[PATCH 11/18] tcp: Convert tcp_data_from_tap() to use iov_tail

[Laurent Vivier <lvivier@redhat.com>]

Use packet_base() and extract headers using IOV_PEEK_HEADER()
rather than packet_get().

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 tcp.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/tcp.c b/tcp.c
index 790714a08793..a9c04551d9d6 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1643,14 +1643,19 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn,
 	for (i = idx, iov_i = 0; i < (int)p->count; i++) {
 		uint32_t seq, seq_offset, ack_seq;
 		const struct tcphdr *th;
-		char *data;
+		struct iov_tail data;
+		unsigned int count;
+		struct tcphdr thc;
 		size_t off;
 
-		th = packet_get(p, i, 0, sizeof(*th), &len);
+		if (!packet_base(p, i, &data))
+			return -1;
+
+		th = IOV_PEEK_HEADER(&data, thc);
 		if (!th)
 			return -1;
-		len += sizeof(*th);
 
+		len = iov_tail_size(&data);
 		off = th->doff * 4UL;
 		if (off < sizeof(*th) || off > len)
 			return -1;
@@ -1661,9 +1666,7 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn,
 		}
 
 		len -= off;
-		data = packet_get(p, i, off, len, NULL);
-		if (!data)
-			continue;
+		data.off = off;
 
 		seq = ntohl(th->seq);
 		if (SEQ_LT(seq, conn->seq_from_tap) && len <= 1) {
@@ -1737,10 +1740,11 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn,
 			continue;
 		}
 
-		tcp_iov[iov_i].iov_base = data + seq_offset;
-		tcp_iov[iov_i].iov_len = len - seq_offset;
-		seq_from_tap += tcp_iov[iov_i].iov_len;
-		iov_i++;
+		count = iov_copy(&tcp_iov[iov_i], UIO_MAXIOV - iov_i,
+				 &data.iov[0], data.cnt, data.off + seq_offset,
+				 len - seq_offset);
+		seq_from_tap += iov_size(&tcp_iov[iov_i], count);
+		iov_i += count;
 
 		if (keep == i)
 			keep = -1;
-- 
@@ -1643,14 +1643,19 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn,
 	for (i = idx, iov_i = 0; i < (int)p->count; i++) {
 		uint32_t seq, seq_offset, ack_seq;
 		const struct tcphdr *th;
-		char *data;
+		struct iov_tail data;
+		unsigned int count;
+		struct tcphdr thc;
 		size_t off;
 
-		th = packet_get(p, i, 0, sizeof(*th), &len);
+		if (!packet_base(p, i, &data))
+			return -1;
+
+		th = IOV_PEEK_HEADER(&data, thc);
 		if (!th)
 			return -1;
-		len += sizeof(*th);
 
+		len = iov_tail_size(&data);
 		off = th->doff * 4UL;
 		if (off < sizeof(*th) || off > len)
 			return -1;
@@ -1661,9 +1666,7 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn,
 		}
 
 		len -= off;
-		data = packet_get(p, i, off, len, NULL);
-		if (!data)
-			continue;
+		data.off = off;
 
 		seq = ntohl(th->seq);
 		if (SEQ_LT(seq, conn->seq_from_tap) && len <= 1) {
@@ -1737,10 +1740,11 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn,
 			continue;
 		}
 
-		tcp_iov[iov_i].iov_base = data + seq_offset;
-		tcp_iov[iov_i].iov_len = len - seq_offset;
-		seq_from_tap += tcp_iov[iov_i].iov_len;
-		iov_i++;
+		count = iov_copy(&tcp_iov[iov_i], UIO_MAXIOV - iov_i,
+				 &data.iov[0], data.cnt, data.off + seq_offset,
+				 len - seq_offset);
+		seq_from_tap += iov_size(&tcp_iov[iov_i], count);
+		iov_i += count;
 
 		if (keep == i)
 			keep = -1;
-- 
2.49.0