From: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
Date: Thu, 21 Aug 2008 05:45:39 +0000 (-0400)
Subject: made monkeysphere subkey-to-ssh-agent more user-friendly.
X-Git-Tag: monkeysphere_0.11-1~2
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=39f3516d7f57397cb61c5a28d3d199ad9bb1a719;p=monkeysphere.git

made monkeysphere subkey-to-ssh-agent more user-friendly.
---

diff --git a/src/common b/src/common
index 6a62080..44bdb67 100644
--- a/src/common
+++ b/src/common
@@ -120,6 +120,52 @@ passphrase_prompt() {
     fi
 }
 
+test_gnu_dummy_s2k_extension() {
+
+# this block contains a demonstration private key that has had the
+# primary key stripped out using the GNU S2K extension known as
+# "gnu-dummy" (see /usr/share/doc/gnupg/DETAILS.gz).  The subkey is
+# present in cleartext, however.
+
+# openpgp2ssh will be able to deal with this based on whether the
+# local copy of GnuTLS contains read_s2k support that can handle it.
+
+# read up on that here:
+
+# http://lists.gnu.org/archive/html/gnutls-devel/2008-08/msg00005.html
+
+echo "
+-----BEGIN PGP PRIVATE KEY BLOCK-----
+Version: GnuPG v1.4.9 (GNU/Linux)
+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+=CR5w
+-----END PGP PRIVATE KEY BLOCK-----
+" | openpgp2ssh 4129E89D17C1D591 >/dev/null 2>/dev/null
+
+}
+
 # remove all lines with specified string from specified file
 remove_line() {
     local file
diff --git a/src/monkeysphere b/src/monkeysphere
index 8f44bf5..2ca3636 100755
--- a/src/monkeysphere
+++ b/src/monkeysphere
@@ -182,25 +182,63 @@ function subkey_to_ssh_agent() {
     local subkey
     local workingdir
     local kname
+    local sshaddresponse
+    local keysuccess
 
+    # if there's no agent running, don't bother:
+    if [ -z "$SSH_AUTH_SOCK" ] || ! which ssh-add >/dev/null ; then
+	failure "No ssh-agent available."
+    fi
+
+    # and if it looks like it's running, but we can't actually talk to
+    # it, bail out:
+    ssh-add -l >/dev/null
+    sshaddresponse="$?"
+    if [ "$sshaddresponse" = "2" ]; then
+	failure "Could not connect to ssh-agent"
+    fi
+    
     # get list of secret keys (to work around https://bugs.g10code.com/gnupg/issue945):
     secretkeys=$(gpg --list-secret-keys --with-colons --fixed-list-mode --fingerprint | grep '^fpr:' | cut -f10 -d: | awk '{ print "0x" $1 "!" }')
+
+    if [ -z "$secretkeys" ]; then
+	failure "You have no secret keys in your keyring!
+You might want to 'gpg --gen-key'"
+    fi
     
     authsubkeys=$(gpg --list-secret-keys --with-colons --fixed-list-mode --fingerprint --fingerprint $secretkeys | cut -f1,5,10,12 -d: | grep -A1 '^ssb:[^:]*::[^:]*a[^:]*$' | grep '^fpr::' | cut -f3 -d: | sort -u)
 
+    if [ -z "$authsubkeys" ]; then
+	failure "no authentication-capable subkeys available.
+You might want to 'monkeysphere gen-subkey'"
+    fi
+
+    if ! test_gnu_dummy_s2k_extension ; then
+	failure "Your version of GnuTLS does not seem capable of using with gpg's exported subkeys.
+You may want to consider patching or upgrading.
+
+For more details, see:
+ http://lists.gnu.org/archive/html/gnutls-devel/2008-08/msg00005.html"
+    fi
+
     workingdir=$(mktemp -d)
     umask 077
     mkfifo "$workingdir/passphrase"
+    keysuccess=1
 
     # FIXME: we're currently allowing any other options to get passed
     # through to ssh-add.  should we limit it to known ones?  For
     # example: -d or -c and/or -t <lifetime> 
 
-    # FIXME: how do we know if we succeeded or failed?  ssh-add gives
-    # weird return values under setsid, and if there are more than one 
-
     for subkey in $authsubkeys; do 
-	kname="MonkeySphere Key $subkey"
+	# choose a label by which this key will be known in the agent:
+	# we are labelling the key by User ID instead of by
+	# fingerprint, but filtering out all / characters to make sure
+	# the filename is legit.
+
+	primaryuid=$(gpg --with-colons --list-key "0x${subkey}!" | grep '^pub:' | cut -f10 -d: | tr -d /)
+
+	kname="[monkeysphere] $primaryuid"
 
 	if [ "$1" = '-d' ]; then
 	    # we're removing the subkey:
@@ -214,13 +252,20 @@ function subkey_to_ssh_agent() {
 		--export-secret-subkeys "0x${subkey}!" | openpgp2ssh "$subkey" > "$workingdir/$kname" &
 	    (cd "$workingdir" && DISPLAY=nosuchdisplay SSH_ASKPASS=/bin/false ssh-add "$@" "$kname" </dev/null )&
 
-	    passphrase_prompt "Enter passphrase for MonkeySphere Key $subkey: " "$workingdir/passphrase"
-	    wait
+	    passphrase_prompt "Enter passphrase for key for $primaryuid: " "$workingdir/passphrase"
+	    wait %2
 	fi
+	keysuccess="$?"
+
 	rm -f "$workingdir/$kname"
     done
 
     rm -rf "$workingdir"
+
+    # FIXME: sort out the return values: we're just returning the
+    # success or failure of the final authentication subkey in this
+    # case.  What if earlier ones failed?
+    exit "$keysuccess"
 }
 
 ########################################################################