farp: Fix BPF jump false offset

Jump to BPF_STMT(BPF_RET+BPF_K, 0) if protocol_size != 4

diff --git a/src/libcharon/plugins/farp/farp_spoofer.c b/src/libcharon/plugins/farp/farp_spoofer.c
index c2715bd5ac9d07108613746a0a72bcaa03e4addc..5753f7910aa64e180b2e6fc9425447522a32f7e4 100644 (file)
--- a/src/libcharon/plugins/farp/farp_spoofer.c
+++ b/src/libcharon/plugins/farp/farp_spoofer.c
@@ -143,7 +143,7 @@ farp_spoofer_t *farp_spoofer_create(farp_listener_t *listener)
                BPF_STMT(BPF_LD+BPF_B+BPF_ABS, offsetof(arp_t, hardware_size)),
                BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 6, 0, 7),
                BPF_STMT(BPF_LD+BPF_B+BPF_ABS, offsetof(arp_t, protocol_size)),
-               BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 4, 0, 4),
+               BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 4, 0, 5),
                BPF_STMT(BPF_LD+BPF_H+BPF_ABS, offsetof(arp_t, opcode)),
                BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ARPOP_REQUEST, 0, 3),
                BPF_STMT(BPF_LD+BPF_W+BPF_LEN, 0),