Added dns_use_edns0 main option.

Is int because need a "do not override default" option, but that stops
us from using the bool expansion logic and so we need to explicitly
set numbers. Should try to find a way around that.

3 files changed, 23 insertions, 0 deletions

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 0ea36fa50..5cfa344c0 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -12669,6 +12669,7 @@ See also the &'Policy controls'& section above.
 .row &%dns_ipv4_lookup%&             "only v4 lookup for these domains"
 .row &%dns_retrans%&                 "parameter for resolver"
 .row &%dns_retry%&                   "parameter for resolver"
+.row &%dns_use_edns0%&               "parameter for resolver"
 .row &%hold_domains%&                "hold delivery for these domains"
 .row &%local_interfaces%&            "for routing checks"
 .row &%queue_domains%&               "no immediate delivery for these"
@@ -13301,6 +13302,19 @@ to set in them.
 See &%dns_retrans%& above.
 
 
+.new
+.option dns_use_edns0 main integer -1
+.cindex "DNS" "resolver options"
+.cindex "DNS" "EDNS0"
+If this option is set to a non-negative number then Exim will initialise the
+DNS resolver library to either use or not use EDNS0 extensions, overriding
+the system default. A value of 0 coerces EDNS0 off, a value of 1 coerces EDNS0
+on.
+
+If the resolver library does not support EDNS0 then this option has no effect.
+.wen
+
+
 .option drop_cr main boolean false
 This is an obsolete option that is now a no-op. It used to affect the way Exim
 handled CR and LF characters in incoming messages. What happens now is
diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 14dac2946..7105e5fc6 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -13,6 +13,8 @@ PP/02 Harmonised TLS library version reporting; only show if debugging.
 
 PP/03 New openssl_options items: no_sslv2 no_sslv3 no_ticket no_tlsv1
 
+PP/04 New "dns_use_edns0" global option.
+
 
 Exim version 4.75
 -----------------
diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff
index b940afe34..c205e9c98 100644
--- a/doc/doc-txt/NewStuff
+++ b/doc/doc-txt/NewStuff
@@ -9,6 +9,13 @@ test from the snapshots or the CVS before the documentation is updated. Once
 the documentation is updated, this file is reduced to a short list.
 
 
+Version 4.76
+------------
+
+ 1. The global option "dns_use_edns0" may be set to coerce EDNS0 usage on
+    or off in the resolver library.
+
+
 Version 4.75
 ------------