[pve-devel] [PATCH common] Network: add helpers to resolve hostnames to IPs

[Thomas Lamprecht]

Add addr_to_ip and get_ip_from_hostname helpers to PVE::Network

The first helper, addr_to_ip, is based on Wolfgangs version of this
[0]
I just moved it from PVE::Tools to PVE::Network, as it seems a more
fitting place.
It uses getnameinfo to extract information from the paddr parameter,
which is sockaddr struct
It gets used in the second helper and in a bug fix series from
Wolfgang [1]

The second helper, get_ip_from_hostname, resolves an hostname to an
IP and checks if it isn't one from the for loopback reserved 127/8
subnet. It will be used in get_remote_nodeip from PVE::CLuster and
for a bugfix in pvecm.

[0]: http://pve.proxmox.com/pipermail/pve-devel/2017-April/026099.html
[1]: http://pve.proxmox.com/pipermail/pve-devel/2017-April/026098.html

Signed-off-by: Thomas Lamprecht <t.lamprecht at proxmox.com>
---
 src/PVE/Network.pm | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/src/PVE/Network.pm b/src/PVE/Network.pm
index c8bd8ab..babc204 100644
--- a/src/PVE/Network.pm
+++ b/src/PVE/Network.pm
@@ -7,6 +7,7 @@ use PVE::ProcFSTools;
 use PVE::INotify;
 use File::Basename;
 use IO::Socket::IP;
+use Socket qw(NI_NUMERICHOST NI_NUMERICSERV);
 use POSIX qw(ECONNREFUSED);
 
 use Net::IP;
@@ -575,6 +576,37 @@ sub get_local_ip_from_cidr {
     return $IPs;
 }
 
+sub addr_to_ip {
+    my ($addr) = @_;
+    my ($err, $host, $port) = Socket::getnameinfo($addr, NI_NUMERICHOST | NI_NUMERICSERV);
+    die "failed to get numerical host address: $err\n" if $err;
+    return ($host, $port) if wantarray;
+    return $host;
+}
+
+sub get_ip_from_hostname {
+    my ($hostname, $noerr) = @_;
+
+    my ($family, $ip);
+
+    eval {
+	my @res = PVE::Tools::getaddrinfo_all($hostname);
+	$family = $res[0]->{family};
+	$ip = addr_to_ip($res[0]->{addr})
+    };
+    if ($@) {
+	die "hostname lookup failed:\n$@" if !$noerr;
+	return undef;
+    }
+
+    if ($ip =~ m/^127\.|^::1$/) {
+	die "hostname lookup failed - got local IP address ($hostname = $ip)\n" if !$noerr;
+	return undef;
+    }
+
+    return wantarray ? ($ip, $family) : $ip;
+}
+
 sub lock_network {
     my ($code, @param) = @_;
     my $res = lock_file('/var/lock/pve-network.lck', 10, $code, @param);
-- 
2.11.0