On Tue, 25 Dec 2007 15:02:38 -0800 (PST)
David Miller [off-list ref] wrote:

From: Stephen Hemminger <redacted>
Date: Tue, 25 Dec 2007 12:43:23 -0800

quoted

The problem is that iproute ss.c needs linux/tcp.h to get the
tcp_info structure definition but linux/tcp.h has incompatible
definitions with netinet/tcp.h.  I propose that the enum be moved
from net/tcp_states.h to linux/tcp.h.

This would be fragile, at best.

We need to solve this in a way such that both linux/tcp.h and
netinet/tcp.h can both be included at the same time by userland.

If we export linux/tcp.h to userspace, we have to make it play nice
with the existing header file namespace.

Well changing netinet/tcp.h is just not a realistic proposition, it takes
too long to filter from glibc through distro's to be worth it. That means
fixing linux/tcp.h to not conflict.  How do you propose to resolve?

In file included from ss.c:37:
../include/linux/tcp.h:24: error: redefinition of ‘struct tcphdr’
../include/linux/tcp.h:106: error: nested redefinition of ‘enum tcp_ca_state’
../include/linux/tcp.h:106: error: redeclaration of ‘enum tcp_ca_state’
../include/linux/tcp.h:107: error: redeclaration of enumerator ‘TCP_CA_Open’
/usr/include/netinet/tcp.h:179: error: previous definition of ‘TCP_CA_Open’ was her

maybe:

--- a/include/linux/tcp.h	2007-12-25 17:09:26.000000000 -0800
+++ b/include/linux/tcp.h	2007-12-25 17:12:12.000000000 -0800

@@ -21,6 +21,9 @@
 #include <asm/byteorder.h>
 #include <linux/socket.h>
 
+#ifndef __KERNEL__
+#include <netinet/tcp.h>
+#else
 struct tcphdr {
 	__be16	source;
 	__be16	dest;

@@ -55,6 +58,7 @@ struct tcphdr {
 	__sum16	check;
 	__be16	urg_ptr;
 };
+#endif
 
 /*
  *	The union cast uses a gcc extension to avoid aliasing problems

@@ -102,6 +106,7 @@ enum { 
 #define TCPI_OPT_WSCALE		4
 #define TCPI_OPT_ECN		8
 
+#ifdef __KERNEL__
 enum tcp_ca_state
 {
 	TCP_CA_Open = 0,

@@ -115,6 +120,7 @@ enum tcp_ca_state
 	TCP_CA_Loss = 4
 #define TCPF_CA_Loss	(1<<TCP_CA_Loss)
 };
+#endif

-- 
Stephen Hemminger <stephen.hemminger@vyatta.com>