Fix ftbfs for Hurd since there is no IPV6_TCLASS defined

src/redir.c

@@ -800,10 +800,12 @@ accept_cb(EV_P_ ev_io *w, int revents)
         if (rc < 0 && errno != ENOPROTOOPT) {
             LOGE("setting ipv4 dscp failed: %d", errno);
         }
+#ifdef IPV6_TCLASS
         rc = setsockopt(remotefd, IPPROTO_IPV6, IPV6_TCLASS, &listener->tos, sizeof(listener->tos));
         if (rc < 0 && errno != ENOPROTOOPT) {
             LOGE("setting ipv6 dscp failed: %d", errno);
         }
+#endif
     }
 
     // Enable MPTCP

src/udprelay.c

@@ -508,11 +508,13 @@ create_server_socket(const char *host, const char *port)
         if (rc < 0 && errno != ENOPROTOOPT) {
             LOGE("setting ipv4 dscp failed: %d", errno);
         }
+#ifdef IPV6_TCLASS
         rc = setsockopt(server_sock, IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos));
         if (rc < 0 && errno != ENOPROTOOPT) {
             LOGE("setting ipv6 dscp failed: %d", errno);
         }
 #endif
+#endif
 
 #ifdef MODULE_REDIR
         int sol    = rp->ai_family == AF_INET ? SOL_IP : SOL_IPV6;
@@ -675,11 +677,13 @@ resolv_cb(struct sockaddr *addr, void *data)
                 if (rc < 0 && errno != ENOPROTOOPT) {
                     LOGE("setting ipv4 dscp failed: %d", errno);
                 }
+#ifdef IPV6_TCLASS
                 rc = setsockopt(remotefd, IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos));
                 if (rc < 0 && errno != ENOPROTOOPT) {
                     LOGE("setting ipv6 dscp failed: %d", errno);
                 }
 #endif
+#endif
 #ifdef SET_INTERFACE
                 if (query_ctx->server_ctx->iface) {
                     if (setinterface(remotefd, query_ctx->server_ctx->iface) == -1)
@@ -872,10 +876,12 @@ remote_recv_cb(EV_P_ ev_io *w, int revents)
     if (rc < 0 && errno != ENOPROTOOPT) {
         LOGE("setting ipv4 dscp failed: %d", errno);
     }
+#ifdef IPV6_TCLASS
     rc = setsockopt(src_fd, IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos));
     if (rc < 0 && errno != ENOPROTOOPT) {
         LOGE("setting ipv6 dscp failed: %d", errno);
     }
+#endif
 #endif
     if (bind(src_fd, (struct sockaddr *)&dst_addr, remote_dst_addr_len) != 0) {
         ERROR("[udp] remote_recv_bind");
@@ -1213,11 +1219,13 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
         if (rc < 0 && errno != ENOPROTOOPT) {
             LOGE("setting ipv4 dscp failed: %d", errno);
         }
+#ifdef IPV6_TCLASS
         rc = setsockopt(remotefd, IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos));
         if (rc < 0 && errno != ENOPROTOOPT) {
             LOGE("setting ipv6 dscp failed: %d", errno);
         }
 #endif
+#endif
 #ifdef SET_INTERFACE
         if (server_ctx->iface) {
             if (setinterface(remotefd, server_ctx->iface) == -1)
@@ -1309,11 +1317,13 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
                 if (rc < 0 && errno != ENOPROTOOPT) {
                     LOGE("setting ipv4 dscp failed: %d", errno);
                 }
+#ifdef IPV6_TCLASS
                 rc = setsockopt(remotefd, IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos));
                 if (rc < 0 && errno != ENOPROTOOPT) {
                     LOGE("setting ipv6 dscp failed: %d", errno);
                 }
 #endif
+#endif
 #ifdef SET_INTERFACE
                 if (server_ctx->iface) {
                     if (setinterface(remotefd, server_ctx->iface) == -1)