The TCP and UDP checksums are computed using the data in the TCP/UDP
payload but also some informations in the IP header (protocol,
length, source and destination addresses).
We add two functions, proto_ipv4_header_psum() and
proto_ipv6_header_psum(), to compute the checksum of the IP
header part.
Signed-off-by: Laurent Vivier
---
Notes:
v3:
- function parameters provide tot_len, saddr, daddr and protocol
rather than an iphdr/ipv6hdr
v2:
- move new function to checksum.c
- use _psum rather than _checksum in the name
- replace csum_udp4() and csum_udp6() by the new function
checksum.c | 67 ++++++++++++++++++++++++++++++++++++++++++------------
checksum.h | 4 ++++
tcp.c | 44 ++++++++++++++++-------------------
udp.c | 10 ++++----
4 files changed, 81 insertions(+), 44 deletions(-)
diff --git a/checksum.c b/checksum.c
index 511b296a9a80..55bf1340a257 100644
--- a/checksum.c
+++ b/checksum.c
@@ -134,6 +134,30 @@ uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol,
return ~csum_fold(sum);
}
+/**
+ * proto_ipv4_header_psum() - Calculates the partial checksum of an
+ * IPv4 header for UDP or TCP
+ * @tot_len: Payload length
+ * @proto: Protocol number
+ * @saddr: Source address
+ * @daddr: Destination address
+ * @proto: proto Protocol number
+ * Returns: Partial checksum of the IPv4 header
+ */
+uint32_t proto_ipv4_header_psum(uint16_t tot_len, uint8_t protocol,
+ uint32_t saddr, uint32_t daddr)
+{
+ uint32_t psum = htons(protocol);
+
+ psum += (saddr >> 16) & 0xffff;
+ psum += saddr & 0xffff;
+ psum += (daddr >> 16) & 0xffff;
+ psum += daddr & 0xffff;
+ psum += htons(ntohs(tot_len) - 20);
+
+ return psum;
+}
+
/**
* csum_udp4() - Calculate and set checksum for a UDP over IPv4 packet
* @udp4hr: UDP header, initialised apart from checksum
@@ -150,14 +174,10 @@ void csum_udp4(struct udphdr *udp4hr,
udp4hr->check = 0;
if (UDP4_REAL_CHECKSUMS) {
- /* UNTESTED: if we did want real UDPv4 checksums, this
- * is roughly what we'd need */
- uint32_t psum = csum_fold(saddr.s_addr)
- + csum_fold(daddr.s_addr)
- + htons(len + sizeof(*udp4hr))
- + htons(IPPROTO_UDP);
- /* Add in partial checksum for the UDP header alone */
- psum += sum_16b(udp4hr, sizeof(*udp4hr));
+ uint32_t psum = proto_ipv4_header_psum(len, IPPROTO_UDP,
+ saddr.s_addr,
+ daddr.s_addr);
+ psum = csum_unfolded(udp4hr, sizeof(struct udphdr), psum);
udp4hr->check = csum(payload, len, psum);
}
}
@@ -180,6 +200,26 @@ void csum_icmp4(struct icmphdr *icmp4hr, const void *payload, size_t len)
icmp4hr->checksum = csum(payload, len, psum);
}
+/**
+ * proto_ipv6_header_psum() - Calculates the partial checksum of an
+ * IPv6 header for UDP or TCP
+ * @payload_len: Payload length
+ * @proto: Protocol number
+ * @saddr: Source address
+ * @daddr: Destination address
+ * Returns: Partial checksum of the IPv6 header
+ */
+uint32_t proto_ipv6_header_psum(uint16_t payload_len, uint8_t protocol,
+ struct in6_addr saddr, struct in6_addr daddr)
+{
+ uint32_t sum = htons(protocol) + payload_len;
+
+ sum += sum_16b(&saddr, sizeof(saddr));
+ sum += sum_16b(&daddr, sizeof(daddr));
+
+ return sum;
+}
+
/**
* csum_udp6() - Calculate and set checksum for a UDP over IPv6 packet
* @udp6hr: UDP header, initialised apart from checksum
@@ -190,14 +230,11 @@ void csum_udp6(struct udphdr *udp6hr,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const void *payload, size_t len)
{
- /* Partial checksum for the pseudo-IPv6 header */
- uint32_t psum = sum_16b(saddr, sizeof(*saddr)) +
- sum_16b(daddr, sizeof(*daddr)) +
- htons(len + sizeof(*udp6hr)) + htons(IPPROTO_UDP);
-
+ uint32_t psum = proto_ipv6_header_psum(len, IPPROTO_UDP,
+ *saddr, *daddr);
udp6hr->check = 0;
- /* Add in partial checksum for the UDP header alone */
- psum += sum_16b(udp6hr, sizeof(*udp6hr));
+
+ psum = csum_unfolded(udp6hr, sizeof(struct udphdr), psum);
udp6hr->check = csum(payload, len, psum);
}
diff --git a/checksum.h b/checksum.h
index 92db73612b6e..b2b5b8e8b77e 100644
--- a/checksum.h
+++ b/checksum.h
@@ -15,10 +15,14 @@ uint16_t csum_fold(uint32_t sum);
uint16_t csum_unaligned(const void *buf, size_t len, uint32_t init);
uint16_t csum_ip4_header(uint16_t tot_len, uint8_t protocol,
uint32_t saddr, uint32_t daddr);
+uint32_t proto_ipv4_header_psum(uint16_t tot_len, uint8_t protocol,
+ uint32_t saddr, uint32_t daddr);
void csum_udp4(struct udphdr *udp4hr,
struct in_addr saddr, struct in_addr daddr,
const void *payload, size_t len);
void csum_icmp4(struct icmphdr *ih, const void *payload, size_t len);
+uint32_t proto_ipv6_header_psum(uint16_t payload_len, uint8_t protocol,
+ struct in6_addr saddr, struct in6_addr daddr);
void csum_udp6(struct udphdr *udp6hr,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const void *payload, size_t len);
diff --git a/tcp.c b/tcp.c
index 8887656d3ee8..8ee252131504 100644
--- a/tcp.c
+++ b/tcp.c
@@ -938,39 +938,29 @@ static void tcp_sock_set_bufsize(const struct ctx *c, int s)
* tcp_update_check_tcp4() - Update TCP checksum from stored one
* @buf: L2 packet buffer with final IPv4 header
*/
-static void tcp_update_check_tcp4(struct tcp4_l2_buf_t *buf)
+static void tcp_update_check_tcp4(struct iphdr *iph)
{
- uint16_t tlen = ntohs(buf->iph.tot_len) - 20;
- uint32_t sum = htons(IPPROTO_TCP);
+ struct tcphdr *th = (struct tcphdr *)(iph + 1);
+ uint16_t tlen = ntohs(iph->tot_len) - 20;
+ uint32_t sum = proto_ipv4_header_psum(iph->tot_len, IPPROTO_TCP,
+ iph->saddr, iph->daddr);
- sum += (buf->iph.saddr >> 16) & 0xffff;
- sum += buf->iph.saddr & 0xffff;
- sum += (buf->iph.daddr >> 16) & 0xffff;
- sum += buf->iph.daddr & 0xffff;
- sum += htons(ntohs(buf->iph.tot_len) - 20);
-
- buf->th.check = 0;
- buf->th.check = csum(&buf->th, tlen, sum);
+ th->check = 0;
+ th->check = csum(th, tlen, sum);
}
/**
* tcp_update_check_tcp6() - Calculate TCP checksum for IPv6
* @buf: L2 packet buffer with final IPv6 header
*/
-static void tcp_update_check_tcp6(struct tcp6_l2_buf_t *buf)
+static void tcp_update_check_tcp6(struct ipv6hdr *ip6h)
{
- int len = ntohs(buf->ip6h.payload_len) + sizeof(struct ipv6hdr);
-
- buf->ip6h.hop_limit = IPPROTO_TCP;
- buf->ip6h.version = 0;
- buf->ip6h.nexthdr = 0;
+ struct tcphdr *th = (struct tcphdr *)(ip6h + 1);
+ uint32_t sum = proto_ipv6_header_psum(ip6h->payload_len, IPPROTO_TCP,
+ ip6h->saddr, ip6h->daddr);
- buf->th.check = 0;
- buf->th.check = csum(&buf->ip6h, len, 0);
-
- buf->ip6h.hop_limit = 255;
- buf->ip6h.version = 6;
- buf->ip6h.nexthdr = IPPROTO_TCP;
+ th->check = 0;
+ th->check = csum(th, ntohs(ip6h->payload_len), sum);
}
/**
@@ -1382,7 +1372,7 @@ do { \
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
- tcp_update_check_tcp4(b);
+ tcp_update_check_tcp4(&b->iph);
tlen = tap_iov_len(c, &b->taph, ip_len);
} else {
@@ -1401,7 +1391,11 @@ do { \
SET_TCP_HEADER_COMMON_V4_V6(b, conn, seq);
- tcp_update_check_tcp6(b);
+ tcp_update_check_tcp6(&b->ip6h);
+
+ b->ip6h.hop_limit = 255;
+ b->ip6h.version = 6;
+ b->ip6h.nexthdr = IPPROTO_TCP;
b->ip6h.flow_lbl[0] = (conn->sock >> 16) & 0xf;
b->ip6h.flow_lbl[1] = (conn->sock >> 8) & 0xff;
diff --git a/udp.c b/udp.c
index cd34f659210b..e123b35a955c 100644
--- a/udp.c
+++ b/udp.c
@@ -670,10 +670,12 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
b->uh.source = b->s_in6.sin6_port;
b->uh.dest = htons(dstport);
b->uh.len = b->ip6h.payload_len;
-
- b->ip6h.hop_limit = IPPROTO_UDP;
- b->ip6h.version = b->ip6h.nexthdr = b->uh.check = 0;
- b->uh.check = csum(&b->ip6h, ip_len, 0);
+ b->uh.check = 0;
+ b->uh.check = csum(&b->uh, ntohs(b->ip6h.payload_len),
+ proto_ipv6_header_psum(b->ip6h.payload_len,
+ IPPROTO_UDP,
+ b->ip6h.saddr,
+ b->ip6h.daddr));
b->ip6h.version = 6;
b->ip6h.nexthdr = IPPROTO_UDP;
b->ip6h.hop_limit = 255;
--
2.42.0