From: Gerrit Renker <[EMAIL PROTECTED]>
Date: Fri, 14 Jul 2006 17:19:02 +0100
> Generic support (header files, configuration, and documentation) for
> the UDP-Lite protocol (RFC 3828).
Gerrit, I tried to bring myself over the edge to accept this
work and push it into my net-2.6.19 tree, but I simply can't
The amount of code duplication is absolutely enormous and
totally unnecessary.
With proper abstractions, you can easily add UDP-lite support to the
existing UDP code. And I would really like it to be in that format
before we put it into the tree.
Then all you need to do is something like add:
__u16 pcslen;
__u16 pcrlen;
/* checksum coverage set indicators used by pcflag */
#define UDPLITE_SEND_CC 0x1
#define UDPLITE_RECV_CC 0x2
__u8 pcflag;
to struct udp_sock.
Add the seperate udp_port_rover and udlite_hash[] table to udp.c, make
the latter sized by UDP_HTABLE_SIZE, with suitable exports, and share
the udp_hash_lock for mutual exclusion. Finally, parameterize all the
UDP hash table routines to take a hash table base and a port rover
pointer so that they can operate on both UDP and UDP-Lite sockets
transparently.
Next make 2 top-level routines for things like udp_err() etc.
So that you can go:
/* Common code */
static void __udp_err(struct sock *sk, struct sk_buff *skb, int type, int code,
u32 info)
{
struct inet_sock *inet;
int type = skb->h.icmph->type;
int code = skb->h.icmph->code;
int harderr, err;
if (sk == NULL) {
ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
return; /* No socket for error */
}
err = 0;
harderr = 0;
inet = inet_sk(sk);
switch (type) {
...
}
/*
* RFC1122: OK. Passes ICMP errors back to application, as per
* 4.1.3.3.
*/
if (!inet->recverr) {
if (!harderr || sk->sk_state != TCP_ESTABLISHED)
goto out;
} else {
ip_icmp_error(sk, skb, err, uh->dest, info, (u8*)(uh+1));
}
sk->sk_err = err;
sk->sk_error_report(sk);
out:
sock_put(sk);
}
void udp_err(struct sk_buff *skb, u32 info)
{
struct iphdr *iph = (struct iphdr*)skb->data;
struct udphdr *uh = (struct udphdr*)(skb->data+(iph->ihl<<2));
int type = skb->h.icmph->type;
int code = skb->h.icmph->code;
struct sock *sk;
sk = udp_v4_lookup(udp_hash,
iph->daddr, uh->dest, iph->saddr,
uh->source, skb->dev->ifindex);
__udp_err(sk, skb, type, code, info);
}
void udplite_err(struct sk_buff *skb, u32 info)
{
struct iphdr *iph = (struct iphdr*)skb->data;
struct udphdr *uh = (struct udphdr*)(skb->data+(iph->ihl<<2));
int type = skb->h.icmph->type;
int code = skb->h.icmph->code;
struct sock *sk;
sk = udp_v4_lookup(udplite_hash,
iph->daddr, uh->dest, iph->saddr,
uh->source, skb->dev->ifindex);
__udp_err(sk, skb, type, code, info);
}
Make similar abstractions for the send and recive path processing,
substituting in the specific UDP vs. UDP-Lite header and
checksum semantic handling along the way.
It's mostly clerical work, but it will mean that we will have one
copy of all this code and as a result we won't even need a config
option for UDP-Lite.
Thanks.
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