Re: [9fans] ftpfs shows empty /n/ftp after login

["Nils M Holm" <nmh@t3x.org>]

On 2015-06-25T19:25:36+0200, Nils M Holm wrote:
> When logging in via ftpfs, though, I get an empty /n/ftp directory.

Turns out that ftpd on FreeBSD announces a port on localhost for
passive mode connections:

227 Entering Passive Mode (127,0,0,1,247,55)

If I understand QEMU user networking correctly, it sees incoming
traffic as originating from localhost, in which case the above
would make sense.

So I patched ftpfs and added an additional command line option to
ignore the host address part of the above message and substitute
the destination system's address.

The patch works fine for me. I'm not a networking expert, though,
so it may have some subtle side effects that I'm not aware of.

The patch is below in case anybody is interested.

Thanks for your help!

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/sys/src/cmd/ip/ftpfs/ftpfs.c.OLD:32,39 - /sys/src/cmd/ip/ftpfs/ftpfs.c:32,37
  int	kapid = -1;
  int	dying;		/* set when any process decides to die */
  int	dokeepalive;
+ char	*system;
+ int		qemu_hack = 0;

  char	*rflush(Fid*), *rnop(Fid*), *rversion(Fid*),
  	*rattach(Fid*), *rclone(Fid*), *rwalk(Fid*),
/sys/src/cmd/ip/ftpfs/ftpfs.c.OLD:151,159 - /sys/src/cmd/ip/ftpfs/ftpfs.c:149,154
  	case 'q':
  		quiet = 1;
  		break;
+ 	case 'Q':
+ 		qemu_hack = 1;
+ 		break;
  	} ARGEND
  	if(argc != 1)
  		usage();
/sys/src/cmd/ip/ftpfs/ftpfs.c.OLD:165,171 - /sys/src/cmd/ip/ftpfs/ftpfs.c:160,165

  	/* initial handshakes with remote side */
  	hello(*argv);
+ 	system = *argv;
  	if(cpassword == 0)
  		rlogin(*argv, keyspec);
  	else
/sys/src/cmd/ip/ftpfs/proto.c.OLD:1272,1277 - /sys/src/cmd/ip/ftpfs/proto.c:1272,1279
  	char *p;
  	int x, fd;
  	TLSconn conn;
+ 	extern char *system;
+ 	extern int	qemu_hack;

  	if(nopassive)
  		return Impossible;
/sys/src/cmd/ip/ftpfs/proto.c.OLD:1297,1305 - /sys/src/cmd/ip/ftpfs/proto.c:1299,1314
  		nopassive = 1;
  		return Impossible;
  	}
- 	snprint(ds, sizeof(ds), "%s!%s.%s.%s.%s!%d", net,
- 		f[0], f[1], f[2], f[3],
- 		((atoi(f[4])&0xff)<<8) + (atoi(f[5])&0xff));
+ 	if (qemu_hack) {
+ 		snprint(ds, sizeof(ds), "%s!%s!%d", net,
+ 			system,
+ 			((atoi(f[4])&0xff)<<8) + (atoi(f[5])&0xff));
+ 	}
+ 	else {
+ 		snprint(ds, sizeof(ds), "%s!%s.%s.%s.%s!%d", net,
+ 			f[0], f[1], f[2], f[3],
+ 			((atoi(f[4])&0xff)<<8) + (atoi(f[5])&0xff));
+ 	}

  	/* open data connection */
  	fd = dial(ds, 0, 0, 0);
/sys/man/4/ftpfs.OLD:4,10 - /sys/man/4/ftpfs:4,10
  .SH SYNOPSIS
  .B ftpfs
  [
- .B -/dqnt
+ .B -/dqntKQ
  ]
  [
  .B -m
/sys/man/4/ftpfs.OLD:96,101 - /sys/man/4/ftpfs:96,107
  option causes ftp to send a NOP command every 15 seconds to attempt
  to keep the connection open.  This command can cause some servers to
  hangup, so you'll have to feel your way.
+ .PP
+ QEMU will see incoming connections as coming from localhost and therefore
+ announce a port for passive mode on 127.0.0.1, which will confuse
+ .I ftpfs.
+ The -Q option ignores the host addresses announced by FTP servers in
+ passive mode negotation and uses the destination address instead.
  .PP
  The
  .B -t
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--
Nils M Holm  < n m h @ t 3 x . o r g >  www.t3x.org