[Bug 9061] New: udhcpc: quick renew and release when link is down doesn't call script to deconfig

bugzilla at busybox.net bugzilla at busybox.net
Fri Jul 1 22:03:56 UTC 2016


            Bug ID: 9061
           Summary: udhcpc: quick renew and release when link is down
                    doesn't call script to deconfig
           Product: Busybox
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P5
         Component: Networking
          Assignee: unassigned at busybox.net
          Reporter: gb2312 at hotmail.com
                CC: busybox-cvs at busybox.net
  Target Milestone: ---

Observed with 1.15.3 but looks like the code is similar: with udhcpc in BOUND=2
state, when the link goes down and external applications ask udhcpc to renew
and release the address, which can be simulated by

  killall 1 udhpc; killall 2 udhpc

then udhcpc gets into RELEASED=6 state without calling script for deconfig.
leaves ip/route still configured with link down and dhcp released.

An instrumented networking/udhcp/udhcpc.c showed this trace:

# link down!
$ killall 1 udhpc; killall 2 udhpc
Performing a DHCP renew
state: 2 -> 5
Sending renew...
Entering released state
state: 5 -> 6  <<<<<<<<<<<<<< not calling script!!!!
# ip/route still present now

This shows:

  SIGUSR1: perform_renew(): state: BOUND=2 -> RENEW_REQUESTED=5
  SIGUSR2: perform_release(): state: RENEW_REQUESTED=5 -> RELEASED=6

RENEW_REQUESTED->RELEASED would not call udhcp_run_script(NULL, "deconfig")
I believe the need to call deconfig should be remembered...

Related functions:

/* Called only on SIGUSR1 */
static void perform_renew(void)
    bb_error_msg("performing DHCP renew");
    switch (state) {
    case BOUND:
    case RENEWING:
    case REBINDING:
        state = RENEW_REQUESTED;
    case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
        udhcp_run_script(NULL, "deconfig");
    case REQUESTING:
    case RELEASED:
        state = INIT_SELECTING;

static void perform_release(uint32_t server_addr, uint32_t requested_ip)
    char buffer[sizeof("")];
    struct in_addr temp_addr;

    /* send release packet */
    if (state == BOUND || state == RENEWING || state == REBINDING) {
        temp_addr.s_addr = server_addr;
        strcpy(buffer, inet_ntoa(temp_addr));
        temp_addr.s_addr = requested_ip;
        bb_error_msg("unicasting a release of %s to %s",
                inet_ntoa(temp_addr), buffer);
        send_release(server_addr, requested_ip); /* unicast */
        udhcp_run_script(NULL, "deconfig");
    bb_error_msg("entering released state");

    state = RELEASED;

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