udp_recv: Replace recv_bin_buffer() by Use para_readv().
authorAndre Noll <maan@systemlinux.org>
Tue, 16 Mar 2010 21:14:31 +0000 (22:14 +0100)
committerAndre Noll <maan@systemlinux.org>
Tue, 16 Mar 2010 21:14:31 +0000 (22:14 +0100)
As pointed out by Gerrit Renker, the UDP receiver suffers from the
same problem that was fixed in commit 9e44ee8 for the DCCP receiver:
recv() might lose data if less than a full datagram is available in
the receiving buffer.

This patch solves the problem for udp_recv in the same way as 9e44ee8
does for dccp_recv.

udp_recv.c

index ae2d49f..c768d32 100644 (file)
@@ -44,14 +44,32 @@ static void udp_recv_pre_select(struct sched *s, struct task *t)
        para_fd_set(purd->fd, &s->rfds, &s->max_fileno);
 }
 
+static int udp_check_eof(size_t sz, struct iovec iov[2])
+{
+       if (sz < FEC_EOF_PACKET_LEN)
+               return 0;
+       if (iov[0].iov_len >= FEC_EOF_PACKET_LEN) {
+               if (memcmp(iov[0].iov_base, FEC_EOF_PACKET,
+                               FEC_EOF_PACKET_LEN) != 0)
+                       return 0;
+               return -E_RECV_EOF;
+       }
+       if (memcmp(iov[0].iov_base, FEC_EOF_PACKET, iov[0].iov_len) != 0)
+               return 0;
+       if (memcmp(iov[1].iov_base, FEC_EOF_PACKET + iov[0].iov_len,
+                       FEC_EOF_PACKET_LEN - iov[0].iov_len) != 0)
+               return 0;
+       return -E_RECV_EOF;
+}
+
 static void udp_recv_post_select(__a_unused struct sched *s, struct task *t)
 {
        struct receiver_node *rn = container_of(t, struct receiver_node, task);
        struct private_udp_recv_data *purd = rn->private_data;
        struct btr_node *btrn = rn->btrn;
-       int ret;
-       char *buf = NULL;
-       size_t packet_size, bufsize;
+       size_t packet_size;
+       struct iovec iov[2];
+       int ret, iovcnt;
 
        t->error = 0;
        ret = btr_node_status(btrn, 0, BTR_NT_ROOT);
@@ -61,24 +79,26 @@ static void udp_recv_post_select(__a_unused struct sched *s, struct task *t)
                return;
        if (!FD_ISSET(purd->fd, &s->rfds))
                return;
-       bufsize = btr_pool_get_buffer(purd->btrp, &buf);
+       iovcnt = btr_pool_get_buffers(purd->btrp, iov);
        ret = -E_UDP_OVERRUN;
-       if (bufsize == 0)
+       if (iovcnt == 0)
                goto err;
-       ret = recv_bin_buffer(purd->fd, buf, bufsize);
+       ret = para_readv(purd->fd, iov, iovcnt);
        if (ret == 0)
                ret = -E_RECV_EOF;
        if (ret < 0)
                goto err;
        packet_size = ret;
-       if (packet_size >= FEC_EOF_PACKET_LEN) {
-               if (!memcmp(buf, FEC_EOF_PACKET, FEC_EOF_PACKET_LEN)) {
-                       PARA_INFO_LOG("received eof packet\n");
-                       ret = -E_RECV_EOF;
-                       goto err;
-               }
+       ret = udp_check_eof(packet_size, iov);
+       if (ret < 0)
+               goto err;
+       if (iov[0].iov_len >= packet_size)
+               btr_add_output_pool(purd->btrp, packet_size, btrn);
+       else { /* both buffers contain data */
+               btr_add_output_pool(purd->btrp, iov[0].iov_len, btrn);
+               btr_add_output_pool(purd->btrp, packet_size - iov[0].iov_len,
+                       btrn);
        }
-       btr_add_output_pool(purd->btrp, packet_size, btrn);
        return;
 err:
        btr_remove_node(btrn);