On Sat, Sep 23, 2023 at 12:06:30AM +1000, David
Gibson wrote:
We have a bunch of variants of the siphash
functions for different data
sizes. The callers, in tcp.c, need to pack the various values they want to
hash into a temporary structure, then call the appropriate version. We can
avoid the copy into the temporary by directly using the incremental
siphash functions.
The length specific hash functions also have an undocumented constraint
that the data pointer they take must, in fact, be aligned to avoid
unaligned accesses, which may cause crashes on some architectures.
So, prefer the incremental approach and remove the length-specific
functions.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
Makefile | 2 +-
inany.h | 16 ++++++-
siphash.c | 121 ---------------------------------------------------
tcp.c | 32 +++++---------
tcp_splice.c | 1 +
5 files changed, 27 insertions(+), 145 deletions(-)
delete mode 100644 siphash.c
diff --git a/Makefile b/Makefile
index 4435bd6..ec3c3fb 100644
--- a/Makefile
+++ b/Makefile
@@ -45,7 +45,7 @@ FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c icmp.c igmp.c \
isolation.c lineread.c log.c mld.c ndp.c netlink.c packet.c passt.c \
- pasta.c pcap.c siphash.c tap.c tcp.c tcp_splice.c udp.c util.c
+ pasta.c pcap.c tap.c tcp.c tcp_splice.c udp.c util.c
QRAP_SRCS = qrap.c
SRCS = $(PASST_SRCS) $(QRAP_SRCS)
diff --git a/inany.h b/inany.h
index aadb20b..266d101 100644
--- a/inany.h
+++ b/inany.h
@@ -14,8 +14,9 @@
* @v4mapped.zero: All zero-bits for an IPv4 address
* @v4mapped.one: All one-bits for an IPv4 address
* @v4mapped.a4: If @a6 is an IPv4 mapped address, the IPv4 address
+ * @u64: As an array of u64s (solely for hashing)
*
- * @v4mapped shouldn't be accessed except via helpers.
+ * @v4mapped and @u64 shouldn't be accessed except via helpers.
*/
union inany_addr {
struct in6_addr a6;
@@ -24,7 +25,9 @@ union inany_addr {
uint8_t one[2];
struct in_addr a4;
} v4mapped;
+ uint64_t u64[2];
I realised this change alters the alignment of inany from 4 bytes to 8
bytes, which causes problems for things I have in the works. Revised
version coming.
Actually, I might as well wait for any comments you have on v1, before
folding that into v2.