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pcap: Update pcap_frame() to take an iovec and offset

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Update the low-level helper pcap_frame() to take a struct iovec and
offset within it, rather than an explicit pointer and length for the
frame.  This moves the handling of an offset (to skip vnet_len) from
pcap_multiple() to pcap_frame().

This doesn't accomplish a great deal immediately, but will make
subsequent changes easier.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2024-02-28 12:52:02 +11:00 committed by Stefano Brivio
parent 64b63d9e3e
commit 24410b37a4
1 changed files with 12 additions and 17 deletions
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29
pcap.c
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@ -67,24 +67,25 @@ struct pcap_pkthdr {
/**
* pcap_frame() - Capture a single frame to pcap file with given timestamp
* @pkt: Pointer to data buffer, including L2 headers
* @len: L2 packet length
* @iov: IO vector referencing buffer containing frame (with L2 headers)
* @offset: Offset of the frame from @iov->iov_base
* @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)
static void pcap_frame(const struct iovec *iov, size_t offset,
const struct timeval *tv)
{
size_t len = iov->iov_len - offset;
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;
if (write(pcap_fd, &h, sizeof(h)) < 0 ||
write(pcap_fd, (char *)iov->iov_base + offset, len) < 0)
debug("Cannot log packet, length %zu", len);
}
/**
@ -94,14 +95,14 @@ static int pcap_frame(const char *pkt, size_t len, const struct timeval *tv)
*/
void pcap(const char *pkt, size_t len)
{
struct iovec iov = { (char *)pkt, 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_frame(&iov, 0, &tv);
}
/**
@ -120,14 +121,8 @@ void pcap_multiple(const struct iovec *iov, unsigned int n, size_t offset)
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;
}
}
for (i = 0; i < n; i++)
pcap_frame(iov + i, offset, &tv);
}
/**