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udp: Factor out control structure management from udp_sock_fill_data_v[46]

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The main purpose of udp_sock_fill_data_v[46]() is to construct the IP, UDP
and other headers we'll need to forward data onto the tap interface.  In
addition they update the control structures (iovec and mmsghdr) we'll need
to send the messages, and in the case of pasta actually sends it.

This leads the control structure management and the send itself awkwardly
split between udp_sock_fill_data_v[46]() and their caller
udp_sock_handler().  In addition, this tail part of udp_sock_fill_datav[46]
is essentially common between the IPv4 and IPv6 versions, apart from which
control array we're working on.

Clean this up by reducing these functions to just construct the headers
and renaming them to udp_update_hdr[46]() accordingly.  The control
structure updates are now all in the caller, and common for IPv4 and IPv6.

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 2022-11-24 19:54:21 +11:00 committed by Stefano Brivio
parent 4b2d227c86
commit 310bdbdcf4
1 changed files with 50 additions and 68 deletions
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118
udp.c
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@ -644,20 +644,17 @@ static void udp_sock_handler_splice(const struct ctx *c, union epoll_ref ref,
} }
/** /**
* udp_sock_fill_data_v4() - Fill and queue one buffer. In pasta mode, write it * udp_update_hdr4() - Update headers for one IPv4 datagram
* @c: Execution context * @c: Execution context
* @n: Index of buffer in udp4_l2_buf pool * @n: Index of buffer in udp4_l2_buf pool
* @ref: epoll reference from socket * @dstport: Destination port number
* @msg_idx: Index within message being prepared (spans multiple buffers)
* @msg_len: Length of current message being prepared for sending
* @now: Current timestamp * @now: Current timestamp
*
* Return: size of tap frame with headers
*/ */
static void udp_sock_fill_data_v4(const struct ctx *c, int n, static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
union epoll_ref ref, const struct timespec *now)
int *msg_idx, int *msg_bufs, ssize_t *msg_len,
const struct timespec *now)
{ {
struct msghdr *mh = &udp4_l2_mh_tap[*msg_idx].msg_hdr;
struct udp4_l2_buf_t *b = &udp4_l2_buf[n]; struct udp4_l2_buf_t *b = &udp4_l2_buf[n];
size_t ip_len, buf_len; size_t ip_len, buf_len;
in_port_t src_port; in_port_t src_port;
@ -691,51 +688,31 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n,
udp_update_check4(b); udp_update_check4(b);
b->uh.source = b->s_in.sin_port; b->uh.source = b->s_in.sin_port;
b->uh.dest = htons(ref.r.p.udp.udp.port); b->uh.dest = htons(dstport);
b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh)); b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));
if (c->mode == MODE_PASTA) { buf_len = ip_len + sizeof(b->eh);
void *frame = udp4_l2_iov_tap[n].iov_base;
if (write(c->fd_tap, frame, sizeof(b->eh) + ip_len) < 0) if (c->mode == MODE_PASST) {
debug("tap write: %s", strerror(errno)); b->vnet_len = htonl(buf_len);
pcap(frame, sizeof(b->eh) + ip_len); buf_len += sizeof(b->vnet_len);
return;
} }
b->vnet_len = htonl(ip_len + sizeof(struct ethhdr)); return buf_len;
buf_len = sizeof(uint32_t) + sizeof(struct ethhdr) + ip_len;
udp4_l2_iov_tap[n].iov_len = buf_len;
/* With bigger messages, qemu closes the connection. */
if (*msg_bufs && *msg_len + buf_len > SHRT_MAX) {
mh->msg_iovlen = *msg_bufs;
(*msg_idx)++;
udp4_l2_mh_tap[*msg_idx].msg_hdr.msg_iov = &udp4_l2_iov_tap[n];
*msg_len = *msg_bufs = 0;
}
*msg_len += buf_len;
(*msg_bufs)++;
} }
/** /**
* udp_sock_fill_data_v6() - Fill and queue one buffer. In pasta mode, write it * udp_update_hdr6() - Update headers for one IPv6 datagram
* @c: Execution context * @c: Execution context
* @n: Index of buffer in udp6_l2_buf pool * @n: Index of buffer in udp6_l2_buf pool
* @ref: epoll reference from socket * @dstport: Destination port number
* @msg_idx: Index within message being prepared (spans multiple buffers)
* @msg_len: Length of current message being prepared for sending
* @now: Current timestamp * @now: Current timestamp
*
* Return: size of tap frame with headers
*/ */
static void udp_sock_fill_data_v6(const struct ctx *c, int n, static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
union epoll_ref ref, const struct timespec *now)
int *msg_idx, int *msg_bufs, ssize_t *msg_len,
const struct timespec *now)
{ {
struct msghdr *mh = &udp6_l2_mh_tap[*msg_idx].msg_hdr;
struct udp6_l2_buf_t *b = &udp6_l2_buf[n]; struct udp6_l2_buf_t *b = &udp6_l2_buf[n];
size_t ip_len, buf_len; size_t ip_len, buf_len;
struct in6_addr *src; struct in6_addr *src;
@ -786,7 +763,7 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
} }
b->uh.source = b->s_in6.sin6_port; b->uh.source = b->s_in6.sin6_port;
b->uh.dest = htons(ref.r.p.udp.udp.port); b->uh.dest = htons(dstport);
b->uh.len = b->ip6h.payload_len; b->uh.len = b->ip6h.payload_len;
b->ip6h.hop_limit = IPPROTO_UDP; b->ip6h.hop_limit = IPPROTO_UDP;
@ -796,31 +773,14 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
b->ip6h.nexthdr = IPPROTO_UDP; b->ip6h.nexthdr = IPPROTO_UDP;
b->ip6h.hop_limit = 255; b->ip6h.hop_limit = 255;
if (c->mode == MODE_PASTA) { buf_len = ip_len + sizeof(b->eh);
void *frame = udp6_l2_iov_tap[n].iov_base;
if (write(c->fd_tap, frame, sizeof(b->eh) + ip_len) < 0) if (c->mode == MODE_PASST) {
debug("tap write: %s", strerror(errno)); b->vnet_len = htonl(buf_len);
pcap(frame, sizeof(b->eh) + ip_len); buf_len += sizeof(b->vnet_len);
return;
} }
b->vnet_len = htonl(ip_len + sizeof(struct ethhdr)); return buf_len;
buf_len = sizeof(uint32_t) + sizeof(struct ethhdr) + ip_len;
udp6_l2_iov_tap[n].iov_len = buf_len;
/* With bigger messages, qemu closes the connection. */
if (*msg_bufs && *msg_len + buf_len > SHRT_MAX) {
mh->msg_iovlen = *msg_bufs;
(*msg_idx)++;
udp6_l2_mh_tap[*msg_idx].msg_hdr.msg_iov = &udp6_l2_iov_tap[n];
*msg_len = *msg_bufs = 0;
}
*msg_len += buf_len;
(*msg_bufs)++;
} }
/** /**
@ -836,6 +796,7 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
void udp_sock_handler(const struct ctx *c, union epoll_ref ref, uint32_t events, void udp_sock_handler(const struct ctx *c, union epoll_ref ref, uint32_t events,
const struct timespec *now) const struct timespec *now)
{ {
in_port_t dstport = ref.r.p.udp.udp.port;
ssize_t n, msg_len = 0, missing = 0; ssize_t n, msg_len = 0, missing = 0;
struct mmsghdr *tap_mmh, *sock_mmh; struct mmsghdr *tap_mmh, *sock_mmh;
int msg_bufs = 0, msg_i = 0, ret; int msg_bufs = 0, msg_i = 0, ret;
@ -867,12 +828,33 @@ void udp_sock_handler(const struct ctx *c, union epoll_ref ref, uint32_t events,
tap_mmh[0].msg_hdr.msg_iov = &tap_iov[0]; tap_mmh[0].msg_hdr.msg_iov = &tap_iov[0];
for (i = 0; i < (unsigned)n; i++) { for (i = 0; i < (unsigned)n; i++) {
size_t buf_len;
if (ref.r.p.udp.udp.v6) if (ref.r.p.udp.udp.v6)
udp_sock_fill_data_v6(c, i, ref, buf_len = udp_update_hdr6(c, i, dstport, now);
&msg_i, &msg_bufs, &msg_len, now);
else else
udp_sock_fill_data_v4(c, i, ref, buf_len = udp_update_hdr4(c, i, dstport, now);
&msg_i, &msg_bufs, &msg_len, now);
if (c->mode == MODE_PASTA) {
void *frame = tap_iov[i].iov_base;
if (write(c->fd_tap, frame, buf_len) < 0)
debug("tap write: %s", strerror(errno));
pcap(frame, buf_len);
} else {
tap_iov[i].iov_len = buf_len;
/* With bigger messages, qemu closes the connection. */
if (msg_bufs && msg_len + buf_len > SHRT_MAX) {
tap_mmh[msg_i].msg_hdr.msg_iovlen = msg_bufs;
msg_i++;
tap_mmh[msg_i].msg_hdr.msg_iov = &tap_iov[i];
msg_len = msg_bufs = 0;
}
msg_len += buf_len;
msg_bufs++;
}
} }
tap_mmh[msg_i].msg_hdr.msg_iovlen = msg_bufs; tap_mmh[msg_i].msg_hdr.msg_iovlen = msg_bufs;