The offset allows any headers that are not part of the data
to checksum to be skipped.
Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>
---
Notes:
v5:
- correctly set the length for the partial csum_unfolded()
v3:
- reorder @offset and @init
v2:
- check iov_skip_bytes() return value
checksum.c | 16 ++++++++++++++--
checksum.h | 3 ++-
2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/checksum.c b/checksum.c
index 006614fcbb28..05d002ab0c25 100644
--- a/checksum.c
+++ b/checksum.c
@@ -59,6 +59,7 @@
#include "util.h"
#include "ip.h"
#include "checksum.h"
+#include "iov.h"
/* Checksums are optional for UDP over IPv4, so we usually just set
* them to 0. Change this to 1 to calculate real UDP over IPv4
@@ -497,16 +498,27 @@ uint16_t csum(const void *buf, size_t len, uint32_t init)
*
* @iov Pointer to the array of IO vectors
* @n Length of the array
+ * @offset: Offset of the data to checksum within the full data length
* @init Initial 32-bit checksum, 0 for no pre-computed checksum
*
* Return: 16-bit folded, complemented checksum
*/
/* cppcheck-suppress unusedFunction */
-uint16_t csum_iov(const struct iovec *iov, size_t n, uint32_t init)
+uint16_t csum_iov(const struct iovec *iov, size_t n, size_t offset,
+ uint32_t init)
{
unsigned int i;
+ size_t first;
- for (i = 0; i < n; i++)
+ i = iov_skip_bytes(iov, n, offset, &first);
+ if (i >= n)
+ return (uint16_t)~csum_fold(init);
+
+ init = csum_unfolded((char *)iov[i].iov_base + first,
+ iov[i].iov_len - first, init);
+ i++;
+
+ for (; i < n; i++)
init = csum_unfolded(iov[i].iov_base, iov[i].iov_len, init);
return (uint16_t)~csum_fold(init);
diff --git a/checksum.h b/checksum.h
index c5964ac78921..49f7472dd1b6 100644
--- a/checksum.h
+++ b/checksum.h
@@ -32,6 +32,7 @@ void csum_icmp6(struct icmp6hdr *icmp6hr,
const void *payload, size_t dlen);
uint32_t csum_unfolded(const void *buf, size_t len, uint32_t init);
uint16_t csum(const void *buf, size_t len, uint32_t init);
-uint16_t csum_iov(const struct iovec *iov, size_t n, uint32_t init);
+uint16_t csum_iov(const struct iovec *iov, size_t n, size_t offset,
+ uint32_t init);
#endif /* CHECKSUM_H */
--
2.46.0