Hi,
> It appears that the CISCO refuses to forward UDP packets if the
> checksum is not correct. Part of the IPConfig documentation
> states that 'UDP checksum not calculated -- explicitly allowed
> in BOOTP RFC'.
Please try the following patch. In addition to some cosmetic changes,
it adds checksumming of BOOTP packets being sent.
Have a nice fortnight
--
Martin `MJ' Mares <[EMAIL PROTECTED]> http://atrey.karlin.mff.cuni.cz/~mj/
Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
"Never make any mistaeks."
--- net/ipv4/ipconfig.c.mj Sun Jan 10 14:30:07 1999
+++ net/ipv4/ipconfig.c Sun Jan 10 22:05:37 1999
@@ -73,7 +73,14 @@
#define CONFIG_IP_PNP_DYNAMIC
-static int ic_proto_enabled __initdata = IC_BOOTP | IC_RARP; /* Protocols enabled */
+static int ic_proto_enabled __initdata = 0 /* Protocols enabled */
+#ifdef CONFIG_IP_PNP_BOOTP
+ | IC_BOOTP
+#endif
+#ifdef CONFIG_IP_PNP_RARP
+ | IC_RARP
+#endif
+ ;
static int ic_got_reply __initdata = 0; /* Protocol(s)
we got reply from */
#else
@@ -491,6 +498,7 @@
struct bootp_pkt *b;
int hh_len = (dev->hard_header_len + 15) & ~15;
struct iphdr *h;
+ int ulen = sizeof(struct bootp_pkt) - sizeof(struct iphdr);
/* Allocate packet */
skb = alloc_skb(sizeof(struct bootp_pkt) + hh_len + 15, GFP_KERNEL);
@@ -509,14 +517,12 @@
h->ttl = 1;
h->protocol = IPPROTO_UDP;
h->daddr = INADDR_BROADCAST;
- h->check = 0;
h->check = ip_fast_csum((unsigned char *) h, h->ihl);
/* Construct UDP header */
b->udph.source = htons(68);
b->udph.dest = htons(67);
- b->udph.len = htons(sizeof(struct bootp_pkt) - sizeof(struct iphdr));
- /* UDP checksum not calculated -- explicitly allowed in BOOTP RFC */
+ b->udph.len = htons(ulen);
/* Construct BOOTP header */
b->op = BOOTP_REQUEST;
@@ -526,6 +532,12 @@
b->secs = htons(jiffies / HZ);
b->xid = ic_bootp_xid;
ic_bootp_init_ext(b->vendor_area);
+
+ /* RFC explicitly allows us to omit UDP checksum. Reality doesn't. */
+ b->udph.check = csum_tcpudp_magic(h->saddr, h->daddr, ulen, IPPROTO_UDP,
+ csum_partial((char *) &b->udph, ulen, 0));
+ if (!b->udph.check)
+ b->udph.check = -1;
/* Chain packet down the line... */
skb->dev = dev;
-
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