Fix #2926: parse_iface_attributes: always break on non-{attribitue, comment} token

There is no requirement to have at least
a blank line, attribute or comment in between two
interface definitions, e.g.
iface lo inet loopback
iface lo inet6 loopback

Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>

src/config/network.rs

@@ -600,4 +600,101 @@ mod test {
 
         Ok(())
     }
+
+    #[test]
+    fn test_network_config_parser_no_blank_1() -> Result<(), Error> {
+        let input = "auto lo\n\
+                     iface lo inet loopback\n\
+                     iface lo inet6 loopback\n\
+                     auto ens18\n\
+                     iface ens18 inet static\n\
+                     \taddress 192.168.20.144/20\n\
+                     \tgateway 192.168.16.1\n\
+                     # comment\n\
+                     iface ens20 inet static\n\
+                     \taddress 192.168.20.145/20\n\
+                     iface ens21 inet manual\n\
+                     iface ens22 inet manual\n";
+
+        let mut parser = NetworkParser::new(&input.as_bytes()[..]);
+
+        let config = parser.parse_interfaces(None)?;
+
+        let output = String::try_from(config)?;
+
+        let expected = "auto lo\n\
+                        iface lo inet loopback\n\
+                        \n\
+                        iface lo inet6 loopback\n\
+                        \n\
+                        auto ens18\n\
+                        iface ens18 inet static\n\
+                        \taddress 192.168.20.144/20\n\
+                        \tgateway 192.168.16.1\n\
+                        #comment\n\
+                        \n\
+                        iface ens20 inet static\n\
+                        \taddress 192.168.20.145/20\n\
+                        \n\
+                        iface ens21 inet manual\n\
+                        \n\
+                        iface ens22 inet manual\n\
+                        \n";
+        assert_eq!(output, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_network_config_parser_no_blank_2() -> Result<(), Error> {
+        // Adapted from bug 2926
+        let input = "### Hetzner Online GmbH installimage\n\
+                     \n\
+                     source /etc/network/interfaces.d/*\n\
+                     \n\
+                     auto lo\n\
+                     iface lo inet loopback\n\
+                     iface lo inet6 loopback\n\
+                     \n\
+                     auto enp4s0\n\
+                     iface enp4s0 inet static\n\
+                     \taddress 10.10.10.10/24\n\
+                     \tgateway 10.10.10.1\n\
+                     \t# route 10.10.20.10/24 via 10.10.20.1\n\
+                     \tup route add -net 10.10.20.10 netmask 255.255.255.0 gw 10.10.20.1 dev enp4s0\n\
+                     \n\
+                     iface enp4s0 inet6 static\n\
+                     \taddress fe80::5496:35ff:fe99:5a6a/64\n\
+                     \tgateway fe80::1\n";
+
+        let mut parser = NetworkParser::new(&input.as_bytes()[..]);
+
+        let config = parser.parse_interfaces(None)?;
+
+        let output = String::try_from(config)?;
+
+        let expected = "### Hetzner Online GmbH installimage\n\
+                        \n\
+                        source /etc/network/interfaces.d/*\n\
+                        \n\
+                        auto lo\n\
+                        iface lo inet loopback\n\
+                        \n\
+                        iface lo inet6 loopback\n\
+                        \n\
+                        auto enp4s0\n\
+                        iface enp4s0 inet static\n\
+                        \taddress 10.10.10.10/24\n\
+                        \tgateway 10.10.10.1\n\
+                        \t# route 10.10.20.10/24 via 10.10.20.1\n\
+                        \tup route add -net 10.10.20.10 netmask 255.255.255.0 gw 10.10.20.1 dev enp4s0\n\
+                        \n\
+                        iface enp4s0 inet6 static\n\
+                        \taddress fe80::5496:35ff:fe99:5a6a/64\n\
+                        \tgateway fe80::1\n\
+                        \n";
+        assert_eq!(output, expected);
+
+        Ok(())
+    }
 }

src/config/network/parser.rs

@@ -210,9 +210,7 @@ impl <R: BufRead> NetworkParser<R> {
                     self.eat(Token::Newline)?;
                     continue;
                 }
-                Token::Newline => break,
-                Token::EOF => break,
-                unexpected => bail!("unexpected token {:?} (expected iface attribute)", unexpected),
+                _ => break,
             }
 
             match self.peek()? {