Re: [U-Boot] DHCP regression on 2009-06

10 Jul 2009

On Fri 10 Jul 2009 12:27, Robin Getz pondered:
...
http://git.denx.de/?p=u-boot/u-boot-net.git;a=commitdiff;h=3c172c4fdbbb5
858fae38478d6399be4a16be3fc
causes a regression on my network's DHCP server.
The part of the diff that causes the problem:
#if defined(CONFIG_CMD_DHCP)
            case DHCP:


                  /* Start with a clean slate... */
                  BootpTry = 0;


                  NetOurIP = 0;


                  NetServerIP = getenv_IPaddr ("serverip");
                  DhcpRequest();          /* Basically same as



BOOTP */
                        break;
Since we are leaving the "NetOurIP" to whatever it was... The test at:
NetReceive():
     case PROT_IP:
        [snip]
            tmp = NetReadIP(&ip->ip_dst);
            if (NetOurIP && tmp != NetOurIP && tmp != 0xFFFFFFFF) {

#ifdef CONFIG_MCAST_TFTP
                        if (Mcast_addr != tmp)
#endif
                        return;
                }
Will return - (we leave the 'NetOurIP' set to the old value, the offered
address (what is in tmp) is not our's and tmp is not 0xFFFFFFFF).
You never process the DHCP_OFFER...
There are multiple ways of fixing things - setting "NetOurIP = 0;"
(revert one line of the change, which may expose the bug that Michael 
was trying to fix) or try to be more tricky in the "not our address"
check....
I did verify that reverting the line exposes the bug that Michael fixed,
and so did this -- which seemed to work for my limited testing...
Index: net/bootp.c
===================================================================

--- net/bootp.c	(revision 1961)
+++ net/bootp.c	(working copy)
@@ -83,7 +83,7 @@
#endif
-static int BootpCheckPkt(uchar *pkt, unsigned dest, unsigned src, unsigned len)
+int BootpCheckPkt(uchar *pkt, unsigned dest, unsigned src, unsigned len)
 {
    Bootp_t *bp = (Bootp_t *) pkt;
    int retval = 0;
Index: net/net.c
===================================================================
--- net/net.c	(revision 1961)
+++ net/net.c	(working copy)
@@ -1368,7 +1377,11 @@
    		return;
    	}
    	tmp = NetReadIP(&ip->ip_dst);
-		if (NetOurIP && tmp != NetOurIP && tmp != 0xFFFFFFFF) {
+		if (NetOurIP && tmp != NetOurIP && tmp != 0xFFFFFFFF &&
+			BootpCheckPkt((uchar *)ip +IP_HDR_SIZE,
+                                                ntohs(ip->udp_dst),
+                                                ntohs(ip->udp_src),
+                                                ntohs(ip->udp_len) - 8)) {
 #ifdef CONFIG_MCAST_TFTP
    		if (Mcast_addr != tmp)
 #endif

    