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checksum: use csum_ip4_header() in udp.c and tcp.c

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We can find the same function to compute the IPv4 header
checksum in tcp.c, udp.c and tap.c

Use the function defined for tap.c, csum_ip4_header(), but
with the code used in tcp.c and udp.c as it doesn't need a fully
initialiazed IPv4 header, only protocol, tot_len, saddr and daddr.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Message-ID: <20240303135114.1023026-7-lvivier@redhat.com>
[dwg: Fix weird cppcheck regression; it appears to be a problem
 in pre-existing code, but somehow this patch is exposing it]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Laurent Vivier 2024-03-06 16:58:35 +11:00 committed by Stefano Brivio
parent e82b4fe5fc
commit feb4900c25
5 changed files with 27 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
checksum.c
View File

@ -57,6 +57,7 @@
#include <linux/icmpv6.h>
#include "util.h"
#include "ip.h"
#include "checksum.h"
/* Checksums are optional for UDP over IPv4, so we usually just set
@ -114,13 +115,26 @@ uint16_t csum_fold(uint32_t sum)
}
/**
* csum_ip4_header() - Calculate and set IPv4 header checksum
* @ip4h: IPv4 header
* csum_ip4_header() - Calculate IPv4 header checksum
* @tot_len: IPv4 payload length (data + IP header, network order)
* @protocol: Protocol number (network order)
* @saddr: IPv4 source address (network order)
* @daddr: IPv4 destination address (network order)
*
* Return: 16-bit folded sum of the IPv4 header
*/
void csum_ip4_header(struct iphdr *ip4h)
uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol,
struct in_addr saddr, struct in_addr daddr)
{
ip4h->check = 0;
ip4h->check = csum(ip4h, (size_t)ip4h->ihl * 4, 0);
uint32_t sum = L2_BUF_IP4_PSUM(protocol);
sum += tot_len;
sum += (saddr.s_addr >> 16) & 0xffff;
sum += saddr.s_addr & 0xffff;
sum += (daddr.s_addr >> 16) & 0xffff;
sum += daddr.s_addr & 0xffff;
return ~csum_fold(sum);
}
/**

3
checksum.h
View File

@ -13,7 +13,8 @@ struct icmp6hdr;
uint32_t sum_16b(const void *buf, size_t len);
uint16_t csum_fold(uint32_t sum);
uint16_t csum_unaligned(const void *buf, size_t len, uint32_t init);
void csum_ip4_header(struct iphdr *ip4h);
uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol,
struct in_addr saddr, struct in_addr daddr);
void csum_udp4(struct udphdr *udp4hr,
struct in_addr saddr, struct in_addr daddr,
const void *payload, size_t len);

2
tap.c
View File

@ -161,7 +161,7 @@ static void *tap_push_ip4h(char *buf, struct in_addr src, struct in_addr dst,
ip4h->protocol = proto;
ip4h->saddr = src.s_addr;
ip4h->daddr = dst.s_addr;
csum_ip4_header(ip4h);
ip4h->check = csum_ip4_header(ip4h->tot_len, proto, src, dst);
return ip4h + 1;
}

24
tcp.c
View File

@ -935,23 +935,6 @@ static void tcp_sock_set_bufsize(const struct ctx *c, int s)
trace("TCP: failed to set SO_SNDBUF to %i", v);
}
/**
* tcp_update_check_ip4() - Update IPv4 with variable parts from stored one
* @buf: L2 packet buffer with final IPv4 header
*/
static void tcp_update_check_ip4(struct tcp4_l2_buf_t *buf)
{
uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_TCP);
sum += buf->iph.tot_len;
sum += (buf->iph.saddr >> 16) & 0xffff;
sum += buf->iph.saddr & 0xffff;
sum += (buf->iph.daddr >> 16) & 0xffff;
sum += buf->iph.daddr & 0xffff;
buf->iph.check = (uint16_t)~csum_fold(sum);
}
/**
* tcp_update_check_tcp4() - Update TCP checksum from stored one
* @buf: L2 packet buffer with final IPv4 header
@ -1394,10 +1377,9 @@ do { \
b->iph.saddr = a4->s_addr;
b->iph.daddr = c->ip4.addr_seen.s_addr;
if (check)
b->iph.check = *check;
else
tcp_update_check_ip4(b);
b->iph.check = check ? *check :
csum_ip4_header(b->iph.tot_len, IPPROTO_TCP,
*a4, c->ip4.addr_seen);
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);

20
udp.c
View File

@ -275,23 +275,6 @@ static void udp_invert_portmap(struct udp_fwd_ports *fwd)
}
}
/**
* udp_update_check4() - Update checksum with variable parts from stored one
* @buf: L2 packet buffer with final IPv4 header
*/
static void udp_update_check4(struct udp4_l2_buf_t *buf)
{
uint32_t sum = L2_BUF_IP4_PSUM(IPPROTO_UDP);
sum += buf->iph.tot_len;
sum += (buf->iph.saddr >> 16) & 0xffff;
sum += buf->iph.saddr & 0xffff;
sum += (buf->iph.daddr >> 16) & 0xffff;
sum += buf->iph.daddr & 0xffff;
buf->iph.check = (uint16_t)~csum_fold(sum);
}
/**
* udp_update_l2_buf() - Update L2 buffers with Ethernet and IPv4 addresses
* @eth_d: Ethernet destination address, NULL if unchanged
@ -619,7 +602,8 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
}
b->iph.saddr = src->s_addr;
udp_update_check4(b);
b->iph.check = csum_ip4_header(b->iph.tot_len, IPPROTO_UDP,
*src, c->ip4.addr_seen);
b->uh.source = b->s_in.sin_port;
b->uh.dest = htons(dstport);
b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));