Add a generic iov_truncate() function that truncates an IO vector to a
given number of bytes, returning the number of iov entries that contain
data after truncation.
Use it in udp_vu_sock_recv() and tcp_vu_sock_recv() to replace the
open-coded truncation logic that adjusted iov entries after recvmsg().
Also convert the direct iov_len assignment in tcp_vu_send_flag() to use
iov_truncate() for consistency.
Add an ASSERT() in tcp_vu_data_from_sock() to quiet the Coverity error:
passt/tcp_vu.c:457:3:
19. overflow_const: Expression "dlen + hdrlen", where "dlen" is known to
be equal to -86, and "hdrlen" is known to be equal to 86, underflows
the type of "dlen + hdrlen", which is type "unsigned long".
Signed-off-by: Laurent Vivier
---
iov.c | 22 ++++++++++++++++++++++
iov.h | 1 +
tcp_vu.c | 20 ++++++++------------
udp_vu.c | 12 +++---------
4 files changed, 34 insertions(+), 21 deletions(-)
diff --git a/iov.c b/iov.c
index ad726daa4cd8..31a3f5bc29e5 100644
--- a/iov.c
+++ b/iov.c
@@ -147,6 +147,28 @@ size_t iov_size(const struct iovec *iov, size_t iov_cnt)
return len;
}
+/**
+ * iov_truncate() - Truncate an IO vector to a given number of bytes
+ * @iov: IO vector (modified)
+ * @iov_cnt: Number of entries in @iov
+ * @size: Total number of bytes to keep
+ *
+ * Return: number of iov entries that contain data after truncation
+ */
+size_t iov_truncate(struct iovec *iov, size_t iov_cnt, size_t size)
+{
+ size_t i, offset;
+
+ i = iov_skip_bytes(iov, iov_cnt, size, &offset);
+
+ if (i < iov_cnt) {
+ iov[i].iov_len = offset;
+ i += !!offset;
+ }
+
+ return i;
+}
+
/**
* iov_tail_prune() - Remove any unneeded buffers from an IOV tail
* @tail: IO vector tail (modified)
diff --git a/iov.h b/iov.h
index d1ab91a94e22..b4e50b0fca5a 100644
--- a/iov.h
+++ b/iov.h
@@ -29,6 +29,7 @@ size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,
size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt,
size_t offset, void *buf, size_t bytes);
size_t iov_size(const struct iovec *iov, size_t iov_cnt);
+size_t iov_truncate(struct iovec *iov, size_t iov_cnt, size_t size);
/*
* DOC: Theory of Operation, struct iov_tail
diff --git a/tcp_vu.c b/tcp_vu.c
index 88be232dca66..fd734e857b3b 100644
--- a/tcp_vu.c
+++ b/tcp_vu.c
@@ -131,7 +131,7 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
return ret;
}
- flags_elem[0].in_sg[0].iov_len = hdrlen + optlen;
+ iov_truncate(&flags_iov[0], 1, hdrlen + optlen);
payload = IOV_TAIL(flags_elem[0].in_sg, 1, hdrlen);
if (flags & KEEPALIVE)
@@ -192,9 +192,9 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
struct msghdr mh_sock = { 0 };
uint16_t mss = MSS_GET(conn);
int s = conn->sock;
- ssize_t ret, len;
size_t hdrlen;
int elem_cnt;
+ ssize_t ret;
int i;
*iov_cnt = 0;
@@ -247,15 +247,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
ret -= already_sent;
/* adjust iov number and length of the last iov */
- len = ret;
- for (i = 0; len && i < elem_cnt; i++) {
- struct iovec *iov = &elem[i].in_sg[0];
-
- if (iov->iov_len > (size_t)len)
- iov->iov_len = len;
-
- len -= iov->iov_len;
- }
+ i = iov_truncate(&iov_vu[DISCARD_IOV_NUM], elem_cnt, ret);
/* adjust head count */
while (*head_cnt > 0 && head[*head_cnt - 1] >= i)
@@ -448,10 +440,14 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
for (i = 0, previous_dlen = -1, check = NULL; i < head_cnt; i++) {
struct iovec *iov = &elem[head[i]].in_sg[0];
int buf_cnt = head[i + 1] - head[i];
- ssize_t dlen = iov_size(iov, buf_cnt) - hdrlen;
+ size_t frame_size = iov_size(iov, buf_cnt);
bool push = i == head_cnt - 1;
+ ssize_t dlen;
size_t l2len;
+ ASSERT(frame_size >= hdrlen);
+
+ dlen = frame_size - hdrlen;
vu_set_vnethdr(iov->iov_base, buf_cnt);
/* The IPv4 header checksum varies only with dlen */
diff --git a/udp_vu.c b/udp_vu.c
index 3520f89e5671..5effca777e0a 100644
--- a/udp_vu.c
+++ b/udp_vu.c
@@ -71,9 +71,9 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
bool v6, ssize_t *dlen)
{
const struct vu_dev *vdev = c->vdev;
- int iov_cnt, idx, iov_used;
- size_t off, hdrlen, l2len;
struct msghdr msg = { 0 };
+ int iov_cnt, iov_used;
+ size_t hdrlen, l2len;
ASSERT(!c->no_udp);
@@ -115,13 +115,7 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
iov_vu[0].iov_base = (char *)iov_vu[0].iov_base - hdrlen;
iov_vu[0].iov_len += hdrlen;
- /* count the numbers of buffer filled by recvmsg() */
- idx = iov_skip_bytes(iov_vu, iov_cnt, *dlen + hdrlen, &off);
-
- /* adjust last iov length */
- if (idx < iov_cnt)
- iov_vu[idx].iov_len = off;
- iov_used = idx + !!off;
+ iov_used = iov_truncate(iov_vu, iov_cnt, *dlen + hdrlen);
/* pad frame to 60 bytes: first buffer is at least ETH_ZLEN long */
l2len = *dlen + hdrlen - VNET_HLEN;
--
2.53.0