File:  [Qemu by Fabrice Bellard] / qemu / slirp / if.c
Revision 1.1.1.4 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 16:54:35 2018 UTC (3 years, 1 month ago) by root
Branches: qemu, MAIN
CVS tags: qemu0105, qemu0104, qemu0103, qemu0102, qemu0101, qemu0100, HEAD
qemu 0.10.0

    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: static void
   19: ifs_insque(struct mbuf *ifm, struct mbuf *ifmhead)
   20: {
   21: 	ifm->ifs_next = ifmhead->ifs_next;
   22: 	ifmhead->ifs_next = ifm;
   23: 	ifm->ifs_prev = ifmhead;
   24: 	ifm->ifs_next->ifs_prev = ifm;
   25: }
   26: 
   27: static void
   28: ifs_remque(struct mbuf *ifm)
   29: {
   30: 	ifm->ifs_prev->ifs_next = ifm->ifs_next;
   31: 	ifm->ifs_next->ifs_prev = ifm->ifs_prev;
   32: }
   33: 
   34: void
   35: if_init()
   36: {
   37: 	if_fastq.ifq_next = if_fastq.ifq_prev = &if_fastq;
   38: 	if_batchq.ifq_next = if_batchq.ifq_prev = &if_batchq;
   39:         //	sl_compress_init(&comp_s);
   40: 	next_m = &if_batchq;
   41: }
   42: 
   43: #if 0
   44: /*
   45:  * This shouldn't be needed since the modem is blocking and
   46:  * we don't expect any signals, but what the hell..
   47:  */
   48: inline int
   49: writen(fd, bptr, n)
   50: 	int fd;
   51: 	char *bptr;
   52: 	int n;
   53: {
   54: 	int ret;
   55: 	int total;
   56: 
   57: 	/* This should succeed most of the time */
   58: 	ret = send(fd, bptr, n,0);
   59: 	if (ret == n || ret <= 0)
   60: 	   return ret;
   61: 
   62: 	/* Didn't write everything, go into the loop */
   63: 	total = ret;
   64: 	while (n > total) {
   65: 		ret = send(fd, bptr+total, n-total,0);
   66: 		if (ret <= 0)
   67: 		   return ret;
   68: 		total += ret;
   69: 	}
   70: 	return total;
   71: }
   72: 
   73: /*
   74:  * if_input - read() the tty, do "top level" processing (ie: check for any escapes),
   75:  * and pass onto (*ttyp->if_input)
   76:  *
   77:  * XXXXX Any zeros arriving by themselves are NOT placed into the arriving packet.
   78:  */
   79: #define INBUFF_SIZE 2048 /* XXX */
   80: void
   81: if_input(ttyp)
   82: 	struct ttys *ttyp;
   83: {
   84: 	u_char if_inbuff[INBUFF_SIZE];
   85: 	int if_n;
   86: 
   87: 	DEBUG_CALL("if_input");
   88: 	DEBUG_ARG("ttyp = %lx", (long)ttyp);
   89: 
   90: 	if_n = recv(ttyp->fd, (char *)if_inbuff, INBUFF_SIZE,0);
   91: 
   92: 	DEBUG_MISC((dfd, " read %d bytes\n", if_n));
   93: 
   94: 	if (if_n <= 0) {
   95: 		if (if_n == 0 || (errno != EINTR && errno != EAGAIN)) {
   96: 			if (ttyp->up)
   97: 			   link_up--;
   98: 			tty_detached(ttyp, 0);
   99: 		}
  100: 		return;
  101: 	}
  102: 	if (if_n == 1) {
  103: 		if (*if_inbuff == '0') {
  104: 			ttyp->ones = 0;
  105: 			if (++ttyp->zeros >= 5)
  106: 			   slirp_exit(0);
  107: 			return;
  108: 		}
  109: 		if (*if_inbuff == '1') {
  110: 			ttyp->zeros = 0;
  111: 			if (++ttyp->ones >= 5)
  112: 			   tty_detached(ttyp, 0);
  113: 			return;
  114: 		}
  115: 	}
  116: 	ttyp->ones = ttyp->zeros = 0;
  117: 
  118: 	(*ttyp->if_input)(ttyp, if_inbuff, if_n);
  119: }
  120: #endif
  121: 
  122: /*
  123:  * if_output: Queue packet into an output queue.
  124:  * There are 2 output queue's, if_fastq and if_batchq.
  125:  * Each output queue is a doubly linked list of double linked lists
  126:  * of mbufs, each list belonging to one "session" (socket).  This
  127:  * way, we can output packets fairly by sending one packet from each
  128:  * session, instead of all the packets from one session, then all packets
  129:  * from the next session, etc.  Packets on the if_fastq get absolute
  130:  * priority, but if one session hogs the link, it gets "downgraded"
  131:  * to the batchq until it runs out of packets, then it'll return
  132:  * to the fastq (eg. if the user does an ls -alR in a telnet session,
  133:  * it'll temporarily get downgraded to the batchq)
  134:  */
  135: void
  136: if_output(so, ifm)
  137: 	struct socket *so;
  138: 	struct mbuf *ifm;
  139: {
  140: 	struct mbuf *ifq;
  141: 	int on_fastq = 1;
  142: 
  143: 	DEBUG_CALL("if_output");
  144: 	DEBUG_ARG("so = %lx", (long)so);
  145: 	DEBUG_ARG("ifm = %lx", (long)ifm);
  146: 
  147: 	/*
  148: 	 * First remove the mbuf from m_usedlist,
  149: 	 * since we're gonna use m_next and m_prev ourselves
  150: 	 * XXX Shouldn't need this, gotta change dtom() etc.
  151: 	 */
  152: 	if (ifm->m_flags & M_USEDLIST) {
  153: 		remque(ifm);
  154: 		ifm->m_flags &= ~M_USEDLIST;
  155: 	}
  156: 
  157: 	/*
  158: 	 * See if there's already a batchq list for this session.
  159: 	 * This can include an interactive session, which should go on fastq,
  160: 	 * but gets too greedy... hence it'll be downgraded from fastq to batchq.
  161: 	 * We mustn't put this packet back on the fastq (or we'll send it out of order)
  162: 	 * XXX add cache here?
  163: 	 */
  164: 	for (ifq = if_batchq.ifq_prev; ifq != &if_batchq; ifq = ifq->ifq_prev) {
  165: 		if (so == ifq->ifq_so) {
  166: 			/* A match! */
  167: 			ifm->ifq_so = so;
  168: 			ifs_insque(ifm, ifq->ifs_prev);
  169: 			goto diddit;
  170: 		}
  171: 	}
  172: 
  173: 	/* No match, check which queue to put it on */
  174: 	if (so && (so->so_iptos & IPTOS_LOWDELAY)) {
  175: 		ifq = if_fastq.ifq_prev;
  176: 		on_fastq = 1;
  177: 		/*
  178: 		 * Check if this packet is a part of the last
  179: 		 * packet's session
  180: 		 */
  181: 		if (ifq->ifq_so == so) {
  182: 			ifm->ifq_so = so;
  183: 			ifs_insque(ifm, ifq->ifs_prev);
  184: 			goto diddit;
  185: 		}
  186: 	} else
  187: 		ifq = if_batchq.ifq_prev;
  188: 
  189: 	/* Create a new doubly linked list for this session */
  190: 	ifm->ifq_so = so;
  191: 	ifs_init(ifm);
  192: 	insque(ifm, ifq);
  193: 
  194: diddit:
  195: 	++if_queued;
  196: 
  197: 	if (so) {
  198: 		/* Update *_queued */
  199: 		so->so_queued++;
  200: 		so->so_nqueued++;
  201: 		/*
  202: 		 * Check if the interactive session should be downgraded to
  203: 		 * the batchq.  A session is downgraded if it has queued 6
  204: 		 * packets without pausing, and at least 3 of those packets
  205: 		 * have been sent over the link
  206: 		 * (XXX These are arbitrary numbers, probably not optimal..)
  207: 		 */
  208: 		if (on_fastq && ((so->so_nqueued >= 6) &&
  209: 				 (so->so_nqueued - so->so_queued) >= 3)) {
  210: 
  211: 			/* Remove from current queue... */
  212: 			remque(ifm->ifs_next);
  213: 
  214: 			/* ...And insert in the new.  That'll teach ya! */
  215: 			insque(ifm->ifs_next, &if_batchq);
  216: 		}
  217: 	}
  218: 
  219: #ifndef FULL_BOLT
  220: 	/*
  221: 	 * This prevents us from malloc()ing too many mbufs
  222: 	 */
  223: 	if (link_up) {
  224: 		/* if_start will check towrite */
  225: 		if_start();
  226: 	}
  227: #endif
  228: }
  229: 
  230: /*
  231:  * Send a packet
  232:  * We choose a packet based on it's position in the output queues;
  233:  * If there are packets on the fastq, they are sent FIFO, before
  234:  * everything else.  Otherwise we choose the first packet from the
  235:  * batchq and send it.  the next packet chosen will be from the session
  236:  * after this one, then the session after that one, and so on..  So,
  237:  * for example, if there are 3 ftp session's fighting for bandwidth,
  238:  * one packet will be sent from the first session, then one packet
  239:  * from the second session, then one packet from the third, then back
  240:  * to the first, etc. etc.
  241:  */
  242: void
  243: if_start(void)
  244: {
  245: 	struct mbuf *ifm, *ifqt;
  246: 
  247: 	DEBUG_CALL("if_start");
  248: 
  249: 	if (if_queued == 0)
  250: 	   return; /* Nothing to do */
  251: 
  252:  again:
  253:         /* check if we can really output */
  254:         if (!slirp_can_output())
  255:             return;
  256: 
  257: 	/*
  258: 	 * See which queue to get next packet from
  259: 	 * If there's something in the fastq, select it immediately
  260: 	 */
  261: 	if (if_fastq.ifq_next != &if_fastq) {
  262: 		ifm = if_fastq.ifq_next;
  263: 	} else {
  264: 		/* Nothing on fastq, see if next_m is valid */
  265: 		if (next_m != &if_batchq)
  266: 		   ifm = next_m;
  267: 		else
  268: 		   ifm = if_batchq.ifq_next;
  269: 
  270: 		/* Set which packet to send on next iteration */
  271: 		next_m = ifm->ifq_next;
  272: 	}
  273: 	/* Remove it from the queue */
  274: 	ifqt = ifm->ifq_prev;
  275: 	remque(ifm);
  276: 	--if_queued;
  277: 
  278: 	/* If there are more packets for this session, re-queue them */
  279: 	if (ifm->ifs_next != /* ifm->ifs_prev != */ ifm) {
  280: 		insque(ifm->ifs_next, ifqt);
  281: 		ifs_remque(ifm);
  282: 	}
  283: 
  284: 	/* Update so_queued */
  285: 	if (ifm->ifq_so) {
  286: 		if (--ifm->ifq_so->so_queued == 0)
  287: 		   /* If there's no more queued, reset nqueued */
  288: 		   ifm->ifq_so->so_nqueued = 0;
  289: 	}
  290: 
  291: 	/* Encapsulate the packet for sending */
  292:         if_encap((uint8_t *)ifm->m_data, ifm->m_len);
  293: 
  294:         m_free(ifm);
  295: 
  296: 	if (if_queued)
  297: 	   goto again;
  298: }

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