network: address-generation: always use the first 64 bits of the prefix

Hopefully, the prefix length is usually 64.

Previously, if the prefix length is smaller than 64, the result address
was undefined.

diff --git a/src/network/networkd-address-generation.c b/src/network/networkd-address-generation.c
index 191a89dfd931c2a691d5e0a5a6aa61811c790407..a4f53436e3186aaee5623a9320139f34d37b113e 100644 (file)
--- a/src/network/networkd-address-generation.c
+++ b/src/network/networkd-address-generation.c
@@ -79,12 +79,11 @@ static bool stable_private_address_is_valid(const struct in6_addr *addr) {
         return true;
 }
 
-static int make_stable_private_address(Link *link, const struct in6_addr *prefix, uint8_t prefix_len, uint8_t dad_counter, struct in6_addr **ret) {
+static int make_stable_private_address(Link *link, const struct in6_addr *prefix, uint8_t dad_counter, struct in6_addr **ret) {
         _cleanup_free_ struct in6_addr *addr = NULL;
         sd_id128_t secret_key;
         struct siphash state;
         uint64_t rid;
-        size_t l;
         int r;
 
         /* According to rfc7217 section 5.1
@@ -96,8 +95,7 @@ static int make_stable_private_address(Link *link, const struct in6_addr *prefix
 
         siphash24_init(&state, secret_key.bytes);
 
-        l = MAX(DIV_ROUND_UP(prefix_len, 8), 8);
-        siphash24_compress(prefix, l, &state);
+        siphash24_compress(prefix, 8, &state);
         siphash24_compress_string(link->ifname, &state);
         /* Only last 8 bytes of IB MAC are stable */
         if (link->iftype == ARPHRD_INFINIBAND)
@@ -112,8 +110,8 @@ static int make_stable_private_address(Link *link, const struct in6_addr *prefix
         if (!addr)
                 return log_oom();
 
-        memcpy(addr->s6_addr, prefix->s6_addr, l);
-        memcpy(addr->s6_addr + l, &rid, 16 - l);
+        memcpy(addr->s6_addr, prefix->s6_addr, 8);
+        memcpy(addr->s6_addr + 8, &rid, 8);
 
         if (!stable_private_address_is_valid(addr)) {
                 *ret = NULL;
@@ -147,7 +145,7 @@ int ndisc_router_generate_addresses(Link *link, struct in6_addr *address, uint8_
                          * only when the address generation algorithm produces an invalid address, and the loop
                          * may exit with an address which ends up being unusable due to duplication on the link. */
                         for (; j->dad_counter < DAD_CONFLICTS_IDGEN_RETRIES_RFC7217; j->dad_counter++) {
-                                r = make_stable_private_address(link, address, prefixlen, j->dad_counter, &new_address);
+                                r = make_stable_private_address(link, address, j->dad_counter, &new_address);
                                 if (r < 0)
                                         return r;
                                 if (r > 0)