net.c: do not print sockaddr_in6.sin6_scope_id unnecessarily

Prior to RFC2553, struct sockaddr_in6 had no sin6_scope_id field.
As the kernel still accepts RFC2133 editions of struct sockaddr_in6,
print sockaddr_in6.sin6_scope_id only when it is specified.

* net.c (SIN6_MIN_LEN): New macro.
(print_sockaddr_data_in6): Print sockaddr_in6.sin6_scope_id only when
socket address length exceeds SIN6_MIN_LEN.

diff --git a/net.c b/net.c
index 938b212653dba4f94a293f3fc9a701109be4a6b6..16548837fe53a9c9d4fb4b1cd7e920cb783b0951 100644 (file)
--- a/net.c
+++ b/net.c
@@ -145,6 +145,8 @@ print_ifindex(unsigned int ifindex)
        tprintf("%u", ifindex);
 }
 
+#define SIN6_MIN_LEN offsetof(struct sockaddr_in6, sin6_scope_id)
+
 static void
 print_sockaddr_data_in6(const void *const buf, const int addrlen)
 {
@@ -157,6 +159,10 @@ print_sockaddr_data_in6(const void *const buf, const int addrlen)
                ", \"%s\", &sin6_addr), sin6_flowinfo=%u",
                ntohs(sa_in6->sin6_port), string_addr,
                sa_in6->sin6_flowinfo);
+
+       if (addrlen <= (int) SIN6_MIN_LEN)
+               return;
+
        tprints(", sin6_scope_id=");
 #if defined IN6_IS_ADDR_LINKLOCAL && defined IN6_IS_ADDR_MC_LINKLOCAL
        if (IN6_IS_ADDR_LINKLOCAL(&sa_in6->sin6_addr)