From 98c63057d2144fb81681580cd84c13c93794c96e Mon Sep 17 00:00:00 2001 From: Guillaume Subiron Date: Tue, 15 Mar 2016 10:31:20 +0100 Subject: slirp: Factorizing tcpiphdr structure with an union 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 Signed-off-by: Samuel Thibault Reviewed-by: Thomas Huth --- slirp/if.h | 4 ++-- slirp/mbuf.c | 4 ++-- slirp/slirp.c | 15 ++++++++------- slirp/socket.c | 13 ++++++++++++- slirp/tcp_input.c | 35 ++++++++++++++++++++++++----------- slirp/tcp_output.c | 18 +++++++++++++----- slirp/tcp_subr.c | 31 ++++++++++++++++++++++--------- slirp/tcpip.h | 31 +++++++++++++++++++++++-------- 8 files changed, 106 insertions(+), 45 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..d688dd4 100644 --- a/slirp/mbuf.c +++ b/slirp/mbuf.c @@ -22,9 +22,9 @@ /* * Find a nice value for msize - * XXX if_maxlinkhdr already in mtu */ -#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/slirp.c b/slirp/slirp.c index 049c2cf..dd4f6d2 100644 --- a/slirp/slirp.c +++ b/slirp/slirp.c @@ -766,15 +766,16 @@ void slirp_input(Slirp *slirp, const uint8_t *pkt, int pkt_len) m = m_get(slirp); if (!m) return; - /* Note: we add to align the IP header */ - if (M_FREEROOM(m) < pkt_len + 2) { - m_inc(m, pkt_len + 2); + /* Note: we add 2 to align the IP header on 4 bytes, + * and add the margin for the tcpiphdr overhead */ + if (M_FREEROOM(m) < pkt_len + TCPIPHDR_DELTA + 2) { + m_inc(m, pkt_len + TCPIPHDR_DELTA + 2); } - m->m_len = pkt_len + 2; - memcpy(m->m_data + 2, pkt, pkt_len); + m->m_len = pkt_len + TCPIPHDR_DELTA + 2; + memcpy(m->m_data + TCPIPHDR_DELTA + 2, pkt, pkt_len); - m->m_data += 2 + ETH_HLEN; - m->m_len -= 2 + ETH_HLEN; + m->m_data += TCPIPHDR_DELTA + 2 + ETH_HLEN; + m->m_len -= TCPIPHDR_DELTA + 2 + ETH_HLEN; if (proto == ETH_P_IP) { ip_input(m); diff --git a/slirp/socket.c b/slirp/socket.c index 55150f5..8df9252 100644 --- a/slirp/socket.c +++ b/slirp/socket.c @@ -483,7 +483,18 @@ sorecvfrom(struct socket *so) if (!m) { return; } - m->m_data += IF_MAXLINKHDR; + switch (so->so_ffamily) { + case AF_INET: + m->m_data += IF_MAXLINKHDR + sizeof(struct udpiphdr); + break; + case AF_INET6: + m->m_data += IF_MAXLINKHDR + sizeof(struct ip6) + + sizeof(struct udphdr); + break; + default: + g_assert_not_reached(); + break; + } /* * XXX Shouldn't FIONREAD packets destined for port 53, diff --git a/slirp/tcp_input.c b/slirp/tcp_input.c index 117a66e..640dd79 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); + 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; } @@ -603,6 +612,10 @@ findso: HTONS(ti->ti_urp); m->m_data -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); m->m_len += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); + m->m_data += sizeof(struct tcpiphdr) - sizeof(struct ip) + - sizeof(struct tcphdr); + m->m_len -= sizeof(struct tcpiphdr) - sizeof(struct ip) + - sizeof(struct tcphdr); *ip=save_ip; icmp_send_error(m, ICMP_UNREACH, code, 0, strerror(errno)); } @@ -1471,7 +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); diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c index b1aa1f2..cd021df 100644 --- a/slirp/tcp_subr.c +++ b/slirp/tcp_subr.c @@ -76,9 +76,10 @@ tcp_template(struct tcpcb *tp) register struct tcpiphdr *n = &tp->t_template; n->ti_mbuf = NULL; - n->ti_x1 = 0; + memset(&n->ti, 0, sizeof(n->ti)); + n->ti_x0 = 0; n->ti_pr = IPPROTO_TCP; - n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); + n->ti_len = htons(sizeof(struct tcphdr)); n->ti_src = so->so_faddr; n->ti_dst = so->so_laddr; n->ti_sport = so->so_fport; @@ -131,6 +132,7 @@ tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m, m->m_data += IF_MAXLINKHDR; *mtod(m, struct tcpiphdr *) = *ti; ti = mtod(m, struct tcpiphdr *); + memset(&ti->ti, 0, sizeof(ti->ti)); flags = TH_ACK; } else { /* @@ -150,8 +152,8 @@ tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m, tlen += sizeof (struct tcpiphdr); m->m_len = tlen; - ti->ti_mbuf = NULL; - ti->ti_x1 = 0; + ti->ti_mbuf = NULL; + ti->ti_x0 = 0; ti->ti_seq = htonl(seq); ti->ti_ack = htonl(ack); ti->ti_x2 = 0; @@ -164,12 +166,23 @@ tcp_respond(struct tcpcb *tp, struct tcpiphdr *ti, struct mbuf *m, ti->ti_urp = 0; ti->ti_sum = 0; ti->ti_sum = cksum(m, tlen); - ((struct ip *)ti)->ip_len = tlen; - if(flags & TH_RST) - ((struct ip *)ti)->ip_ttl = MAXTTL; - else - ((struct ip *)ti)->ip_ttl = IPDEFTTL; + 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 *); + ip->ip_len = tlen; + ip->ip_dst = tcpiph_save.ti_dst; + ip->ip_src = tcpiph_save.ti_src; + ip->ip_p = tcpiph_save.ti_pr; + + if (flags & TH_RST) { + ip->ip_ttl = MAXTTL; + } else { + ip->ip_ttl = IPDEFTTL; + } (void) ip_output((struct socket *)0, m); } diff --git a/slirp/tcpip.h b/slirp/tcpip.h index 7974ce3..3c5d127 100644 --- a/slirp/tcpip.h +++ b/slirp/tcpip.h @@ -37,15 +37,23 @@ * Tcp+ip header, after ip options removed. */ struct tcpiphdr { - struct ipovly ti_i; /* overlaid ip structure */ - struct tcphdr ti_t; /* tcp header */ + struct mbuf_ptr ih_mbuf; /* backpointer to mbuf */ + union { + struct { + struct in_addr ih_src; /* source internet address */ + struct in_addr ih_dst; /* destination internet address */ + uint8_t ih_x1; /* (unused) */ + uint8_t ih_pr; /* protocol */ + } ti_i4; + } ti; + uint16_t ti_x0; + uint16_t ti_len; /* protocol length */ + struct tcphdr ti_t; /* tcp header */ }; -#define ti_mbuf ti_i.ih_mbuf.mptr -#define ti_x1 ti_i.ih_x1 -#define ti_pr ti_i.ih_pr -#define ti_len ti_i.ih_len -#define ti_src ti_i.ih_src -#define ti_dst ti_i.ih_dst +#define ti_mbuf ih_mbuf.mptr +#define ti_pr ti.ti_i4.ih_pr +#define ti_src ti.ti_i4.ih_src +#define ti_dst ti.ti_i4.ih_dst #define ti_sport ti_t.th_sport #define ti_dport ti_t.th_dport #define ti_seq ti_t.th_seq @@ -65,6 +73,13 @@ struct tcpiphdr { #define tcpfrag_list_end(F, T) (tcpiphdr2qlink(F) == (struct qlink*)(T)) #define tcpfrag_list_empty(T) ((T)->seg_next == (struct tcpiphdr*)(T)) +/* This is the difference between the size of a tcpiphdr structure, and the + * size of actual ip+tcp headers, rounded up since we need to align data. */ +#define TCPIPHDR_DELTA\ + (max(0,\ + (sizeof(struct tcpiphdr)\ + - sizeof(struct ip) - sizeof(struct tcphdr) + 3) & ~3)) + /* * Just a clean way to get to the first byte * of the packet -- cgit v1.1