iop: ssh_(install_key): Unify scripts and rework

Unify the iop-subcommands install_key and ssh_install_key to one script.
In addition:

* Support new key types such as ssh-ed25519 which is supported by
  Dropbear nowadays. Also add unsupported ones to make them work
  automatically in the future.
* For the install_key command, do not re-add keys already added
* Read keys loaded into SSH Agent as well, which is useful when working
  with agent forwarding on a remote host or in a Docker container.
* For the ssh_install_key command also add keys added manually to the
  build dir.

iop/scripts/install_key.sh

@@ -1,12 +1,29 @@
 # this is a developer helper script to install the public ssh key in the created image
 
+DROPBEAR_AUTHORIZED_KEYS_FILE=/etc/dropbear/authorized_keys
+
+function get_ssh_public_keys {
+    (
+        shopt -s nullglob
+        # home directory, not all of those are supported by dropbear,
+        # but let's include them now already to decrease future maintenance
+        cat /dev/null ~/.ssh/{id_rsa,id_dsa,id_ecdsa,id_ecdsa_sk,id_ed25519,id_ed25519_sk,id_xmss}.pub 2> /dev/null
+        # keys added manually or automatically to the build dir
+        cat "files${DROPBEAR_AUTHORIZED_KEYS_FILE}" 2>/dev/null
+        # keys in the agent (useful when using SSH agent forwarding)
+        ssh-add -L 2> /dev/null
+    ) | sort | uniq
+}
+
 function install_key {
-
+    local build_dir_dropbear_authorized_keys_file="files${DROPBEAR_AUTHORIZED_KEYS_FILE}"
-    mkdir -p files/etc/dropbear
+    mkdir -p "$(dirname "$build_dir_dropbear_authorized_keys_file")"
-    test -e ~/.ssh/id_dsa.pub && cat ~/.ssh/id_dsa.pub >>files/etc/dropbear/authorized_keys
+    get_ssh_public_keys > "$build_dir_dropbear_authorized_keys_file"
-    test -e ~/.ssh/id_rsa.pub && cat ~/.ssh/id_rsa.pub >>files/etc/dropbear/authorized_keys
+    chmod 0644 "$build_dir_dropbear_authorized_keys_file"
-    chmod 0644 files/etc/dropbear/authorized_keys
+    echo "Keys in "$build_dir_dropbear_authorized_keys_file" are now:"
-
+    cat "$build_dir_dropbear_authorized_keys_file"
+    echo
+    echo "Disabling login on serial console..."
     echo "::sysinit:/etc/init.d/rcS S boot" >files/etc/inittab
     echo "::shutdown:/etc/init.d/rcS K shutdown" >>files/etc/inittab
     echo "console::askconsolelate:/bin/cttyhack /bin/ash --login" >>files/etc/inittab
@@ -14,4 +31,25 @@ function install_key {
     echo Done
 }
 
+function ssh_install_key_help() {
+    echo Usage: $0 ssh_install_key HOSTNAME
+    echo
+    echo "Installs SSH public keys to a device's authorized_keys file"
+}
+
+
+# this is a developer helper script to install the public ssh key on host running dropbear
+function ssh_install_key {
+    if [ $# -ne 1 ] || [ "$1" == '--help' ]; then
+        ssh_install_key_help
+        [ $# -eq 1 ]; return
+    fi
+    host="$1"
+    local keys="$(get_ssh_public_keys)"
+    echo "Adding the following keys to $DROPBEAR_AUTHORIZED_KEYS_FILE on $host:"
+    echo "$keys"
+    ssh root@$host "echo '$keys' >> '$DROPBEAR_AUTHORIZED_KEYS_FILE'" && echo ok
+}
+
+register_command "ssh_install_key" "Install the users public ssh key on host running dropbear"
 register_command "install_key" "Install the user's public ssh key in the created image"

iop/scripts/ssh_install_key.sh

@@ -1,17 +0,0 @@
-# this is a developer helper script to install the public ssh key on host running dropbear
-
-function ssh_install_key {
-	if [ -e ~/.ssh/id_rsa.pub ]; then
-		echo "Adding public RSA key to $1"
-		KEY=`cat ~/.ssh/id_rsa.pub`
-	elif [ -e ~/.ssh/id_dsa.pub ]; then
-		echo "Adding public DSA key to $1"
-		KEY=`cat ~/.ssh/id_dsa.pub`
-	else
-		echo "No public key found"
-		exit 1
-	fi
-	ssh root@$1 "echo '$KEY' >> /etc/dropbear/authorized_keys" && echo ok
-}
-
-register_command "ssh_install_key" "Install the users public ssh key on host running dropbear"