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DEFINITIONS
This source file includes following definitions.
- connection_based
- wait_for_packet
- __skb_recv_datagram
- skb_recv_datagram
- skb_free_datagram
- skb_kill_datagram
- skb_copy_datagram_iovec
- skb_copy_datagram_from_iovec
- skb_copy_and_csum_datagram
- __skb_checksum_complete_head
- __skb_checksum_complete
- skb_copy_and_csum_datagram_iovec
- datagram_poll
/*
* SUCS NET3:
*
* Generic datagram handling routines. These are generic for all
* protocols. Possibly a generic IP version on top of these would
* make sense. Not tonight however 8-).
* This is used because UDP, RAW, PACKET, DDP, IPX, AX.25 and
* NetROM layer all have identical poll code and mostly
* identical recvmsg() code. So we share it here. The poll was
* shared before but buried in udp.c so I moved it.
*
* Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>. (datagram_poll() from old
* udp.c code)
*
* Fixes:
* Alan Cox : NULL return from skb_peek_copy()
* understood
* Alan Cox : Rewrote skb_read_datagram to avoid the
* skb_peek_copy stuff.
* Alan Cox : Added support for SOCK_SEQPACKET.
* IPX can no longer use the SO_TYPE hack
* but AX.25 now works right, and SPX is
* feasible.
* Alan Cox : Fixed write poll of non IP protocol
* crash.
* Florian La Roche: Changed for my new skbuff handling.
* Darryl Miles : Fixed non-blocking SOCK_SEQPACKET.
* Linus Torvalds : BSD semantic fixes.
* Alan Cox : Datagram iovec handling
* Darryl Miles : Fixed non-blocking SOCK_STREAM.
* Alan Cox : POSIXisms
* Pete Wyckoff : Unconnected accept() fix.
*
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/poll.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/checksum.h>
#include <net/sock.h>
#include <net/tcp_states.h>
/*
* Is a socket 'connection oriented' ?
*/
static inline int connection_based(struct sock *sk)
{
return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM;
}
/*
* Wait for a packet..
*/
static int wait_for_packet(struct sock *sk, int *err, long *timeo_p)
{
int error;
DEFINE_WAIT(wait);
prepare_to_wait_exclusive(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
/* Socket errors? */
error = sock_error(sk);
if (error)
goto out_err;
if (!skb_queue_empty(&sk->sk_receive_queue))
goto out;
/* Socket shut down? */
if (sk->sk_shutdown & RCV_SHUTDOWN)
goto out_noerr;
/* Sequenced packets can come disconnected.
* If so we report the problem
*/
error = -ENOTCONN;
if (connection_based(sk) &&
!(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN))
goto out_err;
/* handle signals */
if (signal_pending(current))
goto interrupted;
error = 0;
*timeo_p = schedule_timeout(*timeo_p);
out:
finish_wait(sk->sk_sleep, &wait);
return error;
interrupted:
error = sock_intr_errno(*timeo_p);
out_err:
*err = error;
goto out;
out_noerr:
*err = 0;
error = 1;
goto out;
}
/**
* __skb_recv_datagram - Receive a datagram skbuff
* @sk: socket
* @flags: MSG_ flags
* @peeked: returns non-zero if this packet has been seen before
* @err: error code returned
*
* Get a datagram skbuff, understands the peeking, nonblocking wakeups
* and possible races. This replaces identical code in packet, raw and
* udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
* the long standing peek and read race for datagram sockets. If you
* alter this routine remember it must be re-entrant.
*
* This function will lock the socket if a skb is returned, so the caller
* needs to unlock the socket in that case (usually by calling
* skb_free_datagram)
*
* * It does not lock socket since today. This function is
* * free of race conditions. This measure should/can improve
* * significantly datagram socket latencies at high loads,
* * when data copying to user space takes lots of time.
* * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
* * 8) Great win.)
* * --ANK (980729)
*
* The order of the tests when we find no data waiting are specified
* quite explicitly by POSIX 1003.1g, don't change them without having
* the standard around please.
*/
struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
int *peeked, int *err)
{
struct sk_buff *skb;
long timeo;
/*
* Caller is allowed not to check sk->sk_err before skb_recv_datagram()
*/
int error = sock_error(sk);
if (error)
goto no_packet;
timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
do {
/* Again only user level code calls this function, so nothing
* interrupt level will suddenly eat the receive_queue.
*
* Look at current nfs client by the way...
* However, this function was corrent in any case. 8)
*/
unsigned long cpu_flags;
spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);
skb = skb_peek(&sk->sk_receive_queue);
if (skb) {
*peeked = skb->peeked;
if (flags & MSG_PEEK) {
skb->peeked = 1;
atomic_inc(&skb->users);
} else
__skb_unlink(skb, &sk->sk_receive_queue);
}
spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);
if (skb)
return skb;
/* User doesn't want to wait */
error = -EAGAIN;
if (!timeo)
goto no_packet;
} while (!wait_for_packet(sk, err, &timeo));
return NULL;
no_packet:
*err = error;
return NULL;
}
EXPORT_SYMBOL(__skb_recv_datagram);
struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
int noblock, int *err)
{
int peeked;
return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
&peeked, err);
}
void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
{
kfree_skb(skb);
sk_mem_reclaim(sk);
}
/**
* skb_kill_datagram - Free a datagram skbuff forcibly
* @sk: socket
* @skb: datagram skbuff
* @flags: MSG_ flags
*
* This function frees a datagram skbuff that was received by
* skb_recv_datagram. The flags argument must match the one
* used for skb_recv_datagram.
*
* If the MSG_PEEK flag is set, and the packet is still on the
* receive queue of the socket, it will be taken off the queue
* before it is freed.
*
* This function currently only disables BH when acquiring the
* sk_receive_queue lock. Therefore it must not be used in a
* context where that lock is acquired in an IRQ context.
*
* It returns 0 if the packet was removed by us.
*/
int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
{
int err = 0;
if (flags & MSG_PEEK) {
err = -ENOENT;
spin_lock_bh(&sk->sk_receive_queue.lock);
if (skb == skb_peek(&sk->sk_receive_queue)) {
__skb_unlink(skb, &sk->sk_receive_queue);
atomic_dec(&skb->users);
err = 0;
}
spin_unlock_bh(&sk->sk_receive_queue.lock);
}
kfree_skb(skb);
sk_mem_reclaim(sk);
return err;
}
EXPORT_SYMBOL(skb_kill_datagram);
/**
* skb_copy_datagram_iovec - Copy a datagram to an iovec.
* @skb: buffer to copy
* @offset: offset in the buffer to start copying from
* @to: io vector to copy to
* @len: amount of data to copy from buffer to iovec
*
* Note: the iovec is modified during the copy.
*/
int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset,
struct iovec *to, int len)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
/* Copy header. */
if (copy > 0) {
if (copy > len)
copy = len;
if (memcpy_toiovec(to, skb->data + offset, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
}
/* Copy paged appendix. Hmm... why does this look so complicated? */
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int end;
WARN_ON(start > offset + len);
end = start + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
int err;
u8 *vaddr;
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
struct page *page = frag->page;
if (copy > len)
copy = len;
vaddr = kmap(page);
err = memcpy_toiovec(to, vaddr + frag->page_offset +
offset - start, copy);
kunmap(page);
if (err)
goto fault;
if (!(len -= copy))
return 0;
offset += copy;
}
start = end;
}
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *list = skb_shinfo(skb)->frag_list;
for (; list; list = list->next) {
int end;
WARN_ON(start > offset + len);
end = start + list->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
if (skb_copy_datagram_iovec(list,
offset - start,
to, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
}
start = end;
}
}
if (!len)
return 0;
fault:
return -EFAULT;
}
/**
* skb_copy_datagram_from_iovec - Copy a datagram from an iovec.
* @skb: buffer to copy
* @offset: offset in the buffer to start copying to
* @from: io vector to copy to
* @len: amount of data to copy to buffer from iovec
*
* Returns 0 or -EFAULT.
* Note: the iovec is modified during the copy.
*/
int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
struct iovec *from, int len)
{
int start = skb_headlen(skb);
int i, copy = start - offset;
/* Copy header. */
if (copy > 0) {
if (copy > len)
copy = len;
if (memcpy_fromiovec(skb->data + offset, from, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
}
/* Copy paged appendix. Hmm... why does this look so complicated? */
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int end;
WARN_ON(start > offset + len);
end = start + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
int err;
u8 *vaddr;
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
struct page *page = frag->page;
if (copy > len)
copy = len;
vaddr = kmap(page);
err = memcpy_fromiovec(vaddr + frag->page_offset +
offset - start, from, copy);
kunmap(page);
if (err)
goto fault;
if (!(len -= copy))
return 0;
offset += copy;
}
start = end;
}
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *list = skb_shinfo(skb)->frag_list;
for (; list; list = list->next) {
int end;
WARN_ON(start > offset + len);
end = start + list->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
if (skb_copy_datagram_from_iovec(list,
offset - start,
from, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
}
start = end;
}
}
if (!len)
return 0;
fault:
return -EFAULT;
}
EXPORT_SYMBOL(skb_copy_datagram_from_iovec);
static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
u8 __user *to, int len,
__wsum *csump)
{
int start = skb_headlen(skb);
int pos = 0;
int i, copy = start - offset;
/* Copy header. */
if (copy > 0) {
int err = 0;
if (copy > len)
copy = len;
*csump = csum_and_copy_to_user(skb->data + offset, to, copy,
*csump, &err);
if (err)
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
pos = copy;
}
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int end;
WARN_ON(start > offset + len);
end = start + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
__wsum csum2;
int err = 0;
u8 *vaddr;
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
struct page *page = frag->page;
if (copy > len)
copy = len;
vaddr = kmap(page);
csum2 = csum_and_copy_to_user(vaddr +
frag->page_offset +
offset - start,
to, copy, 0, &err);
kunmap(page);
if (err)
goto fault;
*csump = csum_block_add(*csump, csum2, pos);
if (!(len -= copy))
return 0;
offset += copy;
to += copy;
pos += copy;
}
start = end;
}
if (skb_shinfo(skb)->frag_list) {
struct sk_buff *list = skb_shinfo(skb)->frag_list;
for (; list; list=list->next) {
int end;
WARN_ON(start > offset + len);
end = start + list->len;
if ((copy = end - offset) > 0) {
__wsum csum2 = 0;
if (copy > len)
copy = len;
if (skb_copy_and_csum_datagram(list,
offset - start,
to, copy,
&csum2))
goto fault;
*csump = csum_block_add(*csump, csum2, pos);
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
pos += copy;
}
start = end;
}
}
if (!len)
return 0;
fault:
return -EFAULT;
}
__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
{
__sum16 sum;
sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
if (likely(!sum)) {
if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
netdev_rx_csum_fault(skb->dev);
skb->ip_summed = CHECKSUM_UNNECESSARY;
}
return sum;
}
EXPORT_SYMBOL(__skb_checksum_complete_head);
__sum16 __skb_checksum_complete(struct sk_buff *skb)
{
return __skb_checksum_complete_head(skb, skb->len);
}
EXPORT_SYMBOL(__skb_checksum_complete);
/**
* skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
* @skb: skbuff
* @hlen: hardware length
* @iov: io vector
*
* Caller _must_ check that skb will fit to this iovec.
*
* Returns: 0 - success.
* -EINVAL - checksum failure.
* -EFAULT - fault during copy. Beware, in this case iovec
* can be modified!
*/
int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
int hlen, struct iovec *iov)
{
__wsum csum;
int chunk = skb->len - hlen;
if (!chunk)
return 0;
/* Skip filled elements.
* Pretty silly, look at memcpy_toiovec, though 8)
*/
while (!iov->iov_len)
iov++;
if (iov->iov_len < chunk) {
if (__skb_checksum_complete(skb))
goto csum_error;
if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))
goto fault;
} else {
csum = csum_partial(skb->data, hlen, skb->csum);
if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base,
chunk, &csum))
goto fault;
if (csum_fold(csum))
goto csum_error;
if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
netdev_rx_csum_fault(skb->dev);
iov->iov_len -= chunk;
iov->iov_base += chunk;
}
return 0;
csum_error:
return -EINVAL;
fault:
return -EFAULT;
}
/**
* datagram_poll - generic datagram poll
* @file: file struct
* @sock: socket
* @wait: poll table
*
* Datagram poll: Again totally generic. This also handles
* sequenced packet sockets providing the socket receive queue
* is only ever holding data ready to receive.
*
* Note: when you _don't_ use this routine for this protocol,
* and you use a different write policy from sock_writeable()
* then please supply your own write_space callback.
*/
unsigned int datagram_poll(struct file *file, struct socket *sock,
poll_table *wait)
{
struct sock *sk = sock->sk;
unsigned int mask;
poll_wait(file, sk->sk_sleep, wait);
mask = 0;
/* exceptional events? */
if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
mask |= POLLERR;
if (sk->sk_shutdown & RCV_SHUTDOWN)
mask |= POLLRDHUP;
if (sk->sk_shutdown == SHUTDOWN_MASK)
mask |= POLLHUP;
/* readable? */
if (!skb_queue_empty(&sk->sk_receive_queue) ||
(sk->sk_shutdown & RCV_SHUTDOWN))
mask |= POLLIN | POLLRDNORM;
/* Connection-based need to check for termination and startup */
if (connection_based(sk)) {
if (sk->sk_state == TCP_CLOSE)
mask |= POLLHUP;
/* connection hasn't started yet? */
if (sk->sk_state == TCP_SYN_SENT)
return mask;
}
/* writable? */
if (sock_writeable(sk))
mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
else
set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
return mask;
}
EXPORT_SYMBOL(datagram_poll);
EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec);
EXPORT_SYMBOL(skb_copy_datagram_iovec);
EXPORT_SYMBOL(skb_free_datagram);
EXPORT_SYMBOL(skb_recv_datagram);