[PATCH 3/5] inet: Add ip_make_skb and ip_send_skb

Herbert Xu
2011-02-28T11:41:15Z

inet: Add ip_make_skb and ip_send_skb

This patch adds the helper ip_make_skb which is like ip_append_data
and ip_push_pending_frames all rolled into one, except that it does
not send the skb produced. The sending part is carried out by
ip_send_skb, which the transport protocol can call after it has
tweaked the skb.

It is meant to be called in cases where corking is not used should
have a one-to-one correspondence to sendmsg.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

include/net/ip.h | 8 ++++++
net/ipv4/ip_output.c | 65 ++++++++++++++++++++++++++++++++++++++++-----------
2 files changed, 59 insertions(+), 14 deletions(-)

diff --git a/include/net/ip.h b/include/net/ip.h
index 67fac78..a96e525 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -116,8 +116,16 @@ extern int ip_append_data(struct sock *sk,
extern int ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb);
extern ssize_t ip_append_page(struct sock *sk, struct page *page,
int offset, size_t size, int flags);
+extern int ip_send_skb(struct sk_buff *skb);
extern int ip_push_pending_frames(struct sock *sk);
extern void ip_flush_pending_frames(struct sock *sk);
+extern struct sk_buff *ip_make_skb(struct sock *sk,
+ int getfrag(void *from, char *to, int offset, int len,
+ int odd, struct sk_buff *skb),
+ void *from, int length, int transhdrlen,
+ struct ipcm_cookie *ipc,
+ struct rtable **rtp,
+ unsigned int flags);

/* datagram.c */
extern int ip4_datagram_connect(struct sock *sk,
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 1dd5ecc..dba14c6 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1267,9 +1267,9 @@ static void ip_cork_release(struct inet_cork *cork)
* Combined all pending IP fragments on the socket as one IP datagram
* and push them out.
*/
-static int __ip_push_pending_frames(struct sock *sk,
- struct sk_buff_head *queue,
- struct inet_cork *cork)
+static struct sk_buff *__ip_make_skb(struct sock *sk,
+ struct sk_buff_head *queue,
+ struct inet_cork *cork)
{
struct sk_buff *skb, *tmp_skb;
struct sk_buff **tail_skb;
@@ -1280,7 +1280,6 @@ static int __ip_push_pending_frames(struct sock *sk,
struct iphdr *iph;
__be16 df = 0;
__u8 ttl;
- int err = 0;

if ((skb = __skb_dequeue(queue)) == NULL)
goto out;
@@ -1351,28 +1350,37 @@ static int __ip_push_pending_frames(struct sock *sk,
icmp_out_count(net, ((struct icmphdr *)
skb_transport_header(skb))->type);

- /* Netfilter gets whole the not fragmented skb. */
+ ip_cork_release(cork);
+out:
+ return skb;
+}
+
+int ip_send_skb(struct sk_buff *skb)
+{
+ struct net *net = sock_net(skb->sk);
+ int err;
+
err = ip_local_out(skb);
if (err) {
if (err > 0)
err = net_xmit_errno(err);
if (err)
- goto error;
+ IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
}

-out:
- ip_cork_release(cork);
return err;
-
-error:
- IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
- goto out;
}

int ip_push_pending_frames(struct sock *sk)
{
- return __ip_push_pending_frames(sk, &sk->sk_write_queue,
- &inet_sk(sk)->cork);
+ struct sk_buff *skb;
+
+ skb = __ip_make_skb(sk, &sk->sk_write_queue, &inet_sk(sk)->cork);
+ if (!skb)
+ return 0;
+
+ /* Netfilter gets whole the not fragmented skb. */
+ return ip_send_skb(skb);
}

/*
@@ -1395,6 +1403,35 @@ void ip_flush_pending_frames(struct sock *sk)
__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork);
}

+struct sk_buff *ip_make_skb(struct sock *sk,
+ int getfrag(void *from, char *to, int offset,
+ int len, int odd, struct sk_buff *skb),
+ void *from, int length, int transhdrlen,
+ struct ipcm_cookie *ipc, struct rtable **rtp,
+ unsigned int flags)
+{
+ struct inet_cork cork = {};
+ struct sk_buff_head queue;
+ int err;
+
+ if (flags & MSG_PROBE)
+ return NULL;
+
+ __skb_queue_head_init(&queue);
+
+ err = ip_setup_cork(sk, &cork, ipc, rtp);
+ if (err)
+ return ERR_PTR(err);
+
+ err = __ip_append_data(sk, &queue, &cork, getfrag,
+ from, length, transhdrlen, flags);
+ if (err) {
+ __ip_flush_pending_frames(sk, &queue, &cork);
+ return ERR_PTR(err);
+ }
+
+ return __ip_make_skb(sk, &queue, &cork);
+}

/*
* Fetch data from kernel space and fill in checksum if needed.