--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/curl/lib/hostip.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,1068 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_NETINET_IN6_H
+#include <netinet/in6.h>
+#endif
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+#ifdef HAVE_ARPA_INET_H
+#include <arpa/inet.h>
+#endif
+#ifdef __VMS
+#include <in.h>
+#include <inet.h>
+#endif
+
+#ifdef HAVE_SETJMP_H
+#include <setjmp.h>
+#endif
+#ifdef HAVE_SIGNAL_H
+#include <signal.h>
+#endif
+
+#ifdef HAVE_PROCESS_H
+#include <process.h>
+#endif
+
+#include "urldata.h"
+#include "sendf.h"
+#include "hostip.h"
+#include "hash.h"
+#include "rand.h"
+#include "share.h"
+#include "strerror.h"
+#include "url.h"
+#include "inet_ntop.h"
+#include "multiif.h"
+#include "doh.h"
+#include "warnless.h"
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+
+#if defined(CURLRES_SYNCH) && \
+    defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP)
+/* alarm-based timeouts can only be used with all the dependencies satisfied */
+#define USE_ALARM_TIMEOUT
+#endif
+
+#define MAX_HOSTCACHE_LEN (255 + 7) /* max FQDN + colon + port number + zero */
+
+/*
+ * hostip.c explained
+ * ==================
+ *
+ * The main COMPILE-TIME DEFINES to keep in mind when reading the host*.c
+ * source file are these:
+ *
+ * CURLRES_IPV6 - this host has getaddrinfo() and family, and thus we use
+ * that. The host may not be able to resolve IPv6, but we don't really have to
+ * take that into account. Hosts that aren't IPv6-enabled have CURLRES_IPV4
+ * defined.
+ *
+ * CURLRES_ARES - is defined if libcurl is built to use c-ares for
+ * asynchronous name resolves. This can be Windows or *nix.
+ *
+ * CURLRES_THREADED - is defined if libcurl is built to run under (native)
+ * Windows, and then the name resolve will be done in a new thread, and the
+ * supported API will be the same as for ares-builds.
+ *
+ * If any of the two previous are defined, CURLRES_ASYNCH is defined too. If
+ * libcurl is not built to use an asynchronous resolver, CURLRES_SYNCH is
+ * defined.
+ *
+ * The host*.c sources files are split up like this:
+ *
+ * hostip.c   - method-independent resolver functions and utility functions
+ * hostasyn.c - functions for asynchronous name resolves
+ * hostsyn.c  - functions for synchronous name resolves
+ * hostip4.c  - IPv4 specific functions
+ * hostip6.c  - IPv6 specific functions
+ *
+ * The two asynchronous name resolver backends are implemented in:
+ * asyn-ares.c   - functions for ares-using name resolves
+ * asyn-thread.c - functions for threaded name resolves
+
+ * The hostip.h is the united header file for all this. It defines the
+ * CURLRES_* defines based on the config*.h and curl_setup.h defines.
+ */
+
+static void freednsentry(void *freethis);
+
+/*
+ * Return # of addresses in a Curl_addrinfo struct
+ */
+int Curl_num_addresses(const Curl_addrinfo *addr)
+{
+  int i = 0;
+  while(addr) {
+    addr = addr->ai_next;
+    i++;
+  }
+  return i;
+}
+
+/*
+ * Curl_printable_address() returns a printable version of the 1st address
+ * given in the 'ai' argument. The result will be stored in the buf that is
+ * bufsize bytes big.
+ *
+ * If the conversion fails, it returns NULL.
+ */
+const char *
+Curl_printable_address(const Curl_addrinfo *ai, char *buf, size_t bufsize)
+{
+  const struct sockaddr_in *sa4;
+  const struct in_addr *ipaddr4;
+#ifdef ENABLE_IPV6
+  const struct sockaddr_in6 *sa6;
+  const struct in6_addr *ipaddr6;
+#endif
+
+  switch(ai->ai_family) {
+    case AF_INET:
+      sa4 = (const void *)ai->ai_addr;
+      ipaddr4 = &sa4->sin_addr;
+      return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr4, buf,
+                            bufsize);
+#ifdef ENABLE_IPV6
+    case AF_INET6:
+      sa6 = (const void *)ai->ai_addr;
+      ipaddr6 = &sa6->sin6_addr;
+      return Curl_inet_ntop(ai->ai_family, (const void *)ipaddr6, buf,
+                            bufsize);
+#endif
+    default:
+      break;
+  }
+  return NULL;
+}
+
+/*
+ * Create a hostcache id string for the provided host + port, to be used by
+ * the DNS caching. Without alloc.
+ */
+static void
+create_hostcache_id(const char *name, int port, char *ptr, size_t buflen)
+{
+  size_t len = strlen(name);
+  if(len > (buflen - 7))
+    len = buflen - 7;
+  /* store and lower case the name */
+  while(len--)
+    *ptr++ = (char)TOLOWER(*name++);
+  msnprintf(ptr, 7, ":%u", port);
+}
+
+struct hostcache_prune_data {
+  long cache_timeout;
+  time_t now;
+};
+
+/*
+ * This function is set as a callback to be called for every entry in the DNS
+ * cache when we want to prune old unused entries.
+ *
+ * Returning non-zero means remove the entry, return 0 to keep it in the
+ * cache.
+ */
+static int
+hostcache_timestamp_remove(void *datap, void *hc)
+{
+  struct hostcache_prune_data *data =
+    (struct hostcache_prune_data *) datap;
+  struct Curl_dns_entry *c = (struct Curl_dns_entry *) hc;
+
+  return (0 != c->timestamp)
+    && (data->now - c->timestamp >= data->cache_timeout);
+}
+
+/*
+ * Prune the DNS cache. This assumes that a lock has already been taken.
+ */
+static void
+hostcache_prune(struct curl_hash *hostcache, long cache_timeout, time_t now)
+{
+  struct hostcache_prune_data user;
+
+  user.cache_timeout = cache_timeout;
+  user.now = now;
+
+  Curl_hash_clean_with_criterium(hostcache,
+                                 (void *) &user,
+                                 hostcache_timestamp_remove);
+}
+
+/*
+ * Library-wide function for pruning the DNS cache. This function takes and
+ * returns the appropriate locks.
+ */
+void Curl_hostcache_prune(struct Curl_easy *data)
+{
+  time_t now;
+
+  if((data->set.dns_cache_timeout == -1) || !data->dns.hostcache)
+    /* cache forever means never prune, and NULL hostcache means
+       we can't do it */
+    return;
+
+  if(data->share)
+    Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+  time(&now);
+
+  /* Remove outdated and unused entries from the hostcache */
+  hostcache_prune(data->dns.hostcache,
+                  data->set.dns_cache_timeout,
+                  now);
+
+  if(data->share)
+    Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+}
+
+#ifdef HAVE_SIGSETJMP
+/* Beware this is a global and unique instance. This is used to store the
+   return address that we can jump back to from inside a signal handler. This
+   is not thread-safe stuff. */
+sigjmp_buf curl_jmpenv;
+#endif
+
+/* lookup address, returns entry if found and not stale */
+static struct Curl_dns_entry *
+fetch_addr(struct connectdata *conn,
+                const char *hostname,
+                int port)
+{
+  struct Curl_dns_entry *dns = NULL;
+  size_t entry_len;
+  struct Curl_easy *data = conn->data;
+  char entry_id[MAX_HOSTCACHE_LEN];
+
+  /* Create an entry id, based upon the hostname and port */
+  create_hostcache_id(hostname, port, entry_id, sizeof(entry_id));
+  entry_len = strlen(entry_id);
+
+  /* See if its already in our dns cache */
+  dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len + 1);
+
+  /* No entry found in cache, check if we might have a wildcard entry */
+  if(!dns && data->change.wildcard_resolve) {
+    create_hostcache_id("*", port, entry_id, sizeof(entry_id));
+    entry_len = strlen(entry_id);
+
+    /* See if it's already in our dns cache */
+    dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len + 1);
+  }
+
+  if(dns && (data->set.dns_cache_timeout != -1)) {
+    /* See whether the returned entry is stale. Done before we release lock */
+    struct hostcache_prune_data user;
+
+    time(&user.now);
+    user.cache_timeout = data->set.dns_cache_timeout;
+
+    if(hostcache_timestamp_remove(&user, dns)) {
+      infof(data, "Hostname in DNS cache was stale, zapped\n");
+      dns = NULL; /* the memory deallocation is being handled by the hash */
+      Curl_hash_delete(data->dns.hostcache, entry_id, entry_len + 1);
+    }
+  }
+
+  return dns;
+}
+
+/*
+ * Curl_fetch_addr() fetches a 'Curl_dns_entry' already in the DNS cache.
+ *
+ * Curl_resolv() checks initially and multi_runsingle() checks each time
+ * it discovers the handle in the state WAITRESOLVE whether the hostname
+ * has already been resolved and the address has already been stored in
+ * the DNS cache. This short circuits waiting for a lot of pending
+ * lookups for the same hostname requested by different handles.
+ *
+ * Returns the Curl_dns_entry entry pointer or NULL if not in the cache.
+ *
+ * The returned data *MUST* be "unlocked" with Curl_resolv_unlock() after
+ * use, or we'll leak memory!
+ */
+struct Curl_dns_entry *
+Curl_fetch_addr(struct connectdata *conn,
+                const char *hostname,
+                int port)
+{
+  struct Curl_easy *data = conn->data;
+  struct Curl_dns_entry *dns = NULL;
+
+  if(data->share)
+    Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+  dns = fetch_addr(conn, hostname, port);
+
+  if(dns)
+    dns->inuse++; /* we use it! */
+
+  if(data->share)
+    Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+
+  return dns;
+}
+
+#ifndef CURL_DISABLE_SHUFFLE_DNS
+UNITTEST CURLcode Curl_shuffle_addr(struct Curl_easy *data,
+                                    Curl_addrinfo **addr);
+/*
+ * Curl_shuffle_addr() shuffles the order of addresses in a 'Curl_addrinfo'
+ * struct by re-linking its linked list.
+ *
+ * The addr argument should be the address of a pointer to the head node of a
+ * `Curl_addrinfo` list and it will be modified to point to the new head after
+ * shuffling.
+ *
+ * Not declared static only to make it easy to use in a unit test!
+ *
+ * @unittest: 1608
+ */
+UNITTEST CURLcode Curl_shuffle_addr(struct Curl_easy *data,
+                                    Curl_addrinfo **addr)
+{
+  CURLcode result = CURLE_OK;
+  const int num_addrs = Curl_num_addresses(*addr);
+
+  if(num_addrs > 1) {
+    Curl_addrinfo **nodes;
+    infof(data, "Shuffling %i addresses", num_addrs);
+
+    nodes = malloc(num_addrs*sizeof(*nodes));
+    if(nodes) {
+      int i;
+      unsigned int *rnd;
+      const size_t rnd_size = num_addrs * sizeof(*rnd);
+
+      /* build a plain array of Curl_addrinfo pointers */
+      nodes[0] = *addr;
+      for(i = 1; i < num_addrs; i++) {
+        nodes[i] = nodes[i-1]->ai_next;
+      }
+
+      rnd = malloc(rnd_size);
+      if(rnd) {
+        /* Fisher-Yates shuffle */
+        if(Curl_rand(data, (unsigned char *)rnd, rnd_size) == CURLE_OK) {
+          Curl_addrinfo *swap_tmp;
+          for(i = num_addrs - 1; i > 0; i--) {
+            swap_tmp = nodes[rnd[i] % (i + 1)];
+            nodes[rnd[i] % (i + 1)] = nodes[i];
+            nodes[i] = swap_tmp;
+          }
+
+          /* relink list in the new order */
+          for(i = 1; i < num_addrs; i++) {
+            nodes[i-1]->ai_next = nodes[i];
+          }
+
+          nodes[num_addrs-1]->ai_next = NULL;
+          *addr = nodes[0];
+        }
+        free(rnd);
+      }
+      else
+        result = CURLE_OUT_OF_MEMORY;
+      free(nodes);
+    }
+    else
+      result = CURLE_OUT_OF_MEMORY;
+  }
+  return result;
+}
+#endif
+
+/*
+ * Curl_cache_addr() stores a 'Curl_addrinfo' struct in the DNS cache.
+ *
+ * When calling Curl_resolv() has resulted in a response with a returned
+ * address, we call this function to store the information in the dns
+ * cache etc
+ *
+ * Returns the Curl_dns_entry entry pointer or NULL if the storage failed.
+ */
+struct Curl_dns_entry *
+Curl_cache_addr(struct Curl_easy *data,
+                Curl_addrinfo *addr,
+                const char *hostname,
+                int port)
+{
+  char entry_id[MAX_HOSTCACHE_LEN];
+  size_t entry_len;
+  struct Curl_dns_entry *dns;
+  struct Curl_dns_entry *dns2;
+
+#ifndef CURL_DISABLE_SHUFFLE_DNS
+  /* shuffle addresses if requested */
+  if(data->set.dns_shuffle_addresses) {
+    CURLcode result = Curl_shuffle_addr(data, &addr);
+    if(result)
+      return NULL;
+  }
+#endif
+
+  /* Create a new cache entry */
+  dns = calloc(1, sizeof(struct Curl_dns_entry));
+  if(!dns) {
+    return NULL;
+  }
+
+  /* Create an entry id, based upon the hostname and port */
+  create_hostcache_id(hostname, port, entry_id, sizeof(entry_id));
+  entry_len = strlen(entry_id);
+
+  dns->inuse = 1;   /* the cache has the first reference */
+  dns->addr = addr; /* this is the address(es) */
+  time(&dns->timestamp);
+  if(dns->timestamp == 0)
+    dns->timestamp = 1;   /* zero indicates CURLOPT_RESOLVE entry */
+
+  /* Store the resolved data in our DNS cache. */
+  dns2 = Curl_hash_add(data->dns.hostcache, entry_id, entry_len + 1,
+                       (void *)dns);
+  if(!dns2) {
+    free(dns);
+    return NULL;
+  }
+
+  dns = dns2;
+  dns->inuse++;         /* mark entry as in-use */
+  return dns;
+}
+
+/*
+ * Curl_resolv() is the main name resolve function within libcurl. It resolves
+ * a name and returns a pointer to the entry in the 'entry' argument (if one
+ * is provided). This function might return immediately if we're using asynch
+ * resolves. See the return codes.
+ *
+ * The cache entry we return will get its 'inuse' counter increased when this
+ * function is used. You MUST call Curl_resolv_unlock() later (when you're
+ * done using this struct) to decrease the counter again.
+ *
+ * In debug mode, we specifically test for an interface name "LocalHost"
+ * and resolve "localhost" instead as a means to permit test cases
+ * to connect to a local test server with any host name.
+ *
+ * Return codes:
+ *
+ * CURLRESOLV_ERROR   (-1) = error, no pointer
+ * CURLRESOLV_RESOLVED (0) = OK, pointer provided
+ * CURLRESOLV_PENDING  (1) = waiting for response, no pointer
+ */
+
+int Curl_resolv(struct connectdata *conn,
+                const char *hostname,
+                int port,
+                bool allowDOH,
+                struct Curl_dns_entry **entry)
+{
+  struct Curl_dns_entry *dns = NULL;
+  struct Curl_easy *data = conn->data;
+  CURLcode result;
+  int rc = CURLRESOLV_ERROR; /* default to failure */
+
+  *entry = NULL;
+
+  if(data->share)
+    Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+  dns = fetch_addr(conn, hostname, port);
+
+  if(dns) {
+    infof(data, "Hostname %s was found in DNS cache\n", hostname);
+    dns->inuse++; /* we use it! */
+    rc = CURLRESOLV_RESOLVED;
+  }
+
+  if(data->share)
+    Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+
+  if(!dns) {
+    /* The entry was not in the cache. Resolve it to IP address */
+
+    Curl_addrinfo *addr;
+    int respwait = 0;
+
+    /* Check what IP specifics the app has requested and if we can provide it.
+     * If not, bail out. */
+    if(!Curl_ipvalid(conn))
+      return CURLRESOLV_ERROR;
+
+    /* notify the resolver start callback */
+    if(data->set.resolver_start) {
+      int st;
+      Curl_set_in_callback(data, true);
+      st = data->set.resolver_start(data->state.resolver, NULL,
+                                    data->set.resolver_start_client);
+      Curl_set_in_callback(data, false);
+      if(st)
+        return CURLRESOLV_ERROR;
+    }
+
+    if(allowDOH && data->set.doh) {
+      addr = Curl_doh(conn, hostname, port, &respwait);
+    }
+    else {
+      /* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a
+         non-zero value indicating that we need to wait for the response to the
+         resolve call */
+      addr = Curl_getaddrinfo(conn,
+#ifdef DEBUGBUILD
+                              (data->set.str[STRING_DEVICE]
+                               && !strcmp(data->set.str[STRING_DEVICE],
+                                          "LocalHost"))?"localhost":
+#endif
+                              hostname, port, &respwait);
+    }
+    if(!addr) {
+      if(respwait) {
+        /* the response to our resolve call will come asynchronously at
+           a later time, good or bad */
+        /* First, check that we haven't received the info by now */
+        result = Curl_resolv_check(conn, &dns);
+        if(result) /* error detected */
+          return CURLRESOLV_ERROR;
+        if(dns)
+          rc = CURLRESOLV_RESOLVED; /* pointer provided */
+        else
+          rc = CURLRESOLV_PENDING; /* no info yet */
+      }
+    }
+    else {
+      if(data->share)
+        Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+      /* we got a response, store it in the cache */
+      dns = Curl_cache_addr(data, addr, hostname, port);
+
+      if(data->share)
+        Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+
+      if(!dns)
+        /* returned failure, bail out nicely */
+        Curl_freeaddrinfo(addr);
+      else
+        rc = CURLRESOLV_RESOLVED;
+    }
+  }
+
+  *entry = dns;
+
+  return rc;
+}
+
+#ifdef USE_ALARM_TIMEOUT
+/*
+ * This signal handler jumps back into the main libcurl code and continues
+ * execution.  This effectively causes the remainder of the application to run
+ * within a signal handler which is nonportable and could lead to problems.
+ */
+static
+RETSIGTYPE alarmfunc(int sig)
+{
+  /* this is for "-ansi -Wall -pedantic" to stop complaining!   (rabe) */
+  (void)sig;
+  siglongjmp(curl_jmpenv, 1);
+}
+#endif /* USE_ALARM_TIMEOUT */
+
+/*
+ * Curl_resolv_timeout() is the same as Curl_resolv() but specifies a
+ * timeout.  This function might return immediately if we're using asynch
+ * resolves. See the return codes.
+ *
+ * The cache entry we return will get its 'inuse' counter increased when this
+ * function is used. You MUST call Curl_resolv_unlock() later (when you're
+ * done using this struct) to decrease the counter again.
+ *
+ * If built with a synchronous resolver and use of signals is not
+ * disabled by the application, then a nonzero timeout will cause a
+ * timeout after the specified number of milliseconds. Otherwise, timeout
+ * is ignored.
+ *
+ * Return codes:
+ *
+ * CURLRESOLV_TIMEDOUT(-2) = warning, time too short or previous alarm expired
+ * CURLRESOLV_ERROR   (-1) = error, no pointer
+ * CURLRESOLV_RESOLVED (0) = OK, pointer provided
+ * CURLRESOLV_PENDING  (1) = waiting for response, no pointer
+ */
+
+int Curl_resolv_timeout(struct connectdata *conn,
+                        const char *hostname,
+                        int port,
+                        struct Curl_dns_entry **entry,
+                        timediff_t timeoutms)
+{
+#ifdef USE_ALARM_TIMEOUT
+#ifdef HAVE_SIGACTION
+  struct sigaction keep_sigact;   /* store the old struct here */
+  volatile bool keep_copysig = FALSE; /* whether old sigact has been saved */
+  struct sigaction sigact;
+#else
+#ifdef HAVE_SIGNAL
+  void (*keep_sigact)(int);       /* store the old handler here */
+#endif /* HAVE_SIGNAL */
+#endif /* HAVE_SIGACTION */
+  volatile long timeout;
+  volatile unsigned int prev_alarm = 0;
+  struct Curl_easy *data = conn->data;
+#endif /* USE_ALARM_TIMEOUT */
+  int rc;
+
+  *entry = NULL;
+
+  if(timeoutms < 0)
+    /* got an already expired timeout */
+    return CURLRESOLV_TIMEDOUT;
+
+#ifdef USE_ALARM_TIMEOUT
+  if(data->set.no_signal)
+    /* Ignore the timeout when signals are disabled */
+    timeout = 0;
+  else
+    timeout = (timeoutms > LONG_MAX) ? LONG_MAX : (long)timeoutms;
+
+  if(!timeout)
+    /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */
+    return Curl_resolv(conn, hostname, port, TRUE, entry);
+
+  if(timeout < 1000) {
+    /* The alarm() function only provides integer second resolution, so if
+       we want to wait less than one second we must bail out already now. */
+    failf(data,
+        "remaining timeout of %ld too small to resolve via SIGALRM method",
+        timeout);
+    return CURLRESOLV_TIMEDOUT;
+  }
+  /* This allows us to time-out from the name resolver, as the timeout
+     will generate a signal and we will siglongjmp() from that here.
+     This technique has problems (see alarmfunc).
+     This should be the last thing we do before calling Curl_resolv(),
+     as otherwise we'd have to worry about variables that get modified
+     before we invoke Curl_resolv() (and thus use "volatile"). */
+  if(sigsetjmp(curl_jmpenv, 1)) {
+    /* this is coming from a siglongjmp() after an alarm signal */
+    failf(data, "name lookup timed out");
+    rc = CURLRESOLV_ERROR;
+    goto clean_up;
+  }
+  else {
+    /*************************************************************
+     * Set signal handler to catch SIGALRM
+     * Store the old value to be able to set it back later!
+     *************************************************************/
+#ifdef HAVE_SIGACTION
+    sigaction(SIGALRM, NULL, &sigact);
+    keep_sigact = sigact;
+    keep_copysig = TRUE; /* yes, we have a copy */
+    sigact.sa_handler = alarmfunc;
+#ifdef SA_RESTART
+    /* HPUX doesn't have SA_RESTART but defaults to that behaviour! */
+    sigact.sa_flags &= ~SA_RESTART;
+#endif
+    /* now set the new struct */
+    sigaction(SIGALRM, &sigact, NULL);
+#else /* HAVE_SIGACTION */
+    /* no sigaction(), revert to the much lamer signal() */
+#ifdef HAVE_SIGNAL
+    keep_sigact = signal(SIGALRM, alarmfunc);
+#endif
+#endif /* HAVE_SIGACTION */
+
+    /* alarm() makes a signal get sent when the timeout fires off, and that
+       will abort system calls */
+    prev_alarm = alarm(curlx_sltoui(timeout/1000L));
+  }
+
+#else
+#ifndef CURLRES_ASYNCH
+  if(timeoutms)
+    infof(conn->data, "timeout on name lookup is not supported\n");
+#else
+  (void)timeoutms; /* timeoutms not used with an async resolver */
+#endif
+#endif /* USE_ALARM_TIMEOUT */
+
+  /* Perform the actual name resolution. This might be interrupted by an
+   * alarm if it takes too long.
+   */
+  rc = Curl_resolv(conn, hostname, port, TRUE, entry);
+
+#ifdef USE_ALARM_TIMEOUT
+clean_up:
+
+  if(!prev_alarm)
+    /* deactivate a possibly active alarm before uninstalling the handler */
+    alarm(0);
+
+#ifdef HAVE_SIGACTION
+  if(keep_copysig) {
+    /* we got a struct as it looked before, now put that one back nice
+       and clean */
+    sigaction(SIGALRM, &keep_sigact, NULL); /* put it back */
+  }
+#else
+#ifdef HAVE_SIGNAL
+  /* restore the previous SIGALRM handler */
+  signal(SIGALRM, keep_sigact);
+#endif
+#endif /* HAVE_SIGACTION */
+
+  /* switch back the alarm() to either zero or to what it was before minus
+     the time we spent until now! */
+  if(prev_alarm) {
+    /* there was an alarm() set before us, now put it back */
+    timediff_t elapsed_secs = Curl_timediff(Curl_now(),
+                                            conn->created) / 1000;
+
+    /* the alarm period is counted in even number of seconds */
+    unsigned long alarm_set = prev_alarm - elapsed_secs;
+
+    if(!alarm_set ||
+       ((alarm_set >= 0x80000000) && (prev_alarm < 0x80000000)) ) {
+      /* if the alarm time-left reached zero or turned "negative" (counted
+         with unsigned values), we should fire off a SIGALRM here, but we
+         won't, and zero would be to switch it off so we never set it to
+         less than 1! */
+      alarm(1);
+      rc = CURLRESOLV_TIMEDOUT;
+      failf(data, "Previous alarm fired off!");
+    }
+    else
+      alarm((unsigned int)alarm_set);
+  }
+#endif /* USE_ALARM_TIMEOUT */
+
+  return rc;
+}
+
+/*
+ * Curl_resolv_unlock() unlocks the given cached DNS entry. When this has been
+ * made, the struct may be destroyed due to pruning. It is important that only
+ * one unlock is made for each Curl_resolv() call.
+ *
+ * May be called with 'data' == NULL for global cache.
+ */
+void Curl_resolv_unlock(struct Curl_easy *data, struct Curl_dns_entry *dns)
+{
+  if(data && data->share)
+    Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+  freednsentry(dns);
+
+  if(data && data->share)
+    Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+}
+
+/*
+ * File-internal: release cache dns entry reference, free if inuse drops to 0
+ */
+static void freednsentry(void *freethis)
+{
+  struct Curl_dns_entry *dns = (struct Curl_dns_entry *) freethis;
+  DEBUGASSERT(dns && (dns->inuse>0));
+
+  dns->inuse--;
+  if(dns->inuse == 0) {
+    Curl_freeaddrinfo(dns->addr);
+    free(dns);
+  }
+}
+
+/*
+ * Curl_mk_dnscache() inits a new DNS cache and returns success/failure.
+ */
+int Curl_mk_dnscache(struct curl_hash *hash)
+{
+  return Curl_hash_init(hash, 7, Curl_hash_str, Curl_str_key_compare,
+                        freednsentry);
+}
+
+/*
+ * Curl_hostcache_clean()
+ *
+ * This _can_ be called with 'data' == NULL but then of course no locking
+ * can be done!
+ */
+
+void Curl_hostcache_clean(struct Curl_easy *data,
+                          struct curl_hash *hash)
+{
+  if(data && data->share)
+    Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+  Curl_hash_clean(hash);
+
+  if(data && data->share)
+    Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+}
+
+
+CURLcode Curl_loadhostpairs(struct Curl_easy *data)
+{
+  struct curl_slist *hostp;
+  char hostname[256];
+  int port = 0;
+
+  /* Default is no wildcard found */
+  data->change.wildcard_resolve = false;
+
+  for(hostp = data->change.resolve; hostp; hostp = hostp->next) {
+    char entry_id[MAX_HOSTCACHE_LEN];
+    if(!hostp->data)
+      continue;
+    if(hostp->data[0] == '-') {
+      size_t entry_len;
+
+      if(2 != sscanf(hostp->data + 1, "%255[^:]:%d", hostname, &port)) {
+        infof(data, "Couldn't parse CURLOPT_RESOLVE removal entry '%s'!\n",
+              hostp->data);
+        continue;
+      }
+
+      /* Create an entry id, based upon the hostname and port */
+      create_hostcache_id(hostname, port, entry_id, sizeof(entry_id));
+      entry_len = strlen(entry_id);
+
+      if(data->share)
+        Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+      /* delete entry, ignore if it didn't exist */
+      Curl_hash_delete(data->dns.hostcache, entry_id, entry_len + 1);
+
+      if(data->share)
+        Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+    }
+    else {
+      struct Curl_dns_entry *dns;
+      Curl_addrinfo *head = NULL, *tail = NULL;
+      size_t entry_len;
+      char address[64];
+#if !defined(CURL_DISABLE_VERBOSE_STRINGS)
+      char *addresses = NULL;
+#endif
+      char *addr_begin;
+      char *addr_end;
+      char *port_ptr;
+      char *end_ptr;
+      char *host_end;
+      unsigned long tmp_port;
+      bool error = true;
+
+      host_end = strchr(hostp->data, ':');
+      if(!host_end ||
+         ((host_end - hostp->data) >= (ptrdiff_t)sizeof(hostname)))
+        goto err;
+
+      memcpy(hostname, hostp->data, host_end - hostp->data);
+      hostname[host_end - hostp->data] = '\0';
+
+      port_ptr = host_end + 1;
+      tmp_port = strtoul(port_ptr, &end_ptr, 10);
+      if(tmp_port > USHRT_MAX || end_ptr == port_ptr || *end_ptr != ':')
+        goto err;
+
+      port = (int)tmp_port;
+#if !defined(CURL_DISABLE_VERBOSE_STRINGS)
+      addresses = end_ptr + 1;
+#endif
+
+      while(*end_ptr) {
+        size_t alen;
+        Curl_addrinfo *ai;
+
+        addr_begin = end_ptr + 1;
+        addr_end = strchr(addr_begin, ',');
+        if(!addr_end)
+          addr_end = addr_begin + strlen(addr_begin);
+        end_ptr = addr_end;
+
+        /* allow IP(v6) address within [brackets] */
+        if(*addr_begin == '[') {
+          if(addr_end == addr_begin || *(addr_end - 1) != ']')
+            goto err;
+          ++addr_begin;
+          --addr_end;
+        }
+
+        alen = addr_end - addr_begin;
+        if(!alen)
+          continue;
+
+        if(alen >= sizeof(address))
+          goto err;
+
+        memcpy(address, addr_begin, alen);
+        address[alen] = '\0';
+
+#ifndef ENABLE_IPV6
+        if(strchr(address, ':')) {
+          infof(data, "Ignoring resolve address '%s', missing IPv6 support.\n",
+                address);
+          continue;
+        }
+#endif
+
+        ai = Curl_str2addr(address, port);
+        if(!ai) {
+          infof(data, "Resolve address '%s' found illegal!\n", address);
+          goto err;
+        }
+
+        if(tail) {
+          tail->ai_next = ai;
+          tail = tail->ai_next;
+        }
+        else {
+          head = tail = ai;
+        }
+      }
+
+      if(!head)
+        goto err;
+
+      error = false;
+   err:
+      if(error) {
+        infof(data, "Couldn't parse CURLOPT_RESOLVE entry '%s'!\n",
+              hostp->data);
+        Curl_freeaddrinfo(head);
+        continue;
+      }
+
+      /* Create an entry id, based upon the hostname and port */
+      create_hostcache_id(hostname, port, entry_id, sizeof(entry_id));
+      entry_len = strlen(entry_id);
+
+      if(data->share)
+        Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
+
+      /* See if its already in our dns cache */
+      dns = Curl_hash_pick(data->dns.hostcache, entry_id, entry_len + 1);
+
+      if(dns) {
+        infof(data, "RESOLVE %s:%d is - old addresses discarded!\n",
+                hostname, port);
+        /* delete old entry entry, there are two reasons for this
+         1. old entry may have different addresses.
+         2. even if entry with correct addresses is already in the cache,
+            but if it is close to expire, then by the time next http
+            request is made, it can get expired and pruned because old
+            entry is not necessarily marked as added by CURLOPT_RESOLVE. */
+
+        Curl_hash_delete(data->dns.hostcache, entry_id, entry_len + 1);
+      }
+
+      /* put this new host in the cache */
+      dns = Curl_cache_addr(data, head, hostname, port);
+      if(dns) {
+        dns->timestamp = 0; /* mark as added by CURLOPT_RESOLVE */
+        /* release the returned reference; the cache itself will keep the
+         * entry alive: */
+            dns->inuse--;
+      }
+
+      if(data->share)
+        Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
+
+      if(!dns) {
+        Curl_freeaddrinfo(head);
+        return CURLE_OUT_OF_MEMORY;
+      }
+      infof(data, "Added %s:%d:%s to DNS cache\n",
+            hostname, port, addresses);
+
+      /* Wildcard hostname */
+      if(hostname[0] == '*' && hostname[1] == '\0') {
+        infof(data, "RESOLVE %s:%d is wildcard, enabling wildcard checks\n",
+              hostname, port);
+        data->change.wildcard_resolve = true;
+      }
+    }
+  }
+  data->change.resolve = NULL; /* dealt with now */
+
+  return CURLE_OK;
+}
+
+CURLcode Curl_resolv_check(struct connectdata *conn,
+                           struct Curl_dns_entry **dns)
+{
+  if(conn->data->set.doh)
+    return Curl_doh_is_resolved(conn, dns);
+  return Curl_resolver_is_resolved(conn, dns);
+}
+
+int Curl_resolv_getsock(struct connectdata *conn,
+                        curl_socket_t *socks)
+{
+#ifdef CURLRES_ASYNCH
+  if(conn->data->set.doh)
+    /* nothing to wait for during DOH resolve, those handles have their own
+       sockets */
+    return GETSOCK_BLANK;
+  return Curl_resolver_getsock(conn, socks);
+#else
+  (void)conn;
+  (void)socks;
+  return GETSOCK_BLANK;
+#endif
+}
+
+/* Call this function after Curl_connect() has returned async=TRUE and
+   then a successful name resolve has been received.
+
+   Note: this function disconnects and frees the conn data in case of
+   resolve failure */
+CURLcode Curl_once_resolved(struct connectdata *conn,
+                            bool *protocol_done)
+{
+  CURLcode result;
+
+  if(conn->async.dns) {
+    conn->dns_entry = conn->async.dns;
+    conn->async.dns = NULL;
+  }
+
+  result = Curl_setup_conn(conn, protocol_done);
+
+  if(result)
+    /* We're not allowed to return failure with memory left allocated
+       in the connectdata struct, free those here */
+    Curl_disconnect(conn->data, conn, TRUE); /* close the connection */
+
+  return result;
+}