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qemu/net/l2tpv3.c
Fam Zheng 95b1416ae9 l2tpv3: Drop l2tpv3_can_send 
This callback is called by main loop before polling s->fd, if it returns
false, the fd will not be polled in this iteration.

This is redundant with checks inside read callback. After this patch,
the data will be copied from s->fd to s->msgvec when it arrives. If the
device can't receive, it will be queued to incoming_queue, and when the
device status changes, this queue will be flushed.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 1433400324-7358-4-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2015-06-12 13:26:21 +01:00

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/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2012-2014 Cisco Systems
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <linux/ip.h>
#include <netdb.h>
#include "config-host.h"
#include "net/net.h"
#include "clients.h"
#include "monitor/monitor.h"
#include "qemu-common.h"
#include "qemu/error-report.h"
#include "qemu/option.h"
#include "qemu/sockets.h"
#include "qemu/iov.h"
#include "qemu/main-loop.h"
/* The buffer size needs to be investigated for optimum numbers and
* optimum means of paging in on different systems. This size is
* chosen to be sufficient to accommodate one packet with some headers
*/
#define BUFFER_ALIGN sysconf(_SC_PAGESIZE)
#define BUFFER_SIZE 2048
#define IOVSIZE 2
#define MAX_L2TPV3_MSGCNT 64
#define MAX_L2TPV3_IOVCNT (MAX_L2TPV3_MSGCNT * IOVSIZE)
/* Header set to 0x30000 signifies a data packet */
#define L2TPV3_DATA_PACKET 0x30000
/* IANA-assigned IP protocol ID for L2TPv3 */
#ifndef IPPROTO_L2TP
#define IPPROTO_L2TP 0x73
#endif
typedef struct NetL2TPV3State {
NetClientState nc;
int fd;
/*
* these are used for xmit - that happens packet a time
* and for first sign of life packet (easier to parse that once)
*/
uint8_t *header_buf;
struct iovec *vec;
/*
* these are used for receive - try to "eat" up to 32 packets at a time
*/
struct mmsghdr *msgvec;
/*
* peer address
*/
struct sockaddr_storage *dgram_dst;
uint32_t dst_size;
/*
* L2TPv3 parameters
*/
uint64_t rx_cookie;
uint64_t tx_cookie;
uint32_t rx_session;
uint32_t tx_session;
uint32_t header_size;
uint32_t counter;
/*
* DOS avoidance in error handling
*/
bool header_mismatch;
/*
* Ring buffer handling
*/
int queue_head;
int queue_tail;
int queue_depth;
/*
* Precomputed offsets
*/
uint32_t offset;
uint32_t cookie_offset;
uint32_t counter_offset;
uint32_t session_offset;
/* Poll Control */
bool read_poll;
bool write_poll;
/* Flags */
bool ipv6;
bool udp;
bool has_counter;
bool pin_counter;
bool cookie;
bool cookie_is_64;
} NetL2TPV3State;
static void net_l2tpv3_send(void *opaque);
static void l2tpv3_writable(void *opaque);
static void l2tpv3_update_fd_handler(NetL2TPV3State *s)
{
qemu_set_fd_handler2(s->fd, NULL,
s->read_poll ? net_l2tpv3_send : NULL,
s->write_poll ? l2tpv3_writable : NULL,
s);
}
static void l2tpv3_read_poll(NetL2TPV3State *s, bool enable)
{
if (s->read_poll != enable) {
s->read_poll = enable;
l2tpv3_update_fd_handler(s);
}
}
static void l2tpv3_write_poll(NetL2TPV3State *s, bool enable)
{
if (s->write_poll != enable) {
s->write_poll = enable;
l2tpv3_update_fd_handler(s);
}
}
static void l2tpv3_writable(void *opaque)
{
NetL2TPV3State *s = opaque;
l2tpv3_write_poll(s, false);
qemu_flush_queued_packets(&s->nc);
}
static void l2tpv3_send_completed(NetClientState *nc, ssize_t len)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
l2tpv3_read_poll(s, true);
}
static void l2tpv3_poll(NetClientState *nc, bool enable)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
l2tpv3_write_poll(s, enable);
l2tpv3_read_poll(s, enable);
}
static void l2tpv3_form_header(NetL2TPV3State *s)
{
uint32_t *counter;
if (s->udp) {
stl_be_p((uint32_t *) s->header_buf, L2TPV3_DATA_PACKET);
}
stl_be_p(
(uint32_t *) (s->header_buf + s->session_offset),
s->tx_session
);
if (s->cookie) {
if (s->cookie_is_64) {
stq_be_p(
(uint64_t *)(s->header_buf + s->cookie_offset),
s->tx_cookie
);
} else {
stl_be_p(
(uint32_t *) (s->header_buf + s->cookie_offset),
s->tx_cookie
);
}
}
if (s->has_counter) {
counter = (uint32_t *)(s->header_buf + s->counter_offset);
if (s->pin_counter) {
*counter = 0;
} else {
stl_be_p(counter, ++s->counter);
}
}
}
static ssize_t net_l2tpv3_receive_dgram_iov(NetClientState *nc,
const struct iovec *iov,
int iovcnt)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
struct msghdr message;
int ret;
if (iovcnt > MAX_L2TPV3_IOVCNT - 1) {
error_report(
"iovec too long %d > %d, change l2tpv3.h",
iovcnt, MAX_L2TPV3_IOVCNT
);
return -1;
}
l2tpv3_form_header(s);
memcpy(s->vec + 1, iov, iovcnt * sizeof(struct iovec));
s->vec->iov_base = s->header_buf;
s->vec->iov_len = s->offset;
message.msg_name = s->dgram_dst;
message.msg_namelen = s->dst_size;
message.msg_iov = s->vec;
message.msg_iovlen = iovcnt + 1;
message.msg_control = NULL;
message.msg_controllen = 0;
message.msg_flags = 0;
do {
ret = sendmsg(s->fd, &message, 0);
} while ((ret == -1) && (errno == EINTR));
if (ret > 0) {
ret -= s->offset;
} else if (ret == 0) {
/* belt and braces - should not occur on DGRAM
* we should get an error and never a 0 send
*/
ret = iov_size(iov, iovcnt);
} else {
/* signal upper layer that socket buffer is full */
ret = -errno;
if (ret == -EAGAIN || ret == -ENOBUFS) {
l2tpv3_write_poll(s, true);
ret = 0;
}
}
return ret;
}
static ssize_t net_l2tpv3_receive_dgram(NetClientState *nc,
const uint8_t *buf,
size_t size)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
struct iovec *vec;
struct msghdr message;
ssize_t ret = 0;
l2tpv3_form_header(s);
vec = s->vec;
vec->iov_base = s->header_buf;
vec->iov_len = s->offset;
vec++;
vec->iov_base = (void *) buf;
vec->iov_len = size;
message.msg_name = s->dgram_dst;
message.msg_namelen = s->dst_size;
message.msg_iov = s->vec;
message.msg_iovlen = 2;
message.msg_control = NULL;
message.msg_controllen = 0;
message.msg_flags = 0;
do {
ret = sendmsg(s->fd, &message, 0);
} while ((ret == -1) && (errno == EINTR));
if (ret > 0) {
ret -= s->offset;
} else if (ret == 0) {
/* belt and braces - should not occur on DGRAM
* we should get an error and never a 0 send
*/
ret = size;
} else {
ret = -errno;
if (ret == -EAGAIN || ret == -ENOBUFS) {
/* signal upper layer that socket buffer is full */
l2tpv3_write_poll(s, true);
ret = 0;
}
}
return ret;
}
static int l2tpv3_verify_header(NetL2TPV3State *s, uint8_t *buf)
{
uint32_t *session;
uint64_t cookie;
if ((!s->udp) && (!s->ipv6)) {
buf += sizeof(struct iphdr) /* fix for ipv4 raw */;
}
/* we do not do a strict check for "data" packets as per
* the RFC spec because the pure IP spec does not have
* that anyway.
*/
if (s->cookie) {
if (s->cookie_is_64) {
cookie = ldq_be_p(buf + s->cookie_offset);
} else {
cookie = ldl_be_p(buf + s->cookie_offset);
}
if (cookie != s->rx_cookie) {
if (!s->header_mismatch) {
error_report("unknown cookie id");
}
return -1;
}
}
session = (uint32_t *) (buf + s->session_offset);
if (ldl_be_p(session) != s->rx_session) {
if (!s->header_mismatch) {
error_report("session mismatch");
}
return -1;
}
return 0;
}
static void net_l2tpv3_process_queue(NetL2TPV3State *s)
{
int size = 0;
struct iovec *vec;
bool bad_read;
int data_size;
struct mmsghdr *msgvec;
/* go into ring mode only if there is a "pending" tail */
if (s->queue_depth > 0) {
do {
msgvec = s->msgvec + s->queue_tail;
if (msgvec->msg_len > 0) {
data_size = msgvec->msg_len - s->header_size;
vec = msgvec->msg_hdr.msg_iov;
if ((data_size > 0) &&
(l2tpv3_verify_header(s, vec->iov_base) == 0)) {
vec++;
/* Use the legacy delivery for now, we will
* switch to using our own ring as a queueing mechanism
* at a later date
*/
size = qemu_send_packet_async(
&s->nc,
vec->iov_base,
data_size,
l2tpv3_send_completed
);
if (size == 0) {
l2tpv3_read_poll(s, false);
}
bad_read = false;
} else {
bad_read = true;
if (!s->header_mismatch) {
/* report error only once */
error_report("l2tpv3 header verification failed");
s->header_mismatch = true;
}
}
} else {
bad_read = true;
}
s->queue_tail = (s->queue_tail + 1) % MAX_L2TPV3_MSGCNT;
s->queue_depth--;
} while (
(s->queue_depth > 0) &&
qemu_can_send_packet(&s->nc) &&
((size > 0) || bad_read)
);
}
}
static void net_l2tpv3_send(void *opaque)
{
NetL2TPV3State *s = opaque;
int target_count, count;
struct mmsghdr *msgvec;
/* go into ring mode only if there is a "pending" tail */
if (s->queue_depth) {
/* The ring buffer we use has variable intake
* count of how much we can read varies - adjust accordingly
*/
target_count = MAX_L2TPV3_MSGCNT - s->queue_depth;
/* Ensure we do not overrun the ring when we have
* a lot of enqueued packets
*/
if (s->queue_head + target_count > MAX_L2TPV3_MSGCNT) {
target_count = MAX_L2TPV3_MSGCNT - s->queue_head;
}
} else {
/* we do not have any pending packets - we can use
* the whole message vector linearly instead of using
* it as a ring
*/
s->queue_head = 0;
s->queue_tail = 0;
target_count = MAX_L2TPV3_MSGCNT;
}
msgvec = s->msgvec + s->queue_head;
if (target_count > 0) {
do {
count = recvmmsg(
s->fd,
msgvec,
target_count, MSG_DONTWAIT, NULL);
} while ((count == -1) && (errno == EINTR));
if (count < 0) {
/* Recv error - we still need to flush packets here,
* (re)set queue head to current position
*/
count = 0;
}
s->queue_head = (s->queue_head + count) % MAX_L2TPV3_MSGCNT;
s->queue_depth += count;
}
net_l2tpv3_process_queue(s);
}
static void destroy_vector(struct mmsghdr *msgvec, int count, int iovcount)
{
int i, j;
struct iovec *iov;
struct mmsghdr *cleanup = msgvec;
if (cleanup) {
for (i = 0; i < count; i++) {
if (cleanup->msg_hdr.msg_iov) {
iov = cleanup->msg_hdr.msg_iov;
for (j = 0; j < iovcount; j++) {
g_free(iov->iov_base);
iov++;
}
g_free(cleanup->msg_hdr.msg_iov);
}
cleanup++;
}
g_free(msgvec);
}
}
static struct mmsghdr *build_l2tpv3_vector(NetL2TPV3State *s, int count)
{
int i;
struct iovec *iov;
struct mmsghdr *msgvec, *result;
msgvec = g_new(struct mmsghdr, count);
result = msgvec;
for (i = 0; i < count ; i++) {
msgvec->msg_hdr.msg_name = NULL;
msgvec->msg_hdr.msg_namelen = 0;
iov = g_new(struct iovec, IOVSIZE);
msgvec->msg_hdr.msg_iov = iov;
iov->iov_base = g_malloc(s->header_size);
iov->iov_len = s->header_size;
iov++ ;
iov->iov_base = qemu_memalign(BUFFER_ALIGN, BUFFER_SIZE);
iov->iov_len = BUFFER_SIZE;
msgvec->msg_hdr.msg_iovlen = 2;
msgvec->msg_hdr.msg_control = NULL;
msgvec->msg_hdr.msg_controllen = 0;
msgvec->msg_hdr.msg_flags = 0;
msgvec++;
}
return result;
}
static void net_l2tpv3_cleanup(NetClientState *nc)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
qemu_purge_queued_packets(nc);
l2tpv3_read_poll(s, false);
l2tpv3_write_poll(s, false);
if (s->fd >= 0) {
close(s->fd);
}
destroy_vector(s->msgvec, MAX_L2TPV3_MSGCNT, IOVSIZE);
g_free(s->vec);
g_free(s->header_buf);
g_free(s->dgram_dst);
}
static NetClientInfo net_l2tpv3_info = {
.type = NET_CLIENT_OPTIONS_KIND_L2TPV3,
.size = sizeof(NetL2TPV3State),
.receive = net_l2tpv3_receive_dgram,
.receive_iov = net_l2tpv3_receive_dgram_iov,
.poll = l2tpv3_poll,
.cleanup = net_l2tpv3_cleanup,
};
int net_init_l2tpv3(const NetClientOptions *opts,
const char *name,
NetClientState *peer, Error **errp)
{
/* FIXME error_setg(errp, ...) on failure */
const NetdevL2TPv3Options *l2tpv3;
NetL2TPV3State *s;
NetClientState *nc;
int fd = -1, gairet;
struct addrinfo hints;
struct addrinfo *result = NULL;
char *srcport, *dstport;
nc = qemu_new_net_client(&net_l2tpv3_info, peer, "l2tpv3", name);
s = DO_UPCAST(NetL2TPV3State, nc, nc);
s->queue_head = 0;
s->queue_tail = 0;
s->header_mismatch = false;
assert(opts->kind == NET_CLIENT_OPTIONS_KIND_L2TPV3);
l2tpv3 = opts->l2tpv3;
if (l2tpv3->has_ipv6 && l2tpv3->ipv6) {
s->ipv6 = l2tpv3->ipv6;
} else {
s->ipv6 = false;
}
if ((l2tpv3->has_offset) && (l2tpv3->offset > 256)) {
error_report("l2tpv3_open : offset must be less than 256 bytes");
goto outerr;
}
if (l2tpv3->has_rxcookie || l2tpv3->has_txcookie) {
if (l2tpv3->has_rxcookie && l2tpv3->has_txcookie) {
s->cookie = true;
} else {
goto outerr;
}
} else {
s->cookie = false;
}
if (l2tpv3->has_cookie64 || l2tpv3->cookie64) {
s->cookie_is_64 = true;
} else {
s->cookie_is_64 = false;
}
if (l2tpv3->has_udp && l2tpv3->udp) {
s->udp = true;
if (!(l2tpv3->has_srcport && l2tpv3->has_dstport)) {
error_report("l2tpv3_open : need both src and dst port for udp");
goto outerr;
} else {
srcport = l2tpv3->srcport;
dstport = l2tpv3->dstport;
}
} else {
s->udp = false;
srcport = NULL;
dstport = NULL;
}
s->offset = 4;
s->session_offset = 0;
s->cookie_offset = 4;
s->counter_offset = 4;
s->tx_session = l2tpv3->txsession;
if (l2tpv3->has_rxsession) {
s->rx_session = l2tpv3->rxsession;
} else {
s->rx_session = s->tx_session;
}
if (s->cookie) {
s->rx_cookie = l2tpv3->rxcookie;
s->tx_cookie = l2tpv3->txcookie;
if (s->cookie_is_64 == true) {
/* 64 bit cookie */
s->offset += 8;
s->counter_offset += 8;
} else {
/* 32 bit cookie */
s->offset += 4;
s->counter_offset += 4;
}
}
memset(&hints, 0, sizeof(hints));
if (s->ipv6) {
hints.ai_family = AF_INET6;
} else {
hints.ai_family = AF_INET;
}
if (s->udp) {
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = 0;
s->offset += 4;
s->counter_offset += 4;
s->session_offset += 4;
s->cookie_offset += 4;
} else {
hints.ai_socktype = SOCK_RAW;
hints.ai_protocol = IPPROTO_L2TP;
}
gairet = getaddrinfo(l2tpv3->src, srcport, &hints, &result);
if ((gairet != 0) || (result == NULL)) {
error_report(
"l2tpv3_open : could not resolve src, errno = %s",
gai_strerror(gairet)
);
goto outerr;
}
fd = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
if (fd == -1) {
fd = -errno;
error_report("l2tpv3_open : socket creation failed, errno = %d", -fd);
goto outerr;
}
if (bind(fd, (struct sockaddr *) result->ai_addr, result->ai_addrlen)) {
error_report("l2tpv3_open : could not bind socket err=%i", errno);
goto outerr;
}
if (result) {
freeaddrinfo(result);
}
memset(&hints, 0, sizeof(hints));
if (s->ipv6) {
hints.ai_family = AF_INET6;
} else {
hints.ai_family = AF_INET;
}
if (s->udp) {
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = 0;
} else {
hints.ai_socktype = SOCK_RAW;
hints.ai_protocol = IPPROTO_L2TP;
}
result = NULL;
gairet = getaddrinfo(l2tpv3->dst, dstport, &hints, &result);
if ((gairet != 0) || (result == NULL)) {
error_report(
"l2tpv3_open : could not resolve dst, error = %s",
gai_strerror(gairet)
);
goto outerr;
}
s->dgram_dst = g_new0(struct sockaddr_storage, 1);
memcpy(s->dgram_dst, result->ai_addr, result->ai_addrlen);
s->dst_size = result->ai_addrlen;
if (result) {
freeaddrinfo(result);
}
if (l2tpv3->has_counter && l2tpv3->counter) {
s->has_counter = true;
s->offset += 4;
} else {
s->has_counter = false;
}
if (l2tpv3->has_pincounter && l2tpv3->pincounter) {
s->has_counter = true; /* pin counter implies that there is counter */
s->pin_counter = true;
} else {
s->pin_counter = false;
}
if (l2tpv3->has_offset) {
/* extra offset */
s->offset += l2tpv3->offset;
}
if ((s->ipv6) || (s->udp)) {
s->header_size = s->offset;
} else {
s->header_size = s->offset + sizeof(struct iphdr);
}
s->msgvec = build_l2tpv3_vector(s, MAX_L2TPV3_MSGCNT);
s->vec = g_new(struct iovec, MAX_L2TPV3_IOVCNT);
s->header_buf = g_malloc(s->header_size);
qemu_set_nonblock(fd);
s->fd = fd;
s->counter = 0;
l2tpv3_read_poll(s, true);
snprintf(s->nc.info_str, sizeof(s->nc.info_str),
"l2tpv3: connected");
return 0;
outerr:
qemu_del_net_client(nc);
if (fd >= 0) {
close(fd);
}
if (result) {
freeaddrinfo(result);
}
return -1;
}
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