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
10int     if_queued = 0;                  /* Number of packets queued so far */
11
12struct  mbuf if_fastq;                  /* fast queue (for interactive data) */
13struct  mbuf if_batchq;                 /* queue for non-interactive data */
14struct	mbuf *next_m;			/* Pointer to next mbuf to output */
15
16#define ifs_init(ifm) ((ifm)->ifs_next = (ifm)->ifs_prev = (ifm))
17
18static void
19ifs_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
27static void
28ifs_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
34void
35if_init(void)
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 */
48inline int
49writen(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 = socket_send(fd, bptr, n);
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 = socket_send(fd, bptr+total, n-total);
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 */
80void
81if_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 = socket_recv(ttyp->fd, (char *)if_inbuff, INBUFF_SIZE);
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 */
135void
136if_output(struct socket *so, struct mbuf *ifm)
137{
138	struct mbuf *ifq;
139	int on_fastq = 1;
140
141	DEBUG_CALL("if_output");
142	DEBUG_ARG("so = %lx", (long)so);
143	DEBUG_ARG("ifm = %lx", (long)ifm);
144
145	/*
146	 * First remove the mbuf from m_usedlist,
147	 * since we're gonna use m_next and m_prev ourselves
148	 * XXX Shouldn't need this, gotta change dtom() etc.
149	 */
150	if (ifm->m_flags & M_USEDLIST) {
151		remque(ifm);
152		ifm->m_flags &= ~M_USEDLIST;
153	}
154
155	/*
156	 * See if there's already a batchq list for this session.
157	 * This can include an interactive session, which should go on fastq,
158	 * but gets too greedy... hence it'll be downgraded from fastq to batchq.
159	 * We mustn't put this packet back on the fastq (or we'll send it out of order)
160	 * XXX add cache here?
161	 */
162	for (ifq = if_batchq.ifq_prev; ifq != &if_batchq; ifq = ifq->ifq_prev) {
163		if (so == ifq->ifq_so) {
164			/* A match! */
165			ifm->ifq_so = so;
166			ifs_insque(ifm, ifq->ifs_prev);
167			goto diddit;
168		}
169	}
170
171	/* No match, check which queue to put it on */
172	if (so && (so->so_iptos & IPTOS_LOWDELAY)) {
173		ifq = if_fastq.ifq_prev;
174		on_fastq = 1;
175		/*
176		 * Check if this packet is a part of the last
177		 * packet's session
178		 */
179		if (ifq->ifq_so == so) {
180			ifm->ifq_so = so;
181			ifs_insque(ifm, ifq->ifs_prev);
182			goto diddit;
183		}
184	} else
185		ifq = if_batchq.ifq_prev;
186
187	/* Create a new doubly linked list for this session */
188	ifm->ifq_so = so;
189	ifs_init(ifm);
190	insque(ifm, ifq);
191
192diddit:
193	++if_queued;
194
195	if (so) {
196		/* Update *_queued */
197		so->so_queued++;
198		so->so_nqueued++;
199		/*
200		 * Check if the interactive session should be downgraded to
201		 * the batchq.  A session is downgraded if it has queued 6
202		 * packets without pausing, and at least 3 of those packets
203		 * have been sent over the link
204		 * (XXX These are arbitrary numbers, probably not optimal..)
205		 */
206		if (on_fastq && ((so->so_nqueued >= 6) &&
207				 (so->so_nqueued - so->so_queued) >= 3)) {
208
209			/* Remove from current queue... */
210			remque(ifm->ifs_next);
211
212			/* ...And insert in the new.  That'll teach ya! */
213			insque(ifm->ifs_next, &if_batchq);
214		}
215	}
216
217#ifndef FULL_BOLT
218	/*
219	 * This prevents us from malloc()ing too many mbufs
220	 */
221	if (link_up) {
222		/* if_start will check towrite */
223		if_start();
224	}
225#endif
226}
227
228/*
229 * Send a packet
230 * We choose a packet based on it's position in the output queues;
231 * If there are packets on the fastq, they are sent FIFO, before
232 * everything else.  Otherwise we choose the first packet from the
233 * batchq and send it.  the next packet chosen will be from the session
234 * after this one, then the session after that one, and so on..  So,
235 * for example, if there are 3 ftp session's fighting for bandwidth,
236 * one packet will be sent from the first session, then one packet
237 * from the second session, then one packet from the third, then back
238 * to the first, etc. etc.
239 */
240void
241if_start(void)
242{
243	struct mbuf *ifm, *ifqt;
244
245	DEBUG_CALL("if_start");
246
247	if (if_queued == 0)
248	   return; /* Nothing to do */
249
250 again:
251        /* check if we can really output */
252        if (!slirp_can_output())
253            return;
254
255	/*
256	 * See which queue to get next packet from
257	 * If there's something in the fastq, select it immediately
258	 */
259	if (if_fastq.ifq_next != &if_fastq) {
260		ifm = if_fastq.ifq_next;
261	} else {
262		/* Nothing on fastq, see if next_m is valid */
263		if (next_m != &if_batchq)
264		   ifm = next_m;
265		else
266		   ifm = if_batchq.ifq_next;
267
268		/* Set which packet to send on next iteration */
269		next_m = ifm->ifq_next;
270	}
271	/* Remove it from the queue */
272	ifqt = ifm->ifq_prev;
273	remque(ifm);
274	--if_queued;
275
276	/* If there are more packets for this session, re-queue them */
277	if (ifm->ifs_next != /* ifm->ifs_prev != */ ifm) {
278		insque(ifm->ifs_next, ifqt);
279		ifs_remque(ifm);
280	}
281
282	/* Update so_queued */
283	if (ifm->ifq_so) {
284		if (--ifm->ifq_so->so_queued == 0)
285		   /* If there's no more queued, reset nqueued */
286		   ifm->ifq_so->so_nqueued = 0;
287	}
288
289	/* Encapsulate the packet for sending */
290        if_encap((uint8_t *)ifm->m_data, ifm->m_len);
291
292        m_free(ifm);
293
294	if (if_queued)
295	   goto again;
296}
297