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
|
// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* udp.c - UDP L2-L4 translation routines
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
*/
/**
* DOC: Theory of Operation
*
*
* For UDP, no state machine or any particular tracking is required. Try to
* create and bind sets of 2^16 sockets, one for IPv4 and one for IPv6. Binding
* will fail on ports that are already bound, or low ports depending on
* capabilities.
*
* Packets are forwarded back and forth, by prepending and stripping UDP headers
* in the obvious way, with no port translation.
*
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <limits.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <unistd.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/udp.h>
#include <time.h>
#include "passt.h"
#include "tap.h"
#include "util.h"
static int udp4_sock_port[USHRT_MAX];
static int udp6_sock_port[USHRT_MAX];
/**
* udp_sock_handler() - Handle new data from socket
* @c: Execution context
* @s: File descriptor number for socket
* @events: epoll events bitmap
*/
void udp_sock_handler(struct ctx *c, int s, uint32_t events)
{
struct in6_addr a6 = { .s6_addr = { 0, 0, 0, 0,
0, 0, 0, 0,
0, 0, 0xff, 0xff,
0, 0, 0, 0 } };
struct sockaddr_storage sr, sl;
socklen_t slen = sizeof(sr);
char buf[USHRT_MAX];
struct udphdr *uh;
ssize_t n;
if (events == EPOLLERR)
return;
n = recvfrom(s, buf + sizeof(*uh), sizeof(buf) - sizeof(*uh),
MSG_DONTWAIT, (struct sockaddr *)&sr, &slen);
if (n < 0)
return;
uh = (struct udphdr *)buf;
if (getsockname(s, (struct sockaddr *)&sl, &slen))
return;
if (sl.ss_family == AF_INET) {
struct sockaddr_in *sr4 = (struct sockaddr_in *)&sr;
struct sockaddr_in *sl4 = (struct sockaddr_in *)&sl;
if (ntohl(sr4->sin_addr.s_addr) == INADDR_LOOPBACK ||
ntohl(sr4->sin_addr.s_addr) == INADDR_ANY)
sr4->sin_addr.s_addr = c->gw4;
memcpy(&a6.s6_addr[12], &sr4->sin_addr, sizeof(sr4->sin_addr));
uh->source = sr4->sin_port;
uh->dest = sl4->sin_port;
uh->len = htons(n + sizeof(*uh));
tap_ip_send(c, &a6, IPPROTO_UDP, buf, n + sizeof(*uh));
} else if (sl.ss_family == AF_INET6) {
struct sockaddr_in6 *sr6 = (struct sockaddr_in6 *)&sr;
struct sockaddr_in6 *sl6 = (struct sockaddr_in6 *)&sl;
if (IN6_IS_ADDR_LOOPBACK(&sr6->sin6_addr))
memcpy(&sr6->sin6_addr, &c->gw6, sizeof(c->gw6));
uh->source = sr6->sin6_port;
uh->dest = sl6->sin6_port;
uh->len = htons(n + sizeof(*uh));
tap_ip_send(c, &sr6->sin6_addr, IPPROTO_UDP,
buf, n + sizeof(*uh));
}
}
/**
* udp_tap_handler() - Handle packets from tap
* @c: Execution context
* @af: Address family, AF_INET or AF_INET6
* @msg: Input messages
* @count: Message count
*
* Return: count of consumed packets
*/
int udp_tap_handler(struct ctx *c, int af, void *addr,
struct tap_msg *msg, int count)
{
/* The caller already checks that all the messages have the same source
* and destination, so we can just take those from the first message.
*/
struct udphdr *uh = (struct udphdr *)msg[0].l4h;
struct mmsghdr mm[UIO_MAXIOV] = { 0 };
struct iovec m[UIO_MAXIOV];
struct sockaddr_in6 s_in6;
struct sockaddr_in s_in;
struct sockaddr *sa;
socklen_t sl;
int i, s;
(void)c;
if (af == AF_INET) {
s_in = (struct sockaddr_in) {
.sin_family = AF_INET,
.sin_port = uh->dest,
.sin_addr = *(struct in_addr *)addr,
};
sa = (struct sockaddr *)&s_in;
sl = sizeof(s_in);
} else if (af == AF_INET6) {
s_in6 = (struct sockaddr_in6) {
.sin6_family = AF_INET6,
.sin6_port = uh->dest,
.sin6_addr = *(struct in6_addr *)addr,
};
sa = (struct sockaddr *)&s_in6;
sl = sizeof(s_in6);
} else {
return count;
}
for (i = 0; i < count; i++) {
m[i].iov_base = (char *)((struct udphdr *)msg[i].l4h + 1);
m[i].iov_len = msg[i].l4_len - sizeof(*uh);
mm[i].msg_hdr.msg_name = sa;
mm[i].msg_hdr.msg_namelen = sl;
mm[i].msg_hdr.msg_iov = m + i;
mm[i].msg_hdr.msg_iovlen = 1;
}
if (af == AF_INET) {
if (!(s = udp4_sock_port[ntohs(uh->source)]))
return count;
} else if (af == AF_INET6) {
if (!(s = udp6_sock_port[ntohs(uh->source)]))
return count;
} else {
return count;
}
count = sendmmsg(s, mm, count, MSG_DONTWAIT | MSG_NOSIGNAL);
if (count < 0)
return 1;
return count;
}
/**
* udp_sock_init() - Create and bind listening sockets for inbound packets
* @c: Execution context
*
* Return: 0 on success, -1 on failure
*/
int udp_sock_init(struct ctx *c)
{
in_port_t port;
int s;
c->udp.fd_min = INT_MAX;
c->udp.fd_max = 0;
for (port = 0; port < USHRT_MAX; port++) {
if (c->v4) {
if ((s = sock_l4_add(c, 4, IPPROTO_UDP, port)) < 0)
return -1;
udp4_sock_port[port] = s;
}
if (c->v6) {
if ((s = sock_l4_add(c, 6, IPPROTO_UDP, port)) < 0)
return -1;
udp6_sock_port[port] = s;
}
}
return 0;
}
|
