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
|
/*
* wnix, a Unix-like operating system for WebAssembly applications.
* Copyright (C) 2025 Xavier Del Campo Romero
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <net/if.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
static int getport(const char *const s, unsigned short *const port)
{
char *end;
unsigned long v;
errno = 0;
v = strtoull(s, &end, 10);
if (errno || *end || v > USHRT_MAX)
return -1;
*port = v;
return 0;
}
int main(int argc, char *argv[])
{
static const char path[] = "/dev/net/tun";
char *s = NULL;
int ret = EXIT_FAILURE, cfd = -1, tfd = -1;
unsigned short port;
if (argc != 2)
{
fprintf(stderr, "%s <port>\n", *argv);
goto end;
}
else if (getport(argv[1], &port))
{
fprintf(stderr, "invalid port: %s\n", argv[1]);
goto end;
}
else if ((cfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
perror("socket(2)");
goto end;
}
const struct sockaddr_in addr =
{
.sin_family = AF_INET,
.sin_addr.s_addr = inet_addr("127.0.0.1"),
.sin_port = htons(port)
};
const struct ifreq ifr = {.ifr_flags = IFF_TUN | IFF_NO_PI};
if (connect(cfd, (const struct sockaddr *)&addr, sizeof addr))
{
perror("connect(2)");
goto end;
}
else if ((tfd = open(path, O_RDWR)) < 0)
{
fprintf(stderr, "open(2) %s: %s\n", path, strerror(errno));
goto end;
}
else if (ioctl(tfd, TUNSETIFF, &ifr) < 0)
{
perror("ioctl(2)");
goto end;
}
else if (!(s = strdup(ifr.ifr_name)))
{
perror("strdup(3)");
goto end;
}
fprintf(stderr, "set up TUN device %s\n", s);
unsigned long long total = 0;
for (;;)
{
char b[1500];
ssize_t n = read(tfd, &b, sizeof b);
if (n < 0)
{
perror("read(2)");
goto end;
}
fprintf(stderr, "read %zu bytes\n", n);
size_t rem = n;
while (rem)
{
const void *p = b;
fprintf(stderr, "sending %zu bytes\n", rem);
if ((n = write(cfd, p, rem)) < 0)
{
perror("write(2)");
goto end;
}
fprintf(stderr, "sent %zu bytes, total: %llu\n", n, total += n);
p = (const char *)p + n;
rem -= n;
}
}
ret = EXIT_SUCCESS;
end:
if (cfd >= 0 && close(cfd))
{
ret = EXIT_FAILURE;
perror("close(2)");
}
if (tfd >= 0 && close(tfd))
{
ret = EXIT_FAILURE;
fprintf(stderr, "close(2) %s: %s\n", path, strerror(errno));
}
free(s);
return ret;
}
|
