Commit | Line | Data |
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bc8e4818 | 1 | /* tcp_output.c 4.39 82/06/06 */ |
76ee76df BJ |
2 | |
3 | #include "../h/param.h" | |
4 | #include "../h/systm.h" | |
5 | #include "../h/mbuf.h" | |
405c9168 | 6 | #include "../h/protosw.h" |
76ee76df | 7 | #include "../h/socket.h" |
d52566dd | 8 | #include "../h/socketvar.h" |
0974b45c | 9 | #include "../net/in.h" |
c124e997 | 10 | #include "../net/route.h" |
0974b45c BJ |
11 | #include "../net/in_pcb.h" |
12 | #include "../net/in_systm.h" | |
d52566dd | 13 | #include "../net/ip.h" |
eb44bfb2 | 14 | #include "../net/ip_var.h" |
d52566dd | 15 | #include "../net/tcp.h" |
0974b45c | 16 | #define TCPOUTFLAGS |
d52566dd | 17 | #include "../net/tcp_fsm.h" |
0974b45c BJ |
18 | #include "../net/tcp_seq.h" |
19 | #include "../net/tcp_timer.h" | |
20 | #include "../net/tcp_var.h" | |
21 | #include "../net/tcpip.h" | |
f1dd32da | 22 | #include "../net/tcp_debug.h" |
8a2f82db | 23 | #include <errno.h> |
76ee76df | 24 | |
4aed14e3 | 25 | char *tcpstates[]; /* XXX */ |
8b5a83bb BJ |
26 | |
27 | /* | |
28 | * Initial options: indicate max segment length 1/2 of space | |
29 | * allocated for receive; if TCPTRUEOOB is defined, indicate | |
30 | * willingness to do true out-of-band. | |
31 | */ | |
32 | #ifndef TCPTRUEOOB | |
33 | u_char tcp_initopt[4] = { TCPOPT_MAXSEG, 4, 0x0, 0x0, }; | |
34 | #else | |
35 | u_char tcp_initopt[6] = { TCPOPT_MAXSEG, 4, 0x0, 0x0, TCPOPT_WILLOOB, 2 }; | |
36 | #endif | |
37 | ||
ea727f86 | 38 | /* |
4aed14e3 | 39 | * Tcp output routine: figure out what should be sent and send it. |
ea727f86 | 40 | */ |
a6503abf | 41 | tcp_output(tp) |
53a5409e | 42 | register struct tcpcb *tp; |
ea727f86 | 43 | { |
53a5409e | 44 | register struct socket *so = tp->t_inpcb->inp_socket; |
a6503abf BJ |
45 | register int len; |
46 | struct mbuf *m0; | |
8a2f82db | 47 | int off, flags, win, error; |
a6503abf BJ |
48 | register struct mbuf *m; |
49 | register struct tcpiphdr *ti; | |
8b5a83bb BJ |
50 | u_char *opt; |
51 | unsigned optlen = 0; | |
76ee76df | 52 | |
a6503abf | 53 | COUNT(TCP_OUTPUT); |
76ee76df | 54 | |
a6503abf | 55 | /* |
8ae6c089 | 56 | * Determine length of data that should be transmitted, |
0974b45c BJ |
57 | * and flags that will be used. |
58 | * If there is some data or critical controls (SYN, RST) | |
59 | * to send, then transmit; otherwise, investigate further. | |
a6503abf BJ |
60 | */ |
61 | off = tp->snd_nxt - tp->snd_una; | |
405c9168 | 62 | len = MIN(so->so_snd.sb_cc, tp->snd_wnd+tp->t_force) - off; |
3232ef09 | 63 | if (len < 0) |
8a2f82db | 64 | return (0); /* ??? */ /* past FIN */ |
0974b45c BJ |
65 | if (len > tp->t_maxseg) |
66 | len = tp->t_maxseg; | |
8ae6c089 | 67 | |
0974b45c | 68 | flags = tcp_outflags[tp->t_state]; |
275e05b7 | 69 | if (tp->snd_nxt + len < tp->snd_una + so->so_snd.sb_cc) |
405c9168 | 70 | flags &= ~TH_FIN; |
8ae6c089 BJ |
71 | if (flags & (TH_SYN|TH_RST|TH_FIN)) |
72 | goto send; | |
73 | if (SEQ_GT(tp->snd_up, tp->snd_una)) | |
a6503abf BJ |
74 | goto send; |
75 | ||
8ae6c089 BJ |
76 | /* |
77 | * Sender silly window avoidance. If can send all data, | |
78 | * a maximum segment, at least 1/4 of window do it, | |
79 | * or are forced, do it; otherwise don't bother. | |
80 | */ | |
81 | if (len) { | |
82 | if (len == tp->t_maxseg || off+len >= so->so_snd.sb_cc) | |
83 | goto send; | |
84 | if (len * 4 >= tp->snd_wnd) /* a lot */ | |
85 | goto send; | |
86 | if (tp->t_force) | |
87 | goto send; | |
88 | } | |
89 | ||
a6503abf | 90 | /* |
3232ef09 | 91 | * Send if we owe peer an ACK. |
a6503abf | 92 | */ |
8b5a83bb BJ |
93 | if (tp->t_flags&TF_ACKNOW) |
94 | goto send; | |
95 | ||
96 | #ifdef TCPTRUEOOB | |
97 | /* | |
98 | * Send if an out of band data or ack should be transmitted. | |
99 | */ | |
100 | if (tp->t_oobflags&(TCPOOB_OWEACK|TCPOOB_NEEDACK))) | |
a6503abf | 101 | goto send; |
8b5a83bb | 102 | #endif |
76ee76df | 103 | |
a6503abf BJ |
104 | /* |
105 | * Calculate available window in i, and also amount | |
106 | * of window known to peer (as advertised window less | |
107 | * next expected input.) If this is 35% or more of the | |
108 | * maximum possible window, then want to send a segment to peer. | |
109 | */ | |
0974b45c BJ |
110 | win = sbspace(&so->so_rcv); |
111 | if (win > 0 && | |
112 | ((100*(win-(tp->rcv_adv-tp->rcv_nxt))/so->so_rcv.sb_hiwat) >= 35)) | |
a6503abf BJ |
113 | goto send; |
114 | ||
115 | /* | |
116 | * No reason to send a segment, just return. | |
117 | */ | |
f1b2fa5b | 118 | return (0); |
a6503abf BJ |
119 | |
120 | send: | |
121 | /* | |
122 | * Grab a header mbuf, attaching a copy of data to | |
123 | * be transmitted, and initialize the header from | |
124 | * the template for sends on this connection. | |
125 | */ | |
76ee76df BJ |
126 | MGET(m, 0); |
127 | if (m == 0) | |
8a2f82db | 128 | return (ENOBUFS); |
4aed14e3 | 129 | m->m_off = MMAXOFF - sizeof (struct tcpiphdr); |
53a5409e | 130 | m->m_len = sizeof (struct tcpiphdr); |
a6503abf BJ |
131 | if (len) { |
132 | m->m_next = m_copy(so->so_snd.sb_mb, off, len); | |
133 | if (m->m_next == 0) | |
134 | len = 0; | |
135 | } | |
136 | ti = mtod(m, struct tcpiphdr *); | |
137 | if (tp->t_template == 0) | |
138 | panic("tcp_output"); | |
f1b2fa5b | 139 | bcopy((caddr_t)tp->t_template, (caddr_t)ti, sizeof (struct tcpiphdr)); |
a6503abf BJ |
140 | |
141 | /* | |
142 | * Fill in fields, remembering maximum advertised | |
143 | * window for use in delaying messages about window sizes. | |
144 | */ | |
4aed14e3 BJ |
145 | ti->ti_seq = tp->snd_nxt; |
146 | ti->ti_ack = tp->rcv_nxt; | |
147 | #if vax | |
148 | ti->ti_seq = htonl(ti->ti_seq); | |
149 | ti->ti_ack = htonl(ti->ti_ack); | |
150 | #endif | |
8b5a83bb BJ |
151 | /* |
152 | * Before ESTABLISHED, force sending of initial options | |
153 | * unless TCP set to not do any options. | |
154 | */ | |
155 | if (tp->t_state < TCPS_ESTABLISHED) { | |
156 | if (tp->t_flags&TF_NOOPT) | |
157 | goto noopt; | |
158 | opt = tcp_initopt; | |
159 | optlen = sizeof (tcp_initopt); | |
160 | *(u_short *)(opt + 2) = so->so_rcv.sb_hiwat / 2; | |
161 | #if vax | |
162 | *(u_short *)(opt + 2) = htons(*(u_short *)(opt + 2)); | |
163 | #endif | |
164 | } else { | |
165 | if (tp->t_tcpopt == 0) | |
166 | goto noopt; | |
167 | opt = mtod(tp->t_tcpopt, u_char *); | |
168 | optlen = tp->t_tcpopt->m_len; | |
169 | } | |
170 | #ifndef TCPTRUEOOB | |
171 | if (opt) | |
172 | #else | |
173 | if (opt || (tp->t_oobflags&(TCPOOB_OWEACK|TCPOOB_NEEDACK))) | |
174 | #endif | |
175 | { | |
f1b2fa5b | 176 | m0 = m->m_next; |
ef9b4258 | 177 | m->m_next = m_get(M_DONTWAIT); |
0974b45c BJ |
178 | if (m->m_next == 0) { |
179 | (void) m_free(m); | |
8b5a83bb | 180 | m_freem(m0); |
8a2f82db | 181 | return (ENOBUFS); |
0974b45c BJ |
182 | } |
183 | m->m_next->m_next = m0; | |
8b5a83bb BJ |
184 | m0 = m->m_next; |
185 | m0->m_off = MMINOFF; | |
186 | m0->m_len = optlen; | |
668cc26d | 187 | bcopy((caddr_t)opt, mtod(m0, caddr_t), optlen); |
8b5a83bb BJ |
188 | opt = (u_char *)(mtod(m0, caddr_t) + optlen); |
189 | #ifdef TCPTRUEOOB | |
190 | if (tp->t_oobflags&TCPOOB_OWEACK) { | |
191 | printf("tp %x send OOBACK for %x\n", tp->t_iobseq); | |
192 | *opt++ = TCPOPT_OOBACK; | |
193 | *opt++ = 3; | |
194 | *opt++ = tp->t_iobseq; | |
195 | m0->m_len += 3; | |
196 | tp->t_oobflags &= ~TCPOOB_OWEACK; | |
197 | /* sender should rexmt oob to force ack repeat */ | |
198 | } | |
199 | if (tp->t_oobflags&TCPOOB_NEEDACK) { | |
200 | printf("tp %x send OOBDATA seq %x data %x\n", tp->t_oobseq, tp->t_oobc); | |
201 | *opt++ = TCPOPT_OOBDATA; | |
b2db9217 | 202 | *opt++ = 8; |
8b5a83bb BJ |
203 | *opt++ = tp->t_oobseq; |
204 | *opt++ = tp->t_oobc; | |
b2db9217 BJ |
205 | *(tcp_seq *)opt = tp->t_oobmark - tp->snd_nxt; |
206 | #ifdef vax | |
207 | *(tcp_seq *)opt = htonl((unsigned)*(tcp_seq *)opt); | |
208 | #endif | |
209 | m0->m_len += 8; | |
8b5a83bb BJ |
210 | TCPT_RANGESET(tp->t_timer[TCPT_OOBREXMT], |
211 | tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); | |
212 | } | |
213 | #endif | |
214 | while (m0->m_len & 0x3) { | |
215 | *opt++ = TCPOPT_EOL; | |
216 | m0->m_len++; | |
217 | } | |
218 | optlen = m0->m_len; | |
219 | ti->ti_off = (sizeof (struct tcphdr) + optlen) >> 2; | |
0974b45c | 220 | } |
8b5a83bb | 221 | noopt: |
0974b45c | 222 | ti->ti_flags = flags; |
a6503abf | 223 | win = sbspace(&so->so_rcv); |
8ae6c089 BJ |
224 | if (win < so->so_rcv.sb_hiwat / 4) /* avoid silly window */ |
225 | win = 0; | |
a6503abf | 226 | if (win > 0) |
8ae6c089 | 227 | #if vax |
f1b2fa5b | 228 | ti->ti_win = htons((u_short)win); |
8ae6c089 BJ |
229 | #else |
230 | ti->ti_win = win; | |
231 | #endif | |
0974b45c | 232 | if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { |
5e74df82 BJ |
233 | ti->ti_urp = tp->snd_up - tp->snd_nxt; |
234 | #if vax | |
235 | ti->ti_urp = htons(ti->ti_urp); | |
236 | #endif | |
a6503abf BJ |
237 | ti->ti_flags |= TH_URG; |
238 | } else | |
239 | /* | |
240 | * If no urgent pointer to send, then we pull | |
241 | * the urgent pointer to the left edge of the send window | |
242 | * so that it doesn't drift into the send window on sequence | |
243 | * number wraparound. | |
244 | */ | |
0974b45c BJ |
245 | tp->snd_up = tp->snd_una; /* drag it along */ |
246 | /* PUSH */ | |
a6503abf BJ |
247 | |
248 | /* | |
249 | * Put TCP length in extended header, and then | |
250 | * checksum extended header and data. | |
251 | */ | |
8b5a83bb BJ |
252 | if (len + optlen) { |
253 | ti->ti_len = sizeof (struct tcphdr) + optlen + len; | |
254 | #if vax | |
255 | ti->ti_len = htons((u_short)ti->ti_len); | |
256 | #endif | |
257 | } | |
668cc26d | 258 | ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + (int)optlen + len); |
0974b45c BJ |
259 | |
260 | /* | |
261 | * Advance snd_nxt over sequence space of this segment | |
262 | */ | |
263 | if (flags & (TH_SYN|TH_FIN)) | |
4aed14e3 | 264 | tp->snd_nxt++; |
0974b45c BJ |
265 | tp->snd_nxt += len; |
266 | ||
267 | /* | |
405c9168 | 268 | * If this transmission closes the window, |
4aed14e3 BJ |
269 | * start persistance timer at 2 round trip times |
270 | * but at least TCPTV_PERSMIN ticks. | |
0974b45c | 271 | */ |
89413846 | 272 | if (TCPS_HAVERCVDSYN(tp->t_state) && |
275e05b7 | 273 | SEQ_GEQ(tp->snd_nxt, tp->snd_una+tp->snd_wnd) && |
4aed14e3 BJ |
274 | tp->t_timer[TCPT_PERSIST] == 0) |
275 | TCPT_RANGESET(tp->t_timer[TCPT_PERSIST], | |
276 | 2 * tp->t_srtt, TCPTV_PERSMIN, TCPTV_MAX); | |
405c9168 BJ |
277 | |
278 | /* | |
279 | * Time this transmission if not a retransmission and | |
280 | * not currently timing anything. | |
281 | */ | |
282 | if (SEQ_GT(tp->snd_nxt, tp->snd_max) && tp->t_rtt == 0) { | |
283 | tp->t_rtt = 1; | |
284 | tp->t_rtseq = tp->snd_nxt - len; | |
285 | } | |
286 | ||
287 | /* | |
288 | * Set retransmit timer if not currently set. | |
4aed14e3 | 289 | * Initial value for retransmit timer to tcp_beta*tp->t_srtt. |
405c9168 BJ |
290 | * Initialize shift counter which is used for exponential |
291 | * backoff of retransmit time. | |
292 | */ | |
4aed14e3 BJ |
293 | if (tp->t_timer[TCPT_REXMT] == 0 && tp->snd_nxt != tp->snd_una) { |
294 | TCPT_RANGESET(tp->t_timer[TCPT_REXMT], | |
295 | tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); | |
275e05b7 | 296 | tp->t_rtt = 0; |
405c9168 | 297 | tp->t_rxtshift = 0; |
0974b45c | 298 | } |
a6503abf | 299 | |
f1dd32da BJ |
300 | /* |
301 | * Trace. | |
302 | */ | |
303 | if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG) | |
304 | tcp_trace(TA_OUTPUT, tp->t_state, tp, ti, 0); | |
305 | ||
a6503abf BJ |
306 | /* |
307 | * Fill in IP length and desired time to live and | |
308 | * send to IP level. | |
309 | */ | |
8b5a83bb | 310 | ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + optlen + len; |
a6503abf | 311 | ((struct ip *)ti)->ip_ttl = TCP_TTL; |
8a2f82db SL |
312 | if (error = ip_output(m, tp->t_ipopt, &tp->t_inpcb->inp_route, 0)) |
313 | return (error); | |
a6503abf BJ |
314 | |
315 | /* | |
316 | * Data sent (as far as we can tell). | |
317 | * If this advertises a larger window than any other segment, | |
4aed14e3 | 318 | * then remember the size of the advertised window. |
0974b45c | 319 | * Drop send for purpose of ACK requirements. |
a6503abf | 320 | */ |
be43ac7f | 321 | if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) |
a6503abf | 322 | tp->rcv_adv = tp->rcv_nxt + win; |
0974b45c | 323 | tp->t_flags &= ~(TF_ACKNOW|TF_DELACK); |
4aed14e3 BJ |
324 | if (SEQ_GT(tp->snd_nxt, tp->snd_max)) |
325 | tp->snd_max = tp->snd_nxt; | |
8a2f82db | 326 | return (0); |
76ee76df | 327 | } |