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[NETLINK]: Generic netlink receive queue processor

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Introduces netlink_run_queue() to handle the receive queue of
a netlink socket in a generic way. Processes as much as there
was in the queue upon entry and invokes a callback function
for each netlink message found. The callback function may
refuse a message by returning a negative error code but setting
the error pointer to 0 in which case netlink_run_queue() will
return with a qlen != 0.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Thomas Graf 2005-11-10 02:25:53 +01:00 committed by Thomas Graf
parent a8f74b2288
commit 82ace47a72
2 changed files with 97 additions and 0 deletions
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6
include/net/netlink.h
View File

@ -183,6 +183,12 @@ struct nla_policy {
u16 minlen;
};
extern void netlink_run_queue(struct sock *sk, unsigned int *qlen,
int (*cb)(struct sk_buff *,
struct nlmsghdr *, int *));
extern void netlink_queue_skip(struct nlmsghdr *nlh,
struct sk_buff *skb);
extern int nla_validate(struct nlattr *head, int len, int maxtype,
struct nla_policy *policy);
extern int nla_parse(struct nlattr *tb[], int maxtype,

91
net/netlink/af_netlink.c
View File

@ -58,6 +58,7 @@
#include <net/sock.h>
#include <net/scm.h>
#include <net/netlink.h>
#define Nprintk(a...)
#define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8)
@ -1411,6 +1412,94 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).pid, MSG_DONTWAIT);
}
static int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
struct nlmsghdr *, int *))
{
unsigned int total_len;
struct nlmsghdr *nlh;
int err;
while (skb->len >= nlmsg_total_size(0)) {
nlh = (struct nlmsghdr *) skb->data;
if (skb->len < nlh->nlmsg_len)
return 0;
total_len = min(NLMSG_ALIGN(nlh->nlmsg_len), skb->len);
if (cb(skb, nlh, &err) < 0) {
/* Not an error, but we have to interrupt processing
* here. Note: that in this case we do not pull
* message from skb, it will be processed later.
*/
if (err == 0)
return -1;
netlink_ack(skb, nlh, err);
} else if (nlh->nlmsg_flags & NLM_F_ACK)
netlink_ack(skb, nlh, 0);
skb_pull(skb, total_len);
}
return 0;
}
/**
* nelink_run_queue - Process netlink receive queue.
* @sk: Netlink socket containing the queue
* @qlen: Place to store queue length upon entry
* @cb: Callback function invoked for each netlink message found
*
* Processes as much as there was in the queue upon entry and invokes
* a callback function for each netlink message found. The callback
* function may refuse a message by returning a negative error code
* but setting the error pointer to 0 in which case this function
* returns with a qlen != 0.
*
* qlen must be initialized to 0 before the initial entry, afterwards
* the function may be called repeatedly until qlen reaches 0.
*/
void netlink_run_queue(struct sock *sk, unsigned int *qlen,
int (*cb)(struct sk_buff *, struct nlmsghdr *, int *))
{
struct sk_buff *skb;
if (!*qlen || *qlen > skb_queue_len(&sk->sk_receive_queue))
*qlen = skb_queue_len(&sk->sk_receive_queue);
for (; *qlen; (*qlen)--) {
skb = skb_dequeue(&sk->sk_receive_queue);
if (netlink_rcv_skb(skb, cb)) {
if (skb->len)
skb_queue_head(&sk->sk_receive_queue, skb);
else {
kfree_skb(skb);
(*qlen)--;
}
break;
}
kfree_skb(skb);
}
}
/**
* netlink_queue_skip - Skip netlink message while processing queue.
* @nlh: Netlink message to be skipped
* @skb: Socket buffer containing the netlink messages.
*
* Pulls the given netlink message off the socket buffer so the next
* call to netlink_queue_run() will not reconsider the message.
*/
void netlink_queue_skip(struct nlmsghdr *nlh, struct sk_buff *skb)
{
int msglen = NLMSG_ALIGN(nlh->nlmsg_len);
if (msglen > skb->len)
msglen = skb->len;
skb_pull(skb, msglen);
}
#ifdef CONFIG_PROC_FS
struct nl_seq_iter {
@ -1659,6 +1748,8 @@ static int __init netlink_proto_init(void)
core_initcall(netlink_proto_init);
EXPORT_SYMBOL(netlink_ack);
EXPORT_SYMBOL(netlink_run_queue);
EXPORT_SYMBOL(netlink_queue_skip);
EXPORT_SYMBOL(netlink_broadcast);
EXPORT_SYMBOL(netlink_dump_start);
EXPORT_SYMBOL(netlink_kernel_create);