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tap, tcp: Move tap send path to tap.c

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The functions which do the final steps of sending TCP packets on through
the tap interface - tcp_l2_buf_flush*() - no longer have anything that's
actually specific to TCP in them, other than comments and names.  Move them
all to tap.c.

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 2023-01-06 11:43:11 +11:00 committed by Stefano Brivio
parent e21ee41ac3
commit 6d011c1faa
3 changed files with 89 additions and 81 deletions
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84
tap.c
View file

@ -53,6 +53,7 @@
#include "netlink.h"
#include "pasta.h"
#include "packet.h"
#include "tap.h"
#include "log.h"
/* IPv4 (plus ARP) and IPv6 message batches from tap/guest to IP handlers */
@ -302,6 +303,89 @@ void tap_icmp6_send(const struct ctx *c,
debug("tap: failed to send %lu bytes (IPv6)", len);
}
/**
* tap_send_frames_pasta() - Send multiple frames to the pasta tap
* @c: Execution context
* @iov: Array of buffers, each containing one frame
* @n: Number of buffers/frames in @iov
*
* #syscalls:pasta write
*/
static void tap_send_frames_pasta(struct ctx *c,
const struct iovec *iov, size_t n)
{
size_t i;
for (i = 0; i < n; i++) {
if (write(c->fd_tap, (char *)iov->iov_base + 4,
iov->iov_len - 4) < 0) {
debug("tap write: %s", strerror(errno));
if (errno != EAGAIN && errno != EWOULDBLOCK)
tap_handler(c, c->fd_tap, EPOLLERR, NULL);
i--;
}
}
}
/**
* tap_send_frames_passt() - Send multiple frames to the passt tap
* @c: Execution context
* @iov: Array of buffers, each containing one frame
* @n: Number of buffers/frames in @iov
*
* #syscalls:passt sendmsg send
*/
static void tap_send_frames_passt(const struct ctx *c,
const struct iovec *iov, size_t n)
{
struct msghdr mh = {
.msg_iov = (void *)iov,
.msg_iovlen = n,
};
size_t end = 0, missing;
unsigned int i;
ssize_t sent;
char *p;
sent = sendmsg(c->fd_tap, &mh, MSG_NOSIGNAL | MSG_DONTWAIT);
if (sent < 0)
return;
/* Ensure a complete last message on partial sendmsg() */
for (i = 0; i < n; i++, iov++) {
end += iov->iov_len;
if (end >= (size_t)sent)
break;
}
missing = end - sent;
if (!missing)
return;
p = (char *)iov->iov_base + iov->iov_len - missing;
if (send(c->fd_tap, p, missing, MSG_NOSIGNAL))
debug("tap: failed to flush %lu missing bytes to tap", missing);
}
/**
* tap_send_frames() - Send out multiple prepared frames
* @c: Execution context
* @iov: Array of buffers, each containing one frame (with L2 headers)
* @n: Number of buffers/frames in @iov
*/
void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n)
{
if (!n)
return;
if (c->mode == MODE_PASST)
tap_send_frames_passt(c, iov, n);
else
tap_send_frames_pasta(c, iov, n);
pcap_multiple(iov, n, sizeof(uint32_t));
}
PACKET_POOL_DECL(pool_l4, UIO_MAXIOV, pkt_buf);
/**

1
tap.h
View file

@ -22,6 +22,7 @@ void tap_icmp6_send(const struct ctx *c,
const struct in6_addr *src, const struct in6_addr *dst,
void *in, size_t len);
int tap_send(const struct ctx *c, const void *data, size_t len);
void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n);
void tap_handler(struct ctx *c, int fd, uint32_t events,
const struct timespec *now);
void tap_sock_init(struct ctx *c);

85
tcp.c
View file

@ -1394,93 +1394,16 @@ static void tcp_rst_do(struct ctx *c, struct tcp_tap_conn *conn);
tcp_rst_do(c, conn); \
} while (0)
/**
* tcp_l2_buf_flush_pasta() - Send frames on the pasta tap interface
* @c: Execution context
* @iov: Pointer to array of buffers, one per frame
* @n: Number of buffers/frames to flush
*/
static void tcp_l2_buf_flush_pasta(struct ctx *c,
const struct iovec *iov, size_t n)
{
size_t i;
for (i = 0; i < n; i++) {
if (write(c->fd_tap, (char *)iov->iov_base + 4,
iov->iov_len - 4) < 0) {
debug("tap write: %s", strerror(errno));
if (errno != EAGAIN && errno != EWOULDBLOCK)
tap_handler(c, c->fd_tap, EPOLLERR, NULL);
i--;
}
}
}
/**
* tcp_l2_buf_flush_passt() - Send a message on the passt tap interface
* @c: Execution context
* @iov: Pointer to array of buffers, one per frame
* @n: Number of buffers/frames to flush
*/
static void tcp_l2_buf_flush_passt(const struct ctx *c,
const struct iovec *iov, size_t n)
{
struct msghdr mh = {
.msg_iov = (void *)iov,
.msg_iovlen = n,
};
size_t end = 0, missing;
unsigned int i;
ssize_t sent;
char *p;
sent = sendmsg(c->fd_tap, &mh, MSG_NOSIGNAL | MSG_DONTWAIT);
if (sent < 0)
return;
/* Ensure a complete last message on partial sendmsg() */
for (i = 0; i < n; i++, iov++) {
end += iov->iov_len;
if (end >= (size_t)sent)
break;
}
missing = end - sent;
if (!missing)
return;
p = (char *)iov->iov_base + iov->iov_len - missing;
if (send(c->fd_tap, p, missing, MSG_NOSIGNAL))
debug("TCP: failed to flush %lu missing bytes to tap", missing);
}
/**
* tcp_l2_flags_buf_flush() - Send out buffers for segments with or without data
* @c: Execution context
*/
static void tcp_l2_buf_flush(struct ctx *c, const struct iovec *iov, size_t n)
{
if (!n)
return;
if (c->mode == MODE_PASST)
tcp_l2_buf_flush_passt(c, iov, n);
else
tcp_l2_buf_flush_pasta(c, iov, n);
pcap_multiple(iov, n, sizeof(uint32_t));
}
/**
* tcp_l2_flags_buf_flush() - Send out buffers for segments with no data (flags)
* @c: Execution context
*/
static void tcp_l2_flags_buf_flush(struct ctx *c)
{
tcp_l2_buf_flush(c, tcp6_l2_flags_iov, tcp6_l2_flags_buf_used);
tap_send_frames(c, tcp6_l2_flags_iov, tcp6_l2_flags_buf_used);
tcp6_l2_flags_buf_used = 0;
tcp_l2_buf_flush(c, tcp4_l2_flags_iov, tcp4_l2_flags_buf_used);
tap_send_frames(c, tcp4_l2_flags_iov, tcp4_l2_flags_buf_used);
tcp4_l2_flags_buf_used = 0;
}
@ -1490,10 +1413,10 @@ static void tcp_l2_flags_buf_flush(struct ctx *c)
*/
static void tcp_l2_data_buf_flush(struct ctx *c)
{
tcp_l2_buf_flush(c, tcp6_l2_iov, tcp6_l2_buf_used);
tap_send_frames(c, tcp6_l2_iov, tcp6_l2_buf_used);
tcp6_l2_buf_used = 0;
tcp_l2_buf_flush(c, tcp4_l2_iov, tcp4_l2_buf_used);
tap_send_frames(c, tcp4_l2_iov, tcp4_l2_buf_used);
tcp4_l2_buf_used = 0;
}