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icmpv6.c: Move code generating ipv6 hdr to its own function 

It will be re-used in next commits.

Change-Id: I3c108efad6461cd4e82ef435290005174bc8b30e
This commit is contained in:
Pau Espin 2020-04-15 15:03:50 +02:00
parent e5d71639e5
commit c43e887e9e
1 changed files with 25 additions and 16 deletions
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41
lib/icmpv6.c
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@ -90,6 +90,30 @@ struct icmpv6_opt_prefix {
uint32_t res2;
uint8_t prefix[16];
} __attribute__ ((packed));
/* Prepends the ipv6 header and returns checksum content */
static uint16_t icmpv6_prepend_ip6hdr(struct msgb *msg, const struct in6_addr *saddr,
const struct in6_addr *daddr)
{
uint32_t len;
uint16_t skb_csum;
struct ip6_hdr *i6h;
/* checksum */
skb_csum = csum_partial(msgb_data(msg), msgb_length(msg), 0);
len = msgb_length(msg);
skb_csum = csum_ipv6_magic(saddr, daddr, len, IPPROTO_ICMPV6, skb_csum);
/* Push IPv6 header in front of ICMPv6 packet */
i6h = (struct ip6_hdr *) msgb_push(msg, sizeof(*i6h));
/* 4 bits version, 8 bits TC, 20 bits flow-ID */
i6h->ip6_ctlun.ip6_un1.ip6_un1_flow = htonl(0x60000000);
i6h->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(len);
i6h->ip6_ctlun.ip6_un1.ip6_un1_nxt = IPPROTO_ICMPV6;
i6h->ip6_ctlun.ip6_un1.ip6_un1_hlim = 255;
i6h->ip6_src = *saddr;
i6h->ip6_dst = *daddr;
return skb_csum;
}
/*! construct a 3GPP 29.061 compliant router advertisement for a given prefix
@ -104,9 +128,6 @@ static struct msgb *icmpv6_construct_ra(const struct in6_addr *saddr,
struct msgb *msg = msgb_alloc_headroom(512,128, "IPv6 RA");
struct icmpv6_radv_hdr *ra;
struct icmpv6_opt_prefix *ra_opt_pref;
struct ip6_hdr *i6h;
uint32_t len;
uint16_t skb_csum;
OSMO_ASSERT(msg);
@ -144,19 +165,7 @@ static struct msgb *icmpv6_construct_ra(const struct in6_addr *saddr,
memcpy(ra_opt_pref->prefix, prefix, sizeof(ra_opt_pref->prefix));
/* checksum */
skb_csum = csum_partial(msgb_data(msg), msgb_length(msg), 0);
len = msgb_length(msg);
ra->hdr.csum = csum_ipv6_magic(saddr, daddr, len, IPPROTO_ICMPV6, skb_csum);
/* Push IPv6 header in front of ICMPv6 packet */
i6h = (struct ip6_hdr *) msgb_push(msg, sizeof(*i6h));
/* 4 bits version, 8 bits TC, 20 bits flow-ID */
i6h->ip6_ctlun.ip6_un1.ip6_un1_flow = htonl(0x60000000);
i6h->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(len);
i6h->ip6_ctlun.ip6_un1.ip6_un1_nxt = IPPROTO_ICMPV6;
i6h->ip6_ctlun.ip6_un1.ip6_un1_hlim = 255;
i6h->ip6_src = *saddr;
i6h->ip6_dst = *daddr;
ra->hdr.csum = icmpv6_prepend_ip6hdr(msg, saddr, daddr);
return msg;
}