On 14.02.2016 18:47, Samuel Thibault wrote:
> From: Guillaume Subiron <maet...@subiron.org>
>
> This patch factorizes the tcpiphdr structure to put the IPv4 fields in
> an union, for addition of version 6 in further patch.
> Using some macros, retrocompatibility of the existing code is assured.
>
> This patch also fixes the SLIRP_MSIZE and margin computation in various
> functions, and makes them compatible with the new tcpiphdr structure,
> whose size will be bigger than sizeof(struct tcphdr) + sizeof(struct ip)
>
> Signed-off-by: Guillaume Subiron <maet...@subiron.org>
> Signed-off-by: Samuel Thibault <samuel.thiba...@ens-lyon.org>
> ---
> slirp/if.h | 4 ++--
> slirp/mbuf.c | 3 ++-
> slirp/slirp.c | 15 ++++++++-------
> slirp/socket.c | 13 ++++++++++++-
> slirp/tcp_input.c | 31 ++++++++++++++++++++-----------
> slirp/tcp_output.c | 18 +++++++++++++-----
> slirp/tcp_subr.c | 31 ++++++++++++++++++++++---------
> slirp/tcpip.h | 31 +++++++++++++++++++++++--------
> 8 files changed, 102 insertions(+), 44 deletions(-)
>
> diff --git a/slirp/if.h b/slirp/if.h
> index 3327023..c7a5c57 100644
> --- a/slirp/if.h
> +++ b/slirp/if.h
> @@ -17,7 +17,7 @@
> #define IF_MRU 1500
> #define IF_COMP IF_AUTOCOMP /* Flags for compression */
>
> -/* 2 for alignment, 14 for ethernet, 40 for TCP/IP */
> -#define IF_MAXLINKHDR (2 + 14 + 40)
> +/* 2 for alignment, 14 for ethernet */
> +#define IF_MAXLINKHDR (2 + ETH_HLEN)
>
> #endif
> diff --git a/slirp/mbuf.c b/slirp/mbuf.c
> index c959758..f081c69 100644
> --- a/slirp/mbuf.c
> +++ b/slirp/mbuf.c
> @@ -24,7 +24,8 @@
> * Find a nice value for msize
> * XXX if_maxlinkhdr already in mtu
Maybe you should now remove the XXX line, now that the size of the
TCP/IP headers is counted via IF_MTU instead?
> */
> -#define SLIRP_MSIZE (IF_MTU + IF_MAXLINKHDR + offsetof(struct mbuf, m_dat) +
> 6)
> +#define SLIRP_MSIZE\
> + (offsetof(struct mbuf, m_dat) + IF_MAXLINKHDR + TCPIPHDR_DELTA + IF_MTU)
>
> void
> m_init(Slirp *slirp)
...
> diff --git a/slirp/tcp_input.c b/slirp/tcp_input.c
> index 5f845da..26b0c8b 100644
> --- a/slirp/tcp_input.c
> +++ b/slirp/tcp_input.c
> @@ -256,11 +256,6 @@ tcp_input(struct mbuf *m, int iphlen, struct socket
> *inso)
> }
> slirp = m->slirp;
>
> - /*
> - * Get IP and TCP header together in first mbuf.
> - * Note: IP leaves IP header in first mbuf.
> - */
> - ti = mtod(m, struct tcpiphdr *);
> if (iphlen > sizeof(struct ip )) {
> ip_stripoptions(m, (struct mbuf *)0);
> iphlen=sizeof(struct ip );
> @@ -277,14 +272,28 @@ tcp_input(struct mbuf *m, int iphlen, struct socket
> *inso)
> save_ip.ip_len+= iphlen;
>
> /*
> + * Get IP and TCP header together in first mbuf.
> + * Note: IP leaves IP header in first mbuf.
> + */
> + m->m_data -= sizeof(struct tcpiphdr) - (sizeof(struct ip)
> + + sizeof(struct tcphdr));
> + m->m_len += sizeof(struct tcpiphdr) - (sizeof(struct ip)
> + + sizeof(struct tcphdr));
I'm somewhat having a hard time to understand the "+ sizeof(struct
tcphdr))" here.
In the tcp_output.c code, there is this:
m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
- sizeof(struct ip);
So with my limited point of view, I'd rather expect this here in
tcp_input.c:
m->m_data -= sizeof(struct tcpiphdr) - (sizeof(struct ip)
- sizeof(struct tcphdr));
i.e. "-" instead of "+" here ----------------^
Could you maybe elaborate a little bit on the above calculation? Or is
it just a bug?
> + ti = mtod(m, struct tcpiphdr *);
> +
> + /*
> * Checksum extended TCP header and data.
> */
> - tlen = ((struct ip *)ti)->ip_len;
> - tcpiphdr2qlink(ti)->next = tcpiphdr2qlink(ti)->prev = NULL;
> - memset(&ti->ti_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
> - ti->ti_x1 = 0;
> + tlen = ip->ip_len;
> + tcpiphdr2qlink(ti)->next = tcpiphdr2qlink(ti)->prev = NULL;
> + memset(&ti->ih_mbuf, 0 , sizeof(struct mbuf_ptr));
> + memset(&ti->ti, 0, sizeof(ti->ti));
> + ti->ti_x0 = 0;
> + ti->ti_src = save_ip.ip_src;
> + ti->ti_dst = save_ip.ip_dst;
> + ti->ti_pr = save_ip.ip_p;
> ti->ti_len = htons((uint16_t)tlen);
> - len = sizeof(struct ip ) + tlen;
> + len = ((sizeof(struct tcpiphdr) - sizeof(struct tcphdr)) + tlen);
> if(cksum(m, len)) {
> goto drop;
> }
> @@ -1475,7 +1484,7 @@ tcp_mss(struct tcpcb *tp, u_int offer)
> DEBUG_ARG("tp = %p", tp);
> DEBUG_ARG("offer = %d", offer);
>
> - mss = min(IF_MTU, IF_MRU) - sizeof(struct tcpiphdr);
> + mss = min(IF_MTU, IF_MRU) - sizeof(struct tcphdr) + sizeof(struct ip);
> if (offer)
> mss = min(mss, offer);
> mss = max(mss, 32);
> diff --git a/slirp/tcp_output.c b/slirp/tcp_output.c
> index 34e4d2e..7fc6a87 100644
> --- a/slirp/tcp_output.c
> +++ b/slirp/tcp_output.c
> @@ -448,15 +448,23 @@ send:
> */
> m->m_len = hdrlen + len; /* XXX Needed? m_len should be correct */
>
> - {
> + struct tcpiphdr tcpiph_save = *(mtod(m, struct tcpiphdr *));
> + m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
> + - sizeof(struct ip);
> + m->m_len -= sizeof(struct tcpiphdr) - sizeof(struct tcphdr)
> + - sizeof(struct ip);
> + struct ip *ip = mtod(m, struct ip *);
>
> - ((struct ip *)ti)->ip_len = m->m_len;
> + ip->ip_len = m->m_len;
> + ip->ip_dst = tcpiph_save.ti_dst;
> + ip->ip_src = tcpiph_save.ti_src;
> + ip->ip_p = tcpiph_save.ti_pr;
>
> - ((struct ip *)ti)->ip_ttl = IPDEFTTL;
> - ((struct ip *)ti)->ip_tos = so->so_iptos;
> + ip->ip_ttl = IPDEFTTL;
> + ip->ip_tos = so->so_iptos;
>
> error = ip_output(so, m);
> - }
> +
> if (error) {
> out:
> return (error);
Thomas
