network: avoid inet_ntoa() in favor of inet_ntop()

inet_ntop() is not documented to be thread-safe, so it should not
be used in the DHCP library. Arguably, glibc uses a thread local
buffer, so indeed there is no problem with a suitable libc. Anyway,
just avoid it.

src/libsystemd-network/network-internal.c

@@ -423,13 +423,15 @@ size_t serialize_in_addrs(FILE *f,
         count = 0;
 
         for (i = 0; i < size; i++) {
+                char sbuf[INET_ADDRSTRLEN];
+
                 if (predicate && !predicate(&addresses[i]))
                         continue;
                 if (with_leading_space)
                         fputc(' ', f);
                 else
                         with_leading_space = true;
-                fputs(inet_ntoa(addresses[i]), f);
+                fputs(inet_ntop(AF_INET, &addresses[i], sbuf, sizeof(sbuf)), f);
                 count++;
         }
 
@@ -536,15 +538,16 @@ void serialize_dhcp_routes(FILE *f, const char *key, sd_dhcp_route **routes, siz
         fprintf(f, "%s=", key);
 
         for (i = 0; i < size; i++) {
+                char sbuf[INET_ADDRSTRLEN];
                 struct in_addr dest, gw;
                 uint8_t length;
 
                 assert_se(sd_dhcp_route_get_destination(routes[i], &dest) >= 0);
                 assert_se(sd_dhcp_route_get_gateway(routes[i], &gw) >= 0);
                 assert_se(sd_dhcp_route_get_destination_prefix_length(routes[i], &length) >= 0);
 
-                fprintf(f, "%s/%" PRIu8, inet_ntoa(dest), length);
-                fprintf(f, ",%s%s", inet_ntoa(gw), (i < (size - 1)) ? " ": "");
+                fprintf(f, "%s/%" PRIu8, inet_ntop(AF_INET, &dest, sbuf, sizeof(sbuf)), length);
+                fprintf(f, ",%s%s", inet_ntop(AF_INET, &gw, sbuf, sizeof(sbuf)), (i < (size - 1)) ? " ": "");
         }
 
         fputs("\n", f);

src/libsystemd-network/sd-dhcp-lease.c

@@ -814,6 +814,7 @@ int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file) {
         const struct in_addr *addresses;
         const void *client_id, *data;
         size_t client_id_len, data_len;
+        char sbuf[INET_ADDRSTRLEN];
         const char *string;
         uint16_t mtu;
         _cleanup_free_ sd_dhcp_route **routes = NULL;
@@ -836,11 +837,11 @@ int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file) {
 
         r = sd_dhcp_lease_get_address(lease, &address);
         if (r >= 0)
-                fprintf(f, "ADDRESS=%s\n", inet_ntoa(address));
+                fprintf(f, "ADDRESS=%s\n", inet_ntop(AF_INET, &address, sbuf, sizeof(sbuf)));
 
         r = sd_dhcp_lease_get_netmask(lease, &address);
         if (r >= 0)
-                fprintf(f, "NETMASK=%s\n", inet_ntoa(address));
+                fprintf(f, "NETMASK=%s\n", inet_ntop(AF_INET, &address, sbuf, sizeof(sbuf)));
 
         r = sd_dhcp_lease_get_router(lease, &addresses);
         if (r > 0) {
@@ -851,15 +852,15 @@ int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file) {
 
         r = sd_dhcp_lease_get_server_identifier(lease, &address);
         if (r >= 0)
-                fprintf(f, "SERVER_ADDRESS=%s\n", inet_ntoa(address));
+                fprintf(f, "SERVER_ADDRESS=%s\n", inet_ntop(AF_INET, &address, sbuf, sizeof(sbuf)));
 
         r = sd_dhcp_lease_get_next_server(lease, &address);
         if (r >= 0)
-                fprintf(f, "NEXT_SERVER=%s\n", inet_ntoa(address));
+                fprintf(f, "NEXT_SERVER=%s\n", inet_ntop(AF_INET, &address, sbuf, sizeof(sbuf)));
 
         r = sd_dhcp_lease_get_broadcast(lease, &address);
         if (r >= 0)
-                fprintf(f, "BROADCAST=%s\n", inet_ntoa(address));
+                fprintf(f, "BROADCAST=%s\n", inet_ntop(AF_INET, &address, sbuf, sizeof(sbuf)));
 
         r = sd_dhcp_lease_get_mtu(lease, &mtu);
         if (r >= 0)