address: Add functions to access a specific byte/nibble in an address

[people/ms/libloc.git] / src / libloc / address.h

diff --git a/src/libloc/address.h b/src/libloc/address.h
index d6d7ca5a0bbdc2e58997759f3a90a1196b0030c0..1c1469646813935d632f8912c7310ce66ab4f90c 100644 (file)
--- a/src/libloc/address.h
+++ b/src/libloc/address.h
@@ -300,6 +300,37 @@ static inline int loc_address_count_trailing_zero_bits(const struct in6_addr* ad
        return zeroes;
 }
 
+static inline int loc_address_get_octet(const struct in6_addr* address, const unsigned int i) {
+       if (IN6_IS_ADDR_V4MAPPED(address)) {
+               if (i >= 4)
+                       return -ERANGE;
+
+               return (address->s6_addr32[3] >> (i * 8)) & 0xff;
+
+       } else {
+               if (i >= 32)
+                       return -ERANGE;
+
+               return address->s6_addr[i];
+       }
+}
+
+static inline int loc_address_get_nibble(const struct in6_addr* address, const unsigned int i) {
+       int octet = 0;
+
+       // Fetch the octet
+       octet = loc_address_get_octet(address, i / 2);
+       if (octet < 0)
+               return octet;
+
+       // Shift if we want an uneven nibble
+       if (i % 2 == 0)
+               octet >>= 4;
+
+       // Return the nibble
+       return octet & 0x0f;
+}
+
 #endif /* LIBLOC_PRIVATE */
 
 #endif /* LIBLOC_ADDRESS_H */