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// SPDX-License-Identifier: AGPL-3.0-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 <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"
#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_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)
{
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 || 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 %lu", len);
}
/**
* pcapm() - Capture multiple frames from message header to pcap file
* @mh: Pointer to sendmsg() message header buffer
*/
void pcapm(const struct msghdr *mh)
{
struct timeval tv;
unsigned int i;
if (pcap_fd == -1)
return;
gettimeofday(&tv, NULL);
for (i = 0; i < mh->msg_iovlen; i++) {
const struct iovec *iov = &mh->msg_iov[i];
if (pcap_frame((char *)iov->iov_base + 4,
iov->iov_len - 4, &tv) != 0) {
debug("Cannot log packet, length %lu",
iov->iov_len - 4);
return;
}
}
}
/**
* pcapm() - Capture multiple frames from multiple message headers to pcap file
* @mmh: Pointer to first sendmmsg() header
*/
void pcapmm(const struct mmsghdr *mmh, unsigned int vlen)
{
struct timeval tv;
unsigned int i, j;
if (pcap_fd == -1)
return;
gettimeofday(&tv, NULL);
for (i = 0; i < vlen; i++) {
const struct msghdr *mh = &mmh[i].msg_hdr;
for (j = 0; j < mh->msg_iovlen; j++) {
const struct iovec *iov = &mh->msg_iov[j];
if (pcap_frame((char *)iov->iov_base + 4,
iov->iov_len - 4, &tv) != 0) {
debug("Cannot log packet, length %lu",
iov->iov_len - 4);
return;
}
}
}
}
/**
* 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));
}
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