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ndp: Split out helpers for sending specific NDP message types

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Currently the large ndp() function responds to all NDP messages we handle,
both parsing the message as necessary and sending the response.  Split out
the code to construct and send specific message types into ndp_na() (to
send NA messages) and ndp_ra() (to send RA messages).

As well as breaking up an excessively large function, this is a first step
to being able to send unsolicited NDP messages.

While we're there, remove a slighty ugly goto.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2024-11-14 14:33:05 +11:00 committed by Stefano Brivio
parent 4e47167035
commit cbc83e14df
1 changed files with 76 additions and 56 deletions
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132
ndp.c
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@ -186,16 +186,13 @@ static void ndp_send(const struct ctx *c, const struct in6_addr *dst,
} }
/** /**
* ndp() - Check for NDP solicitations, reply as needed * ndp_na() - Send an NDP Neighbour Advertisement (NA) message
* @c: Execution context * @c: Execution context
* @ih: ICMPv6 header * @dst: IPv6 address to send the NA to
* @saddr: Source IPv6 address * @addr: IPv6 address to advertise
* @p: Packet pool
*
* Return: 0 if not handled here, 1 if handled, -1 on failure
*/ */
int ndp(const struct ctx *c, const struct icmp6hdr *ih, static void ndp_na(const struct ctx *c, const struct in6_addr *dst,
const struct in6_addr *saddr, const struct pool *p) const void *addr)
{ {
struct ndp_na na = { struct ndp_na na = {
.ih = { .ih = {
@ -212,6 +209,20 @@ int ndp(const struct ctx *c, const struct icmp6hdr *ih,
}, },
} }
}; };
memcpy(&na.target_addr, addr, sizeof(na.target_addr));
memcpy(na.target_l2_addr.mac, c->our_tap_mac, ETH_ALEN);
ndp_send(c, dst, &na, sizeof(na));
}
/**
* ndp_ra() - Send an NDP Router Advertisement (RA) message
* @c: Execution context
* @dst: IPv6 address to send the RA to
*/
static void ndp_ra(const struct ctx *c, const struct in6_addr *dst)
{
struct ndp_ra ra = { struct ndp_ra ra = {
.ih = { .ih = {
.icmp6_type = RA, .icmp6_type = RA,
@ -238,58 +249,28 @@ int ndp(const struct ctx *c, const struct icmp6hdr *ih,
}, },
}, },
}; };
unsigned char *ptr = NULL;
if (ih->icmp6_type < RS || ih->icmp6_type > NA) memcpy(&ra.prefix, &c->ip6.addr, sizeof(ra.prefix));
return 0;
if (c->no_ndp) ptr = &ra.var[0];
return 1;
if (ih->icmp6_type == NS) { if (c->mtu != -1) {
const struct ndp_ns *ns = struct opt_mtu *mtu = (struct opt_mtu *)ptr;
packet_get(p, 0, 0, sizeof(struct ndp_ns), NULL); *mtu = (struct opt_mtu) {
.header = {
.type = OPT_MTU,
.len = 1,
},
.value = htonl(c->mtu),
};
ptr += sizeof(struct opt_mtu);
}
if (!ns) if (!c->no_dhcp_dns) {
return -1;
if (IN6_IS_ADDR_UNSPECIFIED(saddr))
return 1;
info("NDP: received NS, sending NA");
memcpy(&na.target_addr, &ns->target_addr,
sizeof(na.target_addr));
memcpy(na.target_l2_addr.mac, c->our_tap_mac, ETH_ALEN);
ndp_send(c, saddr, &na, sizeof(struct ndp_na));
} else if (ih->icmp6_type == RS) {
unsigned char *ptr = NULL;
size_t dns_s_len = 0; size_t dns_s_len = 0;
int i, n; int i, n;
if (c->no_ra)
return 1;
info("NDP: received RS, sending RA");
memcpy(&ra.prefix, &c->ip6.addr, sizeof(ra.prefix));
ptr = &ra.var[0];
if (c->mtu != -1) {
struct opt_mtu *mtu = (struct opt_mtu *)ptr;
*mtu = (struct opt_mtu) {
.header = {
.type = OPT_MTU,
.len = 1,
},
.value = htonl(c->mtu),
};
ptr += sizeof(struct opt_mtu);
}
if (c->no_dhcp_dns)
goto dns_done;
for (n = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns[n]); n++); for (n = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns[n]); n++);
if (n) { if (n) {
struct opt_rdnss *rdnss = (struct opt_rdnss *)ptr; struct opt_rdnss *rdnss = (struct opt_rdnss *)ptr;
@ -343,11 +324,50 @@ int ndp(const struct ctx *c, const struct icmp6hdr *ih,
memset(ptr, 0, 8 - dns_s_len % 8); /* padding */ memset(ptr, 0, 8 - dns_s_len % 8); /* padding */
ptr += 8 - dns_s_len % 8; ptr += 8 - dns_s_len % 8;
} }
}
dns_done: memcpy(&ra.source_ll.mac, c->our_tap_mac, ETH_ALEN);
memcpy(&ra.source_ll.mac, c->our_tap_mac, ETH_ALEN);
ndp_send(c, saddr, &ra, ptr - (unsigned char *)&ra); ndp_send(c, dst, &ra, ptr - (unsigned char *)&ra);
}
/**
* ndp() - Check for NDP solicitations, reply as needed
* @c: Execution context
* @ih: ICMPv6 header
* @saddr: Source IPv6 address
* @p: Packet pool
*
* Return: 0 if not handled here, 1 if handled, -1 on failure
*/
int ndp(const struct ctx *c, const struct icmp6hdr *ih,
const struct in6_addr *saddr, const struct pool *p)
{
if (ih->icmp6_type < RS || ih->icmp6_type > NA)
return 0;
if (c->no_ndp)
return 1;
if (ih->icmp6_type == NS) {
const struct ndp_ns *ns;
ns = packet_get(p, 0, 0, sizeof(struct ndp_ns), NULL);
if (!ns)
return -1;
if (IN6_IS_ADDR_UNSPECIFIED(saddr))
return 1;
info("NDP: received NS, sending NA");
ndp_na(c, saddr, &ns->target_addr);
} else if (ih->icmp6_type == RS) {
if (c->no_ra)
return 1;
info("NDP: received RS, sending RA");
ndp_ra(c, saddr);
} }
return 1; return 1;