2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
6 * The Internet Protocol (IP) output module.
8 * Version: $Id: ip_output.c,v 1.100 2002/02/01 22:01:03 davem Exp $
10 * Authors: Ross Biro, <bir7@leland.Stanford.Edu>
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Donald Becker, <becker@super.org>
13 * Alan Cox, <Alan.Cox@linux.org>
15 * Stefan Becker, <stefanb@yello.ping.de>
16 * Jorge Cwik, <jorge@laser.satlink.net>
17 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
18 * Hirokazu Takahashi, <taka@valinux.co.jp>
20 * See ip_input.c for original log
23 * Alan Cox : Missing nonblock feature in ip_build_xmit.
24 * Mike Kilburn : htons() missing in ip_build_xmit.
25 * Bradford Johnson: Fix faulty handling of some frames when
27 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
28 * (in case if packet not accepted by
29 * output firewall rules)
30 * Mike McLagan : Routing by source
31 * Alexey Kuznetsov: use new route cache
32 * Andi Kleen: Fix broken PMTU recovery and remove
33 * some redundant tests.
34 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
35 * Andi Kleen : Replace ip_reply with ip_send_reply.
36 * Andi Kleen : Split fast and slow ip_build_xmit path
37 * for decreased register pressure on x86
38 * and more readibility.
39 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
40 * silently drop skb instead of failing with -EPERM.
41 * Detlev Wengorz : Copy protocol for fragments.
42 * Hirokazu Takahashi: HW checksumming for outgoing UDP
44 * Hirokazu Takahashi: sendfile() on UDP works now.
47 #include <asm/uaccess.h>
48 #include <asm/system.h>
49 #include <linux/module.h>
50 #include <linux/types.h>
51 #include <linux/kernel.h>
52 #include <linux/sched.h>
54 #include <linux/string.h>
55 #include <linux/errno.h>
56 #include <linux/config.h>
58 #include <linux/socket.h>
59 #include <linux/sockios.h>
61 #include <linux/inet.h>
62 #include <linux/netdevice.h>
63 #include <linux/etherdevice.h>
64 #include <linux/proc_fs.h>
65 #include <linux/stat.h>
66 #include <linux/init.h>
70 #include <net/protocol.h>
71 #include <net/route.h>
74 #include <linux/skbuff.h>
79 #include <net/checksum.h>
80 #include <net/inetpeer.h>
81 #include <net/checksum.h>
82 #include <linux/igmp.h>
83 #include <linux/netfilter_ipv4.h>
84 #include <linux/netfilter_bridge.h>
85 #include <linux/mroute.h>
86 #include <linux/netlink.h>
89 * Shall we try to damage output packets if routing dev changes?
92 int sysctl_ip_dynaddr
;
93 int sysctl_ip_default_ttl
= IPDEFTTL
;
95 /* Generate a checksum for an outgoing IP datagram. */
96 __inline__
void ip_send_check(struct iphdr
*iph
)
99 iph
->check
= ip_fast_csum((unsigned char *)iph
, iph
->ihl
);
102 /* dev_loopback_xmit for use with netfilter. */
103 static int ip_dev_loopback_xmit(struct sk_buff
*newskb
)
105 newskb
->mac
.raw
= newskb
->data
;
106 __skb_pull(newskb
, newskb
->nh
.raw
- newskb
->data
);
107 newskb
->pkt_type
= PACKET_LOOPBACK
;
108 newskb
->ip_summed
= CHECKSUM_UNNECESSARY
;
109 BUG_TRAP(newskb
->dst
);
111 #ifdef CONFIG_NETFILTER_DEBUG
112 nf_debug_ip_loopback_xmit(newskb
);
118 static inline int ip_select_ttl(struct inet_sock
*inet
, struct dst_entry
*dst
)
120 int ttl
= inet
->uc_ttl
;
123 ttl
= dst_metric(dst
, RTAX_HOPLIMIT
);
128 * Add an ip header to a skbuff and send it out.
131 int ip_build_and_send_pkt(struct sk_buff
*skb
, struct sock
*sk
,
132 u32 saddr
, u32 daddr
, struct ip_options
*opt
)
134 struct inet_sock
*inet
= inet_sk(sk
);
135 struct rtable
*rt
= (struct rtable
*)skb
->dst
;
138 /* Build the IP header. */
140 iph
=(struct iphdr
*)skb_push(skb
,sizeof(struct iphdr
) + opt
->optlen
);
142 iph
=(struct iphdr
*)skb_push(skb
,sizeof(struct iphdr
));
146 iph
->tos
= inet
->tos
;
147 if (ip_dont_fragment(sk
, &rt
->u
.dst
))
148 iph
->frag_off
= htons(IP_DF
);
151 iph
->ttl
= ip_select_ttl(inet
, &rt
->u
.dst
);
152 iph
->daddr
= rt
->rt_dst
;
153 iph
->saddr
= rt
->rt_src
;
154 iph
->protocol
= sk
->sk_protocol
;
155 iph
->tot_len
= htons(skb
->len
);
156 ip_select_ident(iph
, &rt
->u
.dst
, sk
);
159 if (opt
&& opt
->optlen
) {
160 iph
->ihl
+= opt
->optlen
>>2;
161 ip_options_build(skb
, opt
, daddr
, rt
, 0);
165 skb
->priority
= sk
->sk_priority
;
168 return NF_HOOK(PF_INET
, NF_IP_LOCAL_OUT
, skb
, NULL
, rt
->u
.dst
.dev
,
172 static inline int ip_finish_output2(struct sk_buff
*skb
)
174 struct dst_entry
*dst
= skb
->dst
;
175 struct hh_cache
*hh
= dst
->hh
;
176 struct net_device
*dev
= dst
->dev
;
177 int hh_len
= LL_RESERVED_SPACE(dev
);
179 /* Be paranoid, rather than too clever. */
180 if (unlikely(skb_headroom(skb
) < hh_len
&& dev
->hard_header
)) {
181 struct sk_buff
*skb2
;
183 skb2
= skb_realloc_headroom(skb
, LL_RESERVED_SPACE(dev
));
189 skb_set_owner_w(skb2
, skb
->sk
);
194 #ifdef CONFIG_NETFILTER_DEBUG
195 nf_debug_ip_finish_output2(skb
);
196 #endif /*CONFIG_NETFILTER_DEBUG*/
201 read_lock_bh(&hh
->hh_lock
);
202 hh_alen
= HH_DATA_ALIGN(hh
->hh_len
);
203 memcpy(skb
->data
- hh_alen
, hh
->hh_data
, hh_alen
);
204 read_unlock_bh(&hh
->hh_lock
);
205 skb_push(skb
, hh
->hh_len
);
206 return hh
->hh_output(skb
);
207 } else if (dst
->neighbour
)
208 return dst
->neighbour
->output(skb
);
211 printk(KERN_DEBUG
"ip_finish_output2: No header cache and no neighbour!\n");
216 int ip_finish_output(struct sk_buff
*skb
)
218 struct net_device
*dev
= skb
->dst
->dev
;
221 skb
->protocol
= htons(ETH_P_IP
);
223 return NF_HOOK(PF_INET
, NF_IP_POST_ROUTING
, skb
, NULL
, dev
,
227 int ip_mc_output(struct sk_buff
*skb
)
229 struct sock
*sk
= skb
->sk
;
230 struct rtable
*rt
= (struct rtable
*)skb
->dst
;
231 struct net_device
*dev
= rt
->u
.dst
.dev
;
234 * If the indicated interface is up and running, send the packet.
236 IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS
);
239 skb
->protocol
= htons(ETH_P_IP
);
242 * Multicasts are looped back for other local users
245 if (rt
->rt_flags
&RTCF_MULTICAST
) {
246 if ((!sk
|| inet_sk(sk
)->mc_loop
)
247 #ifdef CONFIG_IP_MROUTE
248 /* Small optimization: do not loopback not local frames,
249 which returned after forwarding; they will be dropped
250 by ip_mr_input in any case.
251 Note, that local frames are looped back to be delivered
254 This check is duplicated in ip_mr_input at the moment.
256 && ((rt
->rt_flags
&RTCF_LOCAL
) || !(IPCB(skb
)->flags
&IPSKB_FORWARDED
))
259 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
261 NF_HOOK(PF_INET
, NF_IP_POST_ROUTING
, newskb
, NULL
,
263 ip_dev_loopback_xmit
);
266 /* Multicasts with ttl 0 must not go beyond the host */
268 if (skb
->nh
.iph
->ttl
== 0) {
274 if (rt
->rt_flags
&RTCF_BROADCAST
) {
275 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
277 NF_HOOK(PF_INET
, NF_IP_POST_ROUTING
, newskb
, NULL
,
278 newskb
->dev
, ip_dev_loopback_xmit
);
281 if (skb
->len
> dst_mtu(&rt
->u
.dst
))
282 return ip_fragment(skb
, ip_finish_output
);
284 return ip_finish_output(skb
);
287 int ip_output(struct sk_buff
*skb
)
289 IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS
);
291 if (skb
->len
> dst_mtu(skb
->dst
) && !skb_shinfo(skb
)->tso_size
)
292 return ip_fragment(skb
, ip_finish_output
);
294 return ip_finish_output(skb
);
297 int ip_queue_xmit(struct sk_buff
*skb
, int ipfragok
)
299 struct sock
*sk
= skb
->sk
;
300 struct inet_sock
*inet
= inet_sk(sk
);
301 struct ip_options
*opt
= inet
->opt
;
305 /* Skip all of this if the packet is already routed,
306 * f.e. by something like SCTP.
308 rt
= (struct rtable
*) skb
->dst
;
312 /* Make sure we can route this packet. */
313 rt
= (struct rtable
*)__sk_dst_check(sk
, 0);
317 /* Use correct destination address if we have options. */
323 struct flowi fl
= { .oif
= sk
->sk_bound_dev_if
,
326 .saddr
= inet
->saddr
,
327 .tos
= RT_CONN_FLAGS(sk
) } },
328 .proto
= sk
->sk_protocol
,
330 { .sport
= inet
->sport
,
331 .dport
= inet
->dport
} } };
333 /* If this fails, retransmit mechanism of transport layer will
334 * keep trying until route appears or the connection times
337 if (ip_route_output_flow(&rt
, &fl
, sk
, 0))
340 __sk_dst_set(sk
, &rt
->u
.dst
);
341 tcp_v4_setup_caps(sk
, &rt
->u
.dst
);
343 skb
->dst
= dst_clone(&rt
->u
.dst
);
346 if (opt
&& opt
->is_strictroute
&& rt
->rt_dst
!= rt
->rt_gateway
)
349 /* OK, we know where to send it, allocate and build IP header. */
350 iph
= (struct iphdr
*) skb_push(skb
, sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0));
351 *((__u16
*)iph
) = htons((4 << 12) | (5 << 8) | (inet
->tos
& 0xff));
352 iph
->tot_len
= htons(skb
->len
);
353 if (ip_dont_fragment(sk
, &rt
->u
.dst
) && !ipfragok
)
354 iph
->frag_off
= htons(IP_DF
);
357 iph
->ttl
= ip_select_ttl(inet
, &rt
->u
.dst
);
358 iph
->protocol
= sk
->sk_protocol
;
359 iph
->saddr
= rt
->rt_src
;
360 iph
->daddr
= rt
->rt_dst
;
362 /* Transport layer set skb->h.foo itself. */
364 if (opt
&& opt
->optlen
) {
365 iph
->ihl
+= opt
->optlen
>> 2;
366 ip_options_build(skb
, opt
, inet
->daddr
, rt
, 0);
369 ip_select_ident_more(iph
, &rt
->u
.dst
, sk
, skb_shinfo(skb
)->tso_segs
);
371 /* Add an IP checksum. */
374 skb
->priority
= sk
->sk_priority
;
376 return NF_HOOK(PF_INET
, NF_IP_LOCAL_OUT
, skb
, NULL
, rt
->u
.dst
.dev
,
380 IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES
);
382 return -EHOSTUNREACH
;
386 static void ip_copy_metadata(struct sk_buff
*to
, struct sk_buff
*from
)
388 to
->pkt_type
= from
->pkt_type
;
389 to
->priority
= from
->priority
;
390 to
->protocol
= from
->protocol
;
391 to
->security
= from
->security
;
392 dst_release(to
->dst
);
393 to
->dst
= dst_clone(from
->dst
);
396 /* Copy the flags to each fragment. */
397 IPCB(to
)->flags
= IPCB(from
)->flags
;
399 #ifdef CONFIG_NET_SCHED
400 to
->tc_index
= from
->tc_index
;
402 #ifdef CONFIG_NETFILTER
403 to
->nfmark
= from
->nfmark
;
404 to
->nfcache
= from
->nfcache
;
405 /* Connection association is same as pre-frag packet */
406 nf_conntrack_put(to
->nfct
);
407 to
->nfct
= from
->nfct
;
408 nf_conntrack_get(to
->nfct
);
409 to
->nfctinfo
= from
->nfctinfo
;
410 #ifdef CONFIG_BRIDGE_NETFILTER
411 nf_bridge_put(to
->nf_bridge
);
412 to
->nf_bridge
= from
->nf_bridge
;
413 nf_bridge_get(to
->nf_bridge
);
415 #ifdef CONFIG_NETFILTER_DEBUG
416 to
->nf_debug
= from
->nf_debug
;
422 * This IP datagram is too large to be sent in one piece. Break it up into
423 * smaller pieces (each of size equal to IP header plus
424 * a block of the data of the original IP data part) that will yet fit in a
425 * single device frame, and queue such a frame for sending.
428 int ip_fragment(struct sk_buff
*skb
, int (*output
)(struct sk_buff
*))
433 struct net_device
*dev
;
434 struct sk_buff
*skb2
;
435 unsigned int mtu
, hlen
, left
, len
, ll_rs
;
438 struct rtable
*rt
= (struct rtable
*)skb
->dst
;
444 * Point into the IP datagram header.
449 if (unlikely((iph
->frag_off
& htons(IP_DF
)) && !skb
->local_df
)) {
450 icmp_send(skb
, ICMP_DEST_UNREACH
, ICMP_FRAG_NEEDED
,
451 htonl(dst_mtu(&rt
->u
.dst
)));
457 * Setup starting values.
461 mtu
= dst_mtu(&rt
->u
.dst
) - hlen
; /* Size of data space */
463 /* When frag_list is given, use it. First, check its validity:
464 * some transformers could create wrong frag_list or break existing
465 * one, it is not prohibited. In this case fall back to copying.
467 * LATER: this step can be merged to real generation of fragments,
468 * we can switch to copy when see the first bad fragment.
470 if (skb_shinfo(skb
)->frag_list
) {
471 struct sk_buff
*frag
;
472 int first_len
= skb_pagelen(skb
);
474 if (first_len
- hlen
> mtu
||
475 ((first_len
- hlen
) & 7) ||
476 (iph
->frag_off
& htons(IP_MF
|IP_OFFSET
)) ||
480 for (frag
= skb_shinfo(skb
)->frag_list
; frag
; frag
= frag
->next
) {
481 /* Correct geometry. */
482 if (frag
->len
> mtu
||
483 ((frag
->len
& 7) && frag
->next
) ||
484 skb_headroom(frag
) < hlen
)
487 /* Partially cloned skb? */
488 if (skb_shared(frag
))
492 /* Everything is OK. Generate! */
496 frag
= skb_shinfo(skb
)->frag_list
;
497 skb_shinfo(skb
)->frag_list
= NULL
;
498 skb
->data_len
= first_len
- skb_headlen(skb
);
499 skb
->len
= first_len
;
500 iph
->tot_len
= htons(first_len
);
501 iph
->frag_off
= htons(IP_MF
);
505 /* Prepare header of the next frame,
506 * before previous one went down. */
508 frag
->ip_summed
= CHECKSUM_NONE
;
509 frag
->h
.raw
= frag
->data
;
510 frag
->nh
.raw
= __skb_push(frag
, hlen
);
511 memcpy(frag
->nh
.raw
, iph
, hlen
);
513 iph
->tot_len
= htons(frag
->len
);
514 ip_copy_metadata(frag
, skb
);
516 ip_options_fragment(frag
);
517 offset
+= skb
->len
- hlen
;
518 iph
->frag_off
= htons(offset
>>3);
519 if (frag
->next
!= NULL
)
520 iph
->frag_off
|= htons(IP_MF
);
521 /* Ready, complete checksum */
536 IP_INC_STATS(IPSTATS_MIB_FRAGOKS
);
545 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS
);
550 left
= skb
->len
- hlen
; /* Space per frame */
551 ptr
= raw
+ hlen
; /* Where to start from */
553 #ifdef CONFIG_BRIDGE_NETFILTER
554 /* for bridged IP traffic encapsulated inside f.e. a vlan header,
555 * we need to make room for the encapsulating header */
556 ll_rs
= LL_RESERVED_SPACE_EXTRA(rt
->u
.dst
.dev
, nf_bridge_pad(skb
));
557 mtu
-= nf_bridge_pad(skb
);
559 ll_rs
= LL_RESERVED_SPACE(rt
->u
.dst
.dev
);
562 * Fragment the datagram.
565 offset
= (ntohs(iph
->frag_off
) & IP_OFFSET
) << 3;
566 not_last_frag
= iph
->frag_off
& htons(IP_MF
);
569 * Keep copying data until we run out.
574 /* IF: it doesn't fit, use 'mtu' - the data space left */
577 /* IF: we are not sending upto and including the packet end
578 then align the next start on an eight byte boundary */
586 if ((skb2
= alloc_skb(len
+hlen
+ll_rs
, GFP_ATOMIC
)) == NULL
) {
587 NETDEBUG(printk(KERN_INFO
"IP: frag: no memory for new fragment!\n"));
593 * Set up data on packet
596 ip_copy_metadata(skb2
, skb
);
597 skb_reserve(skb2
, ll_rs
);
598 skb_put(skb2
, len
+ hlen
);
599 skb2
->nh
.raw
= skb2
->data
;
600 skb2
->h
.raw
= skb2
->data
+ hlen
;
603 * Charge the memory for the fragment to any owner
608 skb_set_owner_w(skb2
, skb
->sk
);
611 * Copy the packet header into the new buffer.
614 memcpy(skb2
->nh
.raw
, skb
->data
, hlen
);
617 * Copy a block of the IP datagram.
619 if (skb_copy_bits(skb
, ptr
, skb2
->h
.raw
, len
))
624 * Fill in the new header fields.
627 iph
->frag_off
= htons((offset
>> 3));
629 /* ANK: dirty, but effective trick. Upgrade options only if
630 * the segment to be fragmented was THE FIRST (otherwise,
631 * options are already fixed) and make it ONCE
632 * on the initial skb, so that all the following fragments
633 * will inherit fixed options.
636 ip_options_fragment(skb
);
639 * Added AC : If we are fragmenting a fragment that's not the
640 * last fragment then keep MF on each bit
642 if (left
> 0 || not_last_frag
)
643 iph
->frag_off
|= htons(IP_MF
);
648 * Put this fragment into the sending queue.
651 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES
);
653 iph
->tot_len
= htons(len
+ hlen
);
662 IP_INC_STATS(IPSTATS_MIB_FRAGOKS
);
667 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS
);
672 ip_generic_getfrag(void *from
, char *to
, int offset
, int len
, int odd
, struct sk_buff
*skb
)
674 struct iovec
*iov
= from
;
676 if (skb
->ip_summed
== CHECKSUM_HW
) {
677 if (memcpy_fromiovecend(to
, iov
, offset
, len
) < 0)
680 unsigned int csum
= 0;
681 if (csum_partial_copy_fromiovecend(to
, iov
, offset
, len
, &csum
) < 0)
683 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
688 static inline unsigned int
689 csum_page(struct page
*page
, int offset
, int copy
)
694 csum
= csum_partial(kaddr
+ offset
, copy
, 0);
700 * ip_append_data() and ip_append_page() can make one large IP datagram
701 * from many pieces of data. Each pieces will be holded on the socket
702 * until ip_push_pending_frames() is called. Each piece can be a page
705 * Not only UDP, other transport protocols - e.g. raw sockets - can use
706 * this interface potentially.
708 * LATER: length must be adjusted by pad at tail, when it is required.
710 int ip_append_data(struct sock
*sk
,
711 int getfrag(void *from
, char *to
, int offset
, int len
,
712 int odd
, struct sk_buff
*skb
),
713 void *from
, int length
, int transhdrlen
,
714 struct ipcm_cookie
*ipc
, struct rtable
*rt
,
717 struct inet_sock
*inet
= inet_sk(sk
);
720 struct ip_options
*opt
= NULL
;
727 unsigned int maxfraglen
, fragheaderlen
;
728 int csummode
= CHECKSUM_NONE
;
733 if (skb_queue_empty(&sk
->sk_write_queue
)) {
739 if (inet
->cork
.opt
== NULL
) {
740 inet
->cork
.opt
= kmalloc(sizeof(struct ip_options
) + 40, sk
->sk_allocation
);
741 if (unlikely(inet
->cork
.opt
== NULL
))
744 memcpy(inet
->cork
.opt
, opt
, sizeof(struct ip_options
)+opt
->optlen
);
745 inet
->cork
.flags
|= IPCORK_OPT
;
746 inet
->cork
.addr
= ipc
->addr
;
748 dst_hold(&rt
->u
.dst
);
749 inet
->cork
.fragsize
= mtu
= dst_mtu(rt
->u
.dst
.path
);
751 inet
->cork
.length
= 0;
752 sk
->sk_sndmsg_page
= NULL
;
753 sk
->sk_sndmsg_off
= 0;
754 if ((exthdrlen
= rt
->u
.dst
.header_len
) != 0) {
756 transhdrlen
+= exthdrlen
;
760 if (inet
->cork
.flags
& IPCORK_OPT
)
761 opt
= inet
->cork
.opt
;
765 mtu
= inet
->cork
.fragsize
;
767 hh_len
= LL_RESERVED_SPACE(rt
->u
.dst
.dev
);
769 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
770 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
772 if (inet
->cork
.length
+ length
> 0xFFFF - fragheaderlen
) {
773 ip_local_error(sk
, EMSGSIZE
, rt
->rt_dst
, inet
->dport
, mtu
-exthdrlen
);
778 * transhdrlen > 0 means that this is the first fragment and we wish
779 * it won't be fragmented in the future.
782 length
+ fragheaderlen
<= mtu
&&
783 rt
->u
.dst
.dev
->features
&(NETIF_F_IP_CSUM
|NETIF_F_NO_CSUM
|NETIF_F_HW_CSUM
) &&
785 csummode
= CHECKSUM_HW
;
787 inet
->cork
.length
+= length
;
789 /* So, what's going on in the loop below?
791 * We use calculated fragment length to generate chained skb,
792 * each of segments is IP fragment ready for sending to network after
793 * adding appropriate IP header.
796 if ((skb
= skb_peek_tail(&sk
->sk_write_queue
)) == NULL
)
800 /* Check if the remaining data fits into current packet. */
801 copy
= mtu
- skb
->len
;
803 copy
= maxfraglen
- skb
->len
;
806 unsigned int datalen
;
807 unsigned int fraglen
;
808 unsigned int fraggap
;
809 unsigned int alloclen
;
810 struct sk_buff
*skb_prev
;
814 fraggap
= skb_prev
->len
- maxfraglen
;
819 * If remaining data exceeds the mtu,
820 * we know we need more fragment(s).
822 datalen
= length
+ fraggap
;
823 if (datalen
> mtu
- fragheaderlen
)
824 datalen
= maxfraglen
- fragheaderlen
;
825 fraglen
= datalen
+ fragheaderlen
;
827 if ((flags
& MSG_MORE
) &&
828 !(rt
->u
.dst
.dev
->features
&NETIF_F_SG
))
831 alloclen
= datalen
+ fragheaderlen
;
833 /* The last fragment gets additional space at tail.
834 * Note, with MSG_MORE we overallocate on fragments,
835 * because we have no idea what fragment will be
838 if (datalen
== length
)
839 alloclen
+= rt
->u
.dst
.trailer_len
;
842 skb
= sock_alloc_send_skb(sk
,
843 alloclen
+ hh_len
+ 15,
844 (flags
& MSG_DONTWAIT
), &err
);
847 if (atomic_read(&sk
->sk_wmem_alloc
) <=
849 skb
= sock_wmalloc(sk
,
850 alloclen
+ hh_len
+ 15, 1,
852 if (unlikely(skb
== NULL
))
859 * Fill in the control structures
861 skb
->ip_summed
= csummode
;
863 skb_reserve(skb
, hh_len
);
866 * Find where to start putting bytes.
868 data
= skb_put(skb
, fraglen
);
869 skb
->nh
.raw
= data
+ exthdrlen
;
870 data
+= fragheaderlen
;
871 skb
->h
.raw
= data
+ exthdrlen
;
874 skb
->csum
= skb_copy_and_csum_bits(
875 skb_prev
, maxfraglen
,
876 data
+ transhdrlen
, fraggap
, 0);
877 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
880 skb_trim(skb_prev
, maxfraglen
);
883 copy
= datalen
- transhdrlen
- fraggap
;
884 if (copy
> 0 && getfrag(from
, data
+ transhdrlen
, offset
, copy
, fraggap
, skb
) < 0) {
891 length
-= datalen
- fraggap
;
894 csummode
= CHECKSUM_NONE
;
897 * Put the packet on the pending queue.
899 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
906 if (!(rt
->u
.dst
.dev
->features
&NETIF_F_SG
)) {
910 if (getfrag(from
, skb_put(skb
, copy
),
911 offset
, copy
, off
, skb
) < 0) {
912 __skb_trim(skb
, off
);
917 int i
= skb_shinfo(skb
)->nr_frags
;
918 skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
-1];
919 struct page
*page
= sk
->sk_sndmsg_page
;
920 int off
= sk
->sk_sndmsg_off
;
923 if (page
&& (left
= PAGE_SIZE
- off
) > 0) {
926 if (page
!= frag
->page
) {
927 if (i
== MAX_SKB_FRAGS
) {
932 skb_fill_page_desc(skb
, i
, page
, sk
->sk_sndmsg_off
, 0);
933 frag
= &skb_shinfo(skb
)->frags
[i
];
935 } else if (i
< MAX_SKB_FRAGS
) {
936 if (copy
> PAGE_SIZE
)
938 page
= alloc_pages(sk
->sk_allocation
, 0);
943 sk
->sk_sndmsg_page
= page
;
944 sk
->sk_sndmsg_off
= 0;
946 skb_fill_page_desc(skb
, i
, page
, 0, 0);
947 frag
= &skb_shinfo(skb
)->frags
[i
];
948 skb
->truesize
+= PAGE_SIZE
;
949 atomic_add(PAGE_SIZE
, &sk
->sk_wmem_alloc
);
954 if (getfrag(from
, page_address(frag
->page
)+frag
->page_offset
+frag
->size
, offset
, copy
, skb
->len
, skb
) < 0) {
958 sk
->sk_sndmsg_off
+= copy
;
961 skb
->data_len
+= copy
;
970 inet
->cork
.length
-= length
;
971 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS
);
975 ssize_t
ip_append_page(struct sock
*sk
, struct page
*page
,
976 int offset
, size_t size
, int flags
)
978 struct inet_sock
*inet
= inet_sk(sk
);
981 struct ip_options
*opt
= NULL
;
986 unsigned int maxfraglen
, fragheaderlen
, fraggap
;
994 if (skb_queue_empty(&sk
->sk_write_queue
))
998 if (inet
->cork
.flags
& IPCORK_OPT
)
999 opt
= inet
->cork
.opt
;
1001 if (!(rt
->u
.dst
.dev
->features
&NETIF_F_SG
))
1004 hh_len
= LL_RESERVED_SPACE(rt
->u
.dst
.dev
);
1005 mtu
= inet
->cork
.fragsize
;
1007 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
1008 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
1010 if (inet
->cork
.length
+ size
> 0xFFFF - fragheaderlen
) {
1011 ip_local_error(sk
, EMSGSIZE
, rt
->rt_dst
, inet
->dport
, mtu
);
1015 if ((skb
= skb_peek_tail(&sk
->sk_write_queue
)) == NULL
)
1018 inet
->cork
.length
+= size
;
1023 /* Check if the remaining data fits into current packet. */
1024 len
= mtu
- skb
->len
;
1026 len
= maxfraglen
- skb
->len
;
1028 struct sk_buff
*skb_prev
;
1035 fraggap
= skb_prev
->len
- maxfraglen
;
1039 alloclen
= fragheaderlen
+ hh_len
+ fraggap
+ 15;
1040 skb
= sock_wmalloc(sk
, alloclen
, 1, sk
->sk_allocation
);
1041 if (unlikely(!skb
)) {
1047 * Fill in the control structures
1049 skb
->ip_summed
= CHECKSUM_NONE
;
1051 skb_reserve(skb
, hh_len
);
1054 * Find where to start putting bytes.
1056 data
= skb_put(skb
, fragheaderlen
+ fraggap
);
1057 skb
->nh
.iph
= iph
= (struct iphdr
*)data
;
1058 data
+= fragheaderlen
;
1062 skb
->csum
= skb_copy_and_csum_bits(
1063 skb_prev
, maxfraglen
,
1065 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1067 skb_trim(skb_prev
, maxfraglen
);
1071 * Put the packet on the pending queue.
1073 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
1077 i
= skb_shinfo(skb
)->nr_frags
;
1080 if (skb_can_coalesce(skb
, i
, page
, offset
)) {
1081 skb_shinfo(skb
)->frags
[i
-1].size
+= len
;
1082 } else if (i
< MAX_SKB_FRAGS
) {
1084 skb_fill_page_desc(skb
, i
, page
, offset
, len
);
1090 if (skb
->ip_summed
== CHECKSUM_NONE
) {
1092 csum
= csum_page(page
, offset
, len
);
1093 skb
->csum
= csum_block_add(skb
->csum
, csum
, skb
->len
);
1097 skb
->data_len
+= len
;
1104 inet
->cork
.length
-= size
;
1105 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS
);
1110 * Combined all pending IP fragments on the socket as one IP datagram
1111 * and push them out.
1113 int ip_push_pending_frames(struct sock
*sk
)
1115 struct sk_buff
*skb
, *tmp_skb
;
1116 struct sk_buff
**tail_skb
;
1117 struct inet_sock
*inet
= inet_sk(sk
);
1118 struct ip_options
*opt
= NULL
;
1119 struct rtable
*rt
= inet
->cork
.rt
;
1125 if ((skb
= __skb_dequeue(&sk
->sk_write_queue
)) == NULL
)
1127 tail_skb
= &(skb_shinfo(skb
)->frag_list
);
1129 /* move skb->data to ip header from ext header */
1130 if (skb
->data
< skb
->nh
.raw
)
1131 __skb_pull(skb
, skb
->nh
.raw
- skb
->data
);
1132 while ((tmp_skb
= __skb_dequeue(&sk
->sk_write_queue
)) != NULL
) {
1133 __skb_pull(tmp_skb
, skb
->h
.raw
- skb
->nh
.raw
);
1134 *tail_skb
= tmp_skb
;
1135 tail_skb
= &(tmp_skb
->next
);
1136 skb
->len
+= tmp_skb
->len
;
1137 skb
->data_len
+= tmp_skb
->len
;
1138 skb
->truesize
+= tmp_skb
->truesize
;
1139 __sock_put(tmp_skb
->sk
);
1140 tmp_skb
->destructor
= NULL
;
1144 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1145 * to fragment the frame generated here. No matter, what transforms
1146 * how transforms change size of the packet, it will come out.
1148 if (inet
->pmtudisc
!= IP_PMTUDISC_DO
)
1151 /* DF bit is set when we want to see DF on outgoing frames.
1152 * If local_df is set too, we still allow to fragment this frame
1154 if (inet
->pmtudisc
== IP_PMTUDISC_DO
||
1155 (skb
->len
<= dst_mtu(&rt
->u
.dst
) &&
1156 ip_dont_fragment(sk
, &rt
->u
.dst
)))
1159 if (inet
->cork
.flags
& IPCORK_OPT
)
1160 opt
= inet
->cork
.opt
;
1162 if (rt
->rt_type
== RTN_MULTICAST
)
1165 ttl
= ip_select_ttl(inet
, &rt
->u
.dst
);
1167 iph
= (struct iphdr
*)skb
->data
;
1171 iph
->ihl
+= opt
->optlen
>>2;
1172 ip_options_build(skb
, opt
, inet
->cork
.addr
, rt
, 0);
1174 iph
->tos
= inet
->tos
;
1175 iph
->tot_len
= htons(skb
->len
);
1178 __ip_select_ident(iph
, &rt
->u
.dst
, 0);
1180 iph
->id
= htons(inet
->id
++);
1183 iph
->protocol
= sk
->sk_protocol
;
1184 iph
->saddr
= rt
->rt_src
;
1185 iph
->daddr
= rt
->rt_dst
;
1188 skb
->priority
= sk
->sk_priority
;
1189 skb
->dst
= dst_clone(&rt
->u
.dst
);
1191 /* Netfilter gets whole the not fragmented skb. */
1192 err
= NF_HOOK(PF_INET
, NF_IP_LOCAL_OUT
, skb
, NULL
,
1193 skb
->dst
->dev
, dst_output
);
1196 err
= inet
->recverr
? net_xmit_errno(err
) : 0;
1202 inet
->cork
.flags
&= ~IPCORK_OPT
;
1203 if (inet
->cork
.opt
) {
1204 kfree(inet
->cork
.opt
);
1205 inet
->cork
.opt
= NULL
;
1207 if (inet
->cork
.rt
) {
1208 ip_rt_put(inet
->cork
.rt
);
1209 inet
->cork
.rt
= NULL
;
1214 IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS
);
1219 * Throw away all pending data on the socket.
1221 void ip_flush_pending_frames(struct sock
*sk
)
1223 struct inet_sock
*inet
= inet_sk(sk
);
1224 struct sk_buff
*skb
;
1226 while ((skb
= __skb_dequeue_tail(&sk
->sk_write_queue
)) != NULL
)
1229 inet
->cork
.flags
&= ~IPCORK_OPT
;
1230 if (inet
->cork
.opt
) {
1231 kfree(inet
->cork
.opt
);
1232 inet
->cork
.opt
= NULL
;
1234 if (inet
->cork
.rt
) {
1235 ip_rt_put(inet
->cork
.rt
);
1236 inet
->cork
.rt
= NULL
;
1242 * Fetch data from kernel space and fill in checksum if needed.
1244 static int ip_reply_glue_bits(void *dptr
, char *to
, int offset
,
1245 int len
, int odd
, struct sk_buff
*skb
)
1249 csum
= csum_partial_copy_nocheck(dptr
+offset
, to
, len
, 0);
1250 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
1255 * Generic function to send a packet as reply to another packet.
1256 * Used to send TCP resets so far. ICMP should use this function too.
1258 * Should run single threaded per socket because it uses the sock
1259 * structure to pass arguments.
1261 * LATER: switch from ip_build_xmit to ip_append_*
1263 void ip_send_reply(struct sock
*sk
, struct sk_buff
*skb
, struct ip_reply_arg
*arg
,
1266 struct inet_sock
*inet
= inet_sk(sk
);
1268 struct ip_options opt
;
1271 struct ipcm_cookie ipc
;
1273 struct rtable
*rt
= (struct rtable
*)skb
->dst
;
1275 if (ip_options_echo(&replyopts
.opt
, skb
))
1278 daddr
= ipc
.addr
= rt
->rt_src
;
1281 if (replyopts
.opt
.optlen
) {
1282 ipc
.opt
= &replyopts
.opt
;
1285 daddr
= replyopts
.opt
.faddr
;
1289 struct flowi fl
= { .nl_u
= { .ip4_u
=
1291 .saddr
= rt
->rt_spec_dst
,
1292 .tos
= RT_TOS(skb
->nh
.iph
->tos
) } },
1293 /* Not quite clean, but right. */
1295 { .sport
= skb
->h
.th
->dest
,
1296 .dport
= skb
->h
.th
->source
} },
1297 .proto
= sk
->sk_protocol
};
1298 if (ip_route_output_key(&rt
, &fl
))
1302 /* And let IP do all the hard work.
1304 This chunk is not reenterable, hence spinlock.
1305 Note that it uses the fact, that this function is called
1306 with locally disabled BH and that sk cannot be already spinlocked.
1309 inet
->tos
= skb
->nh
.iph
->tos
;
1310 sk
->sk_priority
= skb
->priority
;
1311 sk
->sk_protocol
= skb
->nh
.iph
->protocol
;
1312 ip_append_data(sk
, ip_reply_glue_bits
, arg
->iov
->iov_base
, len
, 0,
1313 &ipc
, rt
, MSG_DONTWAIT
);
1314 if ((skb
= skb_peek(&sk
->sk_write_queue
)) != NULL
) {
1315 if (arg
->csumoffset
>= 0)
1316 *((u16
*)skb
->h
.raw
+ arg
->csumoffset
) = csum_fold(csum_add(skb
->csum
, arg
->csum
));
1317 skb
->ip_summed
= CHECKSUM_NONE
;
1318 ip_push_pending_frames(sk
);
1327 * IP protocol layer initialiser
1330 static struct packet_type ip_packet_type
= {
1331 .type
= __constant_htons(ETH_P_IP
),
1336 * IP registers the packet type and then calls the subprotocol initialisers
1339 void __init
ip_init(void)
1341 dev_add_pack(&ip_packet_type
);
1346 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1347 igmp_mc_proc_init();
1351 EXPORT_SYMBOL(ip_finish_output
);
1352 EXPORT_SYMBOL(ip_fragment
);
1353 EXPORT_SYMBOL(ip_generic_getfrag
);
1354 EXPORT_SYMBOL(ip_queue_xmit
);
1355 EXPORT_SYMBOL(ip_send_check
);
1357 #ifdef CONFIG_SYSCTL
1358 EXPORT_SYMBOL(sysctl_ip_default_ttl
);