diff options
| -rw-r--r-- | include/net.h | 30 | ||||
| -rw-r--r-- | net/Makefile | 1 | ||||
| -rw-r--r-- | net/checksum.c | 60 |
3 files changed, 91 insertions, 0 deletions
diff --git a/include/net.h b/include/net.h index 3da35fe..73ea88b 100644 --- a/include/net.h +++ b/include/net.h @@ -482,6 +482,36 @@ extern void net_set_ip_header(uchar *pkt, IPaddr_t dest, IPaddr_t source); extern void net_set_udp_header(uchar *pkt, IPaddr_t dest, int dport, int sport, int len); +/** + * compute_ip_checksum() - Compute IP checksum + * + * @addr: Address to check (must be 16-bit aligned) + * @nbytes: Number of bytes to check (normally a multiple of 2) + * @return 16-bit IP checksum + */ +unsigned compute_ip_checksum(const void *addr, unsigned nbytes); + +/** + * add_ip_checksums() - add two IP checksums + * + * @offset: Offset of first sum (if odd we do a byte-swap) + * @sum: First checksum + * @new_sum: New checksum to add + * @return updated 16-bit IP checksum + */ +unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new_sum); + +/** + * ip_checksum_ok() - check if a checksum is correct + * + * This works by making sure the checksum sums to 0 + * + * @addr: Address to check (must be 16-bit aligned) + * @nbytes: Number of bytes to check (normally a multiple of 2) + * @return true if the checksum matches, false if not + */ +int ip_checksum_ok(const void *addr, unsigned nbytes); + /* Checksum */ extern int NetCksumOk(uchar *, int); /* Return true if cksum OK */ extern uint NetCksum(uchar *, int); /* Calculate the checksum */ diff --git a/net/Makefile b/net/Makefile index 9425950..e9cc8ad 100644 --- a/net/Makefile +++ b/net/Makefile @@ -7,6 +7,7 @@ #ccflags-y += -DDEBUG +obj-y += checksum.o obj-$(CONFIG_CMD_NET) += arp.o obj-$(CONFIG_CMD_NET) += bootp.o obj-$(CONFIG_CMD_CDP) += cdp.o diff --git a/net/checksum.c b/net/checksum.c new file mode 100644 index 0000000..a8c9ff5 --- /dev/null +++ b/net/checksum.c @@ -0,0 +1,60 @@ +/* + * This file was originally taken from the FreeBSD project. + * + * Copyright (c) 2001 Charles Mott <cm@linktel.net> + * Copyright (c) 2008 coresystems GmbH + * All rights reserved. + * + * SPDX-License-Identifier: BSD-2-Clause + */ + +#include <common.h> +#include <net.h> + +unsigned compute_ip_checksum(const void *vptr, unsigned nbytes) +{ + int sum, oddbyte; + const unsigned short *ptr = vptr; + + sum = 0; + while (nbytes > 1) { + sum += *ptr++; + nbytes -= 2; + } + if (nbytes == 1) { + oddbyte = 0; + ((u8 *)&oddbyte)[0] = *(u8 *)ptr; + ((u8 *)&oddbyte)[1] = 0; + sum += oddbyte; + } + sum = (sum >> 16) + (sum & 0xffff); + sum += (sum >> 16); + sum = ~sum & 0xffff; + + return sum; +} + +unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new) +{ + unsigned long checksum; + + sum = ~sum & 0xffff; + new = ~new & 0xffff; + if (offset & 1) { + /* + * byte-swap the sum if it came from an odd offset; since the + * computation is endian independant this works. + */ + new = ((new >> 8) & 0xff) | ((new << 8) & 0xff00); + } + checksum = sum + new; + if (checksum > 0xffff) + checksum -= 0xffff; + + return (~checksum) & 0xffff; +} + +int ip_checksum_ok(const void *addr, unsigned nbytes) +{ + return !(compute_ip_checksum(addr, nbytes) & 0xfffe); +} |