libsxmp/sxmp/hub.c

/*
 * Secure X Message Passing Library v2 implementation.
 * (sxmplv2) it superseed all versions before due to the:
 * - memory consumption
 * - new features such as pulse emitting
 * - performance optimization
 *
 * (c) Askele Group 2013-2015 <http://askele.com>
 * (c) Alexander Vdolainen 2013-2015, 2016 <avdolainen@zoho.com>
 *
 * libsxmp is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * libsxmp 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.";
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <fcntl.h>

#ifdef WIN32
#include <Winsock2.h>
#define EBADE 1
#define NETDB_SUCCESS 0
#else
#include <sys/select.h>
#include <netdb.h>
#include <unistd.h>
#include <uuid/uuid.h>
#endif

#include <openssl/ssl.h>
#include <openssl/err.h>

#include <tdata/usrtc.h>
#include <sexpr/sexp.h>

#include <sxmp/limits.h>
#include <sxmp/sxmp.h>

#include "internal.h"

static int __insert_rpc_function(usrtc_t *tree, const char *name, int (*rpcf)(void *, sexp_t *))
{
  sxl_rpc_t *ent = malloc(sizeof(sxl_rpc_t));
  usrtc_node_t *node;

  if(!ent) return ENOMEM;
  else node = &ent->node;

  if(!(ent->name = strdup(name))) {
    free(ent);
    return ENOMEM;
  } else ent->rpcf = rpcf;

  usrtc_node_init(node, ent);
  usrtc_insert(tree, node, ent->name);

  return 0;
}

static void __destroy_rpc_list_tree(usrtc_t *tree)
{
  usrtc_node_t *node;
  sxl_rpc_t *ent;

  for(node = usrtc_first(tree); node != NULL; node = usrtc_first(tree)) {
    ent = (sxl_rpc_t *)usrtc_node_getdata(node);
    usrtc_delete(tree, node);
    free(ent->name);
    free(ent);
  }

  return;
}

/* negotiation functions */
/**
 * Proto: (auth-set-credentials "<login>" "<password>")
 * Return - message return; opcode as a return of this function.
 * in batch mode message with 0 index used always
 */
static int __set_credentials(void *cctx, sexp_t *sx)
{
  register int idx;
  sxlink_t *link = (sxlink_t *)cctx;
  sxhub_t *hub = link->hub;
  sexp_t *isx;
  char *login = NULL;
  char *passwd = NULL;

  /* take a deal with S-exp */
  SEXP_ITERATE_LIST(sx, isx, idx) {
    if(isx->ty == SEXP_LIST) return SXE_BADPROTO;

    if(idx > 0 && isx->aty != SEXP_DQUOTE) return SXE_BADPROTO;
    if(idx == 1) login = isx->val;
    else if(idx == 2) passwd = isx->val;
    else if(idx > 2) return SXE_BADPROTO;
  }

  if(!login || !passwd) return SXE_BADPROTO;

  link->pctx->login = strdup(login);
  link->pctx->passwd = strdup(passwd);
  if(!link->pctx->login || !link->pctx->passwd) {
    if(link->pctx->login) free(link->pctx->login);
    if(link->pctx->passwd) free(link->pctx->passwd);
    return SXE_ENOMEM;
  }

  if(hub->secure_check) return hub->secure_check(link);
  else return SXE_SUCCESS;
}

static int __get_channels_list(void *cctx, sexp_t *sx)
{
  sxlink_t *co = (sxlink_t *)cctx;
  sxhub_t *ssys = co->hub;
  sxmsg_t *msg = co->messages[0];
  char *buf = msg->payload;
  usrtc_node_t *node;
  rpc_typed_list_t *list_ent;
  size_t maxlen = 65535 - sizeof(sxmplv2_head_t);
  size_t ulen = 0;

  /* determine how this function was called */
  if(!strcmp(sx->list->val, "get-channels-list"))
    co->cp_version = V2;
  else co->cp_version = V2_1; /* last supported in this version */

  /* call the function */
  if(ssys->get_rpc_typed_list_tree)
    co->rpc_list = ssys->get_rpc_typed_list_tree(co);
  if(!co->rpc_list) return SXE_EPERM;
  //buf += sizeof(sxmplv2_head_t);
  if(co->cp_version == V2)
    ulen += snprintf(buf + ulen, maxlen - ulen, "(set-channels-list ");
  else ulen += snprintf(buf + ulen, maxlen - ulen, "(!@c< ");

  for(node = usrtc_first(co->rpc_list); node != NULL;
      node = usrtc_next(co->rpc_list, node)) { /* fill the list */
    list_ent = (rpc_typed_list_t *)usrtc_node_getdata(node);
    ulen += snprintf(buf + ulen, maxlen - ulen, "(:%d \"%s\")",
                     list_ent->type_id, list_ent->description);
  }
  ulen += snprintf(buf + ulen, maxlen - ulen, ")");
  msg->mhead.payload_length = ulen + 1;

  if(co->cp_version == V2) {
    /* we're ready for messaging mode */
    co->flags |= SXMP_MESSAGINGMODE;
    co->flags &= ~SXMP_BATCHMODE;
  }

  return SXE_SUCCESS;
}

static int __get_streams(void *cctx, sexp_t *sx)
{
  sxlink_t *link = (sxlink_t *)cctx;
  sxhub_t *hub = link->hub;
  sxmsg_t *msg = link->messages[0];
  char *buf = msg->payload;
  usrtc_node_t *node, *rpc_node;
  struct sxstream_description *s_desc;
  size_t maxlen = 65535 - sizeof(sxmplv2_head_t);
  size_t ulen = 0, sts = 0;
  int tcid = 0;

  if(link->cp_version == V_UNKNOWN) /* oops, version doesn't a happy one */
    return SXE_FAILED;

  if(!hub->streams) { /* no streams provided */
  __return_nil:
    ulen = snprintf(buf, maxlen, "(!@s< nil)");
    msg->mhead.payload_length = ulen + 1;
    /* and now we're ready to exit from batch mode */
    link->flags |= SXMP_MESSAGINGMODE;
    link->flags &= ~SXMP_BATCHMODE;

    return SXE_SUCCESS;
  } else { /* set all streams available */
    ulen += snprintf(buf + ulen, maxlen - ulen, "(!@s< ");

    for(node = usrtc_first(hub->streams); node != NULL; node = usrtc_next(hub->streams, node)) {
      s_desc = (struct sxstream_description *)usrtc_node_getdata(node);
      tcid = s_desc->pcid;
      if((rpc_node = usrtc_lookup(link->rpc_list, &tcid))) { /* channel allowed */
        /* ids */
        ulen += snprintf(buf + ulen, maxlen - ulen, "(:tcid %d :stid %d :t ", s_desc->pcid,
                         s_desc->stid);
        /* type */
        switch(s_desc->type) {
        case 0:
          ulen += snprintf(buf + ulen, maxlen - ulen, "e ");
          break;
        case SXE_O_NAMED:
          ulen += snprintf(buf + ulen, maxlen - ulen, "n ");
          break;
        case SXE_O_BINARY:
          ulen += snprintf(buf + ulen, maxlen - ulen, "b ");
          break;
        }
        /* flags */
        ulen += snprintf(buf + ulen, maxlen - ulen, ":a ");
        if(s_desc->flags & SXE_O_READ)
          ulen += snprintf(buf + ulen, maxlen - ulen, "r");
        else ulen += snprintf(buf + ulen, maxlen - ulen, "-");
        if(s_desc->flags & SXE_O_WRITE)
          ulen += snprintf(buf + ulen, maxlen - ulen, "w");
        else ulen += snprintf(buf + ulen, maxlen - ulen, "-");
        if(s_desc->flags & SXE_O_TRUNC)
          ulen += snprintf(buf + ulen, maxlen - ulen, "t");
        else ulen += snprintf(buf + ulen, maxlen - ulen, "-");
        if(s_desc->flags & SXE_O_ASYNC)
          ulen += snprintf(buf + ulen, maxlen - ulen, "a");
        else ulen += snprintf(buf + ulen, maxlen - ulen, "-");

        ulen += snprintf(buf + ulen, maxlen - ulen, ")");

        sts++;
      }
    }

    if(!sts) goto __return_nil;

    ulen += snprintf(buf + ulen, maxlen - ulen, ")");
    msg->mhead.payload_length = ulen + 1;
  }

  link->flags |= SXMP_MESSAGINGMODE;
  link->flags &= ~SXMP_BATCHMODE;

  return SXE_SUCCESS;
}

static long __cmp_uint16(const void *a, const void *b)
{
  return (long) *(uint16_t*)a - *(uint16_t*)b;
}

#define _MOD_STID     0xa
#define _MOD_TCID     0xb
#define _MOD_TYPE     0xc
#define _MOD_FLAGS    0xd
#define _MOD_UNKWN    0x0

static int __set_streams(void *cctx, sexp_t *sx)
{
  register int idx, iidx;
  usrtc_t *tree = NULL;
  sxlink_t *link = (sxlink_t *)cctx;
  sexp_t *isx, *iisx;
  struct sxstream_description *s_desc;
  usrtc_node_t *node = NULL;
  int modp = 0, r, value_mod = 0, mod = _MOD_UNKWN;
  int flags, type, stid, pcid;

  if(!link->remote_streams) {
    tree = malloc(sizeof(usrtc_t));
    if(!tree) return SXE_ENOMEM;
    usrtc_init(tree, USRTC_SPLAY, MAX_STREAMS_TYPES, __cmp_uint16);
    link->remote_streams = tree;
  }

  SEXP_ITERATE_LIST(sx, isx, idx) {
    if(!idx) continue;

    if(isx->ty != SEXP_LIST) {
      free(tree);
      link->remote_streams = NULL;
      if(!strcmp(isx->val, "nil")) goto __fini;
      else return SXE_BADPROTO;
    } else {
      SEXP_ITERATE_LIST(isx, iisx, iidx) {
        if(iisx->ty == SEXP_LIST) {
          r = SXE_BADPROTO;
        __clean_up_on_error:
          /* clean up all stuff */
          for(node = usrtc_first(tree); node != NULL; node = usrtc_first(tree)) {
            s_desc = (struct sxstream_description *)usrtc_node_getdata(node);
            usrtc_delete(tree, node);
            free(s_desc);
          }
          free(tree);
          link->remote_streams = NULL;

          return r;
        }

        if(iisx->val[0] == ':' && value_mod) {
          r = SXE_BADPROTO;
          goto __clean_up_on_error;
        } else if(iisx->val[0] == ':' && !value_mod) {
          value_mod = 1;
          if(!strcmp(iisx->val, ":stid")) mod = _MOD_STID;
          else if(!strcmp(iisx->val, ":tcid")) mod = _MOD_TCID;
          else if(!strcmp(iisx->val, ":t")) mod = _MOD_TYPE;
          else if(!strcmp(iisx->val, ":a")) mod = _MOD_FLAGS;
          else {
            r = SXE_BADPROTO;
            goto __clean_up_on_error;
          }
        } else if(iisx->val[0] != ':' && value_mod) {
          switch(mod) {
          case _MOD_STID:
            stid = atoi(iisx->val);
            modp++;
            break;
          case _MOD_TCID:
            pcid = atoi(iisx->val);
            modp++;
            break;
          case _MOD_TYPE:
            switch(iisx->val[0]) {
            case 'e': type = 0;              break;
            case 'b': type = SXE_O_BINARY;              break;
            case 'n': type = SXE_O_NAMED; break;
            default:
              r = SXE_BADPROTO;
              goto __clean_up_on_error;
            }
            modp++;
            break;
          case _MOD_FLAGS:
            flags = 0;
            if(iisx->val[0] == 'r') flags |= SXE_O_READ;
            else if(iisx->val[1] == 'w') flags |= SXE_O_WRITE;
            else if(iisx->val[2] == 't') flags |= SXE_O_TRUNC;
            else if(iisx->val[3] == 'a') flags |= SXE_O_ASYNC;
            else {
              r = SXE_BADPROTO;
              goto __clean_up_on_error;
            }
            modp++;
            break;
          }
          value_mod = 0;
        } else {
          r = SXE_BADPROTO;
          goto __clean_up_on_error;
        }
      }
      /* here we go */
      if(modp < 4) {
        r = SXE_BADPROTO;
        goto __clean_up_on_error;
      } else if(!(s_desc = malloc(sizeof(struct sxstream_description)))) {
        r = SXE_ENOMEM;
        goto __clean_up_on_error;
      }

      usrtc_node_init(&s_desc->node, s_desc);
      s_desc->ops = NULL;

      s_desc->flags = (uint16_t)flags;
      s_desc->type = (uint16_t)type;
      s_desc->pcid = (uint16_t)pcid;
      s_desc->stid = (uint16_t)stid;

      usrtc_insert(tree, &s_desc->node, &s_desc->stid);

      /* finish */
      modp = 0;
    }
  }

 __fini:
  link->flags |= SXMP_MESSAGINGMODE;
  link->flags &= ~SXMP_BATCHMODE;

  return SXE_SUCCESS;
}

#undef _MOD_STID
#undef _MOD_TCID
#undef _MOD_TYPE
#undef _MOD_FLAGS
#undef _MOD_UNKWN

static int __set_channels_list(void *cctx, sexp_t *sx)
{
  register int idx;
  sxlink_t *co = (sxlink_t *)cctx;
  sxhub_t *ssys = co->hub;
  sexp_t *isx, *iisx;
  int id, r;

  /* determine how this function was called */
  if(!strcmp(sx->list->val, "get-channels-list"))
    co->cp_version = V2;
  else co->cp_version = V2_1; /* last supported in this version */

  SEXP_ITERATE_LIST(sx, isx, idx) {
    if(!idx) continue;

    if(isx->ty != SEXP_LIST) return SXE_BADPROTO;
    if(sexp_list_length(isx) != 2) return SXE_BADPROTO;

    /* get id */
    sexp_list_car(isx, &iisx);
    if(iisx->ty == SEXP_LIST) return SXE_BADPROTO;
    if(iisx->aty != SEXP_BASIC) return SXE_BADPROTO;
    if(iisx->val[0] != ':') return SXE_BADPROTO;
    id = atoi(iisx->val + sizeof(char));

    /* get short description */
    sexp_list_cdr(isx, &iisx);
    if(iisx->ty == SEXP_LIST) return SXE_BADPROTO;
    if(iisx->aty != SEXP_DQUOTE) return SXE_BADPROTO;

    /* ok, here we go */
    if(ssys->set_typed_list_callback) {
      r = ssys->set_typed_list_callback(co, id, iisx->val);
      if(r != SXE_SUCCESS) return r;
    }
  }

  if(co->cp_version == V2) {
    /* we're ready for messaging mode */
    co->flags |= SXMP_MESSAGINGMODE;
    co->flags &= ~SXMP_BATCHMODE;
  }

  return SXE_SUCCESS;
}

static int __my_version_ack(void *cctx, sexp_t *sx)
{
  register int idx;
  sxlink_t *link = (sxlink_t *)cctx;
  sexp_t *isx;

  SEXP_ITERATE_LIST(sx, isx, idx) {
    if(!idx) continue;
    if(idx > 2) return SXE_BADPROTO;
    if(isx->ty == SEXP_LIST) return SXE_BADPROTO;
    if(!strcmp(isx->val, V2_1_TPROT)) link->cp_version = V2_1;
    else link->cp_version = V_UNKNOWN;
  }

  return SXE_SUCCESS;
}

static int __my_version_set(void *cctx, sexp_t *sx)
{
  register int idx;
  sxlink_t *link = (sxlink_t *)cctx;
  sexp_t *isx;

  SEXP_ITERATE_LIST(sx, isx, idx) {
    if(!idx) continue;
    if(idx > 2) return SXE_BADPROTO;
    if(isx->ty == SEXP_LIST) return SXE_BADPROTO;
    if(!strcmp(isx->val, V2_1_TPROT)) link->cp_version = V2_1;
    else return SXE_FAILED; /* failed to set another version */
  }

  return SXE_SUCCESS;
}

static int __init_systemrpc_tree(usrtc_t *rtree)
{
  /* batch mode negotiation context functions */
  if(__insert_rpc_function(rtree, "auth-set-credentials", __set_credentials)) goto __fail;

  /* old version V2 */
  if(__insert_rpc_function(rtree, "get-channels-list", __get_channels_list)) goto __fail; /* old V2 (v1 also) */
  if(__insert_rpc_function(rtree, "set-channels-list", __set_channels_list)) goto __fail;

  /* sync functions */
  /* channels */
  if(__insert_rpc_function(rtree, "!@c>", __get_channels_list)) goto __fail;
  if(__insert_rpc_function(rtree, "!@c<", __set_channels_list)) goto __fail;
  /* version */
  if(__insert_rpc_function(rtree, "!@v>", __my_version_ack)) goto __fail;
  if(__insert_rpc_function(rtree, "!@v<", __my_version_ack)) goto __fail;
  if(__insert_rpc_function(rtree, "!@V>", __my_version_set)) goto __fail;
  /* streams */
  if(__insert_rpc_function(rtree, "!@s>", __get_streams)) goto __fail;
  if(__insert_rpc_function(rtree, "!@s<", __set_streams)) goto __fail;

  return 0;

 __fail:
  __destroy_rpc_list_tree(rtree);
  return ENOMEM;
}

static int __init_builtinrpc_tree(usrtc_t *rtree)
{
  /* streams */
  if(__insert_rpc_function(rtree, _SXSTREAMOPEN_CMD, _builtin_stream_open)) goto __fail;
  if(__insert_rpc_function(rtree, _SXSTREAMCLOSE_CMD, _builtin_stream_close)) goto __fail;
  if(__insert_rpc_function(rtree, _SXSTREAMEREAD_CMD, _builtin_stream_eread)) goto __fail;
  if(__insert_rpc_function(rtree, _SXSTREAMBREAD_CMD, _builtin_stream_bread)) goto __fail;
  if(__insert_rpc_function(rtree, _SXSTREAMBWRITE_CMD, _builtin_stream_bwrite)) goto __fail;

  return 0;

 __fail:
  __destroy_rpc_list_tree(rtree);
  return ENOMEM;
}

static long __cmp_cstr(const void *a, const void *b)
{
  return (long)strcmp((const char *)a, (const char *)b);
}

static int __sxhub_log_dummy(const sxlogtype_t type, const char *fmt, ...)
{
  int r;
  va_list arglist;
  va_start(arglist, fmt);
  r = vfprintf(stderr, fmt, arglist);
  va_end(arglist);
  return r;
}

int sxhub_init(sxhub_t *ssys)
{
  int r = 0;

  if(!ssys) return EINVAL;
  else memset(ssys, 0, sizeof(sxhub_t));

  if(!(ssys->links = malloc(sizeof(usrtc_t)))) return ENOMEM;

  /* init links list */
  usrtc_init(ssys->links, USRTC_REDBLACK, MAX_LINKS,
             __cmp_cstr);
  if((r = pthread_rwlock_init(&(ssys->rwlock), NULL)))
    goto __fini;

  /* init RPC list related functions */
  if(!(ssys->system_rpc = malloc(sizeof(sxl_rpclist_t)))) {
    r = ENOMEM;
    goto __lfini;
  } else {
    if(!(ssys->system_rpc->rpc_tree = malloc(sizeof(usrtc_t)))) {
      r = ENOMEM;
      goto __lfini;
    }
    usrtc_init(ssys->system_rpc->rpc_tree, USRTC_SPLAY, 256, __cmp_cstr);
    r = __init_systemrpc_tree(ssys->system_rpc->rpc_tree);
    if(r) {
      free(ssys->system_rpc->rpc_tree);
      goto __lfini;
    }
  }

  /* init builtin functions list */
  if(!(ssys->stream_rpc = malloc(sizeof(sxl_rpclist_t)))) {
    r = ENOMEM;
    goto __lfini;
  } else {
    if(!(ssys->stream_rpc->rpc_tree = malloc(sizeof(usrtc_t)))) {
      r = ENOMEM;
      goto __lfini;
    }
    usrtc_init(ssys->stream_rpc->rpc_tree, USRTC_SPLAY, 256, __cmp_cstr);
    r = __init_builtinrpc_tree(ssys->stream_rpc->rpc_tree);
    if(r) {
      free(ssys->stream_rpc->rpc_tree);
      goto __lfini;
    }
  }

  /* set function pointers to default implementation */
  sxhub_set_logops(ssys, __sxhub_log_dummy);

  return 0;

 __lfini:
  if(ssys->system_rpc) free(ssys->system_rpc);
  if(ssys->stream_rpc) free(ssys->stream_rpc);
  pthread_rwlock_destroy(&(ssys->rwlock));
 __fini:
  if(ssys->links) free(ssys->links);

  return r;
}

int sxhub_free(sxhub_t *ssys)
{
  usrtc_node_t *node;

  __destroy_rpc_list_tree(ssys->system_rpc->rpc_tree);
  free(ssys->system_rpc->rpc_tree);
  free(ssys->system_rpc);

  /* free streams description tree */
  if(ssys->streams) {
    for(node = usrtc_first(ssys->streams); node != NULL; node = usrtc_first(ssys->streams))
      usrtc_delete(ssys->streams, node);
    free(ssys->streams);
  }

  free(ssys->links);
  pthread_rwlock_destroy(&(ssys->rwlock));
  SSL_CTX_free(ssys->ctx);

  return 0;
}

int sxhub_destroy(sxhub_t *ssys)
{
  int r = sxhub_free(ssys);
  free(ssys);

  return r;
}

sxhub_t *sxhub_create(void)
{
  int r = 0;
  sxhub_t *nsys = malloc(sizeof(sxhub_t));

  if(!nsys) {
    errno = ENOMEM;
    return NULL;
  }

  r = sxhub_init(nsys);
  if(r) {
    errno = r;
    free(nsys);
    return NULL;
  }

  return nsys;
}

int sxhub_setsslserts(sxhub_t *ssys, const char *rootca,
                            const char *certpem, const char *certkey)
{
  int r = ENOMEM;

  if(!ssys) return EINVAL;
  /* simply copying */
  if(!(ssys->rootca = strdup(rootca))) return ENOMEM;
  if(!(ssys->certkey = strdup(certkey)))     goto __fail;
  if(!(ssys->certpem = strdup(certpem)))     goto __fail;

  r = 0;
  return 0;
 __fail:
  if(ssys->rootca) free(ssys->rootca);
  if(ssys->certkey) free(ssys->certkey);
  if(ssys->certpem) free(ssys->certpem);

  return r;
}

int sxhub_stream_register(sxhub_t *hub, const struct sxstream_description *s_desc)
{
  usrtc_t *tree = NULL;
  usrtc_node_t *node = NULL;

  if(!hub->streams) {
    tree = malloc(sizeof(usrtc_t));
    if(!tree) return ENOMEM;
    usrtc_init(tree, USRTC_SPLAY, MAX_STREAMS_TYPES, __cmp_uint16);
    hub->streams = tree;
  } else {
    tree = hub->streams;
    node = usrtc_lookup(tree, &s_desc->stid);
    if(node) return EEXIST;
  }

  node = (usrtc_node_t *)&s_desc->node;
  usrtc_node_init(node, (void *)s_desc);
  usrtc_insert(tree, node, &s_desc->stid);

  return 0;
}

/* internally used functions */
static int __verify_certcall_dummy(int preverify_ok, X509_STORE_CTX *ctx)
{
  return preverify_ok;
}

int ex_ssldata_index;

/* this is a callback to perform a custom SSL certs chain validation,
 * as I promised here the comments, a lot of ...
 * The first shit: 0 means validation failed, 1 otherwise
 * The second shit: X509 API, I guess u will love it ;-)
 * openssl calls this function for each certificate in chain,
 * since our case is a simple (depth of chain is one, since we're
 * don't care for public certificates lists or I cannot find any reasons to
 * do it ...), amount of calls reduced, and in this case we're interested
 * only in top of chain i.e. actual certificate used on client side,
 * the validity of signing for other certificates within chain is
 * guaranteed by the ssl itself.
 * u know, we need to lookup in database, or elsewhere... some information
 * about client certificate, and decide - is it valid, or not?, if so
 * yep I mean it's valid, we can assign it's long fucking number to
 * security context, to use in ongoing full scaled connection handshaking.
 */
static int __verify_certcall(int preverify_ok, X509_STORE_CTX *ctx)
{
  //  X509 *cert = X509_STORE_CTX_get_current_cert(ctx);
  int err = X509_STORE_CTX_get_error(ctx), depth = X509_STORE_CTX_get_error_depth(ctx);
  SSL *ssl = X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
  sxlink_t *link = SSL_get_ex_data(ssl, ex_ssldata_index); /* this is a custom data we're set before */
  sxhub_t *hub = link->hub;

  /* now we need to check for certificates with a long chain,
   * so since we have a short one, reject long ones */
  if(depth > VERIFY_DEPTH) { /* longer than we expect */
    preverify_ok = 0; /* yep, 0 means error for those function callback in openssl, fucking set */
    err = X509_V_ERR_CERT_CHAIN_TOO_LONG;
    X509_STORE_CTX_set_error(ctx, err);
  }

  if(!preverify_ok) return 0;

  /* ok, now we're on top of SSL (depth == 0) certs chain,
   * and we can validate client certificate */
  if(!depth) {
    link->pctx->certid = ASN1_INTEGER_get((const ASN1_INTEGER *)X509_get_serialNumber(ctx->current_cert));
    /* now we're need to check the ssl cert */
    if(hub->validate_sslpem) {
      if(hub->validate_sslpem(link)) return 0;
      else return 1;
    } else return 0;
  }

  return preverify_ok;
}

int _sxhub_settls_ctx(sxhub_t *hub, const char *crtfile)
{
  if(!hub->ctx) {
    /* init SSL certificates and context */
    if(!(hub->ctx = SSL_CTX_new(TLSv1_2_client_method()))) return SXE_ENOMEM;

    /* set verify context */
    SSL_CTX_set_verify(hub->ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
                       __verify_certcall_dummy);
    /* set verify depth */
    SSL_CTX_set_verify_depth(hub->ctx, VERIFY_DEPTH);

    /* load certificates */
    SSL_CTX_load_verify_locations(hub->ctx, hub->rootca, NULL);
  }

  /* set the local certificate from CertFile */
  if(SSL_CTX_use_certificate_file(hub->ctx, crtfile, SSL_FILETYPE_PEM)<=0) return SXE_ESSL;
  /* set the private key from KeyFile (may be the same as CertFile) */
  if(SSL_CTX_use_PrivateKey_file(hub->ctx, crtfile, SSL_FILETYPE_PEM)<=0) return SXE_ESSL;
  /* verify private key */
  if (!SSL_CTX_check_private_key(hub->ctx)) return SXE_ESSL;

  return SXE_SUCCESS;
}

int _sxhub_settls_ctx_s(sxhub_t *hub)
{
  if(hub->ctx) return SXE_SUCCESS;

  /* init SSL certificates and context */
  if(!(hub->ctx = SSL_CTX_new(TLSv1_2_server_method()))) return SXE_ENOMEM;

  /* set verify context */
  SSL_CTX_set_verify(hub->ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
                     __verify_certcall);
  /* set verify depth */
  SSL_CTX_set_verify_depth(hub->ctx, VERIFY_DEPTH);

  /* set cache policy */
  SSL_CTX_set_session_cache_mode(hub->ctx, SSL_SESS_CACHE_OFF);
  SSL_CTX_set_mode(hub->ctx, SSL_MODE_RELEASE_BUFFERS);

  /* load certificates */
  SSL_CTX_load_verify_locations(hub->ctx, hub->rootca, NULL);

  /* set the local certificate from CertFile */
  if(SSL_CTX_use_certificate_file(hub->ctx, hub->certpem, SSL_FILETYPE_PEM) <= 0) return SXE_ESSL;
  /* set the private key from KeyFile (may be the same as CertFile) */
  if(SSL_CTX_use_PrivateKey_file(hub->ctx, hub->certpem, SSL_FILETYPE_PEM) <= 0) return SXE_ESSL;
  /* verify private key */
  if (!SSL_CTX_check_private_key(hub->ctx)) return SXE_ESSL;

  return SXE_SUCCESS;
}