ssh: Query ciphers and macs from ssh before hardcoded fallback

completions/ssh

@@ -6,17 +6,26 @@ _ssh_queries()
         "cipher cipher-auth mac kex key protocol-version" -- "$cur" ) )
 }
 
+_ssh_query()
+{
+    ${1:-ssh} -Q $2 2>/dev/null
+}
+
 _ssh_ciphers()
 {
-    COMPREPLY+=( $( compgen -W '3des-cbc aes128-cbc aes192-cbc aes256-cbc
+    local ciphers="$( _ssh_query $1 cipher )"
+    [[ $ciphers ]] || ciphers="3des-cbc aes128-cbc aes192-cbc aes256-cbc
         aes128-ctr aes192-ctr aes256-ctr arcfour128 arcfour256 arcfour
-        blowfish-cbc cast128-cbc' -- "$cur" ) )
+        blowfish-cbc cast128-cbc"
+    COMPREPLY+=( $( compgen -W "$ciphers" -- "$cur" ) )
 }
 
 _ssh_macs()
 {
-    COMPREPLY+=( $( compgen -W 'hmac-md5 hmac-sha1 umac-64@openssh.com
-        hmac-ripemd160 hmac-sha1-96 hmac-md5-96' -- "$cur" ) )
+    local macs="$( _ssh_query $1 mac )"
+    [[ $macs ]] || macs="hmac-md5 hmac-sha1 umac-64@openssh.com hmac-ripemd160
+        hmac-sha1-96 hmac-md5-96"
+    COMPREPLY+=( $( compgen -W "$macs" -- "$cur" ) )
 }
 
 _ssh_options()
@@ -45,7 +54,8 @@ _ssh_options()
 }
 
 # Complete a ssh suboption (like ForwardAgent=y<tab>)
-# Only one parameter: the string to complete including the equal sign.
+# Two parameters: the string to complete including the equal sign, and
+# the ssh executable to invoke (optional).
 # Not all suboptions are completed.
 # Doesn't handle comma-separated lists.
 _ssh_suboption()
@@ -95,10 +105,10 @@ _ssh_suboption()
                 keyboard-interactive password' -- "$cur" ) )
             ;;
         MACs)
-            _ssh_macs
+            _ssh_macs "$2"
             ;;
         Ciphers)
-            _ssh_ciphers
+            _ssh_ciphers "$2"
             ;;
     esac
     return 0
@@ -112,7 +122,7 @@ _ssh_suboption_check()
     # Get prev and cur words without splitting on =
     local cureq=`_get_cword :=` preveq=`_get_pword :=`
     if [[ $cureq == *=* && $preveq == -o ]]; then
-        _ssh_suboption $cureq
+        _ssh_suboption $cureq "$1"
         return $?
     fi
     return 1
@@ -126,7 +136,7 @@ _ssh()
     local configfile
     local -a config
 
-    _ssh_suboption_check && return 0
+    _ssh_suboption_check "$1" && return 0
 
     case $prev in
         -F|-i|-S)
@@ -134,11 +144,11 @@ _ssh()
             return 0
             ;;
         -c)
-            _ssh_ciphers
+            _ssh_ciphers "$1"
             return 0
             ;;
         -m)
-            _ssh_macs
+            _ssh_macs "$1"
             return 0
             ;;
         -l)