xnu-4570.41.2.tar.gz

[apple/xnu.git] / bsd / netinet6 / in6_cksum.c

diff --git a/bsd/netinet6/in6_cksum.c b/bsd/netinet6/in6_cksum.c
index 2bea8cbcc7bf0a3adef902180160d53e296b4dda..394ea35b22314b7d5f196db4aa4759990a40a90e 100644 (file)
--- a/bsd/netinet6/in6_cksum.c
+++ b/bsd/netinet6/in6_cksum.c
@@ -232,3 +232,47 @@ inet6_cksum(struct mbuf *m, uint32_t nxt, uint32_t off, uint32_t len)
 
        return (~sum & 0xffff);
 }
+
+/*
+ * buffer MUST contain at least an IPv6 header, if nxt is specified;
+ * nxt is the upper layer protocol number;
+ * off is an offset where TCP/UDP/ICMP6 header starts;
+ * len is a total length of a transport segment (e.g. TCP header + TCP payload)
+ */
+u_int16_t
+inet6_cksum_buffer(const uint8_t *buffer, uint32_t nxt, uint32_t off,
+    uint32_t len)
+{
+       uint32_t sum;
+
+       if (off >= len)
+               panic("%s: off (%d) >= len (%d)", __func__, off, len);
+
+       sum = b_sum16(&((const uint8_t *)buffer)[off], len);
+
+       if (nxt != 0) {
+               const struct ip6_hdr *ip6;
+               unsigned char buf[sizeof (*ip6)] __attribute__((aligned(8)));
+
+               /*
+                * In case the IPv6 header is not contiguous, or not 32-bit
+                * aligned, copy it to a local buffer.  Note here that we
+                * expect the data pointer to point to the IPv6 header.
+                */
+               if (!IP6_HDR_ALIGNED_P(buffer)) {
+                       memcpy(buf, buffer, sizeof (*ip6));
+                       ip6 = (const struct ip6_hdr *)(const void *)buf;
+               } else {
+                       ip6 = (const struct ip6_hdr *)buffer;
+               }
+
+               /* add pseudo header checksum */
+               sum += in6_pseudo(&ip6->ip6_src, &ip6->ip6_dst,
+                   htonl(nxt + len));
+
+               /* fold in carry bits */
+               ADDCARRY(sum);
+       }
+
+       return (~sum & 0xffff);
+}