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: 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..16b834641604 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, 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