nameserv_async.c

   1 /*
   2   chronyd/chronyc - Programs for keeping computer clocks accurate.
   3
   4  **********************************************************************
   5  * Copyright (C) Miroslav Lichvar  2014
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of version 2 of the GNU General Public License as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  19  *
  20  **********************************************************************
  21
  22   =======================================================================
  23
  24   Functions to asynchronously convert name to IP address
  25
  26   */
  27
  28 #include "config.h"
  29 #include "sysincl.h"
  30
  31 #include "nameserv_async.h"
  32 #include "logging.h"
  33 #include "memory.h"
  34 #include "privops.h"
  35 #include "sched.h"
  36 #include "util.h"
  37
  38 #ifdef USE_PTHREAD_ASYNCDNS
  39 #include <pthread.h>
  40
  41 /* ================================================== */
  42
  43 struct DNS_Async_Instance {
  44   const char *name;
  45   DNS_Status status;
  46   IPAddr addresses[DNS_MAX_ADDRESSES];
  47   DNS_NameResolveHandler handler;
  48   void *arg;
  49
  50   pthread_t thread;
  51   int pipe[2];
  52 };
  53
  54 static pthread_mutex_t privops_lock = PTHREAD_MUTEX_INITIALIZER;
  55
  56 /* ================================================== */
  57
  58 static void *
  59 start_resolving(void *anything)
  60 {
  61   struct DNS_Async_Instance *inst = (struct DNS_Async_Instance *)anything;
  62
  63   pthread_mutex_lock(&privops_lock);
  64   inst->status = PRV_Name2IPAddress(inst->name, inst->addresses, DNS_MAX_ADDRESSES);
  65   pthread_mutex_unlock(&privops_lock);
  66
  67   /* Notify the main thread that the result is ready */
  68   if (write(inst->pipe[1], "", 1) < 0)
  69     ;
  70
  71   return NULL;
  72 }
  73
  74 /* ================================================== */
  75
  76 static void
  77 end_resolving(int fd, int event, void *anything)
  78 {
  79   struct DNS_Async_Instance *inst = (struct DNS_Async_Instance *)anything;
  80   int i;
  81
  82   if (pthread_join(inst->thread, NULL)) {
  83     LOG_FATAL("pthread_join() failed");
  84   }
  85
  86   SCH_RemoveFileHandler(inst->pipe[0]);
  87   close(inst->pipe[0]);
  88   close(inst->pipe[1]);
  89
  90   for (i = 0; inst->status == DNS_Success && i < DNS_MAX_ADDRESSES &&
  91               inst->addresses[i].family != IPADDR_UNSPEC; i++)
  92     ;
  93
  94   (inst->handler)(inst->status, i, inst->addresses, inst->arg);
  95
  96   Free(inst);
  97 }
  98
  99 /* ================================================== */
 100
 101 void
 102 DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything)
 103 {
 104   struct DNS_Async_Instance *inst;
 105
 106   inst = MallocNew(struct DNS_Async_Instance);
 107   inst->name = name;
 108   inst->handler = handler;
 109   inst->arg = anything;
 110   inst->status = DNS_Failure;
 111
 112   if (pipe(inst->pipe)) {
 113     LOG_FATAL("pipe() failed");
 114   }
 115
 116   UTI_FdSetCloexec(inst->pipe[0]);
 117   UTI_FdSetCloexec(inst->pipe[1]);
 118
 119   if (pthread_create(&inst->thread, NULL, start_resolving, inst)) {
 120     LOG_FATAL("pthread_create() failed");
 121   }
 122
 123   SCH_AddFileHandler(inst->pipe[0], SCH_FILE_INPUT, end_resolving, inst);
 124 }
 125
 126 /* ================================================== */
 127
 128 #else
 129 #error
 130 #endif