bpf: include header length in padding calculation

The bpf man page states when calculating the start of the next packet, use: p = (char *)p + BPF_WORDALIGN(p->bh_hdrlen + p->bh_caplen) Add a BPF_WORDALIGN macro for compat use.
msantos · Apr 20, 2011 · de06651 · de06651
1 parent e87d6a9
commit de06651
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Showing 2 changed files with 4 additions and 3 deletions.
diff --git a/include/bpf.hrl b/include/bpf.hrl
@@ -74,7 +74,10 @@
 -define(SIZEOF_STRUCT_BPF_DLTLIST,
     (?SIZEOF_U_INT + ?SIZEOF_U_INT + 4)).
 
+%% #define BPF_ALIGNMENT sizeof(int32_t)
 -define(BPF_ALIGNMENT, ?SIZEOF_INT32_T).
+%% #define BPF_WORDALIGN(x) (((x)+(BPF_ALIGNMENT-1))&~(BPF_ALIGNMENT-1))
+-define(BPF_WORDALIGN(X), bpf:align(X)).
 
 -define(IOC_IN, 16#80000000).
 -define(IOC_OUT, 16#40000000).

diff --git a/src/bpf.erl b/src/bpf.erl
@@ -225,8 +225,6 @@ bool(<<0:32>>) -> false.
 %% On 32-bit, struct timeval32: 4 bytes tv_sec, 4 bytes tv_usec
 %% On 64-bit, struct timeval: 8 bytes tv_sec, 4 bytes tv_usec
 
-%% #define BPF_ALIGNMENT sizeof(int32_t)
-%% #define BPF_WORDALIGN(x) (((x)+(BPF_ALIGNMENT-1))&~(BPF_ALIGNMENT-1))
 pad(Len) ->
     align(Len) - Len.
 
@@ -245,7 +243,7 @@ data(Data) when is_binary(Data) ->
 
     Time = {Sec div 1000000, Sec rem 1000000, Usec},
 
-    Pad = pad(Caplen),
+    Pad = pad(Hdrlen + Caplen),
 
     % Include the padding
     <<_Hdr:Hdrlen/bytes,