ip_sockglue.c

GNU Hurd 源代码

/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		The IP to API glue.
 *		
 * Version:	$Id: ip_sockglue.c,v 1.42 1999/04/22 10:07:34 davem Exp $
 *
 * Authors:	see ip.c
 *
 * Fixes:
 *		Many		:	Split from ip.c , see ip.c for history.
 *		Martin Mares	:	TOS setting fixed.
 *		Alan Cox	:	Fixed a couple of oopses in Martin's 
 *					TOS tweaks.
 *		Mike McLagan	:	Routing by source
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/netdevice.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/tcp.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/igmp.h>
#include <linux/firewall.h>
#include <linux/ip_fw.h>
#include <linux/route.h>
#include <linux/mroute.h>
#include <net/route.h>
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
#include <net/transp_v6.h>
#endif

#ifdef CONFIG_IP_MASQUERADE
#include <linux/ip_masq.h>
#endif

#include <linux/errqueue.h>
#include <asm/uaccess.h>

#define MAX(a,b) ((a)>(b)?(a):(b))

#define IP_CMSG_PKTINFO		1
#define IP_CMSG_TTL		2
#define IP_CMSG_TOS		4
#define IP_CMSG_RECVOPTS	8
#define IP_CMSG_RETOPTS		16

/*
 *	SOL_IP control messages.
 */

static void ip_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
{
	struct in_pktinfo info;
	struct rtable *rt = (struct rtable *)skb->dst;

	info.ipi_addr.s_addr = skb->nh.iph->daddr;
	if (rt) {
		info.ipi_ifindex = rt->rt_iif;
		info.ipi_spec_dst.s_addr = rt->rt_spec_dst;
	} else {
		info.ipi_ifindex = 0;
		info.ipi_spec_dst.s_addr = 0;
	}

	put_cmsg(msg, SOL_IP, IP_PKTINFO, sizeof(info), &info);
}

static void ip_cmsg_recv_ttl(struct msghdr *msg, struct sk_buff *skb)
{
	int ttl = skb->nh.iph->ttl;
	put_cmsg(msg, SOL_IP, IP_TTL, sizeof(int), &ttl);
}

static void ip_cmsg_recv_tos(struct msghdr *msg, struct sk_buff *skb)
{
	put_cmsg(msg, SOL_IP, IP_TOS, 1, &skb->nh.iph->tos);
}

static void ip_cmsg_recv_opts(struct msghdr *msg, struct sk_buff *skb)
{
	if (IPCB(skb)->opt.optlen == 0)
		return;

	put_cmsg(msg, SOL_IP, IP_RECVOPTS, IPCB(skb)->opt.optlen, skb->nh.iph+1);
}


void ip_cmsg_recv_retopts(struct msghdr *msg, struct sk_buff *skb)
{
	unsigned char optbuf[sizeof(struct ip_options) + 40];
	struct ip_options * opt = (struct ip_options*)optbuf;

	if (IPCB(skb)->opt.optlen == 0)
		return;

	if (ip_options_echo(opt, skb)) {
		msg->msg_flags |= MSG_CTRUNC;
		return;
	}
	ip_options_undo(opt);

	put_cmsg(msg, SOL_IP, IP_RETOPTS, opt->optlen, opt->__data);
}


void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb)
{
	unsigned flags = skb->sk->ip_cmsg_flags;

	/* Ordered by supposed usage frequency */
	if (flags & 1)
		ip_cmsg_recv_pktinfo(msg, skb);
	if ((flags>>=1) == 0)
		return;

	if (flags & 1)
		ip_cmsg_recv_ttl(msg, skb);
	if ((flags>>=1) == 0)
		return;

	if (flags & 1)
		ip_cmsg_recv_tos(msg, skb);
	if ((flags>>=1) == 0)
		return;

	if (flags & 1)
		ip_cmsg_recv_opts(msg, skb);
	if ((flags>>=1) == 0)
		return;

	if (flags & 1)
		ip_cmsg_recv_retopts(msg, skb);
}

int ip_cmsg_send(struct msghdr *msg, struct ipcm_cookie *ipc)
{
	int err;
	struct cmsghdr *cmsg;

	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
		if (cmsg->cmsg_len < sizeof(struct cmsghdr) ||
		    (unsigned long)(((char*)cmsg - (char*)msg->msg_control)
				    + cmsg->cmsg_len) > msg->msg_controllen) {
			return -EINVAL;
		}
		if (cmsg->cmsg_level != SOL_IP)
			continue;
		switch (cmsg->cmsg_type) {
		case IP_RETOPTS:
			err = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr));
			err = ip_options_get(&ipc->opt, CMSG_DATA(cmsg), err < 40 ? err : 40, 0);
			if (err)
				return err;
			break;
		case IP_PKTINFO:
		{
			struct in_pktinfo *info;
			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct in_pktinfo)))
				return -EINVAL;
			info = (struct in_pktinfo *)CMSG_DATA(cmsg);
			ipc->oif = info->ipi_ifindex;
			ipc->addr = info->ipi_spec_dst.s_addr;
			break;
		}
		default:
			return -EINVAL;
		}
	}
	return 0;
}


/* Special input handler for packets catched by router alert option.
   They are selected only by protocol field, and then processed likely
   local ones; but only if someone wants them! Otherwise, router
   not running rsvpd will kill RSVP.

   It is user level problem, what it will make with them.
   I have no idea, how it will masquearde or NAT them (it is joke, joke :-)),
   but receiver should be enough clever f.e. to forward mtrace requests,
   sent to multicast group to reach destination designated router.
 */
struct ip_ra_chain *ip_ra_chain;

int ip_ra_control(struct sock *sk, unsigned char on, void (*destructor)(struct sock *))
{
	struct ip_ra_chain *ra, *new_ra, **rap;

	if (sk->type != SOCK_RAW || sk->num == IPPROTO_RAW)
		return -EINVAL;

	new_ra = on ? kmalloc(sizeof(*new_ra), GFP_KERNEL) : NULL;

	for (rap = &ip_ra_chain; (ra=*rap) != NULL; rap = &ra->next) {
		if (ra->sk == sk) {
			if (on) {
				if (new_ra)
					kfree(new_ra);
				return -EADDRINUSE;
			}
			*rap = ra->next;
			synchronize_bh();

			if (ra->destructor)
				ra->destructor(sk);
			kfree(ra);
			return 0;
		}
	}
	if (new_ra == NULL)
		return -ENOBUFS;
	new_ra->sk = sk;
	new_ra->destructor = destructor;

	new_ra->next = ra;
	wmb();
	*rap = new_ra;

	return 0;
}

void ip_icmp_error(struct sock *sk, struct sk_buff *skb, int err, 
		   u16 port, u32 info, u8 *payload)
{
	struct sock_exterr_skb *serr;

	if (!sk->ip_recverr)
		return;

	skb = skb_clone(skb, GFP_ATOMIC);
	if (!skb)
		return;

	serr = SKB_EXT_ERR(skb);  
	serr->ee.ee_errno = err;
	serr->ee.ee_origin = SO_EE_ORIGIN_ICMP;
	serr->ee.ee_type = skb->h.icmph->type; 
	serr->ee.ee_code = skb->h.icmph->code;
	serr->ee.ee_pad = 0;
	serr->ee.ee_info = info;
	serr->ee.ee_data = 0;
	serr->addr_offset = (u8*)&(((struct iphdr*)(skb->h.icmph+1))->daddr) - skb->nh.raw;
	serr->port = port;

	skb->h.raw = payload;
	skb_pull(skb, payload - skb->data);

	if (sock_queue_err_skb(sk, skb))
		kfree_skb(skb);
}

void ip_local_error(struct sock *sk, int err, u32 daddr, u16 port, u32 info)
{
	struct sock_exterr_skb *serr;
	struct iphdr *iph;
	struct sk_buff *skb;

	if (!sk->ip_recverr)
		return;

	skb = alloc_skb(sizeof(struct iphdr), GFP_ATOMIC);
	if (!skb)
		return;

	iph = (struct iphdr*)skb_put(skb, sizeof(struct iphdr));
	skb->nh.iph = iph;
	iph->daddr = daddr;

	serr = SKB_EXT_ERR(skb);  
	serr->ee.ee_errno = err;
	serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
	serr->ee.ee_type = 0; 
	serr->ee.ee_code = 0;
	serr->ee.ee_pad = 0;
	serr->ee.ee_info = info;
	serr->ee.ee_data = 0;
	serr->addr_offset = (u8*)&iph->daddr - skb->nh.raw;
	serr->port = port;

	skb->h.raw = skb->tail;
	skb_pull(skb, skb->tail - skb->data);

	if (sock_queue_err_skb(sk, skb))
		kfree_skb(skb);
}

/* 
 *	Handle MSG_ERRQUEUE
 */
int ip_recv_error(struct sock *sk, struct msghdr *msg, int len)
{
	struct sock_exterr_skb *serr;
	struct sk_buff *skb, *skb2;
	struct sockaddr_in *sin;
	struct {
		struct sock_extended_err ee;
		struct sockaddr_in	 offender;
	} errhdr;
	int err;
	int copied;

	err = -EAGAIN;
	skb = skb_dequeue(&sk->error_queue);
	if (skb == NULL)
		goto out;

	copied = skb->len;
	if (copied > len) {
		msg->msg_flags |= MSG_TRUNC;
		copied = len;
	}
	err = memcpy_toiovec(msg->msg_iov, skb->data, copied);
	if (err)
		goto out_free_skb;

	serr = SKB_EXT_ERR(skb);

	sin = (struct sockaddr_in *)msg->msg_name;
	if (sin) {
		sin->sin_family = AF_INET; 
		sin->sin_addr.s_addr = *(u32*)(skb->nh.raw + serr->addr_offset);
		sin->sin_port = serr->port; 
	}

	memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
	sin = &errhdr.offender;
	sin->sin_family = AF_UNSPEC;
	if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP) {
		sin->sin_family = AF_INET;
		sin->sin_addr.s_addr = skb->nh.iph->saddr;
		if (sk->ip_cmsg_flags)
			ip_cmsg_recv(msg, skb);
	}

	put_cmsg(msg, SOL_IP, IP_RECVERR, sizeof(errhdr), &errhdr);

	/* Now we could try to dump offended packet options */

	msg->msg_flags |= MSG_ERRQUEUE;
	err = copied;

	/* Reset and regenerate socket error */
	sk->err = 0;
	if ((skb2 = skb_peek(&sk->error_queue)) != NULL) {
		sk->err = SKB_EXT_ERR(skb2)->ee.ee_errno;
		sk->error_report(sk);
	}

out_free_skb:	
	kfree_skb(skb);
out:
	return err;
}


/*
 *	Socket option code for IP. This is the end of the line after any TCP,UDP etc options on
 *	an IP socket.