Switch the entire IPv4 stack to keep the IP packet header

in network byte order. Any host byte order processing is
done in local variables and host byte order values are
never[1] written to a packet.

  After this change a packet processed by the stack isn't
modified at all[2] except for TTL.

  After this change a network stack hacker doesn't need to
scratch his head trying to figure out what is the byte order
at the given place in the stack.

[1] One exception still remains. The raw sockets convert host
byte order before pass a packet to an application. Probably
this would remain for ages for compatibility.

[2] The ip_input() still subtructs header len from ip->ip_len,
but this is planned to be fixed soon.

Reviewed by:	luigi, Maxim Dounin <mdounin mdounin.ru>
Tested by:	ray, Olivier Cochard-Labbe <olivier cochard.me>

1 files changed, 8 insertions, 17 deletions

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 3b21df1..a91062b 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -528,9 +528,6 @@ tcp_input(struct mbuf *m, int off0)
 {
 	struct tcphdr *th = NULL;
 	struct ip *ip = NULL;
-#ifdef INET
-	struct ipovly *ipov;
-#endif
 	struct inpcb *inp = NULL;
 	struct tcpcb *tp = NULL;
 	struct socket *so = NULL;
@@ -643,32 +640,27 @@ tcp_input(struct mbuf *m, int off0)
 			}
 		}
 		ip = mtod(m, struct ip *);
-		ipov = (struct ipovly *)ip;
 		th = (struct tcphdr *)((caddr_t)ip + off0);
-		tlen = ip->ip_len;
+		tlen = ntohs(ip->ip_len);
 
 		if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
 			if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
 				th->th_sum = m->m_pkthdr.csum_data;
 			else
 				th->th_sum = in_pseudo(ip->ip_src.s_addr,
-						ip->ip_dst.s_addr,
-						htonl(m->m_pkthdr.csum_data +
-							ip->ip_len +
-							IPPROTO_TCP));
+				    ip->ip_dst.s_addr,
+				    htonl(m->m_pkthdr.csum_data + tlen +
+				    IPPROTO_TCP));
 			th->th_sum ^= 0xffff;
-#ifdef TCPDEBUG
-			ipov->ih_len = (u_short)tlen;
-			ipov->ih_len = htons(ipov->ih_len);
-#endif
 		} else {
+			struct ipovly *ipov = (struct ipovly *)ip;
+
 			/*
 			 * Checksum extended TCP header and data.
 			 */
-			len = sizeof (struct ip) + tlen;
+			len = off0 + tlen;
 			bzero(ipov->ih_x1, sizeof(ipov->ih_x1));
-			ipov->ih_len = (u_short)tlen;
-			ipov->ih_len = htons(ipov->ih_len);
+			ipov->ih_len = htons(tlen);
 			th->th_sum = in_cksum(m, len);
 		}
 		if (th->th_sum) {
@@ -721,7 +713,6 @@ tcp_input(struct mbuf *m, int off0)
 					return;
 				}
 				ip = mtod(m, struct ip *);
-				ipov = (struct ipovly *)ip;
 				th = (struct tcphdr *)((caddr_t)ip + off0);
 			}
 		}