Add an optional connection timeout option for the net backend. This can be used to prevent the backend from hanging for several minutes when the saned server is unresponsive.

2007-10-24 10:32:46 +00:00 · 2007-10-24 10:32:46 +00:00 · 4cf4d8dd7f
commit 4cf4d8dd7f
--- a/9
+++ b/9
@ -1,3 +1,12 @@
+2007-10-24  Julien Blache <jb@jblache.org>
+	* backends/net.c: Add an optional connection timeout for the
+	initial connection to saned. Based on a patch from Ryan Duryea
+	<rduryea@avanta.com>. Bump net backend version to 1.0.14.
+	* backends/net.conf.in: Add the new connect_timeout option and
+	adjust comments accordingly.
+	* doc/sane-net.man: Document the connect_timeout option and the
+	SANE_NET_TIMEOUT environment variable.
+
 2007-10-19  Stephane Voltz <stef.dev@free.fr>

 	* tools/check-usb-chip.c: added detection of rts8801 and
--- a/backend/net.c
+++ b/backend/net.c
@ -89,13 +89,13 @@
 #if defined (HAVE_GETADDRINFO) && defined (HAVE_GETNAMEINFO)
 # define NET_USES_AF_INDEP
 # ifdef ENABLE_IPV6
-#  define NET_VERSION "1.0.13 (AF-indep+IPv6)"
+#  define NET_VERSION "1.0.14 (AF-indep+IPv6)"
 # else
-#  define NET_VERSION "1.0.13 (AF-indep)"
+#  define NET_VERSION "1.0.14 (AF-indep)"
 # endif /* ENABLE_IPV6 */
 #else
 # undef ENABLE_IPV6
-# define NET_VERSION "1.0.13"
+# define NET_VERSION "1.0.14"
 #endif /* HAVE_GETADDRINFO && HAVE_GETNAMEINFO */

 static SANE_Auth_Callback auth_callback;
@ -105,6 +105,7 @@ static const SANE_Device **devlist;
 static int client_big_endian; /* 1 == big endian; 0 == little endian */
 static int server_big_endian; /* 1 == big endian; 0 == little endian */
 static int depth; /* bits per pixel */
+static int connect_timeout = -1; /* timeout for connection to saned */

 #ifndef NET_USES_AF_INDEP
 static int saned_port;
@ -290,6 +291,7 @@ connect_dev (Net_Device * dev)
  int on = 1;
  int level = -1;
 #endif
+  struct timeval tv;

  int i;

@ -317,6 +319,18 @@ connect_dev (Net_Device * dev)
 	  continue;
 	}

+      /* Set SO_SNDTIMEO for the connection to saned */
+      if (connect_timeout > 0)
+	{
+	  tv.tv_sec = connect_timeout;
+	  tv.tv_usec = 0;
+
+	  if (setsockopt (dev->ctl, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) < 0)
+	    {
+	      DBG (1, "connect_dev: [%d] failed to set SO_SNDTIMEO (%s)\n", i, strerror (errno));
+	    }
+	}
+
      if (connect (dev->ctl, addrp->ai_addr, addrp->ai_addrlen) < 0)
 	{
 	  DBG (1, "connect_dev: [%d] failed to connect (%s)\n", i, strerror (errno));
@ -348,6 +362,7 @@ connect_dev (Net_Device * dev)
  int on = 1;
  int level = -1;
 #endif
+  struct timeval tv;

  DBG (2, "connect_dev: trying to connect to %s\n", dev->name);

@ -369,6 +384,19 @@ connect_dev (Net_Device * dev)
  sin = (struct sockaddr_in *) &dev->addr;
  sin->sin_port = saned_port;

+
+  /* Set SO_SNDTIMEO for the connection to saned */
+  if (connect_timeout > 0)
+    {
+      tv.tv_sec = connect_timeout;
+      tv.tv_usec = 0;
+
+      if (setsockopt (dev->ctl, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) < 0)
+	{
+	  DBG (1, "connect_dev: [%d] failed to set SO_SNDTIMEO (%s)\n", i, strerror (errno));
+	}
+    }
+
  if (connect (dev->ctl, &dev->addr, sizeof (dev->addr)) < 0)
    {
      DBG (1, "connect_dev: failed to connect (%s)\n", strerror (errno));
@ -378,6 +406,18 @@ connect_dev (Net_Device * dev)
  DBG (3, "connect_dev: connection succeeded\n");
 #endif /* NET_USES_AF_INDEP */

+  /* We're connected now, so reset SO_SNDTIMEO to the default value of 0 */
+  if (connect_timeout > 0)
+    {
+      tv.tv_sec = 0;
+      tv.tv_usec = 0;
+
+      if (setsockopt (dev->ctl, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) < 0)
+	{
+	  DBG (1, "connect_dev: [%d] failed to reset SO_SNDTIMEO (%s)\n", i, strerror (errno));
+	}
+    }
+
 #ifdef TCP_NODELAY
 # ifdef SOL_TCP
  level = SOL_TCP;
@ -620,6 +660,7 @@ SANE_Status
 sane_init (SANE_Int * version_code, SANE_Auth_Callback authorize)
 {
  char device_name[PATH_MAX];
+  const char *optval;
  const char *env;
  size_t len;
  FILE *fp;
@ -693,6 +734,29 @@ sane_init (SANE_Int * version_code, SANE_Auth_Callback authorize)
 	  if (!len)
 	    continue;		/* ignore empty lines */

+	  /*
+	   * Check for net backend options.
+	   * Anything that isn't an option is a saned host.
+	   */
+	  if (strstr(device_name, "connect_timeout") != NULL)
+	    {
+	      /* Look for the = sign; if it's not there, error out */
+	      optval = strchr(device_name, '=');
+
+	      if (!optval)
+		continue;
+
+	      optval = sanei_config_skip_whitespace (++optval);
+	      if ((optval != NULL) && (*optval != '\0'))
+		{
+		  connect_timeout = atoi(optval);
+
+		  DBG (2, "sane_init: connect timeout set to %d seconds\n", connect_timeout);
+		}
+
+	      continue;
+	    }
+
 	  DBG (2, "sane_init: trying to add %s\n", device_name);
 	  add_device (device_name, 0);
 	}
@ -747,6 +811,15 @@ sane_init (SANE_Int * version_code, SANE_Auth_Callback authorize)
 	DBG (1, "sane_init: not enough memory to duplicate "
 	     "environment variable\n");
    }
+
+  DBG (2, "sane_init: evaluating environment variable SANE_NET_TIMEOUT\n");
+  env = getenv ("SANE_NET_TIMEOUT");
+  if (env)
+    {
+      connect_timeout = atoi(env);
+      DBG (2, "sane_init: connect timeout set to %d seconds from env\n", connect_timeout);
+    }
+
  DBG (2, "sane_init: done\n");
  return SANE_STATUS_GOOD;
 }
--- a/backend/net.conf.in
+++ b/backend/net.conf.in
@ -1,4 +1,13 @@
-# This is the net config file.  Each line names a host to attach to.
+# This is the net backend config file.
+
+## net backend options
+# Timeout for the initial connection to saned. This will prevent the backend
+# from blocking for several minutes trying to connect to an unresponsive
+# saned host (network outage, host down, ...). Value in seconds.
+# connect_timeout = 60
+
+## saned hosts
+# Each line names a host to attach to.
 # If you list "localhost" then your backends can be accessed either
 # directly or through the net backend.  Going through the net backend
 # may be necessary to access devices that need special privileges.
--- a/doc/descriptions/net.desc
+++ b/doc/descriptions/net.desc
@ -1,5 +1,5 @@
 :backend "net"               ; name of backend
-:version "1.0.13"
+:version "1.0.14"
 :manpage "sane-net"
 :url "http://www.penguin-breeder.org/?page=sane-net"

--- a/doc/sane-net.man
+++ b/doc/sane-net.man
@ -1,4 +1,4 @@
-.TH sane-net 5 "8 Oct 2002" "@PACKAGEVERSION@" "SANE Scanner Access Now Easy"
+.TH sane-net 5 "24 Oct 2007" "@PACKAGEVERSION@" "SANE Scanner Access Now Easy"
 .IX sane-net
 .SH NAME
 sane-net \- SANE network backend
@ -35,10 +35,24 @@ An IPv6 address can be specified enclosed in square brackets:
 .IR [::1] : device
 .RE
 .SH CONFIGURATION
-The contents of the
+The
 .IR net.conf
-file is a list of host names (or IP addresses) that should be contacted for
-scan requests.  Empty lines and lines starting with a hash mark (#) are
+file contains both backend options and a list of host names (or IP
+addresses) that should be contacted for scan requests. Anything that
+isn't one of the options listed below will be treated as an host name.
+.PP
+.TP
+.B connect_timeout = nsecs
+Timeout (in seconds) for the initial connection to the
+.I saned
+server. This will prevent the backend from blocking for several
+minutes trying to connect to an unresponsive
+.I saned
+host (network outage, host down, ...). The environment variable
+.B SANE_NET_TIMEOUT
+can also be used to specify the timeout at runtime.
+.PP
+Empty lines and lines starting with a hash mark (#) are
 ignored.  Note that IPv6 addresses in this file do not need to be enclosed
 in square brackets.  A sample configuration file is shown below:
 .PP
@ -121,6 +135,11 @@ to "/tmp/config:" would result in directories "tmp/config", ".", and
 A colon-separated list of host names or IP addresses to be contacted by this
 backend.
 .TP
+.B SANE_NET_TIMEOUT
+Number of seconds to wait for a response from the
+.I saned
+server for the initial connection request.
+.TP
 .B SANE_DEBUG_NET
 If the library was compiled with debug support enabled, this
 environment variable controls the debug level for this backend.  E.g.,