From d8da8f16860aa710ff322a0425face40de5ad5ad Mon Sep 17 00:00:00 2001
From: EMQ-YangM <yangm@emqx.io>
Date: Tue, 17 May 2022 16:28:39 +0800
Subject: [PATCH] fix: hexstr_to_bin support half byte

---
 apps/emqx/src/emqx_misc.erl                       | 15 ++++++++++++++-
 .../test/emqx_rule_funcs_SUITE.erl                |  4 ++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/apps/emqx/src/emqx_misc.erl b/apps/emqx/src/emqx_misc.erl
index d34ab47e1..9a16f7107 100644
--- a/apps/emqx/src/emqx_misc.erl
+++ b/apps/emqx/src/emqx_misc.erl
@@ -326,7 +326,20 @@ int2hexchar(I, lower) -> I - 10 + $a.
 
 -spec hexstr_to_bin(binary()) -> binary().
 hexstr_to_bin(B) when is_binary(B) ->
-    <<<<(hexchar2int(H) * 16 + hexchar2int(L))>> || <<H:8, L:8>> <= B>>.
+    hexstr_to_bin(B, erlang:bit_size(B)).
+
+hexstr_to_bin(B, Size) when is_binary(B) ->
+    case Size rem 16 of
+        0 ->
+            make_binary(B);
+        8 ->
+            <<BH:((Size - 8) div 8)/binary, BL:8>> = B,
+            <<(make_binary(BH))/binary, <<(hexchar2int(BL) * 16)>>/binary>>;
+        _ ->
+            throw({unsupport_hex_string, B, Size})
+    end.
+
+make_binary(B) -> <<<<(hexchar2int(H) * 16 + hexchar2int(L))>> || <<H:8, L:8>> <= B>>.
 
 hexchar2int(I) when I >= $0 andalso I =< $9 -> I - $0;
 hexchar2int(I) when I >= $A andalso I =< $F -> I - $A + 10;
diff --git a/apps/emqx_rule_engine/test/emqx_rule_funcs_SUITE.erl b/apps/emqx_rule_engine/test/emqx_rule_funcs_SUITE.erl
index 5b27e3efa..0514fc0e9 100644
--- a/apps/emqx_rule_engine/test/emqx_rule_funcs_SUITE.erl
+++ b/apps/emqx_rule_engine/test/emqx_rule_funcs_SUITE.erl
@@ -171,6 +171,10 @@ t_term_encode(_) ->
     ).
 
 t_hexstr2bin(_) ->
+    ?assertEqual(<<99, 100, 240>>, emqx_rule_funcs:hexstr2bin(<<"6364f">>)),
+    ?assertEqual(<<160>>, emqx_rule_funcs:hexstr2bin(<<"a">>)),
+    ?assertEqual(<<240>>, emqx_rule_funcs:hexstr2bin(<<"f">>)),
+    ?assertEqual(<<80>>, emqx_rule_funcs:hexstr2bin(<<"5">>)),
     ?assertEqual(<<1, 2>>, emqx_rule_funcs:hexstr2bin(<<"0102">>)),
     ?assertEqual(<<17, 33>>, emqx_rule_funcs:hexstr2bin(<<"1121">>)).