add support for BSD struct tcphdr in netinet/tcp.h

there are two versions of this structure: the BSD version and the GNU
version. previously only the GNU version was supported. the only way
to support both simultaneously is with an anonymous union, which was a
nonstandard extension prior to C11, so some effort is made to avoid
breakage with compilers which do not support anonymous unions.

this commit is based on a patch by Timo Teräs, but with some changes.
in particular, the GNU version of the structure is not exposed unless
_GNU_SOURCE is defined; this both avoids namespace pollution and
dependency on anonymous unions in the default feature profile.

diff --git a/include/netinet/tcp.h b/include/netinet/tcp.h
index 5639b89a1bde6483dcdf3524773f9d9fd82ee0ed..9be2b94057216083ce168dd8e45e90b4672c44ee 100644 (file)
--- a/include/netinet/tcp.h
+++ b/include/netinet/tcp.h
@@ -44,12 +44,24 @@
 #define SOL_TCP 6
 #include <sys/types.h>
 #include <sys/socket.h>
-#endif
+#include <endian.h>
+
+typedef u_int32_t tcp_seq;
 
+#define TH_FIN 0x01
+#define TH_SYN 0x02
+#define TH_RST 0x04
+#define TH_PUSH 0x08
+#define TH_ACK 0x10
+#define TH_URG 0x20
+
+struct tcphdr {
 #ifdef _GNU_SOURCE
-#include <endian.h>
-struct tcphdr
-{
+#ifdef __GNUC__
+       __extension__
+#endif
+       union { struct {
+
        u_int16_t source;
        u_int16_t dest;
        u_int32_t seq;
@@ -78,8 +90,33 @@ struct tcphdr
        u_int16_t window;
        u_int16_t check;
        u_int16_t urg_ptr;
+
+       }; struct {
+#endif
+
+       u_int16_t th_sport;
+       u_int16_t th_dport;
+       u_int32_t th_seq;
+       u_int32_t th_ack;
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+       u_int8_t th_x2:4;
+       u_int8_t th_off:4;
+#else
+       u_int8_t th_off:4;
+       u_int8_t th_x2:4;
+#endif
+       u_int8_t th_flags;
+       u_int16_t th_win;
+       u_int16_t th_sum;
+       u_int16_t th_urp;
+
+#ifdef _GNU_SOURCE
+       }; };
+#endif
 };
+#endif
 
+#ifdef _GNU_SOURCE
 #define TCPI_OPT_TIMESTAMPS    1
 #define TCPI_OPT_SACK          2
 #define TCPI_OPT_WSCALE                4