basic: add explicit ipv4-specific in_addr classification calls

This adds in4_addr_is_localhost() and in4_addr_is_link_local() that only take
an IPv4 "struct in_addr", to match in_addr_is_localhost() and
in_addr_is_link_local() that that a "union in_addr_union".

This matches the existing in4_addr_is_null() call that already exists.

For IPv6 glibc already exports a set of macros, hence we don't add similar
functions in6_addr_is_localhost(). We also drop in6_addr_is_null() as
IN6_IS_ADDR_UNSPECIFIED() already provides that.

3 files changed, 24 insertions, 15 deletions

diff --git a/src/basic/in-addr-util.c b/src/basic/in-addr-util.c
index aa7ccd1afd..d6c979acef 100644
--- a/src/basic/in-addr-util.c
+++ b/src/basic/in-addr-util.c
@@ -31,15 +31,9 @@
 #include "util.h"
 
 bool in4_addr_is_null(const struct in_addr *a) {
-        return a->s_addr == 0;
-}
+        assert(a);
 
-bool in6_addr_is_null(const struct in6_addr *a) {
-        return
-                a->s6_addr32[0] == 0 &&
-                a->s6_addr32[1] == 0 &&
-                a->s6_addr32[2] == 0 &&
-                a->s6_addr32[3] == 0;
+        return a->s_addr == 0;
 }
 
 int in_addr_is_null(int family, const union in_addr_union *u) {
@@ -49,16 +43,22 @@ int in_addr_is_null(int family, const union in_addr_union *u) {
                 return in4_addr_is_null(&u->in);
 
         if (family == AF_INET6)
-                return in6_addr_is_null(&u->in6);
+                return IN6_IS_ADDR_UNSPECIFIED(&u->in6);
 
         return -EAFNOSUPPORT;
 }
 
+bool in4_addr_is_link_local(const struct in_addr *a) {
+        assert(a);
+
+        return (be32toh(a->s_addr) & UINT32_C(0xFFFF0000)) == (UINT32_C(169) << 24 | UINT32_C(254) << 16);
+}
+
 int in_addr_is_link_local(int family, const union in_addr_union *u) {
         assert(u);
 
         if (family == AF_INET)
-                return (be32toh(u->in.s_addr) & UINT32_C(0xFFFF0000)) == (UINT32_C(169) << 24 | UINT32_C(254) << 16);
+                return in4_addr_is_link_local(&u->in);
 
         if (family == AF_INET6)
                 return IN6_IS_ADDR_LINKLOCAL(&u->in6);
@@ -66,12 +66,18 @@ int in_addr_is_link_local(int family, const union in_addr_union *u) {
         return -EAFNOSUPPORT;
 }
 
+bool in4_addr_is_localhost(const struct in_addr *a) {
+        assert(a);
+
+        /* All of 127.x.x.x is localhost. */
+        return (be32toh(a->s_addr) & UINT32_C(0xFF000000)) == UINT32_C(127) << 24;
+}
+
 int in_addr_is_localhost(int family, const union in_addr_union *u) {
         assert(u);
 
         if (family == AF_INET)
-                /* All of 127.x.x.x is localhost. */
-                return (be32toh(u->in.s_addr) & UINT32_C(0xFF000000)) == UINT32_C(127) << 24;
+                return in4_addr_is_localhost(&u->in);
 
         if (family == AF_INET6)
                 return IN6_IS_ADDR_LOOPBACK(&u->in6);
diff --git a/src/basic/in-addr-util.h b/src/basic/in-addr-util.h
index d60064aef8..64a812c322 100644
--- a/src/basic/in-addr-util.h
+++ b/src/basic/in-addr-util.h
@@ -37,11 +37,14 @@ struct in_addr_data {
 };
 
 bool in4_addr_is_null(const struct in_addr *a);
-bool in6_addr_is_null(const struct in6_addr *a);
-
 int in_addr_is_null(int family, const union in_addr_union *u);
+
+bool in4_addr_is_link_local(const struct in_addr *a);
 int in_addr_is_link_local(int family, const union in_addr_union *u);
+
+bool in4_addr_is_localhost(const struct in_addr *a);
 int in_addr_is_localhost(int family, const union in_addr_union *u);
+
 int in_addr_equal(int family, const union in_addr_union *a, const union in_addr_union *b);
 int in_addr_prefix_intersect(int family, const union in_addr_union *a, unsigned aprefixlen, const union in_addr_union *b, unsigned bprefixlen);
 int in_addr_prefix_next(int family, union in_addr_union *u, unsigned prefixlen);
diff --git a/src/libsystemd-network/ndisc-router.c b/src/libsystemd-network/ndisc-router.c
index 41ff2b353a..cf56c89d76 100644
--- a/src/libsystemd-network/ndisc-router.c
+++ b/src/libsystemd-network/ndisc-router.c
@@ -91,7 +91,7 @@ _public_ int sd_ndisc_router_get_address(sd_ndisc_router *rt, struct in6_addr *r
         assert_return(rt, -EINVAL);
         assert_return(ret_addr, -EINVAL);
 
-        if (in6_addr_is_null(&rt->address))
+        if (IN6_IS_ADDR_UNSPECIFIED(&rt->address))
                 return -ENODATA;
 
         *ret_addr = rt->address;