skbuff: Function to send an skbuf on a socket

Add skb_send_sock to send an skbuff on a socket within the kernel.
Arguments include an offset so that an skbuf might be sent in mulitple
calls (e.g. send buffer limit is hit).

Signed-off-by: Tom Herbert <tom@quantonium.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 101 insertions, 0 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c27da51d14e4..9c0e015ff3fe 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1982,6 +1982,107 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
 }
 EXPORT_SYMBOL_GPL(skb_splice_bits);
 
+/* Send skb data on a socket. Socket must be locked. */
+int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
+                         int len)
+{
+        unsigned int orig_len = len;
+        struct sk_buff *head = skb;
+        unsigned short fragidx;
+        int slen, ret;
+
+do_frag_list:
+
+        /* Deal with head data */
+        while (offset < skb_headlen(skb) && len) {
+                struct kvec kv;
+                struct msghdr msg;
+
+                slen = min_t(int, len, skb_headlen(skb) - offset);
+                kv.iov_base = skb->data + offset;
+                kv.iov_len = len;
+                memset(&msg, 0, sizeof(msg));
+
+                ret = kernel_sendmsg_locked(sk, &msg, &kv, 1, slen);
+                if (ret <= 0)
+                        goto error;
+
+                offset += ret;
+                len -= ret;
+        }
+
+        /* All the data was skb head? */
+        if (!len)
+                goto out;
+
+        /* Make offset relative to start of frags */
+        offset -= skb_headlen(skb);
+
+        /* Find where we are in frag list */
+        for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
+                skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
+
+                if (offset < frag->size)
+                        break;
+
+                offset -= frag->size;
+        }
+
+        for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
+                skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
+
+                slen = min_t(size_t, len, frag->size - offset);
+
+                while (slen) {
+                        ret = kernel_sendpage_locked(sk, frag->page.p,
+                                                     frag->page_offset + offset,
+                                                     slen, MSG_DONTWAIT);
+                        if (ret <= 0)
+                                goto error;
+
+                        len -= ret;
+                        offset += ret;
+                        slen -= ret;
+                }
+
+                offset = 0;
+        }
+
+        if (len) {
+                /* Process any frag lists */
+
+                if (skb == head) {
+                        if (skb_has_frag_list(skb)) {
+                                skb = skb_shinfo(skb)->frag_list;
+                                goto do_frag_list;
+                        }
+                } else if (skb->next) {
+                        skb = skb->next;
+                        goto do_frag_list;
+                }
+        }
+
+out:
+        return orig_len - len;
+
+error:
+        return orig_len == len ? ret : orig_len - len;
+}
+EXPORT_SYMBOL_GPL(skb_send_sock_locked);
+
+/* Send skb data on a socket. */
+int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
+{
+        int ret = 0;
+
+        lock_sock(sk);
+        ret = skb_send_sock_locked(sk, skb, offset, len);
+        release_sock(sk);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(skb_send_sock);
+
 /**
  *      skb_store_bits - store bits from kernel buffer to skb
  *      @skb: destination buffer