Add contrib/credentials/netrc with GPG support

This credential helper supports multiple files, returning the first one
that matches.  It checks file permissions and owner.  For *.gpg files,
it will run GPG to decrypt the file.

Signed-off-by: Ted Zlatanov <tzz@lifelogs.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

4 files changed, 545 insertions, 0 deletions

diff --git a/contrib/credential/netrc/Makefile b/contrib/credential/netrc/Makefile
new file mode 100644
index 0000000000..51b76138a5
--- /dev/null
+++ b/contrib/credential/netrc/Makefile
@@ -0,0 +1,5 @@
+test:
+	./test.pl
+
+testverbose:
+	./test.pl -d -v
diff --git a/contrib/credential/netrc/git-credential-netrc b/contrib/credential/netrc/git-credential-netrc
new file mode 100755
index 0000000000..6c51c43885
--- /dev/null
+++ b/contrib/credential/netrc/git-credential-netrc
@@ -0,0 +1,421 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Getopt::Long;
+use File::Basename;
+
+my $VERSION = "0.1";
+
+my %options = (
+	       help => 0,
+	       debug => 0,
+	       verbose => 0,
+	       insecure => 0,
+	       file => [],
+
+	       # identical token maps, e.g. host -> host, will be inserted later
+	       tmap => {
+			port => 'protocol',
+			machine => 'host',
+			path => 'path',
+			login => 'username',
+			user => 'username',
+			password => 'password',
+		       }
+	      );
+
+# Map each credential protocol token to itself on the netrc side.
+foreach (values %{$options{tmap}}) {
+	$options{tmap}->{$_} = $_;
+}
+
+# Now, $options{tmap} has a mapping from the netrc format to the Git credential
+# helper protocol.
+
+# Next, we build the reverse token map.
+
+# When $rmap{foo} contains 'bar', that means that what the Git credential helper
+# protocol calls 'bar' is found as 'foo' in the netrc/authinfo file.  Keys in
+# %rmap are what we expect to read from the netrc/authinfo file.
+
+my %rmap;
+foreach my $k (keys %{$options{tmap}}) {
+	push @{$rmap{$options{tmap}->{$k}}}, $k;
+}
+
+Getopt::Long::Configure("bundling");
+
+# TODO: maybe allow the token map $options{tmap} to be configurable.
+GetOptions(\%options,
+           "help|h",
+           "debug|d",
+           "insecure|k",
+           "verbose|v",
+           "file|f=s@",
+          );
+
+if ($options{help}) {
+	my $shortname = basename($0);
+	$shortname =~ s/git-credential-//;
+
+	print <<EOHIPPUS;
+
+$0 [-f AUTHFILE1] [-f AUTHFILEN] [-d] [-v] [-k] get
+
+Version $VERSION by tzz\@lifelogs.com.  License: BSD.
+
+Options:
+
+  -f|--file AUTHFILE : specify netrc-style files.  Files with the .gpg extension
+                       will be decrypted by GPG before parsing.  Multiple -f
+                       arguments are OK.  They are processed in order, and the
+                       first matching entry found is returned via the credential
+                       helper protocol (see below).
+
+                       When no -f option is given, .authinfo.gpg, .netrc.gpg,
+		       .authinfo, and .netrc files in your home directory are used
+		       in this order.
+
+  -k|--insecure      : ignore bad file ownership or permissions
+
+  -d|--debug         : turn on debugging (developer info)
+
+  -v|--verbose       : be more verbose (show files and information found)
+
+To enable this credential helper:
+
+  git config credential.helper '$shortname -f AUTHFILE1 -f AUTHFILE2'
+
+(Note that Git will prepend "git-credential-" to the helper name and look for it
+in the path.)
+
+...and if you want lots of debugging info:
+
+  git config credential.helper '$shortname -f AUTHFILE -d'
+
+...or to see the files opened and data found:
+
+  git config credential.helper '$shortname -f AUTHFILE -v'
+
+Only "get" mode is supported by this credential helper.  It opens every AUTHFILE
+and looks for the first entry that matches the requested search criteria:
+
+ 'port|protocol':
+   The protocol that will be used (e.g., https). (protocol=X)
+
+ 'machine|host':
+   The remote hostname for a network credential. (host=X)
+
+ 'path':
+   The path with which the credential will be used. (path=X)
+
+ 'login|user|username':
+   The credential’s username, if we already have one. (username=X)
+
+Thus, when we get this query on STDIN:
+
+host=github.com
+protocol=https
+username=tzz
+
+this credential helper will look for the first entry in every AUTHFILE that
+matches
+
+machine github.com port https login tzz
+
+OR
+
+machine github.com protocol https login tzz
+
+OR... etc. acceptable tokens as listed above.  Any unknown tokens are
+simply ignored.
+
+Then, the helper will print out whatever tokens it got from the entry, including
+"password" tokens, mapping back to Git's helper protocol; e.g. "port" is mapped
+back to "protocol".  Any redundant entry tokens (part of the original query) are
+skipped.
+
+Again, note that only the first matching entry from all the AUTHFILEs, processed
+in the sequence given on the command line, is used.
+
+Netrc/authinfo tokens can be quoted as 'STRING' or "STRING".
+
+No caching is performed by this credential helper.
+
+EOHIPPUS
+
+	exit 0;
+}
+
+my $mode = shift @ARGV;
+
+# Credentials must get a parameter, so die if it's missing.
+die "Syntax: $0 [-f AUTHFILE1] [-f AUTHFILEN] [-d] get" unless defined $mode;
+
+# Only support 'get' mode; with any other unsupported ones we just exit.
+exit 0 unless $mode eq 'get';
+
+my $files = $options{file};
+
+# if no files were given, use a predefined list.
+# note that .gpg files come first
+unless (scalar @$files) {
+	my @candidates = qw[
+				   ~/.authinfo.gpg
+				   ~/.netrc.gpg
+				   ~/.authinfo
+				   ~/.netrc
+			  ];
+
+	$files = $options{file} = [ map { glob $_ } @candidates ];
+}
+
+my $query = read_credential_data_from_stdin();
+
+FILE:
+foreach my $file (@$files) {
+	my $gpgmode = $file =~ m/\.gpg$/;
+	unless (-r $file) {
+		log_verbose("Unable to read $file; skipping it");
+		next FILE;
+	}
+
+	# the following check is copied from Net::Netrc, for non-GPG files
+	# OS/2 and Win32 do not handle stat in a way compatible with this check :-(
+	unless ($gpgmode || $options{insecure} ||
+		$^O eq 'os2'
+		|| $^O eq 'MSWin32'
+		|| $^O eq 'MacOS'
+		|| $^O =~ /^cygwin/) {
+		my @stat = stat($file);
+
+		if (@stat) {
+			if ($stat[2] & 077) {
+				log_verbose("Insecure $file (mode=%04o); skipping it",
+					    $stat[2] & 07777);
+				next FILE;
+			}
+
+			if ($stat[4] != $<) {
+				log_verbose("Not owner of $file; skipping it");
+				next FILE;
+			}
+		}
+	}
+
+	my @entries = load_netrc($file, $gpgmode);
+
+	unless (scalar @entries) {
+		if ($!) {
+			log_verbose("Unable to open $file: $!");
+		} else {
+			log_verbose("No netrc entries found in $file");
+		}
+
+		next FILE;
+	}
+
+	my $entry = find_netrc_entry($query, @entries);
+	if ($entry) {
+		print_credential_data($entry, $query);
+		# we're done!
+		last FILE;
+	}
+}
+
+exit 0;
+
+sub load_netrc {
+	my $file = shift @_;
+	my $gpgmode = shift @_;
+
+	my $io;
+	if ($gpgmode) {
+		my @cmd = (qw(gpg --decrypt), $file);
+		log_verbose("Using GPG to open $file: [@cmd]");
+		open $io, "-|", @cmd;
+	} else {
+		log_verbose("Opening $file...");
+		open $io, '<', $file;
+	}
+
+	# nothing to do if the open failed (we log the error later)
+	return unless $io;
+
+	# Net::Netrc does this, but the functionality is merged with the file
+	# detection logic, so we have to extract just the part we need
+	my @netrc_entries = net_netrc_loader($io);
+
+	# these entries will use the credential helper protocol token names
+	my @entries;
+
+	foreach my $nentry (@netrc_entries) {
+		my %entry;
+		my $num_port;
+
+		if (!defined $nentry->{machine}) {
+			next;
+		}
+		if (defined $nentry->{port} && $nentry->{port} =~ m/^\d+$/) {
+			$num_port = $nentry->{port};
+			delete $nentry->{port};
+		}
+
+		# create the new entry for the credential helper protocol
+		$entry{$options{tmap}->{$_}} = $nentry->{$_} foreach keys %$nentry;
+
+		# for "host X port Y" where Y is an integer (captured by
+		# $num_port above), set the host to "X:Y"
+		if (defined $entry{host} && defined $num_port) {
+			$entry{host} = join(':', $entry{host}, $num_port);
+		}
+
+		push @entries, \%entry;
+	}
+
+	return @entries;
+}
+
+sub net_netrc_loader {
+	my $fh = shift @_;
+	my @entries;
+	my ($mach, $macdef, $tok, @tok);
+
+    LINE:
+	while (<$fh>) {
+		undef $macdef if /\A\n\Z/;
+
+		if ($macdef) {
+			next LINE;
+		}
+
+		s/^\s*//;
+		chomp;
+
+		while (length && s/^("((?:[^"]+|\\.)*)"|((?:[^\\\s]+|\\.)*))\s*//) {
+			(my $tok = $+) =~ s/\\(.)/$1/g;
+			push(@tok, $tok);
+		}
+
+	    TOKEN:
+		while (@tok) {
+			if ($tok[0] eq "default") {
+				shift(@tok);
+				$mach = { machine => undef };
+				next TOKEN;
+			}
+
+			$tok = shift(@tok);
+
+			if ($tok eq "machine") {
+				my $host = shift @tok;
+				$mach = { machine => $host };
+				push @entries, $mach;
+			} elsif (exists $options{tmap}->{$tok}) {
+				unless ($mach) {
+					log_debug("Skipping token $tok because no machine was given");
+					next TOKEN;
+				}
+
+				my $value = shift @tok;
+				unless (defined $value) {
+					log_debug("Token $tok had no value, skipping it.");
+					next TOKEN;
+				}
+
+				# Following line added by rmerrell to remove '/' escape char in .netrc
+				$value =~ s/\/\\/\\/g;
+				$mach->{$tok} = $value;
+			} elsif ($tok eq "macdef") { # we ignore macros
+				next TOKEN unless $mach;
+				my $value = shift @tok;
+				$macdef = 1;
+			}
+		}
+	}
+
+	return @entries;
+}
+
+sub read_credential_data_from_stdin {
+	# the query: start with every token with no value
+	my %q = map { $_ => undef } values(%{$options{tmap}});
+
+	while (<STDIN>) {
+		next unless m/^([^=]+)=(.+)/;
+
+		my ($token, $value) = ($1, $2);
+		die "Unknown search token $token" unless exists $q{$token};
+		$q{$token} = $value;
+		log_debug("We were given search token $token and value $value");
+	}
+
+	foreach (sort keys %q) {
+		log_debug("Searching for %s = %s", $_, $q{$_} || '(any value)');
+	}
+
+	return \%q;
+}
+
+# takes the search tokens and then a list of entries
+# each entry is a hash reference
+sub find_netrc_entry {
+	my $query = shift @_;
+
+    ENTRY:
+	foreach my $entry (@_)
+	{
+		my $entry_text = join ', ', map { "$_=$entry->{$_}" } keys %$entry;
+		foreach my $check (sort keys %$query) {
+			if (defined $query->{$check}) {
+				log_debug("compare %s [%s] to [%s] (entry: %s)",
+					  $check,
+					  $entry->{$check},
+					  $query->{$check},
+					  $entry_text);
+				unless ($query->{$check} eq $entry->{$check}) {
+					next ENTRY;
+				}
+			} else {
+				log_debug("OK: any value satisfies check $check");
+			}
+		}
+
+		return $entry;
+	}
+
+	# nothing was found
+	return;
+}
+
+sub print_credential_data {
+	my $entry = shift @_;
+	my $query = shift @_;
+
+	log_debug("entry has passed all the search checks");
+ TOKEN:
+	foreach my $git_token (sort keys %$entry) {
+		log_debug("looking for useful token $git_token");
+		# don't print unknown (to the credential helper protocol) tokens
+		next TOKEN unless exists $query->{$git_token};
+
+		# don't print things asked in the query (the entry matches them)
+		next TOKEN if defined $query->{$git_token};
+
+		log_debug("FOUND: $git_token=$entry->{$git_token}");
+		printf "%s=%s\n", $git_token, $entry->{$git_token};
+	}
+}
+sub log_verbose {
+	return unless $options{verbose};
+	printf STDERR @_;
+	printf STDERR "\n";
+}
+
+sub log_debug {
+	return unless $options{debug};
+	printf STDERR @_;
+	printf STDERR "\n";
+}
diff --git a/contrib/credential/netrc/test.netrc b/contrib/credential/netrc/test.netrc
new file mode 100644
index 0000000000..ba119a937f
--- /dev/null
+++ b/contrib/credential/netrc/test.netrc
@@ -0,0 +1,13 @@
+machine imap login tzz@lifelogs.com port imaps password letmeknow
+machine imap login bob port imaps password bobwillknow
+
+# comment test
+
+machine imap2 login tzz port 1099 password tzzknow
+machine imap2 login bob password bobwillknow
+
+# another command
+
+machine github.com
+  multilinetoken anothervalue
+  login carol password carolknows
diff --git a/contrib/credential/netrc/test.pl b/contrib/credential/netrc/test.pl
new file mode 100755
index 0000000000..169b6463c3
--- /dev/null
+++ b/contrib/credential/netrc/test.pl
@@ -0,0 +1,106 @@
+#!/usr/bin/perl
+
+use warnings;
+use strict;
+use Test;
+use IPC::Open2;
+
+BEGIN { plan tests => 15 }
+
+my @global_credential_args = @ARGV;
+my $netrc = './test.netrc';
+print "# Testing insecure file, nothing should be found\n";
+chmod 0644, $netrc;
+my $cred = run_credential(['-f', $netrc, 'get'],
+			  { host => 'github.com' });
+
+ok(scalar keys %$cred, 0, "Got 0 keys from insecure file");
+
+print "# Testing missing file, nothing should be found\n";
+chmod 0644, $netrc;
+$cred = run_credential(['-f', '///nosuchfile///', 'get'],
+		       { host => 'github.com' });
+
+ok(scalar keys %$cred, 0, "Got 0 keys from missing file");
+
+chmod 0600, $netrc;
+
+print "# Testing with invalid data\n";
+$cred = run_credential(['-f', $netrc, 'get'],
+		       "bad data");
+ok(scalar keys %$cred, 4, "Got first found keys with bad data");
+
+print "# Testing netrc file for a missing corovamilkbar entry\n";
+$cred = run_credential(['-f', $netrc, 'get'],
+		       { host => 'corovamilkbar' });
+
+ok(scalar keys %$cred, 0, "Got no corovamilkbar keys");
+
+print "# Testing netrc file for a github.com entry\n";
+$cred = run_credential(['-f', $netrc, 'get'],
+		       { host => 'github.com' });
+
+ok(scalar keys %$cred, 2, "Got 2 Github keys");
+
+ok($cred->{password}, 'carolknows', "Got correct Github password");
+ok($cred->{username}, 'carol', "Got correct Github username");
+
+print "# Testing netrc file for a username-specific entry\n";
+$cred = run_credential(['-f', $netrc, 'get'],
+		       { host => 'imap', username => 'bob' });
+
+ok(scalar keys %$cred, 2, "Got 2 username-specific keys");
+
+ok($cred->{password}, 'bobwillknow', "Got correct user-specific password");
+ok($cred->{protocol}, 'imaps', "Got correct user-specific protocol");
+
+print "# Testing netrc file for a host:port-specific entry\n";
+$cred = run_credential(['-f', $netrc, 'get'],
+		       { host => 'imap2:1099' });
+
+ok(scalar keys %$cred, 2, "Got 2 host:port-specific keys");
+
+ok($cred->{password}, 'tzzknow', "Got correct host:port-specific password");
+ok($cred->{username}, 'tzz', "Got correct host:port-specific username");
+
+print "# Testing netrc file that 'host:port kills host' entry\n";
+$cred = run_credential(['-f', $netrc, 'get'],
+		       { host => 'imap2' });
+
+ok(scalar keys %$cred, 2, "Got 2 'host:port kills host' keys");
+
+ok($cred->{password}, 'bobwillknow', "Got correct 'host:port kills host' password");
+ok($cred->{username}, 'bob', "Got correct 'host:port kills host' username");
+
+sub run_credential
+{
+	my $args = shift @_;
+	my $data = shift @_;
+	my $pid = open2(my $chld_out, my $chld_in,
+			'./git-credential-netrc', @global_credential_args,
+			@$args);
+
+	die "Couldn't open pipe to netrc credential helper: $!" unless $pid;
+
+	if (ref $data eq 'HASH')
+	{
+		print $chld_in "$_=$data->{$_}\n" foreach sort keys %$data;
+	}
+	else
+	{
+		print $chld_in "$data\n";
+	}
+
+	close $chld_in;
+	my %ret;
+
+	while (<$chld_out>)
+	{
+		chomp;
+		next unless m/^([^=]+)=(.+)/;
+
+		$ret{$1} = $2;
+	}
+
+	return \%ret;
+}