aboutsummaryrefslogtreecommitdiff
path: root/net/tap-linux.c
blob: e4f7e2723b76bff4b16512bd1dcedf2dc66656c5 (plain)
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
/*
 * QEMU System Emulator
 *
 * Copyright (c) 2003-2008 Fabrice Bellard
 * Copyright (c) 2009 Red Hat, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "net/tap.h"
#include "net/tap-linux.h"

#include <net/if.h>
#include <sys/ioctl.h>

#include "sysemu.h"
#include "qemu-common.h"

int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required)
{
    struct ifreq ifr;
    int fd, ret;

    TFR(fd = open("/dev/net/tun", O_RDWR));
    if (fd < 0) {
        fprintf(stderr, "warning: could not open /dev/net/tun: no virtual network emulation\n");
        return -1;
    }
    memset(&ifr, 0, sizeof(ifr));
    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;

    if (*vnet_hdr) {
        unsigned int features;

        if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
            features & IFF_VNET_HDR) {
            *vnet_hdr = 1;
            ifr.ifr_flags |= IFF_VNET_HDR;
        } else {
            *vnet_hdr = 0;
        }

        if (vnet_hdr_required && !*vnet_hdr) {
            qemu_error("vnet_hdr=1 requested, but no kernel "
                       "support for IFF_VNET_HDR available");
            close(fd);
            return -1;
        }
    }

    if (ifname[0] != '\0')
        pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
    else
        pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
    ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
    if (ret != 0) {
        fprintf(stderr, "warning: could not configure /dev/net/tun: no virtual network emulation\n");
        close(fd);
        return -1;
    }
    pstrcpy(ifname, ifname_size, ifr.ifr_name);
    fcntl(fd, F_SETFL, O_NONBLOCK);
    return fd;
}

/* sndbuf should be set to a value lower than the tx queue
 * capacity of any destination network interface.
 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is
 * a good default, given a 1500 byte MTU.
 */
#define TAP_DEFAULT_SNDBUF 1024*1024

int tap_set_sndbuf(int fd, QemuOpts *opts)
{
    int sndbuf;

    sndbuf = qemu_opt_get_size(opts, "sndbuf", TAP_DEFAULT_SNDBUF);
    if (!sndbuf) {
        sndbuf = INT_MAX;
    }

    if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && qemu_opt_get(opts, "sndbuf")) {
        qemu_error("TUNSETSNDBUF ioctl failed: %s\n", strerror(errno));
        return -1;
    }
    return 0;
}

int tap_probe_vnet_hdr(int fd)
{
    struct ifreq ifr;

    if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
        qemu_error("TUNGETIFF ioctl() failed: %s\n", strerror(errno));
        return 0;
    }

    return ifr.ifr_flags & IFF_VNET_HDR;
}

int tap_probe_has_ufo(int fd)
{
    unsigned offload;

    offload = TUN_F_CSUM | TUN_F_UFO;

    if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
        return 0;

    return 1;
}

void tap_fd_set_offload(int fd, int csum, int tso4,
                        int tso6, int ecn, int ufo)
{
    unsigned int offload = 0;

    if (csum) {
        offload |= TUN_F_CSUM;
        if (tso4)
            offload |= TUN_F_TSO4;
        if (tso6)
            offload |= TUN_F_TSO6;
        if ((tso4 || tso6) && ecn)
            offload |= TUN_F_TSO_ECN;
        if (ufo)
            offload |= TUN_F_UFO;
    }

    if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
        offload &= ~TUN_F_UFO;
        if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
            fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",
                    strerror(errno));
        }
    }
}