From: Andre Noll <maan@systemlinux.org>
Date: Tue, 16 Mar 2010 21:14:31 +0000 (+0100)
Subject: udp_recv: Replace recv_bin_buffer() by Use para_readv().
X-Git-Tag: v0.4.2~21^2
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=a31d410d3dbc0f0c866a11a5a46b58054625f4ba

udp_recv: Replace recv_bin_buffer() by Use para_readv().

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.
---

diff --git a/udp_recv.c b/udp_recv.c
index ae2d49f1..c768d324 100644
--- a/udp_recv.c
+++ b/udp_recv.c
@@ -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);