diff options
| -rw-r--r-- | lib/libutil/realhostname.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/lib/libutil/realhostname.c b/lib/libutil/realhostname.c index 146695e..044c652 100644 --- a/lib/libutil/realhostname.c +++ b/lib/libutil/realhostname.c @@ -83,6 +83,18 @@ realhostname(char *host, size_t hsize, const struct in_addr *ip) return result; } +/* + * struct sockaddr has very lax alignment requirements, since all its + * members are char or equivalent. This is a problem when trying to + * dereference a struct sockaddr_in6 * that was passed in as a struct + * sockaddr *. Although we know (or trust) that the passed-in struct was + * properly aligned, the compiler doesn't, and (rightly) complains. These + * macros perform the cast in a way that the compiler will accept. + */ +#define SOCKADDR_IN6(p) ((struct sockaddr_in6 *)(void *)(p)) +#define SOCKADDR_IN(p) ((struct sockaddr_in *)(void *)(p)) +#define SOCKINET(p) ((struct sockinet *)(void *)(p)) + int realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen) { @@ -96,10 +108,10 @@ realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen) /* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */ if (addr->sa_family == AF_INET6 && addrlen == sizeof(struct sockaddr_in6) && - IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)addr)->sin6_addr)) { + IN6_IS_ADDR_V4MAPPED(&SOCKADDR_IN6(addr)->sin6_addr)) { struct sockaddr_in6 *sin6; - sin6 = (struct sockaddr_in6 *)addr; + sin6 = SOCKADDR_IN6(addr); memset(&lsin, 0, sizeof(lsin)); lsin.sin_len = sizeof(struct sockaddr_in); @@ -142,15 +154,16 @@ realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen) } if (sa->sa_len == addrlen && sa->sa_family == addr->sa_family) { - ((struct sockinet *)sa)->si_port = ((struct sockinet *)addr)->si_port; + SOCKINET(sa)->si_port = SOCKINET(addr)->si_port; #ifdef INET6 /* * XXX: sin6_socpe_id may not been * filled by DNS */ if (sa->sa_family == AF_INET6 && - ((struct sockaddr_in6 *)sa)->sin6_scope_id == 0) - ((struct sockaddr_in6 *)sa)->sin6_scope_id = ((struct sockaddr_in6 *)addr)->sin6_scope_id; + SOCKADDR_IN6(sa)->sin6_scope_id == 0) + SOCKADDR_IN6(sa)->sin6_scope_id = + SOCKADDR_IN6(addr)->sin6_scope_id; #endif if (!memcmp(sa, addr, sa->sa_len)) { result = HOSTNAME_FOUND; |
