From d7af9ef00abb1b022ad743048731664c6c3e0e19 Mon Sep 17 00:00:00 2001
From: Guillem Jover <gjover@sipwise.com>
Date: Fri, 7 Apr 2017 16:45:23 +0200
Subject: [PATCH] Collectd::Unixsock: Make code robust against socket errors
 and disconnections

We should check the errors on socket operations, and in case of EPIPE,
which happens on socket disconnection, such as when the server gets
restarted, we should try to reconnect and retry the last operation
to avoid losing data.
---
 bindings/perl/lib/Collectd/Unixsock.pm | 56 ++++++++++++++++++++++----
 1 file changed, 49 insertions(+), 7 deletions(-)

diff --git a/bindings/perl/lib/Collectd/Unixsock.pm b/bindings/perl/lib/Collectd/Unixsock.pm
index 4ec7993d0..28dbd57e6 100644
--- a/bindings/perl/lib/Collectd/Unixsock.pm
+++ b/bindings/perl/lib/Collectd/Unixsock.pm
@@ -57,6 +57,7 @@ use strict;
 use warnings;
 
 use Carp qw(cluck confess carp croak);
+use POSIX;
 use IO::Socket::UNIX;
 use Scalar::Util qw( looks_like_number );
 
@@ -146,6 +147,24 @@ sub _escape_argument
 	return "\"$arg\"";
 }
 
+# Handle socket errors.
+sub _socket_error {
+	my ($self, $where) = @_;
+
+	# If the peer has reset the connection, try to reconnect,
+	# otherwise fail.
+	if ($! == EPIPE) {
+		_debug "^^ error on $where: $!; reconnecting\n";
+		$self->destroy;
+		$self->{sock} = _create_socket ($self->{path}) or return 1;
+		return;
+	} else {
+		carp ("error on $where: $!; aborting action\n");
+		$self->{error} = $!;
+		return 1;
+	}
+}
+
 # Send a command on a socket, including any required argument escaping.
 # Return a single line of result.
 sub _socket_command {
@@ -160,9 +179,16 @@ sub _socket_command {
 		$command .= "\n";
 	}
 	_debug "-> $command";
-	$fh->print($command);
+	while (not $fh->print($command)) {
+		return if $self->_socket_error ('print');
+		$fh = $self->{sock};
+	}
 
-	my $response = $fh->getline;
+	my $response;
+	while (not defined ($response = $fh->getline)) {
+		return if $self->_socket_error ('getline');
+		$fh = $self->{sock};
+	}
 	chomp $response;
 	_debug "<- $response\n";
 	return $response;
@@ -185,7 +211,11 @@ sub _socket_chat
 
 	for (1 .. $nresults)
 	{
-		my $entry = $fh->getline;
+		my $entry;
+		while (not defined($entry = $fh->getline)) {
+			return if $self->_socket_error ('getline');
+			$fh = $self->{sock};
+		}
 		chomp $entry;
 		_debug "<- $entry\n";
 		$callback->($entry, $cbdata);
@@ -207,9 +237,15 @@ sub _send_message
 	warn "Collectd::Unixsock->_send_message(\$msg): message is too long!" if length($msg) > 1024;
 	
 	_debug "-> $msg";
-	$fh->print($msg);
+	while (not $fh->print($msg)) {
+		return if $self->_socket_error ('print');
+		$fh = $self->{sock};
+	}
 
-	$msg = <$fh>;
+	while (not defined ($msg = <$fh>)) {
+		return if $self->_socket_error ('readline');
+		$fh = $self->{sock};
+	}
 	chomp ($msg);
 	_debug "<- $msg\n";
 
@@ -396,7 +432,10 @@ sub listval_filter
 
 	for (1 .. $nresults)
 	{
-		$msg = <$fh>;
+		while (not defined ($msg = <$fh>)) {
+			return if $self->_socket_error ('readline');
+			$fh = $self->{sock};
+		}
 		chomp $msg;
 		_debug "<- $msg\n";
 		next unless $msg =~ $pattern;
@@ -438,7 +477,10 @@ sub listval
 
 	for (1 .. $nresults)
 	{
-		$msg = <$fh>;
+		while (not defined ($msg = <$fh>)) {
+			return if $self->_socket_error ('readline');
+			$fh = $self->{sock};
+		}
 		chomp $msg;
 		_debug "<- $msg\n";
 
-- 
2.47.2