig_ss7_chan *p, struct ast_channel *ast)
{
   int res;

   ss7_grab(p, p->ss7);
   if (p->call_level < SIG_SS7_CALL_LEVEL_CONNECT) {
      p->call_level = SIG_SS7_CALL_LEVEL_CONNECT;
   }
   sig_ss7_open_media(p);
   res = isup_anm(p->ss7->ss7, p->ss7call);
   ss7_rel(p->ss7);
   return res;
}

/*!
 * \brief Fix up a channel:  If a channel is consumed, this is called.  Basically update any ->owner links.
 * \since 1.8
 *
 * \param oldchan Old channel pointer to replace.
 * \param newchan New channel pointer to set.
 * \param pchan Signaling private structure pointer.
 *
 * \return Nothing
 */
void sig_ss7_fixup(struct ast_channel *oldchan, struct ast_channel *newchan, struct sig_ss7_chan *pchan)
{
   if (pchan->owner == oldchan) {
      pchan->owner = newchan;
   }
}

/*!
 * \brief SS7 answer channel.
 * \since 1.8
 *
 * \param p Signaling private structure pointer.
 * \param chan Asterisk channel structure pointer.
 * \param condition AST control frame subtype.
 * \param data AST control frame payload contents.
 * \param datalen Length of payload contents.
 *
 * \retval 0 on success.
 * \retval -1 on error or indication condition not handled.
 */
int sig_ss7_indicate(struct sig_ss7_chan *p, struct ast_channel *chan, int condition, const void *data, size_t datalen)
{
   int res = -1;

   switch (condition) {
   case AST_CONTROL_BUSY:
      if (p->call_level < SIG_SS7_CALL_LEVEL_CONNECT) {
         chan->hangupcause = AST_CAUSE_USER_BUSY;
         ast_softhangup_nolock(chan, AST_SOFTHANGUP_DEV);
         res = 0;
         break;
      }
      res = sig_ss7_play_tone(p, SIG_SS7_TONE_BUSY);
      break;
   case AST_CONTROL_RINGING:
      ss7_grab(p, p->ss7);
      if (p->call_level < SIG_SS7_CALL_LEVEL_ALERTING && !p->outgoing) {
         p->call_level = SIG_SS7_CALL_LEVEL_ALERTING;
         if ((isup_far(p->ss7->ss7, p->ss7call)) != -1) {
            p->rlt = 1;
         }

         /* No need to send CPG if call will be RELEASE */
         if (p->rlt != 1) {
            isup_cpg(p->ss7->ss7, p->ss7call, CPG_EVENT_ALERTING);
         }
      }
      ss7_rel(p->ss7);

      res = sig_ss7_play_tone(p, SIG_SS7_TONE_RINGTONE);

      if (chan->_state != AST_STATE_UP && chan->_state != AST_STATE_RING) {
         ast_setstate(chan, AST_STATE_RINGING);
      }
      break;
   case AST_CONTROL_PROCEEDING:
      ast_debug(1,"Received AST_CONTROL_PROCEEDING on %s\n",chan->name);
      ss7_grab(p, p->ss7);
      /* This IF sends the FAR for an answered ALEG call */
      if (chan->_state == AST_STATE_UP && (p->rlt != 1)){
         if ((isup_far(p->ss7->ss7, p->ss7call)) != -1) {
            p->rlt = 1;
         }
      }

      if (p->call_level < SIG_SS7_CALL_LEVEL_PROCEEDING && !p->outgoing) {
         p->call_level = SIG_SS7_CALL_LEVEL_PROCEEDING;
         isup_acm(p->ss7->ss7, p->ss7call);
      }
      ss7_rel(p->ss7);
      /* don't continue in ast_indicate */
      res = 0;
      break;
   case AST_CONTROL_PROGRESS:
      ast_debug(1,"Received AST_CONTROL_PROGRESS on %s\n",chan->name);
      ss7_grab(p, p->ss7);
      if (!p->progress && p->call_level < SIG_SS7_CALL_LEVEL_ALERTING && !p->outgoing) {
         p->progress = 1;/* No need to send inband-information progress again. */
         isup_cpg(p->ss7->ss7, p->ss7call, CPG_EVENT_INBANDINFO);
         ss7_rel(p->ss7);

         /* enable echo canceler here on SS7 calls */
         sig_ss7_set_echocanceller(p, 1);
      } else {
         ss7_rel(p->ss7);
      }
      /* don't continue in ast_indicate */
      res = 0;
      break;
   case AST_CONTROL_INCOMPLETE:
      if (p->call_level < SIG_SS7_CALL_LEVEL_CONNECT) {
         chan->hangupcause = AST_CAUSE_INVALID_NUMBER_FORMAT;
         ast_softhangup_nolock(chan, AST_SOFTHANGUP_DEV);
         res = 0;
         break;
      }
      /* Wait for DTMF digits to complete the dialed number. */
      res = 0;
      break;
   case AST_CONTROL_CONGESTION:
      if (p->call_level < SIG_SS7_CALL_LEVEL_CONNECT) {
         chan->hangupcause = AST_CAUSE_CONGESTION;
         ast_softhangup_nolock(chan, AST_SOFTHANGUP_DEV);
         res = 0;
         break;
      }
      res = sig_ss7_play_tone(p, SIG_SS7_TONE_CONGESTION);
      break;
   case AST_CONTROL_HOLD:
      ast_moh_start(chan, data, p->mohinterpret);
      break;
   case AST_CONTROL_UNHOLD:
      ast_moh_stop(chan);
      break;
   case AST_CONTROL_SRCUPDATE:
      res = 0;
      break;
   case -1:
      res = sig_ss7_play_tone(p, -1);
      break;
   }
   return res;
}

/*!
 * \brief SS7 channel request.
 * \since 1.8
 *
 * \param p Signaling private structure pointer.
 * \param law Companding law preferred
 * \param requestor Asterisk channel requesting a channel to dial (Can be NULL)
 * \param transfercapability
 *
 * \retval ast_channel on success.
 * \retval NULL on error.
 */
struct ast_channel *sig_ss7_request(struct sig_ss7_chan *p, enum sig_ss7_law law, const struct ast_channel *requestor, int transfercapability)
{
   struct ast_channel *ast;

   /* Companding law is determined by SS7 signaling type. */
   if (p->ss7->type == SS7_ITU) {
      law = SIG_SS7_ALAW;
   } else {
      law = SIG_SS7_ULAW;
   }

   sig_ss7_set_outgoing(p, 1);
   ast = sig_ss7_new_ast_channel(p, AST_STATE_RESERVED, law, transfercapability, p->exten, requestor);
   if (!ast) {
      sig_ss7_set_outgoing(p, 0);

      /* Release the allocated channel.  Only have to deal with the linkset lock. */
      ast_mutex_lock(&p->ss7->lock);
      p->call_level = SIG_SS7_CALL_LEVEL_IDLE;
      ast_mutex_unlock(&p->ss7->lock);
   }
   return ast;
}

/*!
 * \brief Delete the sig_ss7 private channel structure.
 * \since 1.8
 *
 * \param doomed sig_ss7 private channel structure to delete.
 *
 * \return Nothing
 */
void sig_ss7_chan_delete(struct sig_ss7_chan *doomed)
{
   ast_free(doomed);
}

#define SIG_SS7_SC_HEADER  "%-4s %4s %-4s %-3s %-3s %-10s %-4s %s\n"
#define SIG_SS7_SC_LINE     "%4d %4d %-4s %-3s %-3s %-10s %-4s %s"
void sig_ss7_cli_show_channels_header(int fd)
{
   ast_cli(fd, SIG_SS7_SC_HEADER, "link", "",     "Chan", "Lcl", "Rem", "Call",  "SS7",  "Channel");
   ast_cli(fd, SIG_SS7_SC_HEADER, "set",  "Chan", "Idle", "Blk", "Blk", "Level", "Call", "Name");
}

void sig_ss7_cli_show_channels(int fd, struct sig_ss7_linkset *linkset)
{
   char line[256];
   int idx;
   struct sig_ss7_chan *pvt;

   ast_mutex_lock(&linkset->lock);
   for (idx = 0; idx < linkset->numchans; ++idx) {
      if (!linkset->pvts[idx]) {
         continue;
      }
      pvt = linkset->pvts[idx];
      sig_ss7_lock_private(pvt);
      sig_ss7_lock_owner(linkset, idx);

      snprintf(line, sizeof(line), SIG_SS7_SC_LINE,
         linkset->span,
         pvt->channel,
         sig_ss7_is_chan_available(pvt) ? "Yes" : "No",
         pvt->locallyblocked ? "Yes" : "No",
         pvt->remotelyblocked ? "Yes" : "No",
         sig_ss7_call_level2str(pvt->call_level),
         pvt->ss7call ? "Yes" : "No",
         pvt->owner ? pvt->owner->name : "");

      if (pvt->owner) {
         ast_channel_unlock(pvt->owner);
      }
      sig_ss7_unlock_private(pvt);

      ast_mutex_unlock(&linkset->lock);
      ast_cli(fd, "%s\n", line);
      ast_mutex_lock(&linkset->lock);
   }
   ast_mutex_unlock(&linkset->lock);
}

/*!
 * \brief Create a new sig_ss7 private channel structure.
 * \since 1.8
 *
 * \param pvt_data Upper layer private data structure.
 * \param callback Callbacks to the upper layer.
 * \param ss7 Controlling linkset for the channel.
 *
 * \retval sig_ss7_chan on success.
 * \retval NULL on error.
 */
struct sig_ss7_chan *sig_ss7_chan_new(void *pvt_data, struct sig_ss7_callback *callback, struct sig_ss7_linkset *ss7)
{
   struct sig_ss7_chan *pvt;

   pvt = ast_calloc(1, sizeof(*pvt));
   if (!pvt) {
      return pvt;
   }

   pvt->calls = callback;
   pvt->chan_pvt = pvt_data;
   pvt->ss7 = ss7;

   return pvt;
}

/*!
 * \brief Initialize the SS7 linkset control.
 * \since 1.8
 *
 * \param ss7 SS7 linkset control structure.
 *
 * \return Nothing
 */
void sig_ss7_init_linkset(struct sig_ss7_linkset *ss7)
{
   int idx;

   memset(ss7, 0, sizeof(*ss7));

   ast_mutex_init(&ss7->lock);

   ss7->master = AST_PTHREADT_NULL;
   for (idx = 0; idx < ARRAY_LEN(ss7->fds); ++idx) {
      ss7->fds[idx] = -1;
   }
}

/* ------------------------------------------------------------------- */

#endif   /* defined(HAVE_SS7) */
/* end sig_ss7.c */