1 files changed, 110 insertions, 0 deletions
diff --git a/third_party/nix/perl/lib/Nix/SSH.pm b/third_party/nix/perl/lib/Nix/SSH.pm
new file mode 100644
index 000000000000..490ba0ea991e
--- /dev/null
+++ b/third_party/nix/perl/lib/Nix/SSH.pm
@@ -0,0 +1,110 @@
+package Nix::SSH;
+
+use utf8;
+use strict;
+use File::Temp qw(tempdir);
+use IPC::Open2;
+
+our @ISA = qw(Exporter);
+our @EXPORT = qw(
+  @globalSshOpts
+  readN readInt readString readStrings
+  writeInt writeString writeStrings
+  connectToRemoteNix
+);
+
+
+our @globalSshOpts = split ' ', ($ENV{"NIX_SSHOPTS"} or "");
+
+
+sub readN {
+    my ($bytes, $from) = @_;
+    my $res = "";
+    while ($bytes > 0) {
+        my $s;
+        my $n = sysread($from, $s, $bytes);
+        die "I/O error reading from remote side\n" if !defined $n;
+        die "got EOF while expecting $bytes bytes from remote side\n" if !$n;
+        $bytes -= $n;
+        $res .= $s;
+    }
+    return $res;
+}
+
+
+sub readInt {
+    my ($from) = @_;
+    return unpack("L<x4", readN(8, $from));
+}
+
+
+sub readString {
+    my ($from) = @_;
+    my $len = readInt($from);
+    my $s = readN($len, $from);
+    readN(8 - $len % 8, $from) if $len % 8; # skip padding
+    return $s;
+}
+
+
+sub readStrings {
+    my ($from) = @_;
+    my $n = readInt($from);
+    my @res;
+    push @res, readString($from) while $n--;
+    return @res;
+}
+
+
+sub writeInt {
+    my ($n, $to) = @_;
+    syswrite($to, pack("L<x4", $n)) or die;
+}
+
+
+sub writeString {
+    my ($s, $to) = @_;
+    my $len = length $s;
+    my $req .= pack("L<x4", $len);
+    $req .= $s;
+    $req .= "\000" x (8 - $len % 8) if $len % 8;
+    syswrite($to, $req) or die;
+}
+
+
+sub writeStrings {
+    my ($ss, $to) = @_;
+    writeInt(scalar(@{$ss}), $to);
+    writeString($_, $to) foreach @{$ss};
+}
+
+
+sub connectToRemoteNix {
+    my ($sshHost, $sshOpts, $extraFlags) = @_;
+
+    $extraFlags ||= "";
+
+    # Start ‘nix-store --serve’ on the remote host.
+    my ($from, $to);
+    # FIXME: don't start a shell, start ssh directly.
+    my $pid = open2($from, $to, "exec ssh -x -a $sshHost @globalSshOpts @{$sshOpts} nix-store --serve --write $extraFlags");
+
+    # Do the handshake.
+    my $magic;
+    eval {
+        my $SERVE_MAGIC_1 = 0x390c9deb; # FIXME
+        my $clientVersion = 0x200;
+        syswrite($to, pack("L<x4L<x4", $SERVE_MAGIC_1, $clientVersion)) or die;
+        $magic = readInt($from);
+    };
+    die "unable to connect to '$sshHost'\n" if $@;
+    die "did not get valid handshake from remote host\n" if $magic  != 0x5452eecb;
+
+    my $serverVersion = readInt($from);
+    die "unsupported server version\n" if $serverVersion < 0x200 || $serverVersion >= 0x300;
+
+    return ($from, $to, $pid);
+}
+
+
+1;