Re: URL field / Loading page images / Refreshing DNS cache

Johannes Hofmann <[email protected]>
Newsgroups gmane.comp.web.dillo.devel
Message-ID <[email protected]> 
On Wed, Jul 06, 2016 at 10:28:04AM +0200, Johannes Hofmann wrote:
> On Tue, Jul 05, 2016 at 04:53:45PM -0400, John Gaffney wrote:
> > First, a huge thanks to all the Dillo team for their efforts: I just
> > switched from 3.0.5 to the current snapshot to try out the mbedtls
> > changes, and I am wowed not only by this, but by all the improvements
> > in rendering, etc.  Great work!
> > 
> > A few suggestions, all very minor, that might be added to the back of
> > the development queue:
> > 
> > In the current snapshot, the navigation bar has changed, and the URL
> > field does not seem to be taking into account font_factor -- with the
> > result that the window is smaller than the font height.  You can test
> > this by setting, e.g., font_factor=2.0 in your dillorc (most
> > dramatically for a tiny panel with small icons).  The issue seems to
> > be with this factor not being taken into account when bh and lh are
> > set in make_panel() in ui.cc.
> > 
> > As far as I can see, one can use the context menu to download
> > individual images on a page, or use the panel to toggle image
> > loading.  But if one wants not to download images in general, but to
> > download all the images for some one page (e.g., a weather forecast
> > page), then one has to toggle downloading of images on and then off
> > again.  Maybe a command could be added to KeysCommand_t in keys.hh,
> > bound by default to something like Ctrl-i in keys.cc, with a
> > corresponding call to a_Html_load_images() in handle() in ui.cc?
> > 
> > To make the switch to the current snapshot, I had, sadly, to terminate
> > an instance of 3.0.5 that had been running continuously for 90 days
> > without any issues.  But to get that much up time it was necessary to
> > add a little code so that SIGUSR1 would call a_Dns_freeall() and
> > a_Dns_init(), otherwise (unless I am missing something) Dillo will
> > persist in using the cached lookup indefinitely and not detect when
> > the IP address has changed.  So maybe some sort of key binding could
> > be added that would flush the cache when needed?
> 
> good point. However I'd like to avoid another key-binding and rather
> do the right thing automatically.
> I could think of a general DNS entry timeout of a couple of seconds.
> In many cases DNS responses are cached at OS-level too respecting
> lifetime values given by the server.

Firefox has an option to configure the DNS cache expiration
(network.dnsCacheExpiration).
Attached patch implements a similar feature for Dillo.

Cheers,
Johannes

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dns_cache_expiration.diff (text/plain, 4.2 KB) 
diff -r ff7b186fdf93 dillorc
--- a/dillorc	Fri Jul 08 01:19:56 2016 +0000
+++ b/dillorc	Fri Jul 08 16:11:03 2016 +0200
@@ -228,6 +228,9 @@
 # http_user_agent="Wget/1.13.4 (linux-gnu)"
 #The default is "Dillo/"+current_version_number
 
+# Set the time in seconds for which DNS results should be cached.
+#dns_cache_expiration=300
+
 #-------------------------------------------------------------------------
 #                            COLORS SECTION
 #-------------------------------------------------------------------------
diff -r ff7b186fdf93 src/dns.c
--- a/src/dns.c	Fri Jul 08 01:19:56 2016 +0000
+++ b/src/dns.c	Fri Jul 08 16:11:03 2016 +0200
@@ -36,10 +36,12 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <time.h>
 
 #include "msg.h"
 #include "dns.h"
 #include "list.h"
+#include "prefs.h"
 #include "IO/iowatch.hh"
 
 
@@ -70,6 +72,7 @@
 typedef struct {
    char *hostname;         /* host name for cache */
    Dlist *addr_list;       /* addresses of host */
+   time_t resolve_time;    /* time when we resolved the hostname */
 } GDnsCache;
 
 typedef struct {
@@ -166,10 +169,33 @@
    a_List_add(dns_cache, dns_cache_size, dns_cache_size_max);
    dns_cache[dns_cache_size].hostname = dStrdup(hostname);
    dns_cache[dns_cache_size].addr_list = addr_list;
+   dns_cache[dns_cache_size].resolve_time = time(NULL);
    ++dns_cache_size;
    _MSG("Cache objects: %d\n", dns_cache_size);
 }
 
+static const GDnsCache* Dns_cache_find(const char *hostname)
+{
+   const GDnsCache *result = NULL;
+   time_t now = time(NULL);
+   int i;
+
+   for (i = 0; i < dns_cache_size; i++) {
+      if (now - dns_cache[i].resolve_time > prefs.dns_cache_expiration) {
+          MSG("Dns_cache_find: remove timed out entry for %s\n", dns_cache[i].hostname);
+          a_List_remove(dns_cache, i, dns_cache_size);
+          i--;
+          continue;
+      }
+
+      if (!dStrAsciiCasecmp(hostname, dns_cache[i].hostname)) {
+         result = &dns_cache[i];
+         break;
+      }
+   }
+
+   return result;
+}
 
 /*
  *  Initializer function
@@ -371,18 +397,16 @@
 void a_Dns_resolve(const char *hostname, DnsCallback_t cb_func, void *cb_data)
 {
    int i, channel;
+   const GDnsCache* cached_result;
 
    if (!hostname)
       return;
 
    /* check for cache hit. */
-   for (i = 0; i < dns_cache_size; i++)
-      if (!dStrAsciiCasecmp(hostname, dns_cache[i].hostname))
-         break;
-
-   if (i < dns_cache_size) {
+   cached_result = Dns_cache_find(hostname);
+   if (cached_result) {
       /* already resolved, call the Callback immediately. */
-      cb_func(0, dns_cache[i].addr_list, cb_data);
+      cb_func(0, cached_result->addr_list, cb_data);
 
    } else if ((i = Dns_queue_find(hostname)) != -1) {
       /* hit in queue, but answer hasn't come back yet. */
diff -r ff7b186fdf93 src/prefs.c
--- a/src/prefs.c	Fri Jul 08 01:19:56 2016 +0000
+++ b/src/prefs.c	Fri Jul 08 16:11:03 2016 +0200
@@ -68,6 +68,7 @@
    prefs.http_referer = dStrdup(PREFS_HTTP_REFERER);
    prefs.http_strict_transport_security = TRUE;
    prefs.http_user_agent = dStrdup(PREFS_HTTP_USER_AGENT);
+   prefs.dns_cache_expiration = 300;
    prefs.limit_text_width = FALSE;
    prefs.adjust_min_width = TRUE;
    prefs.adjust_table_min_width = TRUE;
diff -r ff7b186fdf93 src/prefs.h
--- a/src/prefs.h	Fri Jul 08 01:19:56 2016 +0000
+++ b/src/prefs.h	Fri Jul 08 16:11:03 2016 +0200
@@ -40,6 +40,7 @@
    int ypos;
    char *http_language;
    int32_t http_max_conns;
+   int32_t dns_cache_expiration;
    DilloUrl *http_proxy;
    char *http_proxyuser;
    char *http_referer;
diff -r ff7b186fdf93 src/prefsparser.cc
--- a/src/prefsparser.cc	Fri Jul 08 01:19:56 2016 +0000
+++ b/src/prefsparser.cc	Fri Jul 08 16:11:03 2016 +0200
@@ -174,6 +174,7 @@
       { "http_strict_transport_security",&prefs.http_strict_transport_security,
         PREFS_BOOL, 0 },
       { "http_user_agent", &prefs.http_user_agent, PREFS_STRING, 0 },
+      { "dns_cache_expiration", &prefs.dns_cache_expiration, PREFS_INT32, 0 },
       { "limit_text_width", &prefs.limit_text_width, PREFS_BOOL, 0 },
       { "adjust_min_width", &prefs.adjust_min_width, PREFS_BOOL, 0 },
       { "adjust_table_min_width", &prefs.adjust_table_min_width, PREFS_BOOL, 0 },
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