From b9b704f8b584994cbbb4975133d6032d5d0d294e Mon Sep 17 00:00:00 2001
From: Hans Nilsson <hans@erlang.org>
Date: Mon, 4 Jan 2016 15:21:51 +0100
Subject: ssh: Optimization - inline encoding in ssh_message:encode/1, now 8
 times faster. Also fixes minor error in ssh_protocol_SUITE that the new
 encoder found.

---
 lib/ssh/src/ssh_bits.erl | 141 +++++++----------------------------------------
 1 file changed, 20 insertions(+), 121 deletions(-)

(limited to 'lib/ssh/src/ssh_bits.erl')

diff --git a/lib/ssh/src/ssh_bits.erl b/lib/ssh/src/ssh_bits.erl
index 4da3a6018b..101bf76cd3 100644
--- a/lib/ssh/src/ssh_bits.erl
+++ b/lib/ssh/src/ssh_bits.erl
@@ -26,52 +26,30 @@
 
 -include("ssh.hrl").
 
--export([encode/2]).
--export([mpint/1, string/1, name_list/1]).
+-export([mpint/1, name_list/1]).
 -export([random/1]).
 
--define(name_list(X), 
-	(fun(B) -> ?binary(B) end)(list_to_binary(name_concat(X)))).
-
-
-name_concat([Name]) when is_atom(Name) -> atom_to_list(Name);
-name_concat([Name]) when is_list(Name) -> Name;
-name_concat([Name|Ns]) -> 
-    if is_atom(Name) ->
-	    [atom_to_list(Name),"," | name_concat(Ns)];
-       is_list(Name) ->
-	    [Name,"," | name_concat(Ns)]
-    end;
-name_concat([]) -> [].
-
-
-name_list(Ns) ->
-    ?name_list(Ns).
+%%%----------------------------------------------------------------
+name_list([Name]) -> to_bin(Name);
+name_list([Name|Ns]) -> <<(to_bin(Name))/binary, ",", (name_list(Ns))/binary>>;
+name_list([]) -> <<>>.
+
+to_bin(A) when is_atom(A) -> list_to_binary(atom_to_list(A));
+to_bin(S) when is_list(S) -> list_to_binary(S);
+to_bin(B) when is_binary(B) -> B.
+
+%%%----------------------------------------------------------------
+%%% Multi Precision Integer encoding
+mpint(-1) -> <<0,0,0,1,16#ff>>;
+mpint(0) -> <<0,0,0,0>>;
+mpint(X) when X < 0 -> mpint_neg(X,0,[]);
+mpint(X) -> mpint_pos(X,0,[]).
     
-
-string(Str) ->
-    ?string(Str).
-
-
-%% MP representaion  (SSH2)
-mpint(X) when X < 0 ->
-    if X == -1 ->
-	    <<0,0,0,1,16#ff>>;	    
-       true ->
-	    mpint_neg(X,0,[])
-    end;
-mpint(X) ->
-    if X == 0 ->
-	    <<0,0,0,0>>;
-       true ->
-	    mpint_pos(X,0,[])
-    end.
-
 mpint_neg(-1,I,Ds=[MSB|_]) ->
     if MSB band 16#80 =/= 16#80 ->
 	    <<?UINT32((I+1)), (list_to_binary([255|Ds]))/binary>>;
        true ->
-	    (<<?UINT32(I), (list_to_binary(Ds))/binary>>)
+	    <<?UINT32(I), (list_to_binary(Ds))/binary>>
     end;
 mpint_neg(X,I,Ds)  ->
     mpint_neg(X bsr 8,I+1,[(X band 255)|Ds]).
@@ -80,96 +58,17 @@ mpint_pos(0,I,Ds=[MSB|_]) ->
     if MSB band 16#80 == 16#80 ->
 	    <<?UINT32((I+1)), (list_to_binary([0|Ds]))/binary>>;
        true ->
-	    (<<?UINT32(I), (list_to_binary(Ds))/binary>>)
+	    <<?UINT32(I), (list_to_binary(Ds))/binary>>
     end;
 mpint_pos(X,I,Ds) ->
     mpint_pos(X bsr 8,I+1,[(X band 255)|Ds]).
 
 
-encode(List, Types) ->
-    list_to_binary(enc(List, Types)).
-
-%%
-%% Encode record element
-%%
-enc(Xs, Ts) ->
-    enc(Xs, Ts, 0).
-
-enc(Xs, [boolean|Ts], Offset) ->
-    X = hd(Xs),
-    [?boolean(X) | enc(tl(Xs), Ts, Offset+1)];
-enc(Xs, [byte|Ts], Offset) ->
-    X = hd(Xs),
-    [?byte(X) | enc(tl(Xs), Ts,Offset+1)];
-enc(Xs, [uint16|Ts], Offset) ->
-    X = hd(Xs),
-    [?uint16(X) | enc(tl(Xs), Ts,Offset+2)];
-enc(Xs, [uint32 |Ts], Offset) ->
-    X = hd(Xs),
-    [?uint32(X) | enc(tl(Xs), Ts,Offset+4)];
-enc(Xs, [uint64|Ts], Offset) ->
-    X = hd(Xs),
-    [?uint64(X) | enc(tl(Xs), Ts,Offset+8)];
-enc(Xs, [mpint|Ts], Offset) ->
-    Y = mpint(hd(Xs)),
-    [Y | enc(tl(Xs), Ts,Offset+size(Y))];
-enc(Xs, [string|Ts], Offset) ->
-    X0 = hd(Xs),
-    Y = ?string(X0),
-    [Y | enc(tl(Xs),Ts,Offset+size(Y))];
-enc(Xs, [string_utf8|Ts], Offset) ->
-    X0 = hd(Xs),
-    Y = ?string_utf8(X0),
-    [Y | enc(tl(Xs),Ts,Offset+size(Y))];
-enc(Xs, [binary|Ts], Offset) ->
-     X0 = hd(Xs),
-    Y = ?binary(X0),
-    [Y | enc(tl(Xs), Ts,Offset+size(Y))];
-enc(Xs, [name_list|Ts], Offset) ->
-    X0 = hd(Xs),
-    Y = ?name_list(X0),
-    [Y | enc(tl(Xs), Ts, Offset+size(Y))];
-enc(Xs, [cookie|Ts], Offset) ->
-    [random(16) | enc(tl(Xs), Ts, Offset+16)];
-enc(Xs, [{pad,N}|Ts], Offset) ->
-    K = (N - (Offset rem N)) rem N,
-    [fill_bits(K,0) | enc(Xs, Ts, Offset+K)];
-enc(Xs, ['...'| []], _Offset) ->
-    X = hd(Xs),
-    if is_binary(X) ->
-	    [X];
-       is_list(X) ->
-	    [list_to_binary(X)];
-       X==undefined ->
-	    []
-    end;
-enc([], [],_) ->
-    [].
-
-
-%%
-%% Create a binary with constant bytes 
-%%
-fill_bits(N,C) ->
-    list_to_binary(fill(N,C)).
-
-fill(0,_C) -> [];
-fill(1,C) -> [C];
-fill(N,C) ->
-    Cs = fill(N div 2, C),
-    Cs1 = [Cs,Cs],
-    if N band 1 == 0 ->
-	    Cs1;
-       true ->
-	    [C,Cs,Cs]
-    end.
-
-
+%%%----------------------------------------------------------------
 %% random/1
 %%   Generate N random bytes
 %%
-random(N) ->
-    crypto:strong_rand_bytes(N).
+random(N) -> crypto:strong_rand_bytes(N).
 
 
 
-- 
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