/* * INET An implementation of the TCP/IP protocol suite for the LINUX * operating system. INET is implemented using the BSD Socket * interface as the means of communication with the user level. * * Definitions for the TCP module. * * Version: @(#)tcp.h 1.0.5 05/23/93 * * Authors: Ross Biro, * Fred N. van Kempen, * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #ifndef _TCP_H #define _TCP_H #include #include #include #include /* This is for all connections with a full identity, no wildcards. * Half of the table is for TIME_WAIT, the other half is for the * rest. * * This needs to be shared by v4 and v6 because the lookup and hashing * code needs to work with different AF's yet the port space is * shared. */ extern unsigned int tcp_ehash_size; extern struct sock **tcp_ehash; /* This is for listening sockets, thus all sockets which possess wildcards. */ #define TCP_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ extern struct sock *tcp_listening_hash[TCP_LHTABLE_SIZE]; /* There are a few simple rules, which allow for local port reuse by * an application. In essence: * * 1) Sockets bound to different interfaces may share a local port. * Failing that, goto test 2. * 2) If all sockets have sk->reuse set, and none of them are in * TCP_LISTEN state, the port may be shared. * Failing that, goto test 3. * 3) If all sockets are bound to a specific sk->rcv_saddr local * address, and none of them are the same, the port may be * shared. * Failing this, the port cannot be shared. * * The interesting point, is test #2. This is what an FTP server does * all day. To optimize this case we use a specific flag bit defined * below. As we add sockets to a bind bucket list, we perform a * check of: (newsk->reuse && (newsk->state != TCP_LISTEN)) * As long as all sockets added to a bind bucket pass this test, * the flag bit will be set. * The resulting situation is that tcp_v[46]_verify_bind() can just check * for this flag bit, if it is set and the socket trying to bind has * sk->reuse set, we don't even have to walk the owners list at all, * we return that it is ok to bind this socket to the requested local port. * * Sounds like a lot of work, but it is worth it. In a more naive * implementation (ie. current FreeBSD etc.) the entire list of ports * must be walked for each data port opened by an ftp server. Needless * to say, this does not scale at all. With a couple thousand FTP * users logged onto your box, isn't it nice to know that new data * ports are created in O(1) time? I thought so. ;-) -DaveM */ struct tcp_bind_bucket { unsigned short port; unsigned short fastreuse; struct tcp_bind_bucket *next; struct sock *owners; struct tcp_bind_bucket **pprev; }; extern unsigned int tcp_bhash_size; extern struct tcp_bind_bucket **tcp_bhash; extern kmem_cache_t *tcp_bucket_cachep; extern struct tcp_bind_bucket *tcp_bucket_create(unsigned short snum); extern void tcp_bucket_unlock(struct sock *sk); extern int tcp_port_rover; /* Level-1 socket-demux cache. */ #define TCP_NUM_REGS 32 extern struct sock *tcp_regs[TCP_NUM_REGS]; #define TCP_RHASH_FN(__fport) \ ((((__fport) >> 7) ^ (__fport)) & (TCP_NUM_REGS - 1)) #define TCP_RHASH(__fport) tcp_regs[TCP_RHASH_FN((__fport))] #define TCP_SK_RHASH_FN(__sock) TCP_RHASH_FN((__sock)->dport) #define TCP_SK_RHASH(__sock) tcp_regs[TCP_SK_RHASH_FN((__sock))] static __inline__ void tcp_reg_zap(struct sock *sk) { struct sock **rpp; rpp = &(TCP_SK_RHASH(sk)); if(*rpp == sk) *rpp = NULL; } /* These are AF independent. */ static __inline__ int tcp_bhashfn(__u16 lport) { return (lport & (tcp_bhash_size - 1)); } /* This is a TIME_WAIT bucket. It works around the memory consumption * problems of sockets in such a state on heavily loaded servers, but * without violating the protocol specification. */ struct tcp_tw_bucket { /* These _must_ match the beginning of struct sock precisely. * XXX Yes I know this is gross, but I'd have to edit every single * XXX networking file if I created a "struct sock_header". -DaveM * Just don't forget -fno-strict-aliasing, but it should be really * fixed -AK */ struct sock *sklist_next; struct sock *sklist_prev; struct sock *bind_next; struct sock **bind_pprev; __u32 daddr; __u32 rcv_saddr; __u16 dport; unsigned short num; int bound_dev_if; struct sock *next; struct sock **pprev; unsigned char state, zapped; __u16 sport; unsigned short family; unsigned char reuse, nonagle; /* And these are ours. */ __u32 rcv_nxt, snd_nxt; __u16 window; struct tcp_func *af_specific; struct tcp_bind_bucket *tb; struct tcp_tw_bucket *next_death; struct tcp_tw_bucket **pprev_death; int death_slot; #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) struct in6_addr v6_daddr; struct in6_addr v6_rcv_saddr; #endif }; extern kmem_cache_t *tcp_timewait_cachep; /* Socket demux engine toys. */ #ifdef __BIG_ENDIAN #define TCP_COMBINED_PORTS(__sport, __dport) \ (((__u32)(__sport)<<16) | (__u32)(__dport)) #else /* __LITTLE_ENDIAN */ #define TCP_COMBINED_PORTS(__sport, __dport) \ (((__u32)(__dport)<<16) | (__u32)(__sport)) #endif #if (BITS_PER_LONG == 64) #ifdef __BIG_ENDIAN #define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr) \ __u64 __name = (((__u64)(__saddr))<<32)|((__u64)(__daddr)); #else /* __LITTLE_ENDIAN */ #define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr) \ __u64 __name = (((__u64)(__daddr))<<32)|((__u64)(__saddr)); #endif /* __BIG_ENDIAN */ #define TCP_IPV4_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ (((*((__u64 *)&((__sk)->daddr)))== (__cookie)) && \ ((*((__u32 *)&((__sk)->dport)))== (__ports)) && \ (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif)))) #else /* 32-bit arch */ #define TCP_V4_ADDR_COOKIE(__name, __saddr, __daddr) #define TCP_IPV4_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ (((__sk)->daddr == (__saddr)) && \ ((__sk)->rcv_saddr == (__daddr)) && \ ((*((__u32 *)&((__sk)->dport)))== (__ports)) && \ (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif)))) #endif /* 64-bit arch */ #define TCP_IPV6_MATCH(__sk, __saddr, __daddr, __ports, __dif) \ (((*((__u32 *)&((__sk)->dport)))== (__ports)) && \ ((__sk)->family == AF_INET6) && \ !ipv6_addr_cmp(&(__sk)->net_pinfo.af_inet6.daddr, (__saddr)) && \ !ipv6_addr_cmp(&(__sk)->net_pinfo.af_inet6.rcv_saddr, (__daddr)) && \ (!((__sk)->bound_dev_if) || ((__sk)->bound_dev_if == (__dif)))) /* These can have wildcards, don't try too hard. */ static __inline__ int tcp_lhashfn(unsigned short num) { return num & (TCP_LHTABLE_SIZE - 1); } static __inline__ int tcp_sk_listen_hashfn(struct sock *sk) { return tcp_lhashfn(sk->num); } /* Note, that it is > than ipv6 header */ #define NETHDR_SIZE (sizeof(struct iphdr) + 40) /* * 40 is maximal IP options size * 20 is the maximum TCP options size we can currently construct on a SYN. * 40 is the maximum possible TCP options size. */ #define MAX_SYN_SIZE (NETHDR_SIZE + sizeof(struct tcphdr) + 20 + MAX_HEADER + 15) #define MAX_FIN_SIZE (NETHDR_SIZE + sizeof(struct tcphdr) + MAX_HEADER + 15) #define BASE_ACK_SIZE (NETHDR_SIZE + MAX_HEADER + 15) #define MAX_ACK_SIZE (NETHDR_SIZE + sizeof(struct tcphdr) + MAX_HEADER + 15) #define MAX_RESET_SIZE (NETHDR_SIZE + sizeof(struct tcphdr) + MAX_HEADER + 15) #define MAX_TCPHEADER_SIZE (NETHDR_SIZE + sizeof(struct tcphdr) + 20 + MAX_HEADER + 15) /* * Never offer a window over 32767 without using window scaling. Some * poor stacks do signed 16bit maths! */ #define MAX_WINDOW 32767 #define MIN_WINDOW 2048 #define MAX_ACK_BACKLOG 2 #define MAX_DELAY_ACK 2 #define TCP_WINDOW_DIFF 2048 /* urg_data states */ #define URG_VALID 0x0100 #define URG_NOTYET 0x0200 #define URG_READ 0x0400 #define TCP_RETR1 7 /* * This is how many retries it does before it * tries to figure out if the gateway is * down. */ #define TCP_RETR2 15 /* * This should take at least * 90 minutes to time out. */ #define TCP_TIMEOUT_LEN (15*60*HZ) /* should be about 15 mins */ #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to successfully * close the socket, about 60 seconds */ #define TCP_FIN_TIMEOUT (3*60*HZ) /* BSD style FIN_WAIT2 deadlock breaker */ #define TCP_ACK_TIME (3*HZ) /* time to delay before sending an ACK */ #define TCP_DONE_TIME (5*HZ/2)/* maximum time to wait before actually * destroying a socket */ #define TCP_WRITE_TIME (30*HZ) /* initial time to wait for an ACK, * after last transmit */ #define TCP_TIMEOUT_INIT (3*HZ) /* RFC 1122 initial timeout value */ #define TCP_SYN_RETRIES 10 /* number of times to retry opening a * connection (TCP_RETR2-....) */ #define TCP_PROBEWAIT_LEN (1*HZ)/* time to wait between probes when * I've got something to write and * there is no window */ #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ #define TCP_KEEPALIVE_PERIOD ((75*HZ)>>2) /* period of keepalive check */ #define TCP_SYNACK_PERIOD (HZ/2) /* How often to run the synack slow timer */ #define TCP_QUICK_TRIES 8 /* How often we try to retransmit, until * we tell the link layer that it is something * wrong (e.g. that it can expire redirects) */ #define TCP_BUCKETGC_PERIOD (HZ) /* TIME_WAIT reaping mechanism. */ #define TCP_TWKILL_SLOTS 8 /* Please keep this a power of 2. */ #define TCP_TWKILL_PERIOD ((HZ*60)/TCP_TWKILL_SLOTS) /* * TCP option */ #define TCPOPT_NOP 1 /* Padding */ #define TCPOPT_EOL 0 /* End of options */ #define TCPOPT_MSS 2 /* Segment size negotiating */ #define TCPOPT_WINDOW 3 /* Window scaling */ #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ #define TCPOPT_SACK 5 /* SACK Block */ #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ /* * TCP option lengths */ #define TCPOLEN_MSS 4 #define TCPOLEN_WINDOW 3 #define TCPOLEN_SACK_PERM 2 #define TCPOLEN_TIMESTAMP 10 /* But this is what stacks really send out. */ #define TCPOLEN_TSTAMP_ALIGNED 12 #define TCPOLEN_WSCALE_ALIGNED 4 #define TCPOLEN_SACKPERM_ALIGNED 4 #define TCPOLEN_SACK_BASE 2 #define TCPOLEN_SACK_BASE_ALIGNED 4 #define TCPOLEN_SACK_PERBLOCK 8 struct open_request; struct or_calltable { void (*rtx_syn_ack) (struct sock *sk, struct open_request *req); void (*destructor) (struct open_request *req); void (*send_reset) (struct sk_buff *skb); }; struct tcp_v4_open_req { __u32 loc_addr; __u32 rmt_addr; struct ip_options *opt; }; #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) struct tcp_v6_open_req { struct in6_addr loc_addr; struct in6_addr rmt_addr; struct sk_buff *pktopts; int iif; }; #endif /* this structure is too big */ struct open_request { struct open_request *dl_next; /* Must be first member! */ __u32 rcv_isn; __u32 snt_isn; __u16 rmt_port; __u16 mss; __u8 retrans; __u8 __pad; unsigned snd_wscale : 4, rcv_wscale : 4, tstamp_ok : 1, sack_ok : 1, wscale_ok : 1; /* The following two fields can be easily recomputed I think -AK */ __u32 window_clamp; /* window clamp at creation time */ __u32 rcv_wnd; /* rcv_wnd offered first time */ __u32 ts_recent; unsigned long expires; struct or_calltable *class; struct sock *sk; union { struct tcp_v4_open_req v4_req; #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) struct tcp_v6_open_req v6_req; #endif } af; #ifdef CONFIG_IP_TRANSPARENT_PROXY __u16 lcl_port; /* LVE */ #endif }; /* SLAB cache for open requests. */ extern kmem_cache_t *tcp_openreq_cachep; #define tcp_openreq_alloc() kmem_cache_alloc(tcp_openreq_cachep, SLAB_ATOMIC) #define tcp_openreq_free(req) kmem_cache_free(tcp_openreq_cachep, req) /* * Pointers to address related TCP functions * (i.e. things that depend on the address family) * * BUGGG_FUTURE: all the idea behind this struct is wrong. * It mixes socket frontend with transport function. * With port sharing between IPv6/v4 it gives the only advantage, * only poor IPv6 needs to permanently recheck, that it * is still IPv6 8)8) It must be cleaned up as soon as possible. * --ANK (980802) */ struct tcp_func { void (*queue_xmit) (struct sk_buff *skb); void (*send_check) (struct sock *sk, struct tcphdr *th, int len, struct sk_buff *skb); int (*rebuild_header) (struct sock *sk); int (*conn_request) (struct sock *sk, struct sk_buff *skb, __u32 isn); struct sock * (*syn_recv_sock) (struct sock *sk, struct sk_buff *skb, struct open_request *req, struct dst_entry *dst); struct sock * (*get_sock) (struct sk_buff *skb, struct tcphdr *th); __u16 net_header_len; int (*setsockopt) (struct sock *sk, int level, int optname, char *optval, int optlen); int (*getsockopt) (struct sock *sk, int level, int optname, char *optval, int *optlen); void (*addr2sockaddr) (struct sock *sk, struct sockaddr *); int sockaddr_len; }; /* * The next routines deal with comparing 32 bit unsigned ints * and worry about wraparound (automatic with unsigned arithmetic). */ static __inline int before(__u32 seq1, __u32 seq2) { return (__s32)(seq1-seq2) < 0; } static __inline int after(__u32 seq1, __u32 seq2) { return (__s32)(seq2-seq1) < 0; } /* is s2<=s1<=s3 ? */ static __inline int between(__u32 seq1, __u32 seq2, __u32 seq3) { return seq3 - seq2 >= seq1 - seq2; } extern struct proto tcp_prot; extern struct tcp_mib tcp_statistics; extern void tcp_put_port(struct sock *sk); extern void __tcp_put_port(struct sock *sk); extern void tcp_inherit_port(struct sock *sk, struct sock *child); extern void tcp_v4_err(struct sk_buff *skb, unsigned char *, int); extern void tcp_shutdown (struct sock *sk, int how); extern int tcp_v4_rcv(struct sk_buff *skb, unsigned short len); extern int tcp_do_sendmsg(struct sock *sk, struct msghdr *msg); extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, struct tcphdr *th, unsigned len); extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb, struct tcphdr *th, unsigned len); enum tcp_tw_status { TCP_TW_SUCCESS = 0, TCP_TW_RST = 1, TCP_TW_ACK = 2 }; extern enum tcp_tw_status tcp_timewait_state_process(struct tcp_tw_bucket *tw, struct sk_buff *skb, struct tcphdr *th, unsigned len); extern void tcp_close(struct sock *sk, long timeout); extern struct sock * tcp_accept(struct sock *sk, int flags); extern unsigned int tcp_poll(struct file * file, struct socket *sock, struct poll_table_struct *wait); extern void tcp_write_space(struct sock *sk); extern int tcp_getsockopt(struct sock *sk, int level, int optname, char *optval, int *optlen); extern int tcp_setsockopt(struct sock *sk, int level, int optname, char *optval, int optlen); extern void tcp_set_keepalive(struct sock *sk, int val); extern int tcp_recvmsg(struct sock *sk, struct msghdr *msg, int len, int nonblock, int flags, int *addr_len); extern void tcp_parse_options(struct sock *sk, struct tcphdr *th, struct tcp_opt *tp, int no_fancy); /* * TCP v4 functions exported for the inet6 API */ extern int tcp_v4_rebuild_header(struct sock *sk); extern int tcp_v4_build_header(struct sock *sk, struct sk_buff *skb); extern void tcp_v4_send_check(struct sock *sk, struct tcphdr *th, int len, struct sk_buff *skb); extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb, __u32 isn); extern struct sock * tcp_create_openreq_child(struct sock *sk, struct open_request *req, struct sk_buff *skb); extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, struct open_request *req, struct dst_entry *dst); extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); extern void tcp_connect(struct sock *sk, struct sk_buff *skb, int est_mss); extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst, struct open_request *req, int mss); /* From syncookies.c */ extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, struct ip_options *opt); extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mss); /* tcp_output.c */ extern void tcp_read_wakeup(struct sock *); extern void tcp_write_xmit(struct sock *); extern void tcp_time_wait(struct sock *); extern int tcp_retransmit_skb(struct sock *, struct sk_buff *); extern void tcp_fack_retransmit(struct sock *); extern void tcp_xmit_retransmit_queue(struct sock *); extern void tcp_simple_retransmit(struct sock *); extern void tcp_send_probe0(struct sock *); extern void tcp_send_partial(struct sock *); extern void tcp_write_wakeup(struct sock *); extern void tcp_send_fin(struct sock *sk); extern void tcp_send_active_reset(struct sock *sk); extern int tcp_send_synack(struct sock *); extern void tcp_transmit_skb(struct sock *, struct sk_buff *); extern void tcp_send_skb(struct sock *, struct sk_buff *, int force_queue); extern void tcp_send_ack(struct sock *sk); extern void tcp_send_delayed_ack(struct tcp_opt *tp, int max_timeout); /* CONFIG_IP_TRANSPARENT_PROXY */ extern int tcp_chkaddr(struct sk_buff *); /* tcp_timer.c */ #define tcp_reset_msl_timer(x,y,z) net_reset_timer(x,y,z) extern void tcp_reset_xmit_timer(struct sock *, int, unsigned long); extern void tcp_init_xmit_timers(struct sock *); extern void tcp_clear_xmit_timers(struct sock *); extern void tcp_retransmit_timer(unsigned long); extern void tcp_delack_timer(unsigned long); extern void tcp_probe_timer(unsigned long); extern struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, struct open_request *req); /* * TCP slow timer */ extern struct timer_list tcp_slow_timer; struct tcp_sl_timer { atomic_t count; unsigned long period; unsigned long last; void (*handler) (unsigned long); }; #define TCP_SLT_SYNACK 0 #define TCP_SLT_KEEPALIVE 1 #define TCP_SLT_TWKILL 2 #define TCP_SLT_MAX 3 extern struct tcp_sl_timer tcp_slt_array[TCP_SLT_MAX]; extern int tcp_sync_mss(struct sock *sk, u32 pmtu); /* Compute the current effective MSS, taking SACKs and IP options, * and even PMTU discovery events into account. */ static __inline__ unsigned int tcp_current_mss(struct sock *sk) { struct tcp_opt *tp = &sk->tp_pinfo.af_tcp; struct dst_entry *dst = sk->dst_cache; int mss_now = tp->mss_cache; if (dst && dst->pmtu != tp->pmtu_cookie) mss_now = tcp_sync_mss(sk, dst->pmtu); if(tp->sack_ok && tp->num_sacks) mss_now -= (TCPOLEN_SACK_BASE_ALIGNED + (tp->num_sacks * TCPOLEN_SACK_PERBLOCK)); return mss_now > 8 ? mss_now : 8; } /* Compute the actual receive window we are currently advertising. * Rcv_nxt can be after the window if our peer push more data * than the offered window. */ static __inline__ u32 tcp_receive_window(struct tcp_opt *tp) { s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; if (win < 0) win = 0; return (u32) win; } /* Choose a new window, without checks for shrinking, and without * scaling applied to the result. The caller does these things * if necessary. This is a "raw" window selection. */ extern u32 __tcp_select_window(struct sock *sk); /* Chose a new window to advertise, update state in tcp_opt for the * socket, and return result with RFC1323 scaling applied. The return * value can be stuffed directly into th->window for an outgoing * frame. */ static __inline__ u16 tcp_select_window(struct sock *sk) { struct tcp_opt *tp = &(sk->tp_pinfo.af_tcp); u32 cur_win = tcp_receive_window(tp); u32 new_win = __tcp_select_window(sk); /* Never shrink the offered window */ if(new_win < cur_win) { /* Danger Will Robinson! * Don't update rcv_wup/rcv_wnd here or else * we will not be able to advertise a zero * window in time. --DaveM */ new_win = cur_win; } else { tp->rcv_wnd = new_win; tp->rcv_wup = tp->rcv_nxt; } /* RFC1323 scaling applied */ return new_win >> tp->rcv_wscale; } /* See if we can advertise non-zero, and if so how much we * can increase our advertisement. If it becomes more than * twice what we are talking about right now, return true. */ static __inline__ int tcp_raise_window(struct sock *sk) { struct tcp_opt *tp = &(sk->tp_pinfo.af_tcp); u32 cur_win = tcp_receive_window(tp); u32 new_win = __tcp_select_window(sk); return (new_win && (new_win > (cur_win << 1))); } /* Recalculate snd_ssthresh, we want to set it to: * * one half the current congestion window, but no * less than two segments * * We must take into account the current send window * as well, however we keep track of that using different * units so a conversion is necessary. -DaveM */ static __inline__ __u32 tcp_recalc_ssthresh(struct tcp_opt *tp) { __u32 snd_wnd_packets = tp->snd_wnd / max(tp->mss_cache, 1); return max(min(snd_wnd_packets, tp->snd_cwnd) >> 1, 2); } /* TCP timestamps are only 32-bits, this causes a slight * complication on 64-bit systems since we store a snapshot * of jiffies in the buffer control blocks below. We decidedly * only use of the low 32-bits of jiffies and hide the ugly * casts with the following macro. */ #define tcp_time_stamp ((__u32)(jiffies)) /* This is what the send packet queueing engine uses to pass * TCP per-packet control information to the transmission * code. We also store the host-order sequence numbers in * here too. This is 36 bytes on 32-bit architectures, * 40 bytes on 64-bit machines, if this grows please adjust * skbuff.h:skbuff->cb[xxx] size appropriately. */ struct tcp_skb_cb { union { struct inet_skb_parm h4; #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) struct inet6_skb_parm h6; #endif } header; /* For incoming frames */ __u32 seq; /* Starting sequence number */ __u32 end_seq; /* SEQ + FIN + SYN + datalen */ __u32 when; /* used to compute rtt's */ __u8 flags; /* TCP header flags. */ /* NOTE: These must match up to the flags byte in a * real TCP header. */ #define TCPCB_FLAG_FIN 0x01 #define TCPCB_FLAG_SYN 0x02 #define TCPCB_FLAG_RST 0x04 #define TCPCB_FLAG_PSH 0x08 #define TCPCB_FLAG_ACK 0x10 #define TCPCB_FLAG_URG 0x20 __u8 sacked; /* State flags for SACK/FACK. */ #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ __u16 urg_ptr; /* Valid w/URG flags is set. */ __u32 ack_seq; /* Sequence number ACK'd */ }; #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) /* This determines how many packets are "in the network" to the best * of our knowledge. In many cases it is conservative, but where * detailed information is available from the receiver (via SACK * blocks etc.) we can make more aggressive calculations. * * Use this for decisions involving congestion control, use just * tp->packets_out to determine if the send queue is empty or not. * * Read this equation as: * * "Packets sent once on transmission queue" MINUS * "Packets acknowledged by FACK information" PLUS * "Packets fast retransmitted" */ static __inline__ int tcp_packets_in_flight(struct tcp_opt *tp) { return tp->packets_out - tp->fackets_out + tp->retrans_out; } /* This checks if the data bearing packet SKB (usually tp->send_head) * should be put on the wire right now. */ static __inline__ int tcp_snd_test(struct sock *sk, struct sk_buff *skb) { struct tcp_opt *tp = &(sk->tp_pinfo.af_tcp); int nagle_check = 1; /* RFC 1122 - section 4.2.3.4 * * We must queue if * * a) The right edge of this frame exceeds the window * b) There are packets in flight and we have a small segment * [SWS avoidance and Nagle algorithm] * (part of SWS is done on packetization) * c) We are retransmiting [Nagle] * d) We have too many packets 'in flight' * * Don't use the nagle rule for urgent data (or * for the final FIN -DaveM). */ if ((sk->nonagle == 2 && (skb->len < tp->mss_cache)) || (!sk->nonagle && skb->len < (tp->mss_cache >> 1) && tp->packets_out && !(TCP_SKB_CB(skb)->flags & (TCPCB_FLAG_URG|TCPCB_FLAG_FIN)))) nagle_check = 0; /* Don't be strict about the congestion window for the * final FIN frame. -DaveM */ return (nagle_check && ((tcp_packets_in_flight(tp) < tp->snd_cwnd) || (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) && !after(TCP_SKB_CB(skb)->end_seq, tp->snd_una + tp->snd_wnd) && tp->retransmits == 0); } /* Push out any pending frames which were held back due to * TCP_CORK or attempt at coalescing tiny packets. * The socket must be locked by the caller. */ static __inline__ void tcp_push_pending_frames(struct sock *sk, struct tcp_opt *tp) { if(tp->send_head) { if(tcp_snd_test(sk, tp->send_head)) tcp_write_xmit(sk); else if(tp->packets_out == 0 && !tp->pending) { /* We held off on this in tcp_send_skb() */ tp->pending = TIME_PROBE0; tcp_reset_xmit_timer(sk, TIME_PROBE0, tp->rto); } } } /* This tells the input processing path that an ACK should go out * right now. */ #define tcp_enter_quickack_mode(__tp) ((__tp)->ato |= (1<<31)) #define tcp_exit_quickack_mode(__tp) ((__tp)->ato &= ~(1<<31)) #define tcp_in_quickack_mode(__tp) (((__tp)->ato & (1 << 31)) != 0) /* * List all states of a TCP socket that can be viewed as a "connected" * state. This now includes TCP_SYN_RECV, although I am not yet fully * convinced that this is the solution for the 'getpeername(2)' * problem. Thanks to Stephen A. Wood -FvK */ static __inline const int tcp_connected(const int state) { return ((1 << state) & (TCPF_ESTABLISHED|TCPF_CLOSE_WAIT|TCPF_FIN_WAIT1| TCPF_FIN_WAIT2|TCPF_SYN_RECV)); } /* * Calculate(/check) TCP checksum */ static __inline__ u16 tcp_v4_check(struct tcphdr *th, int len, unsigned long saddr, unsigned long daddr, unsigned long base) { return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); } #undef STATE_TRACE #ifdef STATE_TRACE static char *statename[]={ "Unused","Established","Syn Sent","Syn Recv", "Fin Wait 1","Fin Wait 2","Time Wait", "Close", "Close Wait","Last ACK","Listen","Closing" }; #endif static __inline__ void tcp_set_state(struct sock *sk, int state) { int oldstate = sk->state; sk->state = state; #ifdef STATE_TRACE SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]); #endif switch (state) { case TCP_ESTABLISHED: if (oldstate != TCP_ESTABLISHED) tcp_statistics.TcpCurrEstab++; break; case TCP_CLOSE: { struct tcp_opt *tp = &sk->tp_pinfo.af_tcp; /* Should be about 2 rtt's */ net_reset_timer(sk, TIME_DONE, min(tp->srtt * 2, TCP_DONE_TIME)); sk->prot->unhash(sk); /* fall through */ } default: if (oldstate==TCP_ESTABLISHED) tcp_statistics.TcpCurrEstab--; } } static __inline__ void tcp_build_and_update_options(__u32 *ptr, struct tcp_opt *tp, __u32 tstamp) { if (tp->tstamp_ok) { *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); *ptr++ = htonl(tstamp); *ptr++ = htonl(tp->ts_recent); } if(tp->sack_ok && tp->num_sacks) { int this_sack; *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | (TCPOPT_SACK << 8) | (TCPOLEN_SACK_BASE + (tp->num_sacks * TCPOLEN_SACK_PERBLOCK))); for(this_sack = 0; this_sack < tp->num_sacks; this_sack++) { *ptr++ = htonl(tp->selective_acks[this_sack].start_seq); *ptr++ = htonl(tp->selective_acks[this_sack].end_seq); } } } /* Construct a tcp options header for a SYN or SYN_ACK packet. * If this is every changed make sure to change the definition of * MAX_SYN_SIZE to match the new maximum number of options that you * can generate. */ static __inline__ void tcp_syn_build_options(__u32 *ptr, int mss, int ts, int sack, int offer_wscale, int wscale, __u32 tstamp, __u32 ts_recent) { /* We always get an MSS option. * The option bytes which will be seen in normal data * packets should timestamps be used, must be in the MSS * advertised. But we subtract them from sk->mss so * that calculations in tcp_sendmsg are simpler etc. * So account for this fact here if necessary. If we * don't do this correctly, as a receiver we won't * recognize data packets as being full sized when we * should, and thus we won't abide by the delayed ACK * rules correctly. * SACKs don't matter, we never delay an ACK when we * have any of those going out. */ *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss); if (ts) { if(sack) *ptr++ = __constant_htonl((TCPOPT_SACK_PERM << 24) | (TCPOLEN_SACK_PERM << 16) | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); else *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP); *ptr++ = htonl(tstamp); /* TSVAL */ *ptr++ = htonl(ts_recent); /* TSECR */ } else if(sack) *ptr++ = __constant_htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | (TCPOPT_SACK_PERM << 8) | TCPOLEN_SACK_PERM); if (offer_wscale) *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_WINDOW << 16) | (TCPOLEN_WINDOW << 8) | (wscale)); } /* Determine a window scaling and initial window to offer. * Based on the assumption that the given amount of space * will be offered. Store the results in the tp structure. * NOTE: for smooth operation initial space offering should * be a multiple of mss if possible. We assume here that mss >= 1. * This MUST be enforced by all callers. */ static __inline__ void tcp_select_initial_window(__u32 space, __u16 mss, __u32 *rcv_wnd, __u32 *window_clamp, int wscale_ok, __u8 *rcv_wscale) { /* If no clamp set the clamp to the max possible scaled window */ if (*window_clamp == 0) (*window_clamp) = (65535<<14); space = min(*window_clamp,space); /* Quantize space offering to a multiple of mss if possible. */ if (space > mss) space = (space/mss)*mss; /* NOTE: offering an initial window larger than 32767 * will break some buggy TCP stacks. We try to be nice. * If we are not window scaling, then this truncates * our initial window offering to 32k. There should also * be a sysctl option to stop being nice. */ (*rcv_wnd) = min(space, MAX_WINDOW); (*rcv_wscale) = 0; if (wscale_ok) { /* See RFC1323 for an explanation of the limit to 14 */ while (space > 65535 && (*rcv_wscale) < 14) { space >>= 1; (*rcv_wscale)++; } } /* Set the clamp no higher than max representable value */ (*window_clamp) = min(65535<<(*rcv_wscale),*window_clamp); } static __inline__ void tcp_synq_unlink(struct tcp_opt *tp, struct open_request *req, struct open_request *prev) { if(!req->dl_next) tp->syn_wait_last = (struct open_request **)prev; prev->dl_next = req->dl_next; } static __inline__ void tcp_synq_queue(struct tcp_opt *tp, struct open_request *req) { req->dl_next = NULL; *tp->syn_wait_last = req; tp->syn_wait_last = &req->dl_next; } static __inline__ void tcp_synq_init(struct tcp_opt *tp) { tp->syn_wait_queue = NULL; tp->syn_wait_last = &tp->syn_wait_queue; } extern void __tcp_inc_slow_timer(struct tcp_sl_timer *slt); static __inline__ void tcp_inc_slow_timer(int timer) { struct tcp_sl_timer *slt = &tcp_slt_array[timer]; if (atomic_read(&slt->count) == 0) { __tcp_inc_slow_timer(slt); } atomic_inc(&slt->count); } static __inline__ void tcp_dec_slow_timer(int timer) { struct tcp_sl_timer *slt = &tcp_slt_array[timer]; atomic_dec(&slt->count); } extern const char timer_bug_msg[]; static inline void tcp_clear_xmit_timer(struct sock *sk, int what) { struct tcp_opt *tp = &sk->tp_pinfo.af_tcp; struct timer_list *timer; switch (what) { case TIME_RETRANS: timer = &tp->retransmit_timer; break; case TIME_DACK: timer = &tp->delack_timer; break; case TIME_PROBE0: timer = &tp->probe_timer; break; default: printk("%s", timer_bug_msg); return; }; if(timer->prev != NULL) del_timer(timer); } static inline int tcp_timer_is_set(struct sock *sk, int what) { struct tcp_opt *tp = &sk->tp_pinfo.af_tcp; switch (what) { case TIME_RETRANS: return tp->retransmit_timer.prev != NULL; break; case TIME_DACK: return tp->delack_timer.prev != NULL; break; case TIME_PROBE0: return tp->probe_timer.prev != NULL; break; default: printk("%s", timer_bug_msg); }; return 0; } #endif /* _TCP_H */