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From: | Bill Auerbach |
Subject: | RE: [lwip-users] How to securely switch between DHCP and static IP assignment? |
Date: | Thu, 22 Jul 2010 14:59:57 -0400 |
I have to do the same thing as
you, as well as be able to switch from DHCP to static (or back) with an
Ethernet cable change. I also needed to support optional AutoIP or fallback to
static. It’s all possible and quite reliable. You need to add: netif_set_down( &sNetif ); after: dhcp_stop(&sNetif); Otherwise your code is exactly
like mine (for switching from DHCP to static that is). Bill From:
address@hidden
[mailto:address@hidden On Behalf
Of Benjamin Schelte Hallo all, I am having trouble to securely switch between DHCP and
static IP assignment. The way I am doing this at the moment is sometimes
leading to an assert (please read further). So far I am quite satisfied with the lwip-stack and its
performance, but this problem gives me a headache. Description: My environment needs to be able to switch between static IP
and DHCP during runtime. This should be possible at any point in time (although
once configured it will most likely stay the same…). Info: I am using a Realtime OS. So after initialization either with DHCP or static IP
address assignment I use two functions to switch between those 2 modes. Both functions are called out of a user menu. The code looks
like the following: int iEthCtrl_UseStaticIP(unsigned long ulIPAddress, unsigned long ulIPGateway, unsigned long ulIPSubnetMask) { struct ip_addr
xIpAddr, xNetMask, xGateway; // Check, if
the network connection is up and DHCP is activated if ((sNetif.flags &
NETIF_FLAG_UP) && (sNetif.flags & NETIF_FLAG_DHCP)) {
//
Release the DHCP lease (it already calls netif_set_down() function)
dhcp_release(&sNetif);
//
Stop the dhcp service
dhcp_stop(&sNetif);
xIpAddr.addr = ulIPAddress;
xGateway.addr = ulIPGateway;
xNetMask.addr = ulIPSubnetMask;
//
Set the new ip address
netif_set_addr(&sNetif, &xIpAddr, &xNetMask, &xGateway);
//
Bring the interface up again
netif_set_up(&sNetif); } ... } int iEthCtrl_UseDHCP(void) { struct ip_addr
xIpAddr, xNetMask, xGateway;
IP4_ADDR(&xIpAddr, 0, 0, 0, 0);
IP4_ADDR(&xNetMask, 0, 0, 0, 0);
IP4_ADDR(&xGateway, 0, 0, 0, 0); // Check, if
the network connection is up and DHCP is NOT activated if ((sNetif.flags &
NETIF_FLAG_UP) && !(sNetif.flags & NETIF_FLAG_DHCP)) {
//
Bring the current interface down
netif_set_down(&sNetif);
//
Set the IP addresses to "0.0.0.0" so the DHCP server can send a
reply.
//
Otherwise the previous static IP might be out of the network class of the DHCP
server
netif_set_addr(&sNetif, &xIpAddr, &xNetMask, &xGateway);
//
Start DHCP negotiation
if (sNetif.dhcp == NULL) {
dhcp_start(&sNetif);
}
else {
dhcp_network_changed(&sNetif);
} ... } ... } Furthermore I am using a callback function to read the
(cable) link status from the PHY every 500ms: static void vPrvEthCtrl_CheckLinkStatusCallback(void* pvParams) { volatile avr32_macb_t *macb =
&AVR32_MACB; unsigned long ulStatusReg;
ulStatusReg = ulReadMDIO(macb, PHY_BMSR); // Can be
blocking! if (ulStatusReg
& BMSR_LSTATUS) {
//
If the cable was disconnected previously we set the link up again
if (bLinkStatus == FALSE) {
netif_set_link_up(&sNetif);
}
bLinkStatus = TRUE; } else {
if (bLinkStatus == TRUE) {
netif_set_link_down(&sNetif);
netif_set_down(&sNetif);
}
bLinkStatus = FALSE; } } So the problem occurs after calling the function iEthCtrl_UseDHCP(). After doing so it sometimes happens to stop executing on an
assert in dhcp_create_request(). Assert: LWIP_ASSERT("dhcp_create_request: dhcp->p_out ==
NULL", dhcp->p_out == NULL); Callstack: dhcp_create_request dhcp_select dhcp_handle_offer dhcp_recv udp_input ip_input ethernet_input tcpip_thread So my questions are the following. Why is a DHCP-request forwarded to the DHCP-handler,
although dhcp_stop() has been called before? Is the way I switch from static IP to DHCP and vice versa
correct? Any comment or advice is appreciated. Thanks in advance! Best regards, Benjamin Schelte |
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