/* * 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 #define MAX_SYN_SIZE 44 + MAX_HEADER + 15 #define MAX_FIN_SIZE 40 + MAX_HEADER + 15 #define MAX_ACK_SIZE 40 + MAX_HEADER + 15 #define MAX_RESET_SIZE 40 + MAX_HEADER + 15 #define MAX_WINDOW 32767 /* Never offer a window over 32767 without using window scaling (not yet supported). Some poor stacks do signed 16bit maths! */ #define MIN_WINDOW 2048 #define MAX_ACK_BACKLOG 2 #define MIN_WRITE_SPACE 2048 #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_NO_CHECK 0 /* turn to one if you want the default * to be no checksum */ /* * TCP option */ #define TCPOPT_NOP 1 /* Padding */ #define TCPOPT_EOL 0 /* End of options */ #define TCPOPT_MSS 2 /* Segment size negotiating */ /* * We don't use these yet, but they are for PAWS and big windows */ #define TCPOPT_WINDOW 3 /* Window scaling */ #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ /* * The next routines deal with comparing 32 bit unsigned ints * and worry about wraparound (automatic with unsigned arithmetic). */ extern __inline int before(__u32 seq1, __u32 seq2) { return (__s32)(seq1-seq2) < 0; } extern __inline int after(__u32 seq1, __u32 seq2) { return (__s32)(seq2-seq1) < 0; } /* is s2<=s1<=s3 ? */ extern __inline int between(__u32 seq1, __u32 seq2, __u32 seq3) { return (after(seq1+1, seq2) && before(seq1, seq3+1)); } static __inline__ int min(unsigned int a, unsigned int b) { if (a < b) return(a); return(b); } extern struct proto tcp_prot; extern struct tcp_mib tcp_statistics; extern struct wait_queue *master_select_wakeup; extern void tcp_err(int type, int code, unsigned char *header, __u32 daddr, __u32, struct inet_protocol *protocol); extern void tcp_shutdown (struct sock *sk, int how); extern int tcp_rcv(struct sk_buff *skb, struct device *dev, struct options *opt, __u32 daddr, unsigned short len, __u32 saddr, int redo, struct inet_protocol *protocol); extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); extern void tcp_read_wakeup(struct sock *); extern void tcp_write_xmit(struct sock *); extern void tcp_time_wait(struct sock *); extern void tcp_retransmit(struct sock *, int); extern void tcp_do_retransmit(struct sock *, int); extern void tcp_send_check(struct tcphdr *th, unsigned long saddr, unsigned long daddr, int len, struct sk_buff *skb); /* tcp_output.c */ 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_synack(struct sock *, struct sock *, struct sk_buff *); extern void tcp_send_skb(struct sock *, struct sk_buff *); extern void tcp_send_ack(u32, u32, struct sock *sk, struct tcphdr *th, u32); extern void tcp_send_reset(unsigned long saddr, unsigned long daddr, struct tcphdr *th, struct proto *prot, struct options *opt, struct device *dev, int tos, int ttl); extern void tcp_enqueue_partial(struct sk_buff *, struct sock *); extern struct sk_buff * tcp_dequeue_partial(struct sock *); /* tcp_input.c */ extern void tcp_cache_zap(void); /* tcp_timer.c */ #define tcp_reset_msl_timer(x,y,z) reset_timer(x,y,z) extern void tcp_reset_xmit_timer(struct sock *, int, unsigned long); extern void tcp_retransmit_timer(unsigned long); /* * Default sequence number picking algorithm. * As close as possible to RFC 793, which * suggests using a 250kHz clock. * Further reading shows this assumes 2MB/s networks. * For 10MB/s ethernet, a 1MHz clock is appropriate. * That's funny, Linux has one built in! Use it! */ static inline u32 tcp_init_seq(void) { struct timeval tv; do_gettimeofday(&tv); return tv.tv_usec+tv.tv_sec*1000000; } /* * This function returns the amount that we can raise the * usable window based on the following constraints * * 1. The window can never be shrunk once it is offered (RFC 793) * 2. We limit memory per socket */ static __inline__ unsigned short tcp_raise_window(struct sock *sk) { long free_space = sock_rspace(sk); long window; if (free_space > 1024) free_space &= ~0x3FF; /* make free space a multiple of 1024 */ if(sk->window_clamp) free_space = min(sk->window_clamp, free_space); /* * compute the actual window i.e. * old_window - received_bytes_on_that_win */ window = sk->window - (sk->acked_seq - sk->lastwin_seq); if (sk->mss == 0) sk->mss = sk->mtu; if ( window < 0 ) { window = 0; printk(KERN_DEBUG "TRW: win < 0 w=%d 1=%u 2=%u\n", sk->window, sk->acked_seq, sk->lastwin_seq); } if ( (free_space - window) >= min(sk->mss, MAX_WINDOW/2) ) return ((free_space - window) / sk->mss) * sk->mss; return 0; } static __inline__ unsigned short tcp_select_window(struct sock *sk) { long free_space = sock_rspace(sk); long window; if (free_space > 1024) free_space &= ~0x3FF; /* make free space a multiple of 1024 */ if (sk->window_clamp) free_space = min(sk->window_clamp, free_space); /* * compute the actual window i.e. * old_window - received_bytes_on_that_win */ if (sk->mss == 0) sk->mss = sk->mtu; window = sk->window - (sk->acked_seq - sk->lastwin_seq); if ( window < 0 ) { window = 0; printk(KERN_DEBUG "TSW: win < 0 w=%d 1=%u 2=%u\n", sk->window, sk->acked_seq, sk->lastwin_seq); } /* * RFC 1122: * "the suggested [SWS] avoidance algoritm for the receiver is to keep * RECV.NEXT + RCV.WIN fixed until: * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" * * i.e. don't raise the right edge of the window until you can't raise * it MSS bytes */ if ( (free_space - window) >= min(sk->mss, MAX_WINDOW/2) ) window += ((free_space - window) / sk->mss) * sk->mss; sk->window = window; sk->lastwin_seq = sk->acked_seq; return sk->window; } /* * 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 */ extern __inline const int tcp_connected(const int state) { return(state == TCP_ESTABLISHED || state == TCP_CLOSE_WAIT || state == TCP_FIN_WAIT1 || state == TCP_FIN_WAIT2 || state == TCP_SYN_RECV); } /* * Calculate(/check) TCP checksum */ static __inline__ u16 tcp_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 if(sk->debug) printk("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++; /* This is a hack but it doesn't occur often and it's going to be a real to fix nicely */ if (oldstate == TCP_SYN_RECV) wake_up_interruptible(&master_select_wakeup); } break; case TCP_CLOSE: tcp_cache_zap(); /* Should be about 2 rtt's */ reset_timer(sk, TIME_DONE, min(sk->rtt * 2, TCP_DONE_TIME)); /* fall through */ default: if (oldstate==TCP_ESTABLISHED) tcp_statistics.TcpCurrEstab--; } } #endif /* _TCP_H */