1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
package Nix::SSH;
use strict;
use File::Temp qw(tempdir);
use IPC::Open2;
our @ISA = qw(Exporter);
our @EXPORT = qw(
sshOpts openSSHConnection closeSSHConnection
readN readInt writeInt writeString writeStrings
connectToRemoteNix
);
our @sshOpts = split ' ', ($ENV{"NIX_SSHOPTS"} or "");
push @sshOpts, "-x";
my $sshStarted = 0;
my $sshHost;
# Open a master SSH connection to `host', unless there already is a
# running master connection (as determined by `-O check').
sub openSSHConnection {
my ($host) = @_;
die if $sshStarted;
$sshHost = $host;
return 1 if system("ssh $sshHost @sshOpts -O check 2> /dev/null") == 0;
my $tmpDir = tempdir("nix-ssh.XXXXXX", CLEANUP => 1, TMPDIR => 1)
or die "cannot create a temporary directory";
push @sshOpts, "-S", "$tmpDir/control";
# Start the master. We can't use the `-f' flag (fork into
# background after establishing the connection) because then the
# child continues to run if we are killed. So instead make SSH
# print "started" when it has established the connection, and wait
# until we see that.
open SSHPIPE, "ssh $sshHost @sshOpts -M -N -o LocalCommand='echo started' -o PermitLocalCommand=yes |" or die;
while (<SSHPIPE>) {
chomp;
if ($_ eq "started") {
$sshStarted = 1;
return 1;
}
}
return 0;
}
# Tell the master SSH client to exit.
sub closeSSHConnection {
if ($sshStarted) {
system("ssh $sshHost @sshOpts -O exit 2> /dev/null") == 0
or warn "unable to stop SSH master: $?";
$sshStarted = 0;
}
}
sub readN {
my ($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, $from));
}
sub writeInt {
my ($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, $sshOpts) = @_;
# Start ‘nix-store --serve’ on the remote host.
my ($from, $to);
my $pid = open2($from, $to, "ssh $sshHost @{$sshOpts} nix-store --serve --write");
# Do the handshake.
my $SERVE_MAGIC_1 = 0x390c9deb; # FIXME
my $clientVersion = 0x200;
syswrite($to, pack("L<x4L<x4", $SERVE_MAGIC_1, $clientVersion)) or die;
die "did not get valid handshake from remote host\n" if readInt($from) != 0x5452eecb;
my $serverVersion = readInt($from);
die "unsupported server version\n" if $serverVersion < 0x200 || $serverVersion >= 0x300;
return ($from, $to, $pid);
}
END { my $saved = $?; closeSSHConnection; $? = $saved; }
1;
|
