Feature: support SCP/SFTP

[bilbo]

Currently mc supports FISH (copying files over SSH), however, it seems that it does not work on some servers, namely if you don't have shell accound on the machine and only scp/sftp is allowed (for example sourceforge servers used for uploading released files)

FISH does not work, as does not work using ssh to connect (you are kicked out after connecting with message that shell access is denied), but commandline scp and sftp works here.

If would be nice to add support for scp and/or sftp to help transfer files to/from servers where shell is not available.

[iNode]

Thanks for the request.

FISH isn't scp/sftp it runs shell to navigate over remote system, so I think it will be another VFS plugin. But before it will be done, we should rework current VFS mechanisms to avoid some limitations.

[angel_il]

branch: 1535_sftp
changeset: ​1535_sftp

please review

[bilbo]

In current state it fails compilation:

filemanager/.libs/libmcfilemanager.a(libmcfilemanager_la-panel.o): In function `_do_panel_cd':
/home/src/mc/src/filemanager/panel.c:2679: undefined reference to `mc_log'
/home/src/mc/src/filemanager/panel.c:2699: undefined reference to `mc_log'
/home/src/mc/src/filemanager/panel.c:2712: undefined reference to `mc_log'
/home/src/mc/src/filemanager/panel.c:2714: undefined reference to `mc_log'
/home/src/mc/src/filemanager/panel.c:2720: undefined reference to `mc_log'
filemanager/.libs/libmcfilemanager.a(libmcfilemanager_la-panel.o):/home/src/mc/src/filemanager/panel.c:2725: more undefined references to `mc_log' follow
collect2: ld returned 1 exit status

Commenting out all mc_log's fixes the problem.

However, there are more bugs:

If I connect, I see dialog with keys, etc ....

When I leave keys blank, sftpfs requests a password from me (even though ssh and fish does not require nay password due to ssh-agent having keys in memory)

Pressing "Esc" in the password dialog triggers a segmentation fault.

When I tried again and filled out right path to proper ssh key for the given host, it does not work (it asks me for password again aind since that host accepts only ssh keys and no passwords, I can't connect)

Also, when I use Left -> New SFTP link, then I enter machine name (for example "localhost") in first dialog, but then I press cancel at second dialog, I get "Cannot chdir to "/​sftp://localhost" error message.

There also should be some way to set/pre-set all this extra settings for all the machines somewhere and not to ask for it again on each new connection.

[bilbo]

Also, when making connecton to a host which is down (or if you make a typo and connect to a host which does not exist or does not have sshd), the message like "sftpfs: making connection to 192.168.1.203" appears and there is no possibility of cancelling the connection, resulting in mc being freezed.

[slavazanko]

Created branch 1535_vfs_sftp

Review, please.

[replika]

I checked out the branch 1535_vfs_sftp but got this error:

make[3]: Entering directory `/mnt/src/mc/src/filemanager'
  CC     libmcfilemanager_la-achown.lo
  CC     libmcfilemanager_la-boxes.lo
  CC     libmcfilemanager_la-chmod.lo
  CC     libmcfilemanager_la-chown.lo
  CC     libmcfilemanager_la-cmd.lo
cmd.c: In function 'sftplink_cmd':
cmd.c:1520:14: error: too few arguments to function 'nice_cd'
cmd.c:524:1: note: declared here
make[3]: *** [libmcfilemanager_la-cmd.lo] Error 1
make[3]: Leaving directory `/mnt/src/mc/src/filemanager'

./configure --enable-vfs-smb --enable-vfs-sftp --with-screen=ncurses

Which branch should I used to test this feature?

[slavazanko]

This was happens as result of rebasing. Fixed.

[replika]

Thanks for your working on this feature. It works great so far.

BTW, how to disconnect a connection?
Tried cd but it is still connected; cd - will go back to sftp directory.

In "Active VFS list", it is displayed as //sftp://, but cannot change directory nor free the VFS.

Currently, I have to exit mc to close the connection.

[slavazanko]

Merged to master:

git log --pretty=oneline 7893cbf..da03697

[slyfox]

Stock ./configure fails if user does not have libssh2 headers.
The default behaviour is not to enable plugin unless user explicitly
requests is with --enable-vfs-sftp.

Attaching the patch to retain user friendly behaviour.

[slyfox]

fail only if user explicitely requested sftp

[IceMan]

Midnight Commander from current git origin/master doesn't mention SFTP support in mc -V output.

$ LC_ALL=C mc -V

GNU Midnight Commander 4.8.3-95-g8ca27aa
Built with GLib 2.24.2
Using the S-Lang library with terminfo database
With builtin Editor
With subshell support as default
With support for background operations
With mouse support on xterm and Linux console
With support for X11 events
With internationalization support
With multiple codepages support
Virtual File Systems: cpiofs, tarfs, sfs, extfs, ftpfs, fish
Data types: char: 8; int: 32; long: 64; void *: 64; size_t: 64; off_t: 64;

[slavazanko]

Created branch 1535_vfs_sftp_fixes
Review, please.

[slavazanko]

Merged to master:

git log --pretty=oneline a343070..3786051

[IceMan]

When opening SFTP link to the remote server by using host alias from ~/.ssh/config MC start more than one sftp-server instance on the target server. If you use username@1.2.3.4 instead of host alias - MC works fine.

GNU Midnight Commander 4.8.3-121-g54b2b2f
Built with GLib 2.24.2
Using the S-Lang library with terminfo database
With builtin Editor
With subshell support as default
With support for background operations
With mouse support on xterm and Linux console
With support for X11 events
With internationalization support
With multiple codepages support
Virtual File Systems: cpiofs, tarfs, sfs, extfs, ftpfs, sftpfs, fish
Data types: char: 8; int: 32; long: 32; void *: 32; size_t: 32; off_t: 64;

Expected behaviour:
When open SFTP link by host alias MC must start only single sftp-server instance per SFTP link on the target server.

How to reproduce:
1) Create host record in ~/.ssh/config like following:

Host example
HostName 1.2.3.4
User username

2) Open SFTP link by using example as "Machine name"
3) Login to target server and count sftp-server instances

pgrep -u username sftp-server | wc -l

[andrew_b]

Broken aliases will be fixed in #2923.