git-cvsimport: add support for cvs pserver password scrambling.

Instead of a cleartext password, the CVS pserver expects a scrambled one
in the authentication request. With this patch it is possible to import
CVS repositories only accessible via pserver and user/password.
Signed-off-by: NDirk Hoerner <dirker@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

git-cvsimport.perl

@@ -252,7 +252,8 @@ sub conn {
 				}
 			};
 		}
-		$pass="A" unless $pass;
+
+		$pass = $self->_scramble($pass);
 
 		my ($s, $rep);
 		if ($proxyhost) {
@@ -484,6 +485,42 @@ sub _fetchfile {
 	return $res;
 }
 
+sub _scramble {
+	my ($self, $pass) = @_;
+	my $scrambled = "A";
+
+	return $scrambled unless $pass;
+
+	my $pass_len = length($pass);
+	my @pass_arr = split("", $pass);
+	my $i;
+
+	# from cvs/src/scramble.c
+	my @shifts = (
+		  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15,
+		 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+		114,120, 53, 79, 96,109, 72,108, 70, 64, 76, 67,116, 74, 68, 87,
+		111, 52, 75,119, 49, 34, 82, 81, 95, 65,112, 86,118,110,122,105,
+		 41, 57, 83, 43, 46,102, 40, 89, 38,103, 45, 50, 42,123, 91, 35,
+		125, 55, 54, 66,124,126, 59, 47, 92, 71,115, 78, 88,107,106, 56,
+		 36,121,117,104,101,100, 69, 73, 99, 63, 94, 93, 39, 37, 61, 48,
+		 58,113, 32, 90, 44, 98, 60, 51, 33, 97, 62, 77, 84, 80, 85,223,
+		225,216,187,166,229,189,222,188,141,249,148,200,184,136,248,190,
+		199,170,181,204,138,232,218,183,255,234,220,247,213,203,226,193,
+		174,172,228,252,217,201,131,230,197,211,145,238,161,179,160,212,
+		207,221,254,173,202,146,224,151,140,196,205,130,135,133,143,246,
+		192,159,244,239,185,168,215,144,139,165,180,157,147,186,214,176,
+		227,231,219,169,175,156,206,198,129,164,150,210,154,177,134,127,
+		182,128,158,208,162,132,167,209,149,241,153,251,237,236,171,195,
+		243,233,253,240,194,250,191,155,142,137,245,235,163,242,178,152
+	);
+
+	for ($i = 0; $i < $pass_len; $i++) {
+		$scrambled .= pack("C", $shifts[ord($pass_arr[$i])]);
+	}
+
+	return $scrambled;
+}
 
 package main;