exthdr: fix type number saved in udata

This should store the index of the protocol template, but
&x[i] - &x[0] is always i, so remove the divide.  Also add test case.

Fixes: 01fbc1574b9e ("exthdr: add parse and build userdata interface")
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Phil Sutter <phil@nwl.cc>

3 files changed, 11 insertions, 3 deletions

diff --git a/src/exthdr.c b/src/exthdr.c
index 22a08b0c..00d338f0 100644
--- a/src/exthdr.c
+++ b/src/exthdr.c
@@ -165,9 +165,7 @@ static struct expr *exthdr_expr_parse_udata(const struct nftnl_udata *attr)
 static unsigned int expr_exthdr_type(const struct exthdr_desc *desc,
 				     const struct proto_hdr_template *tmpl)
 {
-	unsigned int offset = (unsigned int)(tmpl - &desc->templates[0]);
-
-	return offset / sizeof(*tmpl);
+	return (unsigned int)(tmpl - &desc->templates[0]);
 }
 
 static int exthdr_expr_build_udata(struct nftnl_udata_buf *udbuf,
diff --git a/tests/shell/testcases/sets/dumps/typeof_sets_0.nft b/tests/shell/testcases/sets/dumps/typeof_sets_0.nft
index 565369fb..06d891e6 100644
--- a/tests/shell/testcases/sets/dumps/typeof_sets_0.nft
+++ b/tests/shell/testcases/sets/dumps/typeof_sets_0.nft
@@ -14,6 +14,11 @@ table inet t {
 		elements = { 2, 3, 103 }
 	}
 
+	set s4 {
+		typeof frag frag-off
+		elements = { 1, 1024 }
+	}
+
 	chain c1 {
 		osf name @s1 accept
 	}
diff --git a/tests/shell/testcases/sets/typeof_sets_0 b/tests/shell/testcases/sets/typeof_sets_0
index 9b2712e5..a6ff8ca7 100755
--- a/tests/shell/testcases/sets/typeof_sets_0
+++ b/tests/shell/testcases/sets/typeof_sets_0
@@ -20,6 +20,11 @@ EXPECTED="table inet t {
 		elements = { 2, 3, 103 }
 	}
 
+	set s4 {
+		typeof frag frag-off
+		elements = { 1, 1024 }
+	}
+
 	chain c1 {
 		osf name @s1 accept
 	}