'wormhole ssh' cleanups

- move to 'wormhole ssh' group with accept/invite subcommands
- change names of methods
- check for permissions
- use --user option (instead of --auth-file)
- move implementation to cmd_ssh.py
- if multiple public-keys, ask user

src/wormhole/cli/cli.py

@@ -3,7 +3,6 @@ from __future__ import print_function
 import os
 import time
 start = time.time()
-from os.path import expanduser, exists
 from textwrap import fill, dedent
 from sys import stdout, stderr
 from . import public_relay
@@ -220,41 +219,65 @@ def receive(cfg, code, **kwargs):
     return go(cmd_receive.receive, cfg)
 
 
-@wormhole.command(name="ssh-add")
+@wormhole.group()
+def ssh():
+    """
+    Facilitate sending/receiving SSH public keys
+    """
+    pass
+
+
+@ssh.command(name="invite")
 @click.option(
     "-c", "--code-length", default=2,
     metavar="NUMWORDS",
     help="length of code (in bytes/words)",
 )
 @click.option(
-    "--auth-file", "-f",
-    default=expanduser('~/.ssh/authorized_keys'),
-    type=click.Path(exists=False),
+    "--user", "-u",
+    default=None,
+    metavar="USER",
+    help="Add to USER's ~/.ssh/authorized_keys",
 )
 @click.pass_context
-def ssh_add(ctx, code_length, auth_file):
+def ssh_invite(ctx, code_length, user):
+    """
+    Add a public-key to a ~/.ssh/authorized_keys file
+    """
     from . import cmd_ssh
     ctx.obj.code_length = code_length
-    ctx.obj.auth_file = auth_file
-    return go(cmd_ssh.add, ctx.obj)
+    ctx.obj.ssh_user = user
+    return go(cmd_ssh.invite, ctx.obj)
 
 
-@wormhole.command(name="ssh-send")
+@ssh.command(name="accept")
 @click.argument(
     "code", nargs=1, required=True,
 )
+@click.option(
+    "--key-file", "-F",
+    default=None,
+    type=click.Path(exists=True),
+)
 @click.option(
     "--yes", "-y", is_flag=True,
     help="Skip confirmation prompt to send key",
 )
 @click.pass_obj
-def ssh_send(cfg, code, yes):
+def ssh_accept(cfg, code, key_file, yes):
+    """
+    Send your SSH public-key
+
+    In response to a 'wormhole ssh invite' this will send public-key
+    you specify (if there's only one in ~/.ssh/* that will be sent).
+    """
+
     from . import cmd_ssh
-    kind, keyid, pubkey = cmd_ssh.find_public_key()
+    kind, keyid, pubkey = cmd_ssh.find_public_key(key_file)
     print("Sending public key type='{}' keyid='{}'".format(kind, keyid))
     if yes is not True:
         click.confirm("Really send public key '{}' ?".format(keyid), abort=True)
     cfg.public_key = (kind, keyid, pubkey)
     cfg.code = code
 
-    return go(cmd_ssh.send, cfg)
+    return go(cmd_ssh.accept, cfg)

src/wormhole/cli/cmd_ssh.py

@@ -1,23 +1,55 @@
 from __future__ import print_function
 
-from os.path import expanduser, exists
+import os
+from os.path import expanduser, exists, join
 from twisted.internet.defer import inlineCallbacks
 from twisted.internet import reactor
+import click
 
 from .. import xfer_util
 
 
-def find_public_key():
+def find_public_key(hint=None):
     """
     This looks for an appropriate SSH key to send, possibly querying
-    the user in the meantime.
+    the user in the meantime. DO NOT CALL after reactor.run as this
+    (possibly) does blocking stuff like asking the user questions (via
+    click.prompt())
 
     Returns a 3-tuple: kind, keyid, pubkey_data
     """
 
-    # XXX FIXME don't blindly just send this one...
-    with open(expanduser('~/.ssh/id_rsa.pub'), 'r') as f:
-        pubkey = f.read()
+    if hint is None:
+        hint = expanduser('~/.ssh/')
+    else:
+        if not exists(hint):
+            raise RuntimeError("Can't find '{}'".format(hint))
+
+    pubkeys = [f for f in os.listdir(hint) if f.endswith('.pub')]
+    if len(pubkeys) == 0:
+        raise RuntimeError("No public keys in '{}'".format(hint))
+    elif len(pubkeys) > 1:
+        got_key = False
+        while not got_key:
+            ans = click.prompt(
+                "Multiple public-keys found:\n" + \
+                "\n".join(["  {}: {}".format(a, b) for a, b in enumerate(pubkeys)]) + \
+                "\nSend which one?"
+            )
+            try:
+                ans = int(ans)
+                if ans < 0 or ans >= len(pubkeys):
+                    ans = None
+                else:
+                    got_key = True
+                    with open(join(hint, pubkeys[ans]), 'r') as f:
+                        pubkey = f.read()
+
+            except Exception:
+                got_key = False
+    else:
+        with open(join(hint, pubkeys[0]), 'r') as f:
+            pubkey = f.read()
     parts = pubkey.strip().split()
     kind = parts[0]
     keyid = 'unknown' if len(parts) <= 2 else parts[2]
@@ -26,7 +58,7 @@ def find_public_key():
 
 
 @inlineCallbacks
-def send(cfg, reactor=reactor):
+def accept(cfg, reactor=reactor):
     yield xfer_util.send(
         reactor,
         u"lothar.com/wormhole/ssh-add",
@@ -39,14 +71,35 @@ def send(cfg, reactor=reactor):
 
 
 @inlineCallbacks
-def add(cfg, reactor=reactor):
+def invite(cfg, reactor=reactor):
 
     def on_code_created(code):
         print("Now tell the other user to run:")
         print()
-        print("wormhole ssh-send {}".format(code))
+        print("wormhole ssh accept {}".format(code))
         print()
 
+    if cfg.ssh_user is None:
+        ssh_path = expanduser('~/.ssh/'.format(cfg.ssh_user))
+    else:
+        ssh_path = '/home/{}/.ssh/'.format(cfg.ssh_user)
+    auth_key_path = join(ssh_path, 'authorized_keys')
+    if not exists(auth_key_path):
+        print("Note: '{}' not found; will be created".format(auth_key_path))
+        if not exists(ssh_path):
+            print("      '{}' doesn't exist either".format(ssh_path))
+    else:
+        try:
+            open(auth_key_path, 'a').close()
+        except OSError:
+            print("No write permission on '{}'".format(auth_key_path))
+            return
+    try:
+        os.listdir(ssh_path)
+    except OSError:
+        print("Can't read '{}'".format(ssh_path))
+        return
+
     pubkey = yield xfer_util.receive(
         reactor,
         u"lothar.com/wormhole/ssh-add",
@@ -60,13 +113,10 @@ def add(cfg, reactor=reactor):
     kind = parts[0]
     keyid = 'unknown' if len(parts) <= 2 else parts[2]
 
-    path = cfg.auth_file
-    if path == '-':
-        print(pubkey.strip())
-    else:
-        if not exists(path):
-            print("Note: '{}' not found; will be created".format(path))
-        with open(path, 'a') as f:
-            f.write('{}\n'.format(pubkey.strip()))
-        print("Appended key type='{kind}' id='{key_id}' to '{auth_file}'".format(
-            kind=kind, key_id=keyid, auth_file=path))
+    if not exists(auth_key_path):
+        if not exists(ssh_path):
+            os.mkdir(ssh_path, mode=0o700)
+    with open(auth_key_path, 'a', 0o600) as f:
+        f.write('{}\n'.format(pubkey.strip()))
+    print("Appended key type='{kind}' id='{key_id}' to '{auth_file}'".format(
+        kind=kind, key_id=keyid, auth_file=auth_key_path))