diff -up cups-2.2.0/cups/auth.c.resolv_reload cups-2.2.0/cups/auth.c

--- cups-2.2.0/cups/auth.c.resolv_reload	2016-09-14 01:39:47.000000000 +0200

+++ cups-2.2.0/cups/auth.c	2017-03-30 13:08:06.436258996 +0200

@@ -519,6 +519,16 @@ cups_gss_getname(

   DEBUG_printf(("7cups_gss_getname(http=%p, service_name=\"%s\")", http,

                 service_name));

+#ifdef HAVE_RES_INIT

+ /*

+  * Check if /etc/resolv.conf is modified.

+  * If so, reload resolver.

+  */

+

+  http_resolv_check_t status;

+

+  status = httpCheckResolv();

+#endif /* HAVE_RES_INIT */

  /*

   * Get the hostname...

diff -up cups-2.2.0/cups/http-addr.c.resolv_reload cups-2.2.0/cups/http-addr.c

--- cups-2.2.0/cups/http-addr.c.resolv_reload	2017-03-30 13:08:06.422259148 +0200

+++ cups-2.2.0/cups/http-addr.c	2017-03-30 13:08:06.436258996 +0200

@@ -361,6 +361,17 @@ httpAddrLookup(

 #ifdef HAVE_RES_INIT

  /*

+  * Check if /etc/resolv.conf is modified.

+  * If so, reload resolver and set need_res_init to 0.

+  */

+

+  http_resolv_check_t status;

+

+  status = httpCheckResolv();

+

+  if (status == HTTP_RESOLV_CHECK_RELOADED && cg->need_res_init == 1)

+    cg->need_res_init = 0;

+ /*

   * STR #2920: Initialize resolver after failure in cups-polld

   *

   * If the previous lookup failed, re-initialize the resolver to prevent

diff -up cups-2.2.0/cups/http-addrlist.c.resolv_reload cups-2.2.0/cups/http-addrlist.c

--- cups-2.2.0/cups/http-addrlist.c.resolv_reload	2017-03-30 13:08:06.434259017 +0200

+++ cups-2.2.0/cups/http-addrlist.c	2017-03-30 13:08:06.436258996 +0200

@@ -483,6 +483,17 @@ httpAddrGetList(const char *hostname,	/*

 #ifdef HAVE_RES_INIT

  /*

+  * Check if /etc/resolv.conf is modified.

+  * If so, reload resolver and set cg->need_res_init to 0

+  */

+

+  http_resolv_check_t status;

+

+  status = httpCheckResolv();

+

+  if (status == HTTP_RESOLV_CHECK_RELOADED && cg->need_res_init == 1)

+    cg->need_res_init = 0;

+ /*

   * STR #2920: Initialize resolver after failure in cups-polld

   *

   * If the previous lookup failed, re-initialize the resolver to prevent

diff -up cups-2.2.0/cups/http.c.resolv_reload cups-2.2.0/cups/http.c

--- cups-2.2.0/cups/http.c.resolv_reload	2016-09-14 01:39:47.000000000 +0200

+++ cups-2.2.0/cups/http.c	2017-03-30 13:12:38.411379288 +0200

@@ -107,6 +107,9 @@ static const char * const http_fields[]

 			  "Allow",

 			  "Server"

 			};

+#ifdef HAVE_RES_INIT

+time_t resolv_conf_modtime = 0;

+#endif /* HAVE_RES_INIT */

 /*

@@ -4811,3 +4814,34 @@ http_write_chunk(http_t     *http,	/* I

   return (bytes);

 }

+

+#ifdef HAVE_RES_INIT

+/*

+ * Function to check modification time of resolv.conf. 

+ * If time is changed, it reloads resolver.

+ */

+

+http_resolv_check_t

+httpCheckResolv()

+{

+  http_resolv_check_t status = HTTP_RESOLV_CHECK_OK;

+  struct stat resolv_conf_status;

+

+  status = stat(HTTP_RESOLV_CONF_PATH, &resolv_conf_status);

+

+  if (status == HTTP_RESOLV_CHECK_ERROR)

+    return (status);

+

+  if (resolv_conf_modtime != 0 && resolv_conf_status.st_mtime != resolv_conf_modtime)

+  {

+    res_init();

+

+    status = HTTP_RESOLV_CHECK_RELOADED;

+  }

+

+  resolv_conf_modtime = resolv_conf_status.st_mtime;

+

+  return (status);

+}

+#endif /* HAVE_RES_INIT */

+

diff -up cups-2.2.0/cups/http.h.resolv_reload cups-2.2.0/cups/http.h

--- cups-2.2.0/cups/http.h.resolv_reload	2016-09-14 01:39:47.000000000 +0200

+++ cups-2.2.0/cups/http.h	2017-03-30 13:08:06.437258985 +0200

@@ -55,6 +55,12 @@ typedef off_t ssize_t;			/* @private@ */

 #      define SO_PEERCRED LOCAL_PEERCRED

 #    endif /* LOCAL_PEERCRED && !SO_PEERCRED */

 #  endif /* WIN32 */

+#  ifdef HAVE_RES_INIT

+#    include <sys/stat.h>

+#    include <unistd.h>

+#    include <arpa/nameser.h>

+#    include <resolv.h>

+#  endif /* HAVE_RES_INIT */

 /*

@@ -95,6 +101,13 @@ extern "C" {

 #endif /* AF_INET6 && !s6_addr32 */

+#ifdef HAVE_RES_INIT

+/*

+ * Global variable for storing old modification time of resolv.conf 

+ */

+  extern time_t resolv_conf_modtime;

+#endif /* HAVE_RES_INIT */

+

 /*

  * Limits...

  */

@@ -103,6 +116,9 @@ extern "C" {

 #  define HTTP_MAX_HOST		256	/* Max length of hostname string */

 #  define HTTP_MAX_BUFFER	2048	/* Max length of data buffer */

 #  define HTTP_MAX_VALUE	256	/* Max header field value length */

+#  ifdef HAVE_RES_INIT

+#    define HTTP_RESOLV_CONF_PATH	"/etc/resolv.conf" /* Path to resolv.conf */

+#  endif /* HAVE_RES_INIT */

 /*

@@ -406,6 +422,15 @@ typedef enum http_version_e		/**** HTTP

 #  endif /* !_CUPS_NO_DEPRECATED */

 } http_version_t;

+#ifdef HAVE_RES_INIT

+typedef enum http_resolv_check_e

+{

+  HTTP_RESOLV_CHECK_ERROR = -1,

+  HTTP_RESOLV_CHECK_OK = 0,

+  HTTP_RESOLV_CHECK_RELOADED = 1

+} http_resolv_check_t;

+#endif /* HAVE_RES_INIT */

+

 typedef union _http_addr_u		/**** Socket address union, which

 					 **** makes using IPv6 and other

 					 **** address types easier and

@@ -644,6 +669,11 @@ extern void		httpShutdown(http_t *http)

 extern const char	*httpStateString(http_state_t state) _CUPS_API_2_0;

 extern const char	*httpURIStatusString(http_uri_status_t status) _CUPS_API_2_0;

+/**** Prototype of function to check modification time of /etc/resolv.conf ****/

+#ifdef HAVE_RES_INIT

+extern http_resolv_check_t	httpCheckResolv();

+#endif /* HAVE_RES_INIT */

+

 /*

  * C++ magic...

  */

diff -up cups-2.2.0/cups/http-support.c.resolv_reload cups-2.2.0/cups/http-support.c

--- cups-2.2.0/cups/http-support.c.resolv_reload	2017-03-30 13:08:06.437258985 +0200

+++ cups-2.2.0/cups/http-support.c	2017-03-30 13:19:01.559533564 +0200

@@ -2258,6 +2258,16 @@ http_resolve_cb(

     http_addrlist_t	*addrlist,	/* List of addresses */

 			*addr;		/* Current address */

+#ifdef HAVE_RES_INIT

+   /*

+	* Check if resolv.conf is modified, if so, reload resolver

+	*/

+

+    http_resolv_check_t status;

+

+	status = httpCheckResolv();

+#endif /* HAVE_RES_INIT */

+

     DEBUG_printf(("5http_resolve_cb: Looking up \"%s\".", hostTarget));

     snprintf(fqdn, sizeof(fqdn), "%d", ntohs(port));

diff -up cups-2.2.0/scheduler/conf.c.resolv_reload cups-2.2.0/scheduler/conf.c

--- cups-2.2.0/scheduler/conf.c.resolv_reload	2017-03-30 13:08:06.433259028 +0200

+++ cups-2.2.0/scheduler/conf.c	2017-03-30 13:08:06.439258963 +0200

@@ -937,6 +937,12 @@ cupsdReadConfiguration(void)

   if (!RemotePort)

     BrowseLocalProtocols = 0;		/* Disable sharing - no remote access */

+#ifdef HAVE_RES_INIT

+  http_resolv_check_t res_status;	/* Return status of httpCheckResolv() */

+

+  res_status = httpCheckResolv();

+#endif /* HAVE_RES_INIT */

+

  /*

   * See if the ServerName is an IP address...

   */

diff -up cups-2.2.0/scheduler/main.c.resolv_reload cups-2.2.0/scheduler/main.c

--- cups-2.2.0/scheduler/main.c.resolv_reload	2017-03-30 13:08:06.440258952 +0200

+++ cups-2.2.0/scheduler/main.c	2017-03-30 13:23:38.886665663 +0200

@@ -136,6 +136,17 @@ main(int  argc,				/* I - Number of comm

   long			tmo_delay;	/* Time before it must be called */

 #endif /* HAVE_AVAHI */

+#ifdef HAVE_RES_INIT

+  http_resolv_check_t status;	/* Return status from httpCheckResolv() */

+

+  status = httpCheckResolv();

+  if (status == HTTP_RESOLV_CHECK_ERROR)

+  {

+    fputs("cupsd: Cannot get a status of /etc/resolv.conf\n", stderr);

+	return (1);

+  }

+#endif /* HAVE_RES_INIT */

+

 #ifdef HAVE_GETEUID

  /*

   * Check for setuid invocation, which we do not support!