[Babel-users] [PATCH 2/2] interface.c: interface_set_status() minor refactoring

[Christof Schulze]

* clarify code flow, only checking for future state once
* clarify error messages when MTU is guessed by including the MTU value
* remove useless comment about the need to run an IP check that already
   is run
* allocate exactly as much space as required. Not more for good luck
---
  interface.c | 17 ++++++-----------
  1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/interface.c b/interface.c
index 4feea7e..f4629ab 100644
--- a/interface.c
+++ b/interface.c
@@ -279,12 +279,8 @@ interface_set_status(struct interface *ifp, int up)
      if((!!up) == if_up(ifp))
          return 0;

-    if(up)
-        ifp->flags |= IF_UP;
-    else
-        ifp->flags &= ~IF_UP;
-
      if(up) {
+        ifp->flags |= IF_UP;
          if(ifp->ifindex <= 0) {
              fprintf(stderr,
                      "Upping unknown interface %s.\n", ifp->name);
@@ -306,7 +302,7 @@ interface_set_status(struct interface *ifp, int up)

          mtu = kernel_interface_mtu(ifp->name, ifp->ifindex);
          if(mtu < 0) {
-            fprintf(stderr, "Warning: couldn't get MTU of interface %s (%u).\n",
+            fprintf(stderr, "Warning: couldn't get MTU of interface %s (%u), using 1280.\n",
                      ifp->name, ifp->ifindex);
              mtu = 1280;
          }
@@ -316,7 +312,7 @@ interface_set_status(struct interface *ifp, int up)
          /* In IPv6, the minimum MTU is 1280, and every host must be able
             to reassemble up to 1500 bytes, but I'd rather not rely on this. */
          if(mtu < 128) {
-            fprintf(stderr, "Suspiciously low MTU %d on interface %s (%u).\n",
+            fprintf(stderr, "Suspiciously low MTU %d on interface %s (%u), using 128 and require lower-level fragmentation.\n",
                      mtu, ifp->name, ifp->ifindex);
              mtu = 128;
          }
@@ -324,8 +320,8 @@ interface_set_status(struct interface *ifp, int up)
          if(ifp->buf.buf)
              free(ifp->buf.buf);

-        /* 40 for IPv6 header, 8 for UDP header, 12 for good luck. */
-        ifp->buf.size = mtu - sizeof(packet_header) - 60;
+        /* 40 for IPv6 header, 8 for UDP header */
+        ifp->buf.size = mtu - sizeof(packet_header) - ( 40 + 8 );
          ifp->buf.buf = malloc(ifp->buf.size);
          if(ifp->buf.buf == NULL) {
              fprintf(stderr, "Couldn't allocate sendbuf.\n");
@@ -483,6 +479,7 @@ interface_set_status(struct interface *ifp, int up)
              send_update(ifp, 0, NULL, 0, NULL, 0);
          send_multicast_request(ifp, NULL, 0, NULL, 0);
      } else {
+        ifp->flags &= ~IF_UP;
          flush_interface_routes(ifp, 0);
          ifp->buf.len = 0;
          ifp->buf.size = 0;
@@ -559,8 +556,6 @@ check_interfaces(void)
          }

          if(if_up(ifp)) {
-            /* Bother, said Pooh.  We should probably check for a change
-               in IPv4 addresses at this point. */
              check_link_local_addresses(ifp);
              check_interface_channel(ifp);
              rc = check_interface_ipv4(ifp);
--
2.11.0