src/slirp/if.c

/*
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#include <slirp.h>

int if_mtu, if_mru;
int if_comp;
int if_maxlinkhdr;
int     if_queued = 0;                  /* Number of packets queued so far */
int     if_thresh = 10;                 /* Number of packets queued before we start sending
                                         * (to prevent allocing too many mbufs) */

struct  mbuf if_fastq;                  /* fast queue (for interactive data) */
struct  mbuf if_batchq;                 /* queue for non-interactive data */
struct  mbuf *next_m;                   /* Pointer to next mbuf to output */

#define ifs_init(ifm) ((ifm)->ifs_next = (ifm)->ifs_prev = (ifm))

void
ifs_insque(ifm, ifmhead)
        struct mbuf *ifm, *ifmhead;
{
        ifm->ifs_next = ifmhead->ifs_next;
        ifmhead->ifs_next = ifm;
        ifm->ifs_prev = ifmhead;
        ifm->ifs_next->ifs_prev = ifm;
}

void
ifs_remque(ifm)
        struct mbuf *ifm;
{
        ifm->ifs_prev->ifs_next = ifm->ifs_next;
        ifm->ifs_next->ifs_prev = ifm->ifs_prev;
}

void
if_init()
{
#if 0
        /*
         * Set if_maxlinkhdr to 48 because it's 40 bytes for TCP/IP,
         * and 8 bytes for PPP, but need to have it on an 8byte boundary
         */
#ifdef USE_PPP
        if_maxlinkhdr = 48;
#else
        if_maxlinkhdr = 40;
#endif
#else
        /* 14 for ethernet + 40 */
        if_maxlinkhdr = 14 + 40;
#endif
        if_mtu = 1500;
        if_mru = 1500;
        if_comp = IF_AUTOCOMP;
        if_fastq.ifq_next = if_fastq.ifq_prev = &if_fastq;
        if_batchq.ifq_next = if_batchq.ifq_prev = &if_batchq;
        //      sl_compress_init(&comp_s);
        next_m = &if_batchq;
}

#if 0
/*
 * This shouldn't be needed since the modem is blocking and
 * we don't expect any signals, but what the hell..
 */
inline int
writen(fd, bptr, n)
        int fd;
        char *bptr;
        int n;
{
        int ret;
        int total;
        
        /* This should succeed most of the time */
        ret = send(fd, bptr, n,0);
        if (ret == n || ret <= 0)
           return ret;
        
        /* Didn't write everything, go into the loop */
        total = ret;
        while (n > total) {
                ret = send(fd, bptr+total, n-total,0);
                if (ret <= 0)
                   return ret;
                total += ret;
        }
        return total;
}

/*
 * if_input - read() the tty, do "top level" processing (ie: check for any escapes),
 * and pass onto (*ttyp->if_input)
 * 
 * XXXXX Any zeros arriving by themselves are NOT placed into the arriving packet.
 */
#define INBUFF_SIZE 2048 /* XXX */
void
if_input(ttyp)
        struct ttys *ttyp;
{
        u_char if_inbuff[INBUFF_SIZE];
        int if_n;
        
        DEBUG_CALL("if_input");
        DEBUG_ARG("ttyp = %lx", (long)ttyp);
        
        if_n = recv(ttyp->fd, (char *)if_inbuff, INBUFF_SIZE,0);
        
        DEBUG_MISC((dfd, " read %d bytes\n", if_n));
        
        if (if_n <= 0) {
                if (if_n == 0 || (errno != EINTR && errno != EAGAIN)) {
                        if (ttyp->up)
                           link_up--;
                        tty_detached(ttyp, 0);
                }
                return;
        }
        if (if_n == 1) {
                if (*if_inbuff == '0') {
                        ttyp->ones = 0;
                        if (++ttyp->zeros >= 5)
                           slirp_exit(0);
                        return;
                }
                if (*if_inbuff == '1') {
                        ttyp->zeros = 0;
                        if (++ttyp->ones >= 5)
                           tty_detached(ttyp, 0);
                        return;
                }
        }
        ttyp->ones = ttyp->zeros = 0;
        
        (*ttyp->if_input)(ttyp, if_inbuff, if_n);
}
#endif  
        
/*
 * if_output: Queue packet into an output queue.
 * There are 2 output queue's, if_fastq and if_batchq. 
 * Each output queue is a doubly linked list of double linked lists
 * of mbufs, each list belonging to one "session" (socket).  This
 * way, we can output packets fairly by sending one packet from each
 * session, instead of all the packets from one session, then all packets
 * from the next session, etc.  Packets on the if_fastq get absolute 
 * priority, but if one session hogs the link, it gets "downgraded"
 * to the batchq until it runs out of packets, then it'll return
 * to the fastq (eg. if the user does an ls -alR in a telnet session,
 * it'll temporarily get downgraded to the batchq)
 */
void
if_output(so, ifm)
        struct socket *so;
        struct mbuf *ifm;
{
        struct mbuf *ifq;
        int on_fastq = 1;
        
        DEBUG_CALL("if_output");
        DEBUG_ARG("so = %lx", (long)so);
        DEBUG_ARG("ifm = %lx", (long)ifm);
        
        /*
         * First remove the mbuf from m_usedlist,
         * since we're gonna use m_next and m_prev ourselves
         * XXX Shouldn't need this, gotta change dtom() etc.
         */
        if (ifm->m_flags & M_USEDLIST) {
                remque(ifm);
                ifm->m_flags &= ~M_USEDLIST;
        }
        
        /*
         * See if there's already a batchq list for this session.  
         * This can include an interactive session, which should go on fastq,
         * but gets too greedy... hence it'll be downgraded from fastq to batchq.
         * We mustn't put this packet back on the fastq (or we'll send it out of order)
         * XXX add cache here?
         */
        for (ifq = if_batchq.ifq_prev; ifq != &if_batchq; ifq = ifq->ifq_prev) {
                if (so == ifq->ifq_so) {
                        /* A match! */
                        ifm->ifq_so = so;
                        ifs_insque(ifm, ifq->ifs_prev);
                        goto diddit;
                }
        }
        
        /* No match, check which queue to put it on */
        if (so && (so->so_iptos & IPTOS_LOWDELAY)) {
                ifq = if_fastq.ifq_prev;
                on_fastq = 1;
                /*
                 * Check if this packet is a part of the last
                 * packet's session
                 */
                if (ifq->ifq_so == so) {
                        ifm->ifq_so = so;
                        ifs_insque(ifm, ifq->ifs_prev);
                        goto diddit;
                }
        } else
                ifq = if_batchq.ifq_prev;
        
        /* Create a new doubly linked list for this session */
        ifm->ifq_so = so;
        ifs_init(ifm);
        insque(ifm, ifq);
        
diddit:
        ++if_queued;
        
        if (so) {
                /* Update *_queued */
                so->so_queued++;
                so->so_nqueued++;
                /*
                 * Check if the interactive session should be downgraded to
                 * the batchq.  A session is downgraded if it has queued 6
                 * packets without pausing, and at least 3 of those packets
                 * have been sent over the link
                 * (XXX These are arbitrary numbers, probably not optimal..)
                 */
                if (on_fastq && ((so->so_nqueued >= 6) && 
                                 (so->so_nqueued - so->so_queued) >= 3)) {
                        
                        /* Remove from current queue... */
                        remque(ifm->ifs_next);
                        
                        /* ...And insert in the new.  That'll teach ya! */
                        insque(ifm->ifs_next, &if_batchq);
                }
        }

#ifndef FULL_BOLT
        /*
         * This prevents us from malloc()ing too many mbufs
         */
        if (link_up) {
                /* if_start will check towrite */
                if_start();
        }
#endif
}

/*
 * Send a packet
 * We choose a packet based on it's position in the output queues;
 * If there are packets on the fastq, they are sent FIFO, before
 * everything else.  Otherwise we choose the first packet from the
 * batchq and send it.  the next packet chosen will be from the session
 * after this one, then the session after that one, and so on..  So,
 * for example, if there are 3 ftp session's fighting for bandwidth,
 * one packet will be sent from the first session, then one packet
 * from the second session, then one packet from the third, then back
 * to the first, etc. etc.
 */
void
if_start(void)
{
        struct mbuf *ifm, *ifqt;
        
        DEBUG_CALL("if_start");
        
        if (if_queued == 0)
           return; /* Nothing to do */
        
 again:
        /* check if we can really output */
        if (!slirp_can_output())
            return;

        /*
         * See which queue to get next packet from
         * If there's something in the fastq, select it immediately
         */
        if (if_fastq.ifq_next != &if_fastq) {
                ifm = if_fastq.ifq_next;
        } else {
                /* Nothing on fastq, see if next_m is valid */
                if (next_m != &if_batchq)
                   ifm = next_m;
                else
                   ifm = if_batchq.ifq_next;
                
                /* Set which packet to send on next iteration */
                next_m = ifm->ifq_next;
        }
        /* Remove it from the queue */
        ifqt = ifm->ifq_prev;
        remque(ifm);
        --if_queued;
        
        /* If there are more packets for this session, re-queue them */
        if (ifm->ifs_next != /* ifm->ifs_prev != */ ifm) {
                insque(ifm->ifs_next, ifqt);
                ifs_remque(ifm);
        }
        
        /* Update so_queued */
        if (ifm->ifq_so) {
                if (--ifm->ifq_so->so_queued == 0)
                   /* If there's no more queued, reset nqueued */
                   ifm->ifq_so->so_nqueued = 0;
        }
        
        /* Encapsulate the packet for sending */
        if_encap(ifm->m_data, ifm->m_len);

        m_free(ifm);

        if (if_queued)
           goto again;
}
Revision:	1.1
Committed:	2005-05-13T09:00:59Z (19 years, 6 months ago) by gbeauche
Content type:	text/plain
Branch:	MAIN
CVS Tags:	nigel-build-17
Log Message:	slirp user mode network emulation code from qemu
#	User	Rev	Content
1	gbeauche	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_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			/* 14 for ethernet + 40 */
56			if_maxlinkhdr = 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			}