File:  [Qemu by Fabrice Bellard] / qemu / slirp / if.c
Revision 1.1.1.3 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 16:49:15 2018 UTC (3 years, 3 months ago) by root
Branches: qemu, MAIN
CVS tags: qemu0091, HEAD
qemu 0.9.1

    1: /*
    2:  * Copyright (c) 1995 Danny Gasparovski.
    3:  *
    4:  * Please read the file COPYRIGHT for the
    5:  * terms and conditions of the copyright.
    6:  */
    7: 
    8: #include <slirp.h>
    9: 
   10: int     if_queued = 0;                  /* Number of packets queued so far */
   11: 
   12: struct  mbuf if_fastq;                  /* fast queue (for interactive data) */
   13: struct  mbuf if_batchq;                 /* queue for non-interactive data */
   14: struct	mbuf *next_m;			/* Pointer to next mbuf to output */
   15: 
   16: #define ifs_init(ifm) ((ifm)->ifs_next = (ifm)->ifs_prev = (ifm))
   17: 
   18: void
   19: ifs_insque(ifm, ifmhead)
   20: 	struct mbuf *ifm, *ifmhead;
   21: {
   22: 	ifm->ifs_next = ifmhead->ifs_next;
   23: 	ifmhead->ifs_next = ifm;
   24: 	ifm->ifs_prev = ifmhead;
   25: 	ifm->ifs_next->ifs_prev = ifm;
   26: }
   27: 
   28: void
   29: ifs_remque(ifm)
   30: 	struct mbuf *ifm;
   31: {
   32: 	ifm->ifs_prev->ifs_next = ifm->ifs_next;
   33: 	ifm->ifs_next->ifs_prev = ifm->ifs_prev;
   34: }
   35: 
   36: void
   37: if_init()
   38: {
   39: 	if_fastq.ifq_next = if_fastq.ifq_prev = &if_fastq;
   40: 	if_batchq.ifq_next = if_batchq.ifq_prev = &if_batchq;
   41:         //	sl_compress_init(&comp_s);
   42: 	next_m = &if_batchq;
   43: }
   44: 
   45: #if 0
   46: /*
   47:  * This shouldn't be needed since the modem is blocking and
   48:  * we don't expect any signals, but what the hell..
   49:  */
   50: inline int
   51: writen(fd, bptr, n)
   52: 	int fd;
   53: 	char *bptr;
   54: 	int n;
   55: {
   56: 	int ret;
   57: 	int total;
   58: 
   59: 	/* This should succeed most of the time */
   60: 	ret = send(fd, bptr, n,0);
   61: 	if (ret == n || ret <= 0)
   62: 	   return ret;
   63: 
   64: 	/* Didn't write everything, go into the loop */
   65: 	total = ret;
   66: 	while (n > total) {
   67: 		ret = send(fd, bptr+total, n-total,0);
   68: 		if (ret <= 0)
   69: 		   return ret;
   70: 		total += ret;
   71: 	}
   72: 	return total;
   73: }
   74: 
   75: /*
   76:  * if_input - read() the tty, do "top level" processing (ie: check for any escapes),
   77:  * and pass onto (*ttyp->if_input)
   78:  *
   79:  * XXXXX Any zeros arriving by themselves are NOT placed into the arriving packet.
   80:  */
   81: #define INBUFF_SIZE 2048 /* XXX */
   82: void
   83: if_input(ttyp)
   84: 	struct ttys *ttyp;
   85: {
   86: 	u_char if_inbuff[INBUFF_SIZE];
   87: 	int if_n;
   88: 
   89: 	DEBUG_CALL("if_input");
   90: 	DEBUG_ARG("ttyp = %lx", (long)ttyp);
   91: 
   92: 	if_n = recv(ttyp->fd, (char *)if_inbuff, INBUFF_SIZE,0);
   93: 
   94: 	DEBUG_MISC((dfd, " read %d bytes\n", if_n));
   95: 
   96: 	if (if_n <= 0) {
   97: 		if (if_n == 0 || (errno != EINTR && errno != EAGAIN)) {
   98: 			if (ttyp->up)
   99: 			   link_up--;
  100: 			tty_detached(ttyp, 0);
  101: 		}
  102: 		return;
  103: 	}
  104: 	if (if_n == 1) {
  105: 		if (*if_inbuff == '0') {
  106: 			ttyp->ones = 0;
  107: 			if (++ttyp->zeros >= 5)
  108: 			   slirp_exit(0);
  109: 			return;
  110: 		}
  111: 		if (*if_inbuff == '1') {
  112: 			ttyp->zeros = 0;
  113: 			if (++ttyp->ones >= 5)
  114: 			   tty_detached(ttyp, 0);
  115: 			return;
  116: 		}
  117: 	}
  118: 	ttyp->ones = ttyp->zeros = 0;
  119: 
  120: 	(*ttyp->if_input)(ttyp, if_inbuff, if_n);
  121: }
  122: #endif
  123: 
  124: /*
  125:  * if_output: Queue packet into an output queue.
  126:  * There are 2 output queue's, if_fastq and if_batchq.
  127:  * Each output queue is a doubly linked list of double linked lists
  128:  * of mbufs, each list belonging to one "session" (socket).  This
  129:  * way, we can output packets fairly by sending one packet from each
  130:  * session, instead of all the packets from one session, then all packets
  131:  * from the next session, etc.  Packets on the if_fastq get absolute
  132:  * priority, but if one session hogs the link, it gets "downgraded"
  133:  * to the batchq until it runs out of packets, then it'll return
  134:  * to the fastq (eg. if the user does an ls -alR in a telnet session,
  135:  * it'll temporarily get downgraded to the batchq)
  136:  */
  137: void
  138: if_output(so, ifm)
  139: 	struct socket *so;
  140: 	struct mbuf *ifm;
  141: {
  142: 	struct mbuf *ifq;
  143: 	int on_fastq = 1;
  144: 
  145: 	DEBUG_CALL("if_output");
  146: 	DEBUG_ARG("so = %lx", (long)so);
  147: 	DEBUG_ARG("ifm = %lx", (long)ifm);
  148: 
  149: 	/*
  150: 	 * First remove the mbuf from m_usedlist,
  151: 	 * since we're gonna use m_next and m_prev ourselves
  152: 	 * XXX Shouldn't need this, gotta change dtom() etc.
  153: 	 */
  154: 	if (ifm->m_flags & M_USEDLIST) {
  155: 		remque(ifm);
  156: 		ifm->m_flags &= ~M_USEDLIST;
  157: 	}
  158: 
  159: 	/*
  160: 	 * See if there's already a batchq list for this session.
  161: 	 * This can include an interactive session, which should go on fastq,
  162: 	 * but gets too greedy... hence it'll be downgraded from fastq to batchq.
  163: 	 * We mustn't put this packet back on the fastq (or we'll send it out of order)
  164: 	 * XXX add cache here?
  165: 	 */
  166: 	for (ifq = if_batchq.ifq_prev; ifq != &if_batchq; ifq = ifq->ifq_prev) {
  167: 		if (so == ifq->ifq_so) {
  168: 			/* A match! */
  169: 			ifm->ifq_so = so;
  170: 			ifs_insque(ifm, ifq->ifs_prev);
  171: 			goto diddit;
  172: 		}
  173: 	}
  174: 
  175: 	/* No match, check which queue to put it on */
  176: 	if (so && (so->so_iptos & IPTOS_LOWDELAY)) {
  177: 		ifq = if_fastq.ifq_prev;
  178: 		on_fastq = 1;
  179: 		/*
  180: 		 * Check if this packet is a part of the last
  181: 		 * packet's session
  182: 		 */
  183: 		if (ifq->ifq_so == so) {
  184: 			ifm->ifq_so = so;
  185: 			ifs_insque(ifm, ifq->ifs_prev);
  186: 			goto diddit;
  187: 		}
  188: 	} else
  189: 		ifq = if_batchq.ifq_prev;
  190: 
  191: 	/* Create a new doubly linked list for this session */
  192: 	ifm->ifq_so = so;
  193: 	ifs_init(ifm);
  194: 	insque(ifm, ifq);
  195: 
  196: diddit:
  197: 	++if_queued;
  198: 
  199: 	if (so) {
  200: 		/* Update *_queued */
  201: 		so->so_queued++;
  202: 		so->so_nqueued++;
  203: 		/*
  204: 		 * Check if the interactive session should be downgraded to
  205: 		 * the batchq.  A session is downgraded if it has queued 6
  206: 		 * packets without pausing, and at least 3 of those packets
  207: 		 * have been sent over the link
  208: 		 * (XXX These are arbitrary numbers, probably not optimal..)
  209: 		 */
  210: 		if (on_fastq && ((so->so_nqueued >= 6) &&
  211: 				 (so->so_nqueued - so->so_queued) >= 3)) {
  212: 
  213: 			/* Remove from current queue... */
  214: 			remque(ifm->ifs_next);
  215: 
  216: 			/* ...And insert in the new.  That'll teach ya! */
  217: 			insque(ifm->ifs_next, &if_batchq);
  218: 		}
  219: 	}
  220: 
  221: #ifndef FULL_BOLT
  222: 	/*
  223: 	 * This prevents us from malloc()ing too many mbufs
  224: 	 */
  225: 	if (link_up) {
  226: 		/* if_start will check towrite */
  227: 		if_start();
  228: 	}
  229: #endif
  230: }
  231: 
  232: /*
  233:  * Send a packet
  234:  * We choose a packet based on it's position in the output queues;
  235:  * If there are packets on the fastq, they are sent FIFO, before
  236:  * everything else.  Otherwise we choose the first packet from the
  237:  * batchq and send it.  the next packet chosen will be from the session
  238:  * after this one, then the session after that one, and so on..  So,
  239:  * for example, if there are 3 ftp session's fighting for bandwidth,
  240:  * one packet will be sent from the first session, then one packet
  241:  * from the second session, then one packet from the third, then back
  242:  * to the first, etc. etc.
  243:  */
  244: void
  245: if_start(void)
  246: {
  247: 	struct mbuf *ifm, *ifqt;
  248: 
  249: 	DEBUG_CALL("if_start");
  250: 
  251: 	if (if_queued == 0)
  252: 	   return; /* Nothing to do */
  253: 
  254:  again:
  255:         /* check if we can really output */
  256:         if (!slirp_can_output())
  257:             return;
  258: 
  259: 	/*
  260: 	 * See which queue to get next packet from
  261: 	 * If there's something in the fastq, select it immediately
  262: 	 */
  263: 	if (if_fastq.ifq_next != &if_fastq) {
  264: 		ifm = if_fastq.ifq_next;
  265: 	} else {
  266: 		/* Nothing on fastq, see if next_m is valid */
  267: 		if (next_m != &if_batchq)
  268: 		   ifm = next_m;
  269: 		else
  270: 		   ifm = if_batchq.ifq_next;
  271: 
  272: 		/* Set which packet to send on next iteration */
  273: 		next_m = ifm->ifq_next;
  274: 	}
  275: 	/* Remove it from the queue */
  276: 	ifqt = ifm->ifq_prev;
  277: 	remque(ifm);
  278: 	--if_queued;
  279: 
  280: 	/* If there are more packets for this session, re-queue them */
  281: 	if (ifm->ifs_next != /* ifm->ifs_prev != */ ifm) {
  282: 		insque(ifm->ifs_next, ifqt);
  283: 		ifs_remque(ifm);
  284: 	}
  285: 
  286: 	/* Update so_queued */
  287: 	if (ifm->ifq_so) {
  288: 		if (--ifm->ifq_so->so_queued == 0)
  289: 		   /* If there's no more queued, reset nqueued */
  290: 		   ifm->ifq_so->so_nqueued = 0;
  291: 	}
  292: 
  293: 	/* Encapsulate the packet for sending */
  294:         if_encap(ifm->m_data, ifm->m_len);
  295: 
  296:         m_free(ifm);
  297: 
  298: 	if (if_queued)
  299: 	   goto again;
  300: }

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