1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
|
/*
* Copyright (c) 1995 Danny Gasparovski.
*
* Please read the file COPYRIGHT for the
* terms and conditions of the copyright.
*/
#include <slirp.h>
#include "qemu-timer.h"
#define ifs_init(ifm) ((ifm)->ifs_next = (ifm)->ifs_prev = (ifm))
static void
ifs_insque(struct mbuf *ifm, struct mbuf *ifmhead)
{
ifm->ifs_next = ifmhead->ifs_next;
ifmhead->ifs_next = ifm;
ifm->ifs_prev = ifmhead;
ifm->ifs_next->ifs_prev = ifm;
}
static void
ifs_remque(struct mbuf *ifm)
{
ifm->ifs_prev->ifs_next = ifm->ifs_next;
ifm->ifs_next->ifs_prev = ifm->ifs_prev;
}
void
if_init(Slirp *slirp)
{
slirp->if_fastq.ifq_next = slirp->if_fastq.ifq_prev = &slirp->if_fastq;
slirp->if_batchq.ifq_next = slirp->if_batchq.ifq_prev = &slirp->if_batchq;
slirp->next_m = &slirp->if_batchq;
}
/*
* 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(struct socket *so, struct mbuf *ifm)
{
Slirp *slirp = ifm->slirp;
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 = slirp->if_batchq.ifq_prev; ifq != &slirp->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 = slirp->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 = slirp->if_batchq.ifq_prev;
/* Create a new doubly linked list for this session */
ifm->ifq_so = so;
ifs_init(ifm);
insque(ifm, ifq);
/* Expiration date = Now + 1 second */
ifm->expiration_date = qemu_get_clock_ns(rt_clock) + 1000000000ULL;
diddit:
slirp->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, &slirp->if_batchq);
}
}
#ifndef FULL_BOLT
/*
* This prevents us from malloc()ing too many mbufs
*/
if_start(ifm->slirp);
#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(Slirp *slirp)
{
uint64_t now = qemu_get_clock_ns(rt_clock);
int requeued = 0;
struct mbuf *ifm, *ifqt;
DEBUG_CALL("if_start");
if (slirp->if_queued == 0)
return; /* Nothing to do */
again:
/* check if we can really output */
if (!slirp_can_output(slirp->opaque))
return;
/*
* See which queue to get next packet from
* If there's something in the fastq, select it immediately
*/
if (slirp->if_fastq.ifq_next != &slirp->if_fastq) {
ifm = slirp->if_fastq.ifq_next;
} else {
/* Nothing on fastq, see if next_m is valid */
if (slirp->next_m != &slirp->if_batchq)
ifm = slirp->next_m;
else
ifm = slirp->if_batchq.ifq_next;
/* Set which packet to send on next iteration */
slirp->next_m = ifm->ifq_next;
}
/* Remove it from the queue */
ifqt = ifm->ifq_prev;
remque(ifm);
slirp->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;
}
if (ifm->expiration_date < now) {
/* Expired */
m_free(ifm);
} else {
/* Encapsulate the packet for sending */
if (if_encap(slirp, ifm)) {
m_free(ifm);
} else {
/* re-queue */
insque(ifm, ifqt);
requeued++;
}
}
if (slirp->if_queued)
goto again;
slirp->if_queued = requeued;
}
|
