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
| | // SPDX-License-Identifier: GPL-2.0-or-later
/* PASST - Plug A Simple Socket Transport
* for qemu/UNIX domain socket mode
*
* PASTA - Pack A Subtle Tap Abstraction
* for network namespace/tap device mode
*
* pcap.c - Packet capture for PASST/PASTA
*
* Copyright (c) 2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <fcntl.h>
#include <time.h>
#include <errno.h>
#include <net/ethernet.h>
#include <netinet/in.h>
#include <unistd.h>
#include <net/if.h>
#include "util.h"
#include "passt.h"
#include "log.h"
#include "iov.h"
#define PCAP_VERSION_MINOR 4
static int pcap_fd = -1;
/* See pcap.h from libpcap, or pcap-savefile(5) */
static const struct {
uint32_t magic;
#define PCAP_MAGIC 0xa1b2c3d4
uint16_t major;
#define PCAP_VERSION_MAJOR 2
uint16_t minor;
#define PCAP_VERSION_MINOR 4
int32_t thiszone;
uint32_t sigfigs;
uint32_t snaplen;
uint32_t linktype;
#define PCAP_LINKTYPE_ETHERNET 1
} pcap_hdr = {
PCAP_MAGIC, PCAP_VERSION_MAJOR, PCAP_VERSION_MINOR, 0, 0, ETH_MAX_MTU,
PCAP_LINKTYPE_ETHERNET
};
struct pcap_pkthdr {
uint32_t tv_sec;
uint32_t tv_usec;
uint32_t caplen;
uint32_t len;
};
/*
* pcap_header() - Write a pcap packet header to pcap file
*
* @len: Length of the packet data.
* @tv: Timestamp for the packet.
*
* Return: -1 in case of error, otherwise, 0 to indicate success.
*/
static int pcap_header(size_t len, const struct timeval *tv)
{
struct pcap_pkthdr h;
h.tv_sec = tv->tv_sec;
h.tv_usec = tv->tv_usec;
h.caplen = h.len = len;
if (write(pcap_fd, &h, sizeof(h)) < 0)
return -1;
return 0;
}
/**
* pcap_frame() - Capture a single frame to pcap file with given timestamp
* @pkt: Pointer to data buffer, including L2 headers
* @len: L2 packet length
* @tv: Timestamp
*
* Returns: 0 on success, -errno on error writing to the file
*/
static int pcap_frame(const char *pkt, size_t len, const struct timeval *tv)
{
if (pcap_header(len, tv) < 0 || write(pcap_fd, pkt, len) < 0)
return -errno;
return 0;
}
/**
* pcap() - Capture a single frame to pcap file
* @pkt: Pointer to data buffer, including L2 headers
* @len: L2 packet length
*/
void pcap(const char *pkt, size_t len)
{
struct timeval tv;
if (pcap_fd == -1)
return;
gettimeofday(&tv, NULL);
if (pcap_frame(pkt, len, &tv) != 0)
debug("Cannot log packet, length %zu", len);
}
/**
* pcap_multiple() - Capture multiple frames
* @iov: Array of iovecs, one entry per frame
* @n: Number of frames to capture
* @offset: Offset of the frame within each iovec buffer
*/
void pcap_multiple(const struct iovec *iov, unsigned int n, size_t offset)
{
struct timeval tv;
unsigned int i;
if (pcap_fd == -1)
return;
gettimeofday(&tv, NULL);
for (i = 0; i < n; i++) {
if (pcap_frame((char *)iov[i].iov_base + offset,
iov[i].iov_len - offset, &tv) != 0) {
debug("Cannot log packet, length %zu",
iov->iov_len - offset);
return;
}
}
}
/*
* pcap_iov - Write packet data described by a scatter/gather I/O vector (iov)
* to a pcap file descriptor (pcap_fd).
*
* @iov: Pointer to the array of struct iovec describing the scatter/gather
* I/O vector containing packet data to write, including L2 header
* @n: Number of elements in the iov array.
*/
void pcap_iov(const struct iovec *iov, size_t n)
{
struct timeval tv;
size_t len;
if (pcap_fd == -1)
return;
gettimeofday(&tv, NULL);
len = iov_size(iov, n);
if (pcap_header(len, &tv) < 0) {
debug("Cannot write pcap header");
return;
}
if (writev(pcap_fd, iov, n) < 0)
debug("Cannot log packet using writev(): %s\n",
strerror(errno));
}
/**
* pcap_init() - Initialise pcap file
* @c: Execution context
*/
void pcap_init(struct ctx *c)
{
int flags = O_WRONLY | O_CREAT | O_TRUNC;
if (pcap_fd != -1)
return;
if (!*c->pcap)
return;
flags |= c->foreground ? O_CLOEXEC : 0;
pcap_fd = open(c->pcap, flags, S_IRUSR | S_IWUSR);
if (pcap_fd == -1) {
perror("open");
return;
}
info("Saving packet capture to %s", c->pcap);
if (write(pcap_fd, &pcap_hdr, sizeof(pcap_hdr)) < 0)
warn("Cannot write PCAP header: %s", strerror(errno));
}
|