C++ sock_alloc_send_skb函数代码示例

struct sk_buff *ndisc_build_skb(struct net_device *dev,
				const struct in6_addr *daddr,
				const struct in6_addr *saddr,
				struct icmp6hdr *icmp6h,
				const struct in6_addr *target,
				int llinfo)
{
	struct net *net = dev_net(dev);
	struct sock *sk = net->ipv6.ndisc_sk;
	struct sk_buff *skb;
	struct icmp6hdr *hdr;
	int hlen = LL_RESERVED_SPACE(dev);
	int tlen = dev->needed_tailroom;
	int len;
	int err;
	u8 *opt;

	if (!dev->addr_len)
		llinfo = 0;

	len = sizeof(struct icmp6hdr) + (target ? sizeof(*target) : 0);
	if (llinfo)
		len += ndisc_opt_addr_space(dev);

	skb = sock_alloc_send_skb(sk,
				  (MAX_HEADER + sizeof(struct ipv6hdr) +
				   len + hlen + tlen),
				  1, &err);
	if (!skb) {
		ND_PRINTK(0, err, "ND: %s failed to allocate an skb, err=%d\n",
			  __func__, err);
		return NULL;
	}

	skb_reserve(skb, hlen);
	ip6_nd_hdr(sk, skb, dev, saddr, daddr, IPPROTO_ICMPV6, len);

	skb->transport_header = skb->tail;
	skb_put(skb, len);

	hdr = (struct icmp6hdr *)skb_transport_header(skb);
	memcpy(hdr, icmp6h, sizeof(*hdr));

	opt = skb_transport_header(skb) + sizeof(struct icmp6hdr);
	if (target) {
		*(struct in6_addr *)opt = *target;
		opt += sizeof(*target);
	}

	if (llinfo)
		ndisc_fill_addr_option(opt, llinfo, dev->dev_addr,
				       dev->addr_len, dev->type);

	hdr->icmp6_cksum = csum_ipv6_magic(saddr, daddr, len,
					   IPPROTO_ICMPV6,
					   csum_partial(hdr,
							len, 0));

	return skb;
}

static inline int ip6_ufo_append_data(struct sock *sk,
			struct sk_buff_head *queue,
			int getfrag(void *from, char *to, int offset, int len,
			int odd, struct sk_buff *skb),
			void *from, int length, int hh_len, int fragheaderlen,
			int exthdrlen, int transhdrlen, int mtu,
			unsigned int flags, const struct flowi6 *fl6)

{
	struct sk_buff *skb;
	int err;

	/* There is support for UDP large send offload by network
	 * device, so create one single skb packet containing complete
	 * udp datagram
	 */
	skb = skb_peek_tail(queue);
	if (!skb) {
		skb = sock_alloc_send_skb(sk,
			hh_len + fragheaderlen + transhdrlen + 20,
			(flags & MSG_DONTWAIT), &err);
		if (!skb)
			return err;

		/* reserve space for Hardware header */
		skb_reserve(skb, hh_len);

		/* create space for UDP/IP header */
		skb_put(skb, fragheaderlen + transhdrlen);

		/* initialize network header pointer */
		skb_set_network_header(skb, exthdrlen);

		/* initialize protocol header pointer */
		skb->transport_header = skb->network_header + fragheaderlen;

		skb->protocol = htons(ETH_P_IPV6);
		skb->csum = 0;

		__skb_queue_tail(queue, skb);
	} else if (skb_is_gso(skb)) {
		goto append;
	}

	skb->ip_summed = CHECKSUM_PARTIAL;
	/* Specify the length of each IPv6 datagram fragment.
	 * It has to be a multiple of 8.
	 */
	skb_shinfo(skb)->gso_size = (mtu - fragheaderlen -
				     sizeof(struct frag_hdr)) & ~7;
	skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
	skb_shinfo(skb)->ip6_frag_id = ipv6_select_ident(sock_net(sk),
							 &fl6->daddr,
							 &fl6->saddr);

append:
	return skb_append_datato_frags(sk, skb, getfrag, from,
				       (length - transhdrlen));
}

int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
		 size_t len)
{
	const struct dccp_sock *dp = dccp_sk(sk);
	const int flags = msg->msg_flags;
	const int noblock = flags & MSG_DONTWAIT;
	struct sk_buff *skb;
	int rc, size;
	long timeo;

	if (len > dp->dccps_mss_cache)
		return -EMSGSIZE;

	lock_sock(sk);

	if (sysctl_dccp_tx_qlen &&
	    (sk->sk_write_queue.qlen >= sysctl_dccp_tx_qlen)) {
		rc = -EAGAIN;
		goto out_release;
	}

	timeo = sock_sndtimeo(sk, noblock);

	/*
	 * We have to use sk_stream_wait_connect here to set sk_write_pending,
	 * so that the trick in dccp_rcv_request_sent_state_process.
	 */
	/* Wait for a connection to finish. */
	if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
		if ((rc = sk_stream_wait_connect(sk, &timeo)) != 0)
			goto out_release;

	size = sk->sk_prot->max_header + len;
	release_sock(sk);
	skb = sock_alloc_send_skb(sk, size, noblock, &rc);
	lock_sock(sk);
	if (skb == NULL)
		goto out_release;

	skb_reserve(skb, sk->sk_prot->max_header);
	rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
	if (rc != 0)
		goto out_discard;

	skb_queue_tail(&sk->sk_write_queue, skb);
	/*
	 * The xmit_timer is set if the TX CCID is rate-based and will expire
	 * when congestion control permits to release further packets into the
	 * network. Window-based CCIDs do not use this timer.
	 */
	if (!timer_pending(&dp->dccps_xmit_timer))
		dccp_write_xmit(sk);
out_release:
	release_sock(sk);
	return rc ? : len;
out_discard:
	kfree_skb(skb);
	goto out_release;
}

static int raw_sendmsg(struct kiocb *iocb, struct socket *sock,
		       struct msghdr *msg, size_t size)
{
	struct sock *sk = sock->sk;
	struct raw_sock *ro = raw_sk(sk);
	struct sk_buff *skb;
	struct net_device *dev;
	int ifindex;
	int err;

	if (msg->msg_name) {
		struct sockaddr_can *addr =
			(struct sockaddr_can *)msg->msg_name;

		if (addr->can_family != AF_CAN)
			return -EINVAL;

		ifindex = addr->can_ifindex;
	} else
		ifindex = ro->ifindex;

	if (size != sizeof(struct can_frame))
		return -EINVAL;

	dev = dev_get_by_index(&init_net, ifindex);
	if (!dev)
		return -ENXIO;

	skb = sock_alloc_send_skb(sk, size, msg->msg_flags & MSG_DONTWAIT,
				  &err);
	if (!skb)
		goto put_dev;

	err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
	if (err < 0)
		goto free_skb;
	err = sock_tx_timestamp(msg, sk, skb_tx(skb));
	if (err < 0)
		goto free_skb;
	skb->dev = dev;
	skb->sk  = sk;

	err = can_send(skb, ro->loopback);

	dev_put(dev);

	if (err)
		goto send_failed;

	return size;

free_skb:
	kfree_skb(skb);
put_dev:
	dev_put(dev);
send_failed:
	return err;
}

/*
 *	This is where all X.25 information frames pass.
 *
 *      Returns the amount of user data bytes sent on success
 *      or a negative error code on failure.
 */
int x25_output(struct sock *sk, struct sk_buff *skb)
{
	struct sk_buff *skbn;
	unsigned char header[X25_EXT_MIN_LEN];
	int err, frontlen, len, header_len, max_len;
	int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;

	header_len = (sk->protinfo.x25->neighbour->extended) ? X25_EXT_MIN_LEN : X25_STD_MIN_LEN;
	max_len    = x25_pacsize_to_bytes(sk->protinfo.x25->facilities.pacsize_out);

	if (skb->len - header_len > max_len) {
		/* Save a copy of the Header */
		memcpy(header, skb->data, header_len);
		skb_pull(skb, header_len);

		frontlen = skb_headroom(skb);

		while (skb->len > 0) {
			if ((skbn = sock_alloc_send_skb(sk, frontlen + max_len, noblock, &err)) == NULL){
				if(err == -EWOULDBLOCK && noblock){
					kfree_skb(skb);
					return sent;
				}
				SOCK_DEBUG(sk, "x25_output: fragment allocation failed, err=%d, %d bytes sent\n", err, sent);
				return err;
			}
				
			skb_reserve(skbn, frontlen);

			len = (max_len > skb->len) ? skb->len : max_len;

			/* Copy the user data */
			memcpy(skb_put(skbn, len), skb->data, len);
			skb_pull(skb, len);

			/* Duplicate the Header */
			skb_push(skbn, header_len);
			memcpy(skbn->data, header, header_len);

			if (skb->len > 0) {
				if (sk->protinfo.x25->neighbour->extended)
					skbn->data[3] |= X25_EXT_M_BIT;
				else
					skbn->data[2] |= X25_STD_M_BIT;
			}

			skb_queue_tail(&sk->write_queue, skbn);
			sent += len;
		}
		
		kfree_skb(skb);
	} else {
		skb_queue_tail(&sk->write_queue, skb);
		sent = skb->len - header_len;
	}
	return sent;
}

int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
		 size_t len)
{
	const struct dccp_sock *dp = dccp_sk(sk);
	const int flags = msg->msg_flags;
	const int noblock = flags & MSG_DONTWAIT;
	struct sk_buff *skb;
	int rc, size;
	long timeo;

	if (len > dp->dccps_mss_cache)
		return -EMSGSIZE;

	lock_sock(sk);
	timeo = sock_sndtimeo(sk, noblock);

	/*
	 * We have to use sk_stream_wait_connect here to set sk_write_pending,
	 * so that the trick in dccp_rcv_request_sent_state_process.
	 */
	/* Wait for a connection to finish. */
	if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN | DCCPF_CLOSING))
		if ((rc = sk_stream_wait_connect(sk, &timeo)) != 0)
			goto out_release;

	size = sk->sk_prot->max_header + len;
	release_sock(sk);
	skb = sock_alloc_send_skb(sk, size, noblock, &rc);
	lock_sock(sk);
	if (skb == NULL)
		goto out_release;

	skb_reserve(skb, sk->sk_prot->max_header);
	rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
	if (rc != 0)
		goto out_discard;

	rc = dccp_write_xmit(sk, skb, &timeo);
	/*
	 * XXX we don't use sk_write_queue, so just discard the packet.
	 *     Current plan however is to _use_ sk_write_queue with
	 *     an algorith similar to tcp_sendmsg, where the main difference
	 *     is that in DCCP we have to respect packet boundaries, so
	 *     no coalescing of skbs.
	 *
	 *     This bug was _quickly_ found & fixed by just looking at an OSTRA
	 *     generated callgraph 8) -acme
	 */
out_release:
	release_sock(sk);
	return rc ? : len;
out_discard:
	kfree_skb(skb);
	goto out_release;
}

static inline int ip6_ufo_append_data(struct sock *sk,
			int getfrag(void *from, char *to, int offset, int len,
			int odd, struct sk_buff *skb),
			void *from, int length, int hh_len, int fragheaderlen,
			int transhdrlen, int mtu,unsigned int flags,
			struct rt6_info *rt)

{
	struct sk_buff *skb;
	int err;

	/* There is support for UDP large send offload by network
	 * device, so create one single skb packet containing complete
	 * udp datagram
	 */
	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
		struct frag_hdr fhdr;

		skb = sock_alloc_send_skb(sk,
			hh_len + fragheaderlen + transhdrlen + 20,
			(flags & MSG_DONTWAIT), &err);
		if (skb == NULL)
			return err;

		/* reserve space for Hardware header */
		skb_reserve(skb, hh_len);

		/* create space for UDP/IP header */
		skb_put(skb,fragheaderlen + transhdrlen);

		/* initialize network header pointer */
		skb_reset_network_header(skb);

		/* initialize protocol header pointer */
		skb->transport_header = skb->network_header + fragheaderlen;

		skb->ip_summed = CHECKSUM_PARTIAL;
		skb->csum = 0;

		/* Specify the length of each IPv6 datagram fragment.
		 * It has to be a multiple of 8.
		 */
		skb_shinfo(skb)->gso_size = (mtu - fragheaderlen -
					     sizeof(struct frag_hdr)) & ~7;
		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
		ipv6_select_ident(&fhdr, rt);
		skb_shinfo(skb)->ip6_frag_id = fhdr.identification;
		__skb_queue_tail(&sk->sk_write_queue, skb);
	}

	return skb_append_datato_frags(sk, skb, getfrag, from,
				       (length - transhdrlen));
}

static struct sk_buff *__xip_start_skb(struct sock *sk, struct xip_dst *xdst,
	const struct xia_addr *src, int src_n, const struct xia_addr *dest,
	int dest_n, u8 dest_last_node, int transhdrlen, int noblock)
{
	struct net_device *dev = xdst->dst.dev;
	struct sk_buff *skb;
	u32 mtu, alloclen;
	int hh_len, xh_len, rc;

	if (!dev) {
		net_warn_ratelimited("XIP %s: there is a bug somewhere, tried to send a datagram, but dst.dev is NULL\n",
				     __func__);
		return ERR_PTR(-ENODEV);
	}

	mtu = dst_mtu(&xdst->dst);
	if (mtu < XIP_MIN_MTU) {
		net_warn_ratelimited("XIP %s: cannot send datagram out because mtu (= %u) of dev %s is less than minimum MTU (= %u)\n",
				     __func__, mtu, dev->name, XIP_MIN_MTU);
		return ERR_PTR(-EMSGSIZE);
	}

	hh_len = LL_RESERVED_SPACE(dev);
	alloclen = hh_len + mtu;
	skb = sock_alloc_send_skb(sk, alloclen, noblock, &rc);
	if (unlikely(!skb))
		return ERR_PTR(rc);

	/* Fill in the control structures. */

	/* Reserve space for the link layer header */
	skb_reserve(skb, hh_len);

	/* Fill XIP header. */
	skb_reset_network_header(skb);
	xh_len = xip_hdr_size(dest_n, src_n);
	skb_put(skb, xh_len);
	xip_fill_in_hdr(skb, xdst, src->s_row, src_n,
			dest->s_row, dest_n, dest_last_node);

	skb_set_transport_header(skb, xh_len);
	skb_put(skb, transhdrlen);

	/* XXX Does we need to set skb_shinfo(skb)->tx_flags? */

	skb->priority = sk->sk_priority;
	skb->mark = sk->sk_mark;
	xdst_hold(xdst);
	skb_dst_set(skb, &xdst->dst);
	return skb;
}

/*
 *	This is where all X.25 information frames pass.
 *
 *      Returns the amount of user data bytes sent on success
 *      or a negative error code on failure.
 */
int x25_output(struct sock *sk, struct sk_buff *skb)
{
	struct sk_buff *skbn;
	unsigned char header[X25_EXT_MIN_LEN];
	int err, frontlen, len;
	int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;
	struct x25_sock *x25 = x25_sk(sk);
	int header_len = x25->neighbour->extended ? X25_EXT_MIN_LEN :
						    X25_STD_MIN_LEN;
	int max_len = x25_pacsize_to_bytes(x25->facilities.pacsize_out);

	if (skb->len - header_len > max_len) {
		/* Save a copy of the Header */
		skb_copy_from_linear_data(skb, header, header_len);
		skb_pull(skb, header_len);

		frontlen = skb_headroom(skb);

		while (skb->len > 0) {
<<<<<<< HEAD
			release_sock(sk);
			skbn = sock_alloc_send_skb(sk, frontlen + max_len,
						   noblock, &err);
			lock_sock(sk);
			if (!skbn) {
=======
			if ((skbn = sock_alloc_send_skb(sk, frontlen + max_len,
							noblock, &err)) == NULL){
>>>>>>> 296c66da8a02d52243f45b80521febece5ed498a
				if (err == -EWOULDBLOCK && noblock){
					kfree_skb(skb);
					return sent;
				}
				SOCK_DEBUG(sk, "x25_output: fragment alloc"
					       " failed, err=%d, %d bytes "
					       "sent\n", err, sent);
				return err;
			}

void nr_output(struct sock *sk, struct sk_buff *skb)
{
	struct sk_buff *skbn;
	unsigned char transport[NR_TRANSPORT_LEN];
	int err, frontlen, len;

	if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) {
		/* Save a copy of the Transport Header */
		skb_copy_from_linear_data(skb, transport, NR_TRANSPORT_LEN);
		skb_pull(skb, NR_TRANSPORT_LEN);

		frontlen = skb_headroom(skb);

		while (skb->len > 0) {
			if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
				return;

			skb_reserve(skbn, frontlen);

			len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE;

			/* Copy the user data */
			skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
			skb_pull(skb, len);

			/* Duplicate the Transport Header */
			skb_push(skbn, NR_TRANSPORT_LEN);
			skb_copy_to_linear_data(skbn, transport,
						NR_TRANSPORT_LEN);
			if (skb->len > 0)
				skbn->data[4] |= NR_MORE_FLAG;

			skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */
		}

		kfree_skb(skb);
	} else {
		skb_queue_tail(&sk->sk_write_queue, skb);		/* Throw it on the queue */
	}

	nr_kick(sk);
}

static int rawsock_sendmsg(struct kiocb *iocb, struct socket *sock,
					struct msghdr *msg, size_t len)
{
	struct sock *sk = sock->sk;
	struct nfc_dev *dev = nfc_rawsock(sk)->dev;
	struct sk_buff *skb;
	int rc;

	nfc_dbg("sock=%p sk=%p len=%zu", sock, sk, len);

	if (msg->msg_namelen)
		return -EOPNOTSUPP;

	if (sock->state != SS_CONNECTED)
		return -ENOTCONN;

	skb = sock_alloc_send_skb(sk, len + dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE,
					msg->msg_flags & MSG_DONTWAIT, &rc);
	if (!skb)
		return rc;

	skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);

	rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
	if (rc < 0) {
		kfree_skb(skb);
		return rc;
	}

	spin_lock_bh(&sk->sk_write_queue.lock);
	__skb_queue_tail(&sk->sk_write_queue, skb);
	if (!nfc_rawsock(sk)->tx_work_scheduled) {
		schedule_work(&nfc_rawsock(sk)->tx_work);
		nfc_rawsock(sk)->tx_work_scheduled = true;
	}
	spin_unlock_bh(&sk->sk_write_queue.lock);

	return len;
}

static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
			   void *from, size_t length,
			   struct rtable **rtp,
			   unsigned int flags)
{
	struct inet_sock *inet = inet_sk(sk);
	struct net *net = sock_net(sk);
	struct iphdr *iph;
	struct sk_buff *skb;
	unsigned int iphlen;
	int err;
	struct rtable *rt = *rtp;
	int hlen, tlen;

	if (length > rt->dst.dev->mtu) {
		ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
			       rt->dst.dev->mtu);
		return -EMSGSIZE;
	}
	if (flags&MSG_PROBE)
		goto out;

	hlen = LL_RESERVED_SPACE(rt->dst.dev);
	tlen = rt->dst.dev->needed_tailroom;
	skb = sock_alloc_send_skb(sk,
				  length + hlen + tlen + 15,
				  flags & MSG_DONTWAIT, &err);
	if (skb == NULL)
		goto error;
	skb_reserve(skb, hlen);

	skb->priority = sk->sk_priority;
	skb->mark = sk->sk_mark;
	skb_dst_set(skb, &rt->dst);
	*rtp = NULL;

	skb_reset_network_header(skb);
	iph = ip_hdr(skb);
	skb_put(skb,sizeof(*iph));

	skb->ip_summed = CHECKSUM_NONE;

	skb->transport_header = skb->network_header;
	err = -EFAULT;
	if (!memcpy_fromiovecend2((void *)iph, from, 0, length))
		goto error_free;

	iphlen = iph->ihl * 4;

	/*
	 * We don't want to modify the ip header, but we do need to
	 * be sure that it won't cause problems later along the network
	 * stack.  Specifically we want to make sure that iph->ihl is a
	 * sane value.  If ihl points beyond the length of the buffer passed
	 * in, reject the frame as invalid
	 */
	err = -EINVAL;
	if (iphlen > length)
		goto error_free;

	if (iphlen >= sizeof(*iph)) {
		if (!iph->saddr)
			iph->saddr = fl4->saddr;
		iph->check   = 0;
		iph->tot_len = htons(length);
		if (!iph->id)
			ip_select_ident(skb, &rt->dst, NULL);

		iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
	}
	if (iph->protocol == IPPROTO_ICMP)
		icmp_out_count(net, ((struct icmphdr *)
			skb_transport_header(skb))->type);

	err = NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
		      rt->dst.dev, dst_output);
	if (err > 0)
		err = net_xmit_errno(err);
	if (err)
		goto error;
out:
	return 0;

error_free:
	kfree_skb(skb);
error:
	IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
	if (err == -ENOBUFS && !inet->recverr)
		err = 0;
	return err;
}

static int CVE_2010_3848_linux2_6_23_econet_sendmsg(struct kiocb *iocb, struct socket *sock,
			  struct msghdr *msg, size_t len)
{
	struct sock *sk = sock->sk;
	struct sockaddr_ec *saddr=(struct sockaddr_ec *)msg->msg_name;
	struct net_device *dev;
	struct ec_addr addr;
	int err;
	unsigned char port, cb;
#if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)
	struct sk_buff *skb;
	struct ec_cb *eb;
#endif
#ifdef CONFIG_ECONET_AUNUDP
	struct msghdr udpmsg;
	struct iovec iov[msg->msg_iovlen+1];
	struct aunhdr ah;
	struct sockaddr_in udpdest;
	__kernel_size_t size;
	int i;
	mm_segment_t oldfs;
#endif

	/*
	 *	Check the flags.
	 */

	if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_CMSG_COMPAT))
		return -EINVAL;

	/*
	 *	Get and verify the address.
	 */

	mutex_lock(&econet_mutex);

	if (saddr == NULL) {
		struct econet_sock *eo = ec_sk(sk);

		addr.station = eo->station;
		addr.net     = eo->net;
		port	     = eo->port;
		cb	     = eo->cb;
	} else {
		if (msg->msg_namelen < sizeof(struct sockaddr_ec)) {
			mutex_unlock(&econet_mutex);
			return -EINVAL;
		}
		addr.station = saddr->addr.station;
		addr.net = saddr->addr.net;
		port = saddr->port;
		cb = saddr->cb;
	}

	/* Look for a device with the right network number. */
	dev = net2dev_map[addr.net];

	/* If not directly reachable, use some default */
	if (dev == NULL) {
		dev = net2dev_map[0];
		/* No interfaces at all? */
		if (dev == NULL) {
			mutex_unlock(&econet_mutex);
			return -ENETDOWN;
		}
	}

	if (len + 15 > dev->mtu) {
		mutex_unlock(&econet_mutex);
		return -EMSGSIZE;
	}

	if (dev->type == ARPHRD_ECONET) {
		/* Real hardware Econet.  We're not worthy etc. */
#ifdef CONFIG_ECONET_NATIVE
		unsigned short proto = 0;

		dev_hold(dev);

		skb = sock_alloc_send_skb(sk, len+LL_RESERVED_SPACE(dev),
					  msg->msg_flags & MSG_DONTWAIT, &err);
		if (skb==NULL)
			goto out_unlock;

		skb_reserve(skb, LL_RESERVED_SPACE(dev));
		skb_reset_network_header(skb);

		eb = (struct ec_cb *)&skb->cb;

		/* BUG: saddr may be NULL */
		eb->cookie = saddr->cookie;
		eb->sec = *saddr;
		eb->sent = ec_tx_done;

		if (dev->hard_header) {
			int res;
			struct ec_framehdr *fh;
			err = -EINVAL;
			res = dev->hard_header(skb, dev, ntohs(proto),
					       &addr, NULL, len);
//.........这里部分代码省略.........

static int raw_sendmsg(struct kiocb *iocb, struct socket *sock,
		       struct msghdr *msg, size_t size)
{
	struct sock *sk = sock->sk;
	struct raw_sock *ro = raw_sk(sk);
	struct sk_buff *skb;
	struct net_device *dev;
	int ifindex;
	int err;

	if (msg->msg_name) {
		struct sockaddr_can *addr =
			(struct sockaddr_can *)msg->msg_name;

		if (msg->msg_namelen < sizeof(*addr))
			return -EINVAL;

		if (addr->can_family != AF_CAN)
			return -EINVAL;

		ifindex = addr->can_ifindex;
	} else
		ifindex = ro->ifindex;

	if (size != sizeof(struct can_frame))
		return -EINVAL;

	dev = dev_get_by_index(&init_net, ifindex);
	if (!dev)
		return -ENXIO;

	skb = sock_alloc_send_skb(sk, size, msg->msg_flags & MSG_DONTWAIT,
				  &err);
	if (!skb)
		goto put_dev;

	err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
	if (err < 0)
		goto free_skb;
	err = sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
	if (err < 0)
		goto free_skb;

	/* to be able to check the received tx sock reference in raw_rcv() */
	skb_shinfo(skb)->tx_flags |= SKBTX_DRV_NEEDS_SK_REF;

	skb->dev = dev;
	skb->sk  = sk;

	err = can_send(skb, ro->loopback);

	dev_put(dev);

	if (err)
		goto send_failed;

	return size;

free_skb:
	kfree_skb(skb);
put_dev:
	dev_put(dev);
send_failed:
	return err;
}

//.........这里部分代码省略.........
		if (pktlength > 0xFFFF + sizeof(struct ipv6hdr)) {
			/* Jumbo datagram.
			   It is assumed, that in the case of hdrincl
			   jumbo option is supplied by user.
			 */
			pktlength += 8;
			jumbolen = pktlength - sizeof(struct ipv6hdr);
		}
	}

	mtu = dst->pmtu;
	if (np->frag_size < mtu) {
		if (np->frag_size)
			mtu = np->frag_size;
		else if (np->pmtudisc == IPV6_PMTUDISC_DONT)
			mtu = IPV6_MIN_MTU;
	}

	/* Critical arithmetic overflow check.
	   FIXME: may gcc optimize it out? --ANK (980726)
	 */
	if (pktlength < length) {
		ipv6_local_error(sk, EMSGSIZE, fl, mtu);
		err = -EMSGSIZE;
		goto out;
	}

	if (flags&MSG_CONFIRM)
		dst_confirm(dst);

	if (pktlength <= mtu) {
		struct sk_buff *skb;
		struct ipv6hdr *hdr;
		struct net_device *dev = dst->dev;

		err = 0;
		if (flags&MSG_PROBE)
			goto out;

		skb = sock_alloc_send_skb(sk, pktlength + 15 +
					  dev->hard_header_len,
					  flags & MSG_DONTWAIT, &err);

		if (skb == NULL) {
			IP6_INC_STATS(Ip6OutDiscards);
			goto out;
		}

		skb->dst = dst_clone(dst);

		skb_reserve(skb, (dev->hard_header_len + 15) & ~15);

		hdr = (struct ipv6hdr *) skb->tail;
		skb->nh.ipv6h = hdr;

		if (!sk->protinfo.af_inet.hdrincl) {
			ip6_bld_1(sk, skb, fl, hlimit,
				  jumbolen ? sizeof(struct ipv6hdr) : pktlength);

			if (opt || jumbolen) {
				u8 *prev_hdr = &hdr->nexthdr;
				prev_hdr = ipv6_build_nfrag_opts(skb, prev_hdr, opt, final_dst, jumbolen);
				if (opt && opt->opt_flen)
					ipv6_build_frag_opts(skb, prev_hdr, opt);
			}
		}

		skb_put(skb, length);
		err = getfrag(data, &hdr->saddr,
			      ((char *) hdr) + (pktlength - length),
			      0, length);

		if (!err) {
			IP6_INC_STATS(Ip6OutRequests);
			err = NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, dst->dev, ip6_maybe_reroute);
		} else {
			err = -EFAULT;
			kfree_skb(skb);
		}
	} else {
		if (sk->protinfo.af_inet.hdrincl || jumbolen ||
		    np->pmtudisc == IPV6_PMTUDISC_DO) {
			ipv6_local_error(sk, EMSGSIZE, fl, mtu);
			err = -EMSGSIZE;
			goto out;
		}

		err = ip6_frag_xmit(sk, getfrag, data, dst, fl, opt, final_dst, hlimit,
				    flags, length, mtu);
	}

	/*
	 *	cleanup
	 */
out:
	ip6_dst_store(sk, dst, fl->nl_u.ip6_u.daddr == &np->daddr ? &np->daddr : NULL);
	if (err > 0)
		err = np->recverr ? net_xmit_errno(err) : 0;
	return err;
}