📄 tcp.lst
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363 5 {
364 6 index=j;
C51 COMPILER V8.02 TCP 09/21/2006 20:16:32 PAGE 7
365 6 // Initialize new connection
366 6 conxn[index].state=STATE_LISTEN;
367 6 conxn[index].socket_type=SERVER;
368 6 break;
369 6 }
370 5 }
371 4 //所有的连接都被占有，则丢弃该包
372 4 if (NO_CONNECTION==j) return;
373 4 }
374 3 else
375 3 return;
376 3 }
377 2 //保证程序不出错
378 2 if (index > NO_CONNECTION-1)
379 2 {
380 3 // if (debug) PrintStr("TCP: Error in assigning conxn number\r");
381 3 return;
382 3 }
383 2 //检查收到的包的序列号是否出错
384 2 if (pRxdnet->tcpframe.seqnumber > 0xFFFFFF00L)
385 2 {
386 3 // if (debug) PrintStr("TCP: Rcvd a high sequence number\r");
387 3 InerClose(index);
388 3 tcp_send(&TCPSend,FLG_RST, 20, NO_CONNECTION);
389 3 return;
390 3 }
391 2 if (pRxdnet->tcpframe.control & FLG_RST)
392 2 {
393 3 // An RST does not depend on state at all. And it does
394 3 // not count as data so do not send an ACK here. Close
395 3 // connection
396 3 // if (debug) PrintStr("TCP: Rcvd a reset\r");
397 3 InerClose(index);
398 3 return;
399 3 }
400 2 else if (pRxdnet->tcpframe.control & FLG_SYN)
401 2 {
402 3 //收到一个SYN+ACK包，则该包只有在STATE_SYN_SEND时才有效
403 3 //由Mingtree添加，以适应当单片机为客户端时的情况
404 3 if(pRxdnet->tcpframe.control & FLG_ACK)
405 3 {
406 4 if (conxn[index].state != STATE_SYN_SENT)
407 4 {
408 5 // if (debug) PrintStr("TCP: Error, rcvd bogus SYN AND ACK\r");
409 5 tcp_send(&TCPSend,FLG_RST, 20, NO_CONNECTION);
410 5 return;
411 5 }
412 4 }
413 3
414 3 // A SYN segment only makes sense if connection is in LISTEN
415 3 else if ((conxn[index].state != STATE_LISTEN) &&
416 3 (conxn[index].state != STATE_CLOSED))
417 3 {
418 4 // if (debug) PrintStr("TCP: Error, rcvd bogus SYN\r");
419 4 InerClose(index);
420 4 tcp_send(&TCPSend,FLG_RST, 20, NO_CONNECTION);
421 4 return;
422 4 }
423 3 }
424 2 else if ((pRxdnet->tcpframe.control & FLG_ACK) == 0)
425 2 {
426 3 // Incoming segments except SYN or RST must have ACK bit set
C51 COMPILER V8.02 TCP 09/21/2006 20:16:32 PAGE 8
427 3 // See TCP/IP Illustrated, Vol 2, Page 965
428 3 // Drop segment but do not send a reset
429 3 // if (debug) PrintStr("TCP: Error, rcvd segment has no ACK\r");
430 3 return;
431 3 }
432 2 // Compute length of header including options, and from that
433 2 // compute length of actual data
434 2 //计算头部长度，并计算实际长度
435 2 header_len=(pRxdnet->tcpframe.offset&0xF0)>>2;
436 2 data_len=pRxdnet->ipframe.totallength-((pRxdnet->ipframe.verandihl& 0x0F)*4)-header_len;
437 2 packACK = pRxdnet->tcpframe.acknumber;
438 2 packSeq = pRxdnet->tcpframe.seqnumber;
439 2 // Handle TCP state machine for this connection
440 2 switch (conxn[index].state)
441 2 {
442 3 case STATE_CLOSED:
443 3 case STATE_LISTEN:
444 3 // If incoming segment contains SYN and no ACK, then handle
445 3 if ((pRxdnet->tcpframe.control & FLG_SYN) && ((pRxdnet->tcpframe.control & FLG_ACK) == 0))
446 3 {
447 4 // Capture his starting sequence number and generate
448 4 // my starting sequence number
449 4 // Fill in connection information
450 4 conxn[index].ip.words[0]= pRxdnet->ipframe.sourceip[0];
451 4 conxn[index].ip.words[1]= pRxdnet->ipframe.sourceip[1];
452 4 conxn[index].port = pRxdnet->tcpframe.sourceport;
453 4 conxn[index].state = STATE_LISTEN;
454 4 conxn[index].his_sequence = 1 + packACK;
455 4 conxn[index].his_ack = packSeq;
456 4
457 4 // Use system clock for initial sequence number
458 4 EA = 0;
459 4 conxn[index].my_sequence = initial_sequence_nr;
460 4 initial_sequence_nr += 64000L;
461 4 EA = 1;
462 4
463 4 // Send header options with the next message
464 4 // Since timestamps are optional and we do not use
465 4 // them, do not have to send them
466 4 // After sending the SYN ACK the client browser will
467 4 // blast me with 2 messages, an ACK, and a HTTP GET
468 4 tcp_send(&TCPSend,FLG_SYN | FLG_ACK, 28, index);
469 4
470 4 // My SYN flag increments my sequence number
471 4 // My sequence number is always updated to point to
472 4 // the next byte to be sent. So the incoming ack
473 4 // number should equal my sequence number
474 4 conxn[index].my_sequence++;
475 4
476 4 conxn[index].state = STATE_SYN_RCVD;
477 4 // if (debug) PrintStr("TCP: Entered SYN RCVD state\r");
478 4 }
479 3 else
480 3 {
481 4 // Sender is out of sync so send reset
482 4 InerClose(index);
483 4 tcp_send(&TCPSend,FLG_RST, 20, NO_CONNECTION);
484 4 }
485 3 break;
486 3
487 3 case STATE_SYN_RCVD:
488 3 // He may already be sending me data - should process it
C51 COMPILER V8.02 TCP 09/21/2006 20:16:32 PAGE 9
489 3 conxn[index].his_sequence += data_len;
490 3 conxn[index].his_ack = packACK;
491 3
492 3 if (pRxdnet->tcpframe.control & FLG_FIN)
493 3 {
494 4 // His FIN counts as a byte of data
495 4 conxn[index].his_sequence++;
496 4 tcp_send(&TCPSend,FLG_ACK, 20, index);
497 4 conxn[index].state = STATE_CLOSE_WAIT;
498 4 // if (debug) PrintStr("TCP: Entered CLOSE_WAIT state\r");
499 4
500 4 // At this point we would normally wait for the application
501 4 // to close. For now, send FIN right away.
502 4 tcp_send(&TCPSend,FLG_FIN | FLG_ACK, 20, index);
503 4 conxn[index].my_sequence++; // For my FIN
504 4 conxn[index].state = STATE_LAST_ACK;
505 4 // if (debug) PrintStr("TCP: Entered LAST ACK state\r");
506 4 }
507 3
508 3 // Make sure he is ACKing my SYN
509 3 else if (packACK == conxn[index].my_sequence)
510 3 {
511 4 conxn[index].state = STATE_ESTABLISHED;
512 4 // if (debug) PrintStr("TCP: Entered ESTABLISHED state\r");
513 4 // If sender sent data ignore it and he will resend
514 4 // Do not send response because we received no
515 4
516 4 //--------------------------------------------------------
517 4 //
518 4 // 进入连接状态，可以发送数据
519 4 //
520 4 //--------------------------------------------------------
521 4 //调用服务器OnConnect()回调函数，该函数在TCPListen时被实体化
522 4 (* conxn[index].connect)();
523 4 }
524 3 break;
525 3 case STATE_ESTABLISHED:
526 3 conxn[index].his_ack = packACK;
527 3
528 3 if (pRxdnet->tcpframe.control & FLG_FIN)
529 3 {
530 4 // His FIN counts as a byte of data
531 4 conxn[index].his_sequence++;
532 4 tcp_send(&TCPSend,FLG_ACK, 20, index);
533 4 conxn[index].state = STATE_CLOSE_WAIT;
534 4 // if (debug) PrintStr("TCP: Entered CLOSE_WAIT state\r");
535 4
536 4 // At this point we would normally wait for the application
537 4 // to close. For now, send FIN immediately.
538 4 tcp_send(&TCPSend,FLG_FIN | FLG_ACK, 20, index);
539 4 conxn[index].my_sequence++; // For my FIN
540 4 conxn[index].state = STATE_LAST_ACK;
541 4 // if (debug) PrintStr("TCP: Entered LAST ACK state\r");
542 4 }
543 3 else if (data_len != 0)
544 3 {
545 4 //先判断对方的序列号是否小于conxn[index].his_sequence
546 4 if(packSeq < conxn[index].his_sequence)
547 4 {
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