4 * Generic datagram handling routines. These are generic for all
5 * protocols. Possibly a generic IP version on top of these would
6 * make sense. Not tonight however 8-).
7 * This is used because UDP, RAW, PACKET, DDP, IPX, AX.25 and
8 * NetROM layer all have identical poll code and mostly
9 * identical recvmsg() code. So we share it here. The poll was
10 * shared before but buried in udp.c so I moved it.
12 * Authors: Alan Cox <alan@redhat.com>. (datagram_poll() from old
16 * Alan Cox : NULL return from skb_peek_copy()
18 * Alan Cox : Rewrote skb_read_datagram to avoid the
19 * skb_peek_copy stuff.
20 * Alan Cox : Added support for SOCK_SEQPACKET.
21 * IPX can no longer use the SO_TYPE hack
22 * but AX.25 now works right, and SPX is
24 * Alan Cox : Fixed write poll of non IP protocol
26 * Florian La Roche: Changed for my new skbuff handling.
27 * Darryl Miles : Fixed non-blocking SOCK_SEQPACKET.
28 * Linus Torvalds : BSD semantic fixes.
29 * Alan Cox : Datagram iovec handling
30 * Darryl Miles : Fixed non-blocking SOCK_STREAM.
31 * Alan Cox : POSIXisms
32 * Pete Wyckoff : Unconnected accept() fix.
36 #include <linux/module.h>
37 #include <linux/types.h>
38 #include <linux/kernel.h>
39 #include <asm/uaccess.h>
40 #include <asm/system.h>
42 #include <linux/interrupt.h>
43 #include <linux/errno.h>
44 #include <linux/sched.h>
45 #include <linux/inet.h>
46 #include <linux/netdevice.h>
47 #include <linux/rtnetlink.h>
48 #include <linux/poll.h>
49 #include <linux/highmem.h>
51 #include <net/protocol.h>
52 #include <linux/skbuff.h>
54 #include <net/checksum.h>
56 #include <net/tcp_states.h>
59 * Is a socket 'connection oriented' ?
61 static inline int connection_based(struct sock *sk)
63 return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM;
69 static int wait_for_packet(struct sock *sk, int *err, long *timeo_p)
74 prepare_to_wait_exclusive(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
77 error = sock_error(sk);
81 if (!skb_queue_empty(&sk->sk_receive_queue))
84 /* Socket shut down? */
85 if (sk->sk_shutdown & RCV_SHUTDOWN)
88 /* Sequenced packets can come disconnected.
89 * If so we report the problem
92 if (connection_based(sk) &&
93 !(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN))
97 if (signal_pending(current))
101 *timeo_p = schedule_timeout(*timeo_p);
103 finish_wait(sk->sk_sleep, &wait);
106 error = sock_intr_errno(*timeo_p);
117 * skb_recv_datagram - Receive a datagram skbuff
120 * @noblock: blocking operation?
121 * @err: error code returned
123 * Get a datagram skbuff, understands the peeking, nonblocking wakeups
124 * and possible races. This replaces identical code in packet, raw and
125 * udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
126 * the long standing peek and read race for datagram sockets. If you
127 * alter this routine remember it must be re-entrant.
129 * This function will lock the socket if a skb is returned, so the caller
130 * needs to unlock the socket in that case (usually by calling
133 * * It does not lock socket since today. This function is
134 * * free of race conditions. This measure should/can improve
135 * * significantly datagram socket latencies at high loads,
136 * * when data copying to user space takes lots of time.
137 * * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
141 * The order of the tests when we find no data waiting are specified
142 * quite explicitly by POSIX 1003.1g, don't change them without having
143 * the standard around please.
145 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
146 int noblock, int *err)
151 * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
153 int error = sock_error(sk);
158 timeo = sock_rcvtimeo(sk, noblock);
161 /* Again only user level code calls this function, so nothing
162 * interrupt level will suddenly eat the receive_queue.
164 * Look at current nfs client by the way...
165 * However, this function was corrent in any case. 8)
167 if (flags & MSG_PEEK) {
168 unsigned long cpu_flags;
170 spin_lock_irqsave(&sk->sk_receive_queue.lock,
172 skb = skb_peek(&sk->sk_receive_queue);
174 atomic_inc(&skb->users);
175 spin_unlock_irqrestore(&sk->sk_receive_queue.lock,
178 skb = skb_dequeue(&sk->sk_receive_queue);
183 /* User doesn't want to wait */
188 } while (!wait_for_packet(sk, err, &timeo));
197 void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
203 * skb_copy_datagram_iovec - Copy a datagram to an iovec.
204 * @skb: buffer to copy
205 * @offset: offset in the buffer to start copying from
206 * @to: io vector to copy to
207 * @len: amount of data to copy from buffer to iovec
209 * Note: the iovec is modified during the copy.
211 int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset,
212 struct iovec *to, int len)
214 int i, err, fraglen, end = 0;
215 struct sk_buff *next = skb_shinfo(skb)->frag_list;
221 fraglen = skb_headlen(skb);
227 if ((end += fraglen) > offset) {
228 int copy = end - offset, o = offset - start;
233 err = memcpy_toiovec(to, skb->data + o, copy);
235 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
236 struct page *page = frag->page;
237 void *p = kmap(page) + frag->page_offset + o;
238 err = memcpy_toiovec(to, p, copy);
247 if (++i >= skb_shinfo(skb)->nr_frags)
249 fraglen = skb_shinfo(skb)->frags[i].size;
253 BUG_ON(skb_shinfo(skb)->frag_list);
261 static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
262 u8 __user *to, int len,
265 int start = skb_headlen(skb);
267 int i, copy = start - offset;
274 *csump = csum_and_copy_to_user(skb->data + offset, to, copy,
278 if ((len -= copy) == 0)
285 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
288 BUG_TRAP(start <= offset + len);
290 end = start + skb_shinfo(skb)->frags[i].size;
291 if ((copy = end - offset) > 0) {
295 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
296 struct page *page = frag->page;
301 csum2 = csum_and_copy_to_user(vaddr +
308 *csump = csum_block_add(*csump, csum2, pos);
318 if (skb_shinfo(skb)->frag_list) {
319 struct sk_buff *list = skb_shinfo(skb)->frag_list;
321 for (; list; list=list->next) {
324 BUG_TRAP(start <= offset + len);
326 end = start + list->len;
327 if ((copy = end - offset) > 0) {
328 unsigned int csum2 = 0;
331 if (skb_copy_and_csum_datagram(list,
336 *csump = csum_block_add(*csump, csum2, pos);
337 if ((len -= copy) == 0)
353 unsigned int __skb_checksum_complete(struct sk_buff *skb)
357 sum = (u16)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));
359 if (unlikely(skb->ip_summed == CHECKSUM_HW))
360 netdev_rx_csum_fault(skb->dev);
361 skb->ip_summed = CHECKSUM_UNNECESSARY;
365 EXPORT_SYMBOL(__skb_checksum_complete);
368 * skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
370 * @hlen: hardware length
373 * Caller _must_ check that skb will fit to this iovec.
375 * Returns: 0 - success.
376 * -EINVAL - checksum failure.
377 * -EFAULT - fault during copy. Beware, in this case iovec
380 int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
381 int hlen, struct iovec *iov)
384 int chunk = skb->len - hlen;
386 /* Skip filled elements.
387 * Pretty silly, look at memcpy_toiovec, though 8)
389 while (!iov->iov_len)
392 if (iov->iov_len < chunk) {
393 if (__skb_checksum_complete(skb))
395 if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))
398 csum = csum_partial(skb->data, hlen, skb->csum);
399 if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base,
402 if ((unsigned short)csum_fold(csum))
404 if (unlikely(skb->ip_summed == CHECKSUM_HW))
405 netdev_rx_csum_fault(skb->dev);
406 iov->iov_len -= chunk;
407 iov->iov_base += chunk;
417 * datagram_poll - generic datagram poll
422 * Datagram poll: Again totally generic. This also handles
423 * sequenced packet sockets providing the socket receive queue
424 * is only ever holding data ready to receive.
426 * Note: when you _don't_ use this routine for this protocol,
427 * and you use a different write policy from sock_writeable()
428 * then please supply your own write_space callback.
430 unsigned int datagram_poll(struct file *file, struct socket *sock,
433 struct sock *sk = sock->sk;
436 poll_wait(file, sk->sk_sleep, wait);
439 /* exceptional events? */
440 if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
442 if (sk->sk_shutdown == SHUTDOWN_MASK)
446 if (!skb_queue_empty(&sk->sk_receive_queue) ||
447 (sk->sk_shutdown & RCV_SHUTDOWN))
448 mask |= POLLIN | POLLRDNORM;
450 /* Connection-based need to check for termination and startup */
451 if (connection_based(sk)) {
452 if (sk->sk_state == TCP_CLOSE)
454 /* connection hasn't started yet? */
455 if (sk->sk_state == TCP_SYN_SENT)
460 if (sock_writeable(sk))
461 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
463 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
468 EXPORT_SYMBOL(datagram_poll);
469 EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec);
470 EXPORT_SYMBOL(skb_copy_datagram_iovec);
471 EXPORT_SYMBOL(skb_free_datagram);
472 EXPORT_SYMBOL(skb_recv_datagram);