From bc26d2e6b287cc6693f41e1a2d48b0dd77d2e427 Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Tue, 18 Jun 2019 14:59:00 +1000
Subject: [PATCH] (perl #133936) make send() a bit saner
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This undoes some of the effect of f1000aa2d in that TO will always
be supplied to CORE::send() if it's supplied, otherwise whether
TO is supplied to CORE::send() is based on whether the socket is
connected.

On Linux you appear to be able to sendto() to a different address on
a connected UDP socket, but this doesn't appear to be portable,
failing on darwin, and presumably on other BSDs.

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 dist/IO/lib/IO/Socket.pm | 25 +++++++++++++++++--------
 dist/IO/t/io_udp.t       | 11 ++++++++---
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/dist/IO/lib/IO/Socket.pm b/dist/IO/lib/IO/Socket.pm
index 345ffd475d..28fa1ec149 100644
--- a/dist/IO/lib/IO/Socket.pm
+++ b/dist/IO/lib/IO/Socket.pm
@@ -277,13 +277,22 @@ sub send {
     @_ >= 2 && @_ <= 4 or croak 'usage: $sock->send(BUF, [FLAGS, [TO]])';
     my $sock  = $_[0];
     my $flags = $_[2] || 0;
-    my $peer  = $_[3] || $sock->peername;
+    my $peer;
 
-    croak 'send: Cannot determine peer address'
-	 unless(defined $peer);
+    if ($_[3]) {
+        # the caller explicitly requested a TO, so use it
+        # this is non-portable for "connected" UDP sockets
+        $peer = $_[3];
+    }
+    elsif (!defined getpeername($sock)) {
+        # we're not connected, so we require a peer from somewhere
+        $peer = $sock->peername;
+
+	croak 'send: Cannot determine peer address'
+	    unless(defined $peer);
+    }
 
-    my $type = $sock->socktype;
-    my $r = $type == SOCK_DGRAM || $type == SOCK_RAW
+    my $r = $peer
       ? send($sock, $_[1], $flags, $peer)
       : send($sock, $_[1], $flags);
 
@@ -526,9 +535,9 @@ C<FLAGS> is optional and defaults to C<0>, and
 
 =item *
 
-after a successful send with C<TO>, further calls to send() without
-C<TO> will send to the same address, and C<TO> will be used as the
-result of peername().
+after a successful send with C<TO>, further calls to send() on an
+unconnected socket without C<TO> will send to the same address, and
+C<TO> will be used as the result of peername().
 
 =back
 
diff --git a/dist/IO/t/io_udp.t b/dist/IO/t/io_udp.t
index 571e4303bb..2adc6a4a69 100644
--- a/dist/IO/t/io_udp.t
+++ b/dist/IO/t/io_udp.t
@@ -89,9 +89,14 @@ is($buf, 'FOObar');
     ok($udpa->recv($buf = "", 8), "recv it");
     is($buf, "fromctoa", "check value received");
 
-    ok($udpc->send("fromctob", 0, $udpb->sockname), "send to non-connected socket");
-    ok($udpb->recv($buf = "", 8), "recv it");
-    is($buf, "fromctob", "check value received");
+  SKIP:
+    {
+        $^O eq "linux"
+	  or skip "This is non-portable, known to 'work' on Linux", 3;
+        ok($udpc->send("fromctob", 0, $udpb->sockname), "send to non-connected socket");
+        ok($udpb->recv($buf = "", 8), "recv it");
+        is($buf, "fromctob", "check value received");
+    }
 }
 
 exit(0);
-- 
2.20.1