From: David Gibson <david@gibson.dropbear.id.au>
To: Laurent Vivier <lvivier@redhat.com>
Cc: passt-dev@passt.top
Subject: Re: [PATCH v2 2/8] pcap: add pcap_iov()
Date: Thu, 15 Feb 2024 11:35:56 +1100 [thread overview]
Message-ID: <Zc1cbGj90EIxUBGz@zatzit> (raw)
In-Reply-To: <20240214085628.210783-3-lvivier@redhat.com>
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On Wed, Feb 14, 2024 at 09:56:22AM +0100, Laurent Vivier wrote:
Some kind of commit message, please, even if it's minimal.
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>
> Notes:
> v2:
> - introduce pcap_header(), a common helper to write
> packet header
> - use writev() rather than write() in a loop
> - add functions comment
>
> pcap.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++-------
> pcap.h | 1 +
> 2 files changed, 55 insertions(+), 7 deletions(-)
>
> diff --git a/pcap.c b/pcap.c
> index 501d52d4992b..3869a403dd0f 100644
> --- a/pcap.c
> +++ b/pcap.c
> @@ -20,6 +20,7 @@
> #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>
> @@ -31,6 +32,7 @@
> #include "util.h"
> #include "passt.h"
> #include "log.h"
> +#include "iov.h"
>
> #define PCAP_VERSION_MINOR 4
>
> @@ -65,6 +67,28 @@ struct pcap_pkthdr {
> uint32_t len;
> };
>
> +/*
> + * pcap_header - Write a pcap packet header to the pcap file descriptor (pcap_fd).
> + *
> + * @len: Length of the packet data.
> + * @tv: Pointer to a timeval struct containing the timestamp for the packet.
Just "timestamp for packet" would suffice.
> + *
> + * Returns; -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
> @@ -75,13 +99,7 @@ struct pcap_pkthdr {
> */
> 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)
> + if (pcap_header(len, tv) < 0 || write(pcap_fd, pkt, len) < 0)
> return -errno;
>
> return 0;
> @@ -130,6 +148,35 @@ void pcap_multiple(const struct iovec *iov, unsigned int n, size_t offset)
> }
> }
>
> +/*
> + * 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, unsigned int 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(), n = %u\n", n);
I'm not convinced the length of the io vector is particularly useful
here. strerror(errno) might be more useful, although the existing
pcap() helpers also don't print that.
> +}
> +
> /**
> * pcap_init() - Initialise pcap file
> * @c: Execution context
> diff --git a/pcap.h b/pcap.h
> index da5a7e846b72..732a0ddf14cc 100644
> --- a/pcap.h
> +++ b/pcap.h
> @@ -8,6 +8,7 @@
>
> void pcap(const char *pkt, size_t len);
> void pcap_multiple(const struct iovec *iov, unsigned int n, size_t offset);
> +void pcap_iov(const struct iovec *iov, unsigned int n);
> void pcap_init(struct ctx *c);
>
> #endif /* PCAP_H */
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2024-02-15 0:40 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-14 8:56 [PATCH v2 0/8] Add vhost-user support to passt (part 1) Laurent Vivier
2024-02-14 8:56 ` [PATCH v2 1/8] iov: add some functions to manage iovec Laurent Vivier
2024-02-15 0:24 ` David Gibson
2024-02-15 0:32 ` David Gibson
2024-02-16 5:29 ` Stefano Brivio
2024-02-14 8:56 ` [PATCH v2 2/8] pcap: add pcap_iov() Laurent Vivier
2024-02-15 0:35 ` David Gibson [this message]
2024-02-16 5:30 ` Stefano Brivio
2024-02-14 8:56 ` [PATCH v2 3/8] checksum: align buffers Laurent Vivier
2024-02-15 0:40 ` David Gibson
2024-02-14 8:56 ` [PATCH v2 4/8] checksum: add csum_iov() Laurent Vivier
2024-02-15 0:44 ` David Gibson
2024-02-14 8:56 ` [PATCH v2 5/8] util: move IP stuff from util.[ch] to ip.[ch] Laurent Vivier
2024-02-15 2:29 ` David Gibson
2024-02-14 8:56 ` [PATCH v2 6/8] checksum: use csum_ip4_header() in udp.c and tcp.c Laurent Vivier
2024-02-15 2:51 ` David Gibson
2024-02-16 9:08 ` Stefano Brivio
2024-02-16 14:17 ` Laurent Vivier
2024-02-16 14:54 ` Stefano Brivio
2024-02-16 18:05 ` Laurent Vivier
2024-02-16 18:24 ` Stefano Brivio
2024-02-17 14:22 ` Laurent Vivier
2024-02-17 14:37 ` Stefano Brivio
2024-02-19 2:06 ` David Gibson
2024-02-14 8:56 ` [PATCH v2 7/8] checksum: introduce functions to compute the header part checksum for TCP/UDP Laurent Vivier
2024-02-15 3:12 ` David Gibson
2024-02-14 8:56 ` [PATCH v2 8/8] tap: make tap_update_mac() generic Laurent Vivier
2024-02-15 3:13 ` David Gibson
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