Add functions for dealing with PGP armor header lines to pgcrypto.

This add a new pgp_armor_headers function to extract armor headers from an
ASCII-armored blob, and a new overloaded variant of the armor function, for
constructing an ASCII-armor with extra headers.

Marko Tiikkaja and me.

contrib/pgcrypto/sql/pgp-armor.sql

@@ -56,3 +56,161 @@ em9va2E=
 =ZZZZ
 -----END PGP MESSAGE-----
 ');
+
+-- corrupt (no space after the colon)
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+foo:
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- corrupt (no empty line)
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- no headers
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- header with empty value
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+foo: 
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- simple
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+fookey: foovalue
+barkey: barvalue
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- insane keys, part 1
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+insane:key : 
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- insane keys, part 2
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+insane:key : text value here
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- long value
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+long: this value is more than 76 characters long, but it should still parse correctly as that''s permitted by RFC 4880
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- long value, split up
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+long: this value is more than 76 characters long, but it should still 
+long: parse correctly as that''s permitted by RFC 4880
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- long value, split up, part 2
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+long: this value is more than 
+long: 76 characters long, but it should still 
+long: parse correctly as that''s permitted by RFC 4880
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+-- long value, split up, part 3
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+emptykey: 
+long: this value is more than 
+emptykey: 
+long: 76 characters long, but it should still 
+emptykey: 
+long: parse correctly as that''s permitted by RFC 4880
+emptykey: 
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+');
+
+select * from pgp_armor_headers('
+-----BEGIN PGP MESSAGE-----
+Comment: dat1.blowfish.sha1.mdc.s2k3.z0
+
+jA0EBAMCfFNwxnvodX9g0jwB4n4s26/g5VmKzVab1bX1SmwY7gvgvlWdF3jKisvS
+yA6Ce1QTMK3KdL2MPfamsTUSAML8huCJMwYQFfE=
+=JcP+
+-----END PGP MESSAGE-----
+');
+
+-- test CR+LF line endings
+select * from pgp_armor_headers(replace('
+-----BEGIN PGP MESSAGE-----
+fookey: foovalue
+barkey: barvalue
+
+em9va2E=
+=ZZZZ
+-----END PGP MESSAGE-----
+', E'\n', E'\r\n'));
+
+-- test header generation
+select armor('zooka', array['foo'], array['bar']);
+select armor('zooka', array['Version', 'Comment'], array['Created by pgcrypto', 'PostgreSQL, the world''s most advanced open source database']);
+select * from pgp_armor_headers(
+  armor('zooka', array['Version', 'Comment'],
+                 array['Created by pgcrypto', 'PostgreSQL, the world''s most advanced open source database']));
+
+-- error/corner cases
+select armor('', array['foo'], array['too', 'many']);
+select armor('', array['too', 'many'], array['foo']);
+select armor('', array[['']], array['foo']);
+select armor('', array['foo'], array[['']]);
+select armor('', array[null], array['foo']);
+select armor('', array['foo'], array[null]);
+select armor('', '[0:0]={"foo"}', array['foo']);
+select armor('', array['foo'], '[0:0]={"foo"}');
+select armor('', array[E'embedded\nnewline'], array['foo']);
+select armor('', array['foo'], array[E'embedded\nnewline']);
+select armor('', array['embedded: colon+space'], array['foo']);