File:  [Qemu by Fabrice Bellard] / qemu / slirp / if.c
Revision 1.1.1.2 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 16:43:55 2018 UTC (3 years, 3 months ago) by root
Branches: qemu, MAIN
CVS tags: qemu0090, qemu0082, HEAD
qemu 0.8.2

    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_mtu, if_mru;
   11: int if_comp;
   12: int if_maxlinkhdr;
   13: int     if_queued = 0;                  /* Number of packets queued so far */
   14: int     if_thresh = 10;                 /* Number of packets queued before we start sending
   15: 					 * (to prevent allocing too many mbufs) */
   16: 
   17: struct  mbuf if_fastq;                  /* fast queue (for interactive data) */
   18: struct  mbuf if_batchq;                 /* queue for non-interactive data */
   19: struct	mbuf *next_m;			/* Pointer to next mbuf to output */
   20: 
   21: #define ifs_init(ifm) ((ifm)->ifs_next = (ifm)->ifs_prev = (ifm))
   22: 
   23: void
   24: ifs_insque(ifm, ifmhead)
   25: 	struct mbuf *ifm, *ifmhead;
   26: {
   27: 	ifm->ifs_next = ifmhead->ifs_next;
   28: 	ifmhead->ifs_next = ifm;
   29: 	ifm->ifs_prev = ifmhead;
   30: 	ifm->ifs_next->ifs_prev = ifm;
   31: }
   32: 
   33: void
   34: ifs_remque(ifm)
   35: 	struct mbuf *ifm;
   36: {
   37: 	ifm->ifs_prev->ifs_next = ifm->ifs_next;
   38: 	ifm->ifs_next->ifs_prev = ifm->ifs_prev;
   39: }
   40: 
   41: void
   42: if_init()
   43: {
   44: #if 0
   45: 	/*
   46: 	 * Set if_maxlinkhdr to 48 because it's 40 bytes for TCP/IP,
   47: 	 * and 8 bytes for PPP, but need to have it on an 8byte boundary
   48: 	 */
   49: #ifdef USE_PPP
   50: 	if_maxlinkhdr = 48;
   51: #else
   52: 	if_maxlinkhdr = 40;
   53: #endif
   54: #else
   55:         /* 2 for alignment, 14 for ethernet, 40 for TCP/IP */
   56:         if_maxlinkhdr = 2 + 14 + 40;
   57: #endif
   58: 	if_mtu = 1500;
   59: 	if_mru = 1500;
   60: 	if_comp = IF_AUTOCOMP;
   61: 	if_fastq.ifq_next = if_fastq.ifq_prev = &if_fastq;
   62: 	if_batchq.ifq_next = if_batchq.ifq_prev = &if_batchq;
   63:         //	sl_compress_init(&comp_s);
   64: 	next_m = &if_batchq;
   65: }
   66: 
   67: #if 0
   68: /*
   69:  * This shouldn't be needed since the modem is blocking and
   70:  * we don't expect any signals, but what the hell..
   71:  */
   72: inline int
   73: writen(fd, bptr, n)
   74: 	int fd;
   75: 	char *bptr;
   76: 	int n;
   77: {
   78: 	int ret;
   79: 	int total;
   80: 	
   81: 	/* This should succeed most of the time */
   82: 	ret = send(fd, bptr, n,0);
   83: 	if (ret == n || ret <= 0)
   84: 	   return ret;
   85: 	
   86: 	/* Didn't write everything, go into the loop */
   87: 	total = ret;
   88: 	while (n > total) {
   89: 		ret = send(fd, bptr+total, n-total,0);
   90: 		if (ret <= 0)
   91: 		   return ret;
   92: 		total += ret;
   93: 	}
   94: 	return total;
   95: }
   96: 
   97: /*
   98:  * if_input - read() the tty, do "top level" processing (ie: check for any escapes),
   99:  * and pass onto (*ttyp->if_input)
  100:  * 
  101:  * XXXXX Any zeros arriving by themselves are NOT placed into the arriving packet.
  102:  */
  103: #define INBUFF_SIZE 2048 /* XXX */
  104: void
  105: if_input(ttyp)
  106: 	struct ttys *ttyp;
  107: {
  108: 	u_char if_inbuff[INBUFF_SIZE];
  109: 	int if_n;
  110: 	
  111: 	DEBUG_CALL("if_input");
  112: 	DEBUG_ARG("ttyp = %lx", (long)ttyp);
  113: 	
  114: 	if_n = recv(ttyp->fd, (char *)if_inbuff, INBUFF_SIZE,0);
  115: 	
  116: 	DEBUG_MISC((dfd, " read %d bytes\n", if_n));
  117: 	
  118: 	if (if_n <= 0) {
  119: 		if (if_n == 0 || (errno != EINTR && errno != EAGAIN)) {
  120: 			if (ttyp->up)
  121: 			   link_up--;
  122: 			tty_detached(ttyp, 0);
  123: 		}
  124: 		return;
  125: 	}
  126: 	if (if_n == 1) {
  127: 		if (*if_inbuff == '0') {
  128: 			ttyp->ones = 0;
  129: 			if (++ttyp->zeros >= 5)
  130: 			   slirp_exit(0);
  131: 			return;
  132: 		}
  133: 		if (*if_inbuff == '1') {
  134: 			ttyp->zeros = 0;
  135: 			if (++ttyp->ones >= 5)
  136: 			   tty_detached(ttyp, 0);
  137: 			return;
  138: 		}
  139: 	}
  140: 	ttyp->ones = ttyp->zeros = 0;
  141: 	
  142: 	(*ttyp->if_input)(ttyp, if_inbuff, if_n);
  143: }
  144: #endif	
  145: 	
  146: /*
  147:  * if_output: Queue packet into an output queue.
  148:  * There are 2 output queue's, if_fastq and if_batchq. 
  149:  * Each output queue is a doubly linked list of double linked lists
  150:  * of mbufs, each list belonging to one "session" (socket).  This
  151:  * way, we can output packets fairly by sending one packet from each
  152:  * session, instead of all the packets from one session, then all packets
  153:  * from the next session, etc.  Packets on the if_fastq get absolute 
  154:  * priority, but if one session hogs the link, it gets "downgraded"
  155:  * to the batchq until it runs out of packets, then it'll return
  156:  * to the fastq (eg. if the user does an ls -alR in a telnet session,
  157:  * it'll temporarily get downgraded to the batchq)
  158:  */
  159: void
  160: if_output(so, ifm)
  161: 	struct socket *so;
  162: 	struct mbuf *ifm;
  163: {
  164: 	struct mbuf *ifq;
  165: 	int on_fastq = 1;
  166: 	
  167: 	DEBUG_CALL("if_output");
  168: 	DEBUG_ARG("so = %lx", (long)so);
  169: 	DEBUG_ARG("ifm = %lx", (long)ifm);
  170: 	
  171: 	/*
  172: 	 * First remove the mbuf from m_usedlist,
  173: 	 * since we're gonna use m_next and m_prev ourselves
  174: 	 * XXX Shouldn't need this, gotta change dtom() etc.
  175: 	 */
  176: 	if (ifm->m_flags & M_USEDLIST) {
  177: 		remque(ifm);
  178: 		ifm->m_flags &= ~M_USEDLIST;
  179: 	}
  180: 	
  181: 	/*
  182: 	 * See if there's already a batchq list for this session.  
  183: 	 * This can include an interactive session, which should go on fastq,
  184: 	 * but gets too greedy... hence it'll be downgraded from fastq to batchq.
  185: 	 * We mustn't put this packet back on the fastq (or we'll send it out of order)
  186: 	 * XXX add cache here?
  187: 	 */
  188: 	for (ifq = if_batchq.ifq_prev; ifq != &if_batchq; ifq = ifq->ifq_prev) {
  189: 		if (so == ifq->ifq_so) {
  190: 			/* A match! */
  191: 			ifm->ifq_so = so;
  192: 			ifs_insque(ifm, ifq->ifs_prev);
  193: 			goto diddit;
  194: 		}
  195: 	}
  196: 	
  197: 	/* No match, check which queue to put it on */
  198: 	if (so && (so->so_iptos & IPTOS_LOWDELAY)) {
  199: 		ifq = if_fastq.ifq_prev;
  200: 		on_fastq = 1;
  201: 		/*
  202: 		 * Check if this packet is a part of the last
  203: 		 * packet's session
  204: 		 */
  205: 		if (ifq->ifq_so == so) {
  206: 			ifm->ifq_so = so;
  207: 			ifs_insque(ifm, ifq->ifs_prev);
  208: 			goto diddit;
  209: 		}
  210: 	} else
  211: 		ifq = if_batchq.ifq_prev;
  212: 	
  213: 	/* Create a new doubly linked list for this session */
  214: 	ifm->ifq_so = so;
  215: 	ifs_init(ifm);
  216: 	insque(ifm, ifq);
  217: 	
  218: diddit:
  219: 	++if_queued;
  220: 	
  221: 	if (so) {
  222: 		/* Update *_queued */
  223: 		so->so_queued++;
  224: 		so->so_nqueued++;
  225: 		/*
  226: 		 * Check if the interactive session should be downgraded to
  227: 		 * the batchq.  A session is downgraded if it has queued 6
  228: 		 * packets without pausing, and at least 3 of those packets
  229: 		 * have been sent over the link
  230: 		 * (XXX These are arbitrary numbers, probably not optimal..)
  231: 		 */
  232: 		if (on_fastq && ((so->so_nqueued >= 6) && 
  233: 				 (so->so_nqueued - so->so_queued) >= 3)) {
  234: 			
  235: 			/* Remove from current queue... */
  236: 			remque(ifm->ifs_next);
  237: 			
  238: 			/* ...And insert in the new.  That'll teach ya! */
  239: 			insque(ifm->ifs_next, &if_batchq);
  240: 		}
  241: 	}
  242: 
  243: #ifndef FULL_BOLT
  244: 	/*
  245: 	 * This prevents us from malloc()ing too many mbufs
  246: 	 */
  247: 	if (link_up) {
  248: 		/* if_start will check towrite */
  249: 		if_start();
  250: 	}
  251: #endif
  252: }
  253: 
  254: /*
  255:  * Send a packet
  256:  * We choose a packet based on it's position in the output queues;
  257:  * If there are packets on the fastq, they are sent FIFO, before
  258:  * everything else.  Otherwise we choose the first packet from the
  259:  * batchq and send it.  the next packet chosen will be from the session
  260:  * after this one, then the session after that one, and so on..  So,
  261:  * for example, if there are 3 ftp session's fighting for bandwidth,
  262:  * one packet will be sent from the first session, then one packet
  263:  * from the second session, then one packet from the third, then back
  264:  * to the first, etc. etc.
  265:  */
  266: void
  267: if_start(void)
  268: {
  269: 	struct mbuf *ifm, *ifqt;
  270: 	
  271: 	DEBUG_CALL("if_start");
  272: 	
  273: 	if (if_queued == 0)
  274: 	   return; /* Nothing to do */
  275: 	
  276:  again:
  277:         /* check if we can really output */
  278:         if (!slirp_can_output())
  279:             return;
  280: 
  281: 	/*
  282: 	 * See which queue to get next packet from
  283: 	 * If there's something in the fastq, select it immediately
  284: 	 */
  285: 	if (if_fastq.ifq_next != &if_fastq) {
  286: 		ifm = if_fastq.ifq_next;
  287: 	} else {
  288: 		/* Nothing on fastq, see if next_m is valid */
  289: 		if (next_m != &if_batchq)
  290: 		   ifm = next_m;
  291: 		else
  292: 		   ifm = if_batchq.ifq_next;
  293: 		
  294: 		/* Set which packet to send on next iteration */
  295: 		next_m = ifm->ifq_next;
  296: 	}
  297: 	/* Remove it from the queue */
  298: 	ifqt = ifm->ifq_prev;
  299: 	remque(ifm);
  300: 	--if_queued;
  301: 	
  302: 	/* If there are more packets for this session, re-queue them */
  303: 	if (ifm->ifs_next != /* ifm->ifs_prev != */ ifm) {
  304: 		insque(ifm->ifs_next, ifqt);
  305: 		ifs_remque(ifm);
  306: 	}
  307: 	
  308: 	/* Update so_queued */
  309: 	if (ifm->ifq_so) {
  310: 		if (--ifm->ifq_so->so_queued == 0)
  311: 		   /* If there's no more queued, reset nqueued */
  312: 		   ifm->ifq_so->so_nqueued = 0;
  313: 	}
  314: 	
  315: 	/* Encapsulate the packet for sending */
  316:         if_encap(ifm->m_data, ifm->m_len);
  317: 
  318:         m_free(ifm);
  319: 
  320: 	if (if_queued)
  321: 	   goto again;
  322: }

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