/********************************************************************** * Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. * * All Rights Reserved. * * Reference "/usr/src/COPYRIGHT" for applicable restrictions. * **********************************************************************/ /* * Copyright (c) 1982 Regents of the University of California. * All rights reserved. The Berkeley software License Agreement * specifies the terms and conditions for redistribution. * * SCCSID: @(#)tcp_subr.c 3.0 (ULTRIX-11) 4/21/86 * @(#)tcp_subr.c 6.6 (Berkeley) 6/8/85 */ #include <sys/param.h> #include <sys/systm.h> #include <sys/mbuf.h> #include <sys/socket.h> #include <sys/socketvar.h> #include <sys/protosw.h> #include <errno.h> #include <net/route.h> #include <net/if.h> #include <netinet/in.h> #include <netinet/in_pcb.h> #include <netinet/in_systm.h> #include <netinet/ip.h> #include <netinet/ip_var.h> #include <netinet/ip_icmp.h> #include <netinet/tcp.h> #include <netinet/tcp_fsm.h> #include <netinet/tcp_seq.h> #include <netinet/tcp_timer.h> #include <netinet/tcp_var.h> #include <netinet/tcpip.h> /* * Tcp initialization */ tcp_init() { tcp_iss = 1; /* wrong */ tcb.inp_next = tcb.inp_prev = &tcb; tcp_alpha = TCP_ALPHA; tcp_beta = TCP_BETA; } /* * Create template to be used to send tcp packets on a connection. * Call after host entry created, allocates an mbuf and fills * in a skeletal tcp/ip header, minimizing the amount of work * necessary when the connection is used. */ struct tcpiphdr * tcp_template(tp) struct tcpcb *tp; { register struct inpcb *inp = tp->t_inpcb; #ifdef vax register struct mbuf *m; #endif vax register struct tcpiphdr *n; #ifdef vax m = m_get(M_WAIT, MT_HEADER); if (m == NULL) return (0); m->m_off = MMAXOFF - sizeof (struct tcpiphdr); m->m_len = sizeof (struct tcpiphdr); n = mtod(m, struct tcpiphdr *); #else pdp11 MSGET(n, struct tcpiphdr, MT_HEADER, 1, M_DONTWAIT); if (n == NULL) return (0); #endif n->ti_next = n->ti_prev = 0; #ifdef pdp11 n->ti_pad = 0; #endif pdp11 n->ti_x1 = 0; n->ti_pr = IPPROTO_TCP; n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); n->ti_src = inp->inp_laddr; n->ti_dst = inp->inp_faddr; n->ti_sport = inp->inp_lport; n->ti_dport = inp->inp_fport; n->ti_seq = 0; n->ti_ack = 0; n->ti_x2 = 0; n->ti_off = 5; n->ti_flags = 0; n->ti_win = 0; n->ti_sum = 0; n->ti_urp = 0; return (n); } /* * Send a single message to the TCP at address specified by * the given TCP/IP header. If flags==0, then we make a copy * of the tcpiphdr at ti and send directly to the addressed host. * This is used to force keep alive messages out using the TCP * template for a connection tp->t_template. If flags are given * then we send a message back to the TCP which originated the * segment ti, and discard the mbuf containing it and any other * attached mbufs. * * In any case the ack and sequence number of the transmitted * segment are as specified by the parameters. */ tcp_respond(tp, ti, ack, seq, flags) struct tcpcb *tp; register struct tcpiphdr *ti; tcp_seq ack, seq; int flags; { struct mbuf *m; int win = 0, tlen; struct route *ro = 0; if (tp) { win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); ro = &tp->t_inpcb->inp_route; } if (flags == 0) { m = m_get(M_DONTWAIT, MT_HEADER); if (m == NULL) return; m->m_len = sizeof (struct tcpiphdr) + 1; *mtod(m, struct tcpiphdr *) = *ti; ti = mtod(m, struct tcpiphdr *); flags = TH_ACK; tlen = 1; } else { m = dtom(ti); m_freem(m->m_next); m->m_next = 0; #ifndef pdp11 m->m_off = (int)ti - (int)m; #else pdp11 m->m_off = (caddr_t)ti - (caddr_t)MBX; #endif pdp11 m->m_len = sizeof (struct tcpiphdr); #define xchg(a,b,type) { type t; t=a; a=b; b=t; } xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); xchg(ti->ti_dport, ti->ti_sport, u_short); #undef xchg tlen = 0; } ti->ti_next = ti->ti_prev = 0; #ifdef pdp11 ti->ti_pad = 0; #endif pdp11 ti->ti_x1 = 0; ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); ti->ti_seq = htonl(seq); ti->ti_ack = htonl(ack); ti->ti_x2 = 0; ti->ti_off = sizeof (struct tcphdr) >> 2; ti->ti_flags = flags; ti->ti_win = htons((u_short)win); ti->ti_urp = 0; #ifdef TCPLOOPBACK if (ti->ti_src.s_addr == ti->ti_dst.s_addr) { /* Fake IP transit and get to TCP layer fast */ ((struct ip *)ti)->ip_hl = sizeof (struct ip) >> 2; ((struct ip *)ti)->ip_len = sizeof (struct tcphdr) + tlen; tcp_input(m); } else { #endif TCPLOOPBACK ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + tlen); ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + tlen; ((struct ip *)ti)->ip_ttl = TCP_TTL; (void) ip_output(m, (struct mbuf *)0, ro, 0); #ifdef TCPLOOPBACK } #endif TCPLOOPBACK } /* * Create a new TCP control block, making an * empty reassembly queue and hooking it to the argument * protocol control block. */ struct tcpcb * tcp_newtcpcb(inp) struct inpcb *inp; { #ifdef vax struct mbuf *m = m_getclr(M_DONTWAIT, MT_PCB); #endif vax register struct tcpcb *tp; #ifdef vax if (m == NULL) return ((struct tcpcb *)0); tp = mtod(m, struct tcpcb *); #else pdp11 MSGET(tp, struct tcpcb, MT_PCB, 1, M_DONTWAIT); if (tp == NULL) return ((struct tcpcb *)0); #endif tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; tp->t_maxseg = TCP_MSS; tp->t_flags = 0; /* sends options! */ tp->t_inpcb = inp; tp->t_srtt = TCPTV_SRTTBASE; tp->snd_cwnd = sbspace(&inp->inp_socket->so_snd); inp->inp_ppcb = (caddr_t)tp; return (tp); } /* * Drop a TCP connection, reporting * the specified error. If connection is synchronized, * then send a RST to peer. */ struct tcpcb * tcp_drop(tp, errno) register struct tcpcb *tp; int errno; { struct socket *so = tp->t_inpcb->inp_socket; if (TCPS_HAVERCVDSYN(tp->t_state)) { tp->t_state = TCPS_CLOSED; (void) tcp_output(tp); } so->so_error = errno; return (tcp_close(tp)); } tcp_abort(inp) struct inpcb *inp; { (void) tcp_close((struct tcpcb *)inp->inp_ppcb); } #ifdef pdp11 #define ti_mbuf ti_sum #define DTOM(d) ((struct mbuf *)((d)->ti_mbuf)) #endif pdp11 /* * Close a TCP control block: * discard all space held by the tcp * discard internet protocol block * wake up any sleepers */ struct tcpcb * tcp_close(tp) register struct tcpcb *tp; { register struct tcpiphdr *t; struct inpcb *inp = tp->t_inpcb; struct socket *so = inp->inp_socket; #ifndef pdp11 register struct mbuf *m; #else pdp11 register struct tcpiphdr *to; #endif pdp11 t = tp->seg_next; while (t != (struct tcpiphdr *)tp) { #ifdef pdp11 to = t; t = (struct tcpiphdr *)t->ti_next; remque(to); m_freem(DTOM(to)); MSFREE(to); #else t = (struct tcpiphdr *)t->ti_next; m = dtom(t->ti_prev); remque(t->ti_prev); m_freem(m); #endif pdp11 } if (tp->t_template) #ifdef vax (void) m_free(dtom(tp->t_template)); #else pdp11 MSFREE(tp->t_template); #endif if (tp->t_tcpopt) (void) m_free(dtom(tp->t_tcpopt)); if (tp->t_ipopt) (void) m_free(dtom(tp->t_ipopt)); #ifndef pdp11 (void) m_free(dtom(tp)); #else pdp11 MSFREE(tp); #endif pdp11 inp->inp_ppcb = 0; soisdisconnected(so); in_pcbdetach(inp); return ((struct tcpcb *)0); } tcp_drain() { } tcp_ctlinput(cmd, arg) int cmd; caddr_t arg; { struct in_addr *in; extern u_char inetctlerrmap[]; int tcp_quench(), in_rtchange(); if (cmd < 0 || cmd > PRC_NCMDS) return; switch (cmd) { case PRC_ROUTEDEAD: break; case PRC_QUENCH: in = &((struct icmp *)arg)->icmp_ip.ip_dst; in_pcbnotify(&tcb, in, 0, tcp_quench); break; case PRC_REDIRECT_NET: case PRC_REDIRECT_HOST: in = &((struct icmp *)arg)->icmp_ip.ip_dst; in_pcbnotify(&tcb, in, 0, in_rtchange); break; case PRC_IFDOWN: in = &((struct sockaddr_in *)arg)->sin_addr; goto notify; case PRC_HOSTDEAD: case PRC_HOSTUNREACH: in = (struct in_addr *)arg; goto notify; default: if (inetctlerrmap[cmd] == 0) return; /* XXX */ in = &((struct icmp *)arg)->icmp_ip.ip_dst; notify: in_pcbnotify(&tcb, in, (int)inetctlerrmap[cmd], tcp_abort); } } /* * When a source quench is received, close congestion window * to 80% of the outstanding data (but not less than one segment). */ tcp_quench(inp) struct inpcb *inp; { struct tcpcb *tp = intotcpcb(inp); #ifdef vax tp->snd_cwnd = MAX(8 * (tp->snd_nxt - tp->snd_una) / 10, tp->t_maxseg); #else pdp11 register unsigned x1; x1 = (tp->snd_nxt - tp->snd_una)/10; /* make sure x1 not 0 -- Fred 2/20/86 */ if(x1 == 0) x1++; x1 *= 8; tp->snd_cwnd = MAX(x1, tp->t_maxseg); #endif }