From ffc90a11962274ac597b7838f31a4aff0362aa46 Mon Sep 17 00:00:00 2001 From: Michal Sekletar Date: Mon, 7 Jul 2014 15:27:24 +0200 Subject: [PATCH] dhcp-network: make clear that we are ANDing Fragment offset field with mask Reading BPF assembly written as C macros is inherently difficult. Don't make it harder than necessary and provide clearer explanation in the comment. --- src/libsystemd-network/dhcp-network.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/libsystemd-network/dhcp-network.c b/src/libsystemd-network/dhcp-network.c index 17020b0a0..16411cc41 100644 --- a/src/libsystemd-network/dhcp-network.c +++ b/src/libsystemd-network/dhcp-network.c @@ -46,7 +46,7 @@ int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags + Fragment offset */ - BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x1fff), /* A <- A & 0x1fff */ + BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x1fff), /* A <- A & 0x1fff (Fragment offset) */ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, udp.dest)), /* A <- UDP destination port */ -- 2.30.2