Subject: Re: [PATCH] net: santize headers for iproute2

From: Stephen Hemminger <[email-masked]>
Date: Tue, 25 Dec 2007 17:13:10 -0800

On Tue, 25 Dec 2007 15:02:38 -0800 (PST)
David Miller <[email-masked]> wrote:

> From: Stephen Hemminger <[email-masked]>
> Date: Tue, 25 Dec 2007 12:43:23 -0800
> 
> > 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 <[email-masked]>