lib: add internet checksum with pseudoheaders

Add convenience functions to compute the Internet checksum of a data
block, including a pseudoheader.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

diff --git a/lib/checksum.c b/lib/checksum.c
index 18e385047443ff829defdab2bb0ac528c1f5454d..34733700417f1f3020df37dc71aab0e1957129ff 100644 (file)
--- a/lib/checksum.c
+++ b/lib/checksum.c
@@ -46,6 +46,24 @@ int /* return checksum in low-order 16 bits */
        return (answer);
 }
 
+int in_cksum_with_ph4(struct ipv4_ph *ph, void *data, int nbytes)
+{
+       uint8_t dat[sizeof(struct ipv4_ph) + nbytes];
+
+       memcpy(dat, ph, sizeof(struct ipv4_ph));
+       memcpy(dat + sizeof(struct ipv4_ph), data, nbytes);
+       return in_cksum(dat, sizeof(dat));
+}
+
+int in_cksum_with_ph6(struct ipv6_ph *ph, void *data, int nbytes)
+{
+       uint8_t dat[sizeof(struct ipv6_ph) + nbytes];
+
+       memcpy(dat, ph, sizeof(struct ipv6_ph));
+       memcpy(dat + sizeof(struct ipv6_ph), data, nbytes);
+       return in_cksum(dat, sizeof(dat));
+}
+
 /* Fletcher Checksum -- Refer to RFC1008. */
 #define MODX                 4102U   /* 5802 should be fine */
 

diff --git a/lib/checksum.h b/lib/checksum.h
index 7d5037143975e4882a177c5beef846e7352b9893..56771d4f24ea6cceec0e6bbe56e0d2833bf6309c 100644 (file)
--- a/lib/checksum.h
+++ b/lib/checksum.h
@@ -1,8 +1,33 @@
+#include <stdint.h>
+#include <netinet/in.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-extern int in_cksum(void *, int);
+
+/* IPv4 pseudoheader */
+struct ipv4_ph {
+       struct in_addr src;
+       struct in_addr dst;
+       uint8_t rsvd;
+       uint8_t proto;
+       uint16_t len;
+} __attribute__((packed));
+
+/* IPv6 pseudoheader */
+struct ipv6_ph {
+       struct in6_addr src;
+       struct in6_addr dst;
+       uint32_t ulpl;
+       uint8_t zero[3];
+       uint8_t next_hdr;
+} __attribute__((packed));
+
+extern int in_cksum(void *data, int nbytes);
+extern int in_cksum_with_ph4(struct ipv4_ph *ph, void *data, int nbytes);
+extern int in_cksum_with_ph6(struct ipv6_ph *ph, void *data, int nbytes);
+
 #define FLETCHER_CHECKSUM_VALIDATE 0xffff
 extern uint16_t fletcher_checksum(uint8_t *, const size_t len,
                                  const uint16_t offset);