Per-datagram TTL and TOS via sendmsg()

This patch adds support for specifying IPv4 Time-To-Live (IP_TTL) and/or Type-Of-Service (IP_TOS) values on a per datagram basis through sendmsg() ancilliary data. Until then, it only worked for IPv6 sockets (using IPV6_HOPLIMIT and IPV6_TCLASS).

index 62daf21..7a6dc33 100644
@@ -140,6 +140,8 @@ struct inet_sock {
 		int			length; /* Total length of all frames */
 		__be32			addr;
 		struct flowi		fl;
+		__s16			ttl;
+		__s16			tos;
 	} cork;
 };
 

index abf2820..dcfdb41 100644
@@ -54,6 +54,8 @@ struct ipcm_cookie
 	__be32			addr;
 	int			oif;
 	struct ip_options	*opt;
+	__s16			ttl;
+	__s16			tos;
 };
 
 #define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))

index 02a899b..e10852d 100644
@@ -392,8 +392,9 @@ static void icmp_reply(struct icmp_bxm *icmp_param, 

struct sk_buff *skb)
icmp_param->data.icmph.checksum = 0; icmp_out_count(icmp_param->data.icmph.type);

- inet->tos = ip_hdr(skb)->tos;
daddr = ipc.addr = rt->rt_src;
+ ipc.tos = ip_hdr(skb)->tos;
+ ipc.ttl = MULTICAST(daddr) ? inet->mc_ttl : inet->uc_ttl;
ipc.opt = NULL;
if (icmp_param->replyopts.optlen) {
ipc.opt = &icmp_param->replyopts;
@@ -438,7 +439,6 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
struct rtable *rt = (struct rtable *)skb_in->dst; struct ipcm_cookie ipc;
__be32 saddr;
- u8 tos;

if (!rt)
goto out;
@@ -526,9 +526,9 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
saddr = 0;
}

- tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
- IPTOS_PREC_INTERNETCONTROL) :
- iph->tos;
+ ipc.tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
+ IPTOS_PREC_INTERNETCONTROL) :
+ iph->tos;

if (ip_options_echo(&icmp_param.replyopts, skb_in))
goto out_unlock;
@@ -545,7 +545,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
icmp_param.skb = skb_in;
icmp_param.offset = skb_network_offset(skb_in); icmp_out_count(icmp_param.data.icmph.type);
- inet_sk(icmp_socket->sk)->tos = tos;
+ ipc.ttl = -1;
ipc.addr = iph->saddr;
ipc.opt = &icmp_param.replyopts;

@@ -557,7 +557,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
icmp_param.replyopts.faddr :
iph->saddr,
.saddr = saddr,
- .tos = RT_TOS(tos)
+ .tos = RT_TOS(ipc.tos)
}
},
.proto = IPPROTO_ICMP,

index 34ea454..67ce657 100644
@@ -806,6 +806,8 @@ int ip_append_data(struct sock *sk,
 					    dst_mtu(rt->u.dst.path);
 		inet->cork.rt = rt;
 		inet->cork.length = 0;
+		inet->cork.ttl = ipc->ttl;
+		inet->cork.tos = ipc->tos;
 		sk->sk_sndmsg_page = NULL;
 		sk->sk_sndmsg_off = 0;
 		if ((exthdrlen = rt->u.dst.header_len) != 0) {

@@ -1233,7 +1235,9 @@ int ip_push_pending_frames(struct sock *sk)
 	if (inet->cork.flags & IPCORK_OPT)
 		opt = inet->cork.opt;
 
-	if (rt->rt_type == RTN_MULTICAST)
+	if (inet->cork.ttl != -1)
+		ttl = inet->cork.ttl;
+	else if (rt->rt_type == RTN_MULTICAST)
 		ttl = inet->mc_ttl;
 	else
 		ttl = ip_select_ttl(inet, &rt->u.dst);

@@ -1245,7 +1249,7 @@ int ip_push_pending_frames(struct sock *sk)
 		iph->ihl += opt->optlen>>2;
 		ip_options_build(skb, opt, inet->cork.addr, rt, 0);
 	}
-	iph->tos = inet->tos;
+	iph->tos = (inet->cork.tos != -1) ? inet->cork.tos : inet->tos;
 	iph->tot_len = htons(skb->len);
 	iph->frag_off = df;
 	ip_select_ident(iph, &rt->u.dst, sk);

@@ -1343,6 +1347,8 @@ void ip_send_reply(struct sock *sk, struct sk_buff 

*skb, struct ip_reply_arg *ar

daddr = ipc.addr = rt->rt_src;
ipc.opt = NULL;
+ ipc.tos = ip_hdr(skb)->tos;
+ ipc.ttl = inet->uc_ttl;

if (replyopts.opt.optlen) {
ipc.opt = &replyopts.opt;
@@ -1374,7 +1380,6 @@ void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *ar
with locally disabled BH and that sk cannot be already spinlocked.
*/
bh_lock_sock(sk);
- inet->tos = ip_hdr(skb)->tos;
sk->sk_priority = skb->priority;
sk->sk_protocol = ip_hdr(skb)->protocol; sk->sk_bound_dev_if = arg->bound_dev_if;

index 4d54457..02c47ff 100644
@@ -190,6 +190,16 @@ int ip_cmsg_send(struct msghdr *msg, struct 

ipcm_cookie *ipc)
ipc->addr = info->ipi_spec_dst.s_addr; break;
}
+ case IP_TTL:
+ if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))
+ return -EINVAL;
+ ipc->ttl = *(int *)CMSG_DATA(cmsg);
+ break;
+ case IP_TOS:
+ if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))
+ return -EINVAL;
+ ipc->tos = *(int *)CMSG_DATA(cmsg);
+ break;
default:
return -EINVAL;
}

index 24d7c9f..035bb37 100644
@@ -436,6 +436,8 @@ static int raw_sendmsg(struct kiocb *iocb, struct 

sock *sk, struct msghdr *msg,
ipc.addr = inet->saddr;
ipc.opt = NULL;
ipc.oif = sk->sk_bound_dev_if;
+ ipc.ttl = MULTICAST(daddr) ? inet->mc_ttl : inet->uc_ttl;
+ ipc.tos = inet->tos;

if (msg->msg_controllen) {
err = ip_cmsg_send(msg, &ipc);

index facb7e2..d7d6a02 100644
@@ -581,6 +581,8 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, 

struct msghdr *msg,
}
ipc.addr = inet->saddr;

+ ipc.ttl = MULTICAST(daddr) ? inet->mc_ttl : inet->uc_ttl;
+ ipc.tos = inet->tos;
ipc.oif = sk->sk_bound_dev_if;
if (msg->msg_controllen) {
err = ip_cmsg_send(msg, &ipc);

Rémi Denis-Courmont
http://www.remlab.net/

From: Rémi_Denis-Courmont <[email protected]>
Date: Sat, 7 Jul 2007 14:21:43 +0300

Your email client corrupted your patch by adding newline breaks all over the place, please correct this and make a full resubmission. Resubmit the full changelog and patch, don't just reply to this email with the patch as that screws up how I integrate people's work, thanks :)