address: Simplify functions

This patch improves looping through the octets of an IP address and
avoids that we will read anything that isn't for us.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

diff --git a/src/libloc/address.h b/src/libloc/address.h
index 754387e97b7a21cad596cc5b574d1d31558e6afd..bc1d7444c1db4baf9eab7a61e9a714cd50934c34 100644 (file)
--- a/src/libloc/address.h
+++ b/src/libloc/address.h
@@ -78,6 +78,9 @@ static inline int loc_address_cmp(const struct in6_addr* a1, const struct in6_ad
 #define foreach_octet_in_address(octet, address) \
        for (octet = (IN6_IS_ADDR_V4MAPPED(address) ? 12 : 0); octet <= 15; octet++)
 
+#define foreach_octet_in_address_reverse(octet, address) \
+       for (octet = 15; octet >= (IN6_IS_ADDR_V4MAPPED(address) ? 12 : 0); octet--)
+
 static inline int loc_address_all_zeroes(const struct in6_addr* address) {
        int octet = 0;
 
@@ -124,39 +127,14 @@ static inline struct in6_addr loc_prefix_to_bitmask(const unsigned int prefix) {
        return bitmask;
 }
 
-static inline unsigned int __loc_address6_bit_length(const struct in6_addr* address) {
-       unsigned int length = 128;
-
-       for (int octet = 0; octet <= 15; octet++) {
-               if (address->s6_addr[octet]) {
-                       length -= __builtin_clz(address->s6_addr[octet]) - 24;
-                       break;
-               } else
-                       length -= 8;
-       }
-
-       return length;
-}
-
-static inline unsigned int __loc_address4_bit_length(const struct in6_addr* address) {
-       unsigned int length = 32;
-
-       for (int octet = 12; octet <= 15; octet++) {
-               if (address->s6_addr[octet]) {
-                       length -= __builtin_clz(address->s6_addr[octet]) - 24;
-                       break;
-               } else
-                       length -= 8;
+static inline unsigned int loc_address_bit_length(const struct in6_addr* address) {
+       int octet = 0;
+       foreach_octet_in_address(octet, address) {
+               if (address->s6_addr[octet])
+                       return (15 - octet) * 8 + 32 - __builtin_clz(address->s6_addr[octet]);
        }
 
-       return length;
-}
-
-static inline unsigned int loc_address_bit_length(const struct in6_addr* address) {
-       if (IN6_IS_ADDR_V4MAPPED(address))
-               return __loc_address4_bit_length(address);
-       else
-               return __loc_address6_bit_length(address);
+       return 0;
 }
 
 static inline int loc_address_reset(struct in6_addr* address, int family) {
@@ -221,38 +199,6 @@ static inline struct in6_addr loc_address_or(
        return a;
 }
 
-static inline int __loc_address6_sub(struct in6_addr* result,
-               const struct in6_addr* address1, const struct in6_addr* address2) {
-       int remainder = 0;
-
-       for (int octet = 15; octet >= 0; octet--) {
-               int x = address1->s6_addr[octet] - address2->s6_addr[octet] + remainder;
-
-               // Store remainder for the next iteration
-               remainder = (x >> 8);
-
-               result->s6_addr[octet] = x & 0xff;
-       }
-
-       return 0;
-}
-
-static inline int __loc_address4_sub(struct in6_addr* result,
-               const struct in6_addr* address1, const struct in6_addr* address2) {
-       int remainder = 0;
-
-       for (int octet = 15; octet >= 12; octet--) {
-               int x = address1->s6_addr[octet] - address2->s6_addr[octet] + remainder;
-
-               // Store remainder for the next iteration
-               remainder = (x >> 8);
-
-               result->s6_addr[octet] = x & 0xff;
-       }
-
-       return 0;
-}
-
 static inline int loc_address_sub(struct in6_addr* result,
                const struct in6_addr* address1, const struct in6_addr* address2) {
        int family1 = loc_address_family(address1);
@@ -269,17 +215,19 @@ static inline int loc_address_sub(struct in6_addr* result,
        if (r)
                return r;
 
-       switch (family1) {
-               case AF_INET6:
-                       return __loc_address6_sub(result, address1, address2);
+       int octet = 0;
+       int remainder = 0;
 
-               case AF_INET:
-                       return __loc_address4_sub(result, address1, address2);
+       foreach_octet_in_address_reverse(octet, address1) {
+               int x = address1->s6_addr[octet] - address2->s6_addr[octet] + remainder;
 
-               default:
-                       errno = ENOTSUP;
-                       return 1;
+               // Store remainder for the next iteration
+               remainder = (x >> 8);
+
+               result->s6_addr[octet] = x & 0xff;
        }
+
+       return 0;
 }
 
 static inline void loc_address_increment(struct in6_addr* address) {
@@ -287,7 +235,8 @@ static inline void loc_address_increment(struct in6_addr* address) {
        if (loc_address_all_ones(address))
                return;
 
-       for (int octet = 15; octet >= 0; octet--) {
+       int octet = 0;
+       foreach_octet_in_address_reverse(octet, address) {
                if (address->s6_addr[octet] < 255) {
                        address->s6_addr[octet]++;
                        break;
@@ -302,7 +251,8 @@ static inline void loc_address_decrement(struct in6_addr* address) {
        if (loc_address_all_zeroes(address))
                return;
 
-       for (int octet = 15; octet >= 0; octet--) {
+       int octet = 0;
+       foreach_octet_in_address_reverse(octet, address) {
                if (address->s6_addr[octet] > 0) {
                        address->s6_addr[octet]--;
                        break;
@@ -313,7 +263,8 @@ static inline void loc_address_decrement(struct in6_addr* address) {
 static inline int loc_address_count_trailing_zero_bits(const struct in6_addr* address) {
        int zeroes = 0;
 
-       for (int octet = 15; octet >= 0; octet--) {
+       int octet = 0;
+       foreach_octet_in_address_reverse(octet, address) {
                if (address->s6_addr[octet]) {
                        zeroes += __builtin_ctz(address->s6_addr[octet]);
                        break;