- u_short th_sport; /* source port */
- u_short th_dport; /* destination port */
- tcp_seq th_seq; /* sequence number */
- tcp_seq th_ack; /* acknowledgement number */
-#if BYTE_ORDER == LITTLE_ENDIAN
- u_char th_x2:4, /* (unused) */
- th_off:4; /* data offset */
-#endif
-#if BYTE_ORDER == BIG_ENDIAN
- u_char th_off:4, /* data offset */
- th_x2:4; /* (unused) */
-#endif
- u_char th_flags;
-#define TH_FIN 0x01
-#define TH_SYN 0x02
-#define TH_RST 0x04
-#define TH_PUSH 0x08
-#define TH_ACK 0x10
-#define TH_URG 0x20
- u_short th_win; /* window */
- u_short th_sum; /* checksum */
- u_short th_urp; /* urgent pointer */
-};
+ uint16_t th_sport; /* source port */
+ uint16_t th_dport; /* destination port */
+ tcp_seq th_seq; /* sequence number */
+ tcp_seq th_ack; /* acknowledgement number */
+ uint8_t th_offx2; /* data offset, rsvd */
+ uint8_t th_flags;
+ uint16_t th_win; /* window */
+ uint16_t th_sum; /* checksum */
+ uint16_t th_urp; /* urgent pointer */
+} UNALIGNED;
+
+#define TH_OFF(th) (((th)->th_offx2 & 0xf0) >> 4)
+
+/* TCP flags */
+#define TH_FIN 0x01
+#define TH_SYN 0x02
+#define TH_RST 0x04
+#define TH_PUSH 0x08
+#define TH_ACK 0x10
+#define TH_URG 0x20
+#define TH_ECNECHO 0x40 /* ECN Echo */
+#define TH_CWR 0x80 /* ECN Cwnd Reduced */
+