Split tap_ip_send() into IPv4 and IPv6 specific functions
The IPv4 and IPv6 paths in tap_ip_send() have very little in common, and
it turns out that every caller (statically) knows if it is using IPv4 or
IPv6. So split into separate tap_ip4_send() and tap_ip6_send() functions.
Use a new tap_l2_hdr() function for the very small common part.
While we're there, make some minor cleanups:
- We were double writing some fields in the IPv6 header, so that it
temporary matched the pseudo-header for checksum calculation. With
recent checksum reworks, this isn't neccessary any more.
- We don't use any IPv4 header options, so use some sizeof() constructs
instead of some open coded values for header length.
- The comment used to say that the flow label was for TCP over IPv6, but
in fact the only thing we used it for was DHCPv6 over UDP traffic
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
Stefano Brivio
parent
fb5d1c5d7d
commit
f616ca231e
4 changed files with 101 additions and 94 deletions
6
dhcpv6.c
6
dhcpv6.c
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@ -531,8 +531,8 @@ int dhcpv6(struct ctx *c, const struct pool *p,
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resp_not_on_link.hdr.xid = mh->xid;
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tap_ip_send(c, src, IPPROTO_UDP,
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(char *)&resp_not_on_link, n, mh->xid);
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tap_ip6_send(c, src, IPPROTO_UDP,
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(char *)&resp_not_on_link, n, mh->xid);
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return 1;
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}
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@ -580,7 +580,7 @@ int dhcpv6(struct ctx *c, const struct pool *p,
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resp.hdr.xid = mh->xid;
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tap_ip_send(c, src, IPPROTO_UDP, (char *)&resp, n, mh->xid);
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tap_ip6_send(c, src, IPPROTO_UDP, (char *)&resp, n, mh->xid);
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c->ip6.addr_seen = c->ip6.addr;
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return 1;
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10
icmp.c
10
icmp.c
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@ -69,10 +69,6 @@ static uint8_t icmp_act[IP_VERSIONS][DIV_ROUND_UP(ICMP_NUM_IDS, 8)];
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void icmp_sock_handler(const struct ctx *c, union epoll_ref ref,
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uint32_t events, const struct timespec *now)
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{
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struct in6_addr a6 = { .s6_addr = { 0, 0, 0, 0,
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0, 0, 0, 0,
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0, 0, 0xff, 0xff,
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0, 0, 0, 0 } };
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union icmp_epoll_ref *iref = &ref.r.p.icmp;
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struct sockaddr_storage sr;
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socklen_t sl = sizeof(sr);
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@ -109,7 +105,7 @@ void icmp_sock_handler(const struct ctx *c, union epoll_ref ref,
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icmp_id_map[V6][id].seq = seq;
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}
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tap_ip_send(c, &sr6->sin6_addr, IPPROTO_ICMPV6, buf, n, 0);
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tap_ip6_send(c, &sr6->sin6_addr, IPPROTO_ICMPV6, buf, n, 0);
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} else {
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struct sockaddr_in *sr4 = (struct sockaddr_in *)&sr;
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struct icmphdr *ih = (struct icmphdr *)buf;
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@ -127,9 +123,7 @@ void icmp_sock_handler(const struct ctx *c, union epoll_ref ref,
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icmp_id_map[V4][id].seq = seq;
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}
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memcpy(&a6.s6_addr[12], &sr4->sin_addr, sizeof(sr4->sin_addr));
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tap_ip_send(c, &a6, IPPROTO_ICMP, buf, n, 0);
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tap_ip4_send(c, sr4->sin_addr.s_addr, IPPROTO_ICMP, buf, n);
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}
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}
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173
tap.c
173
tap.c
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@ -113,100 +113,111 @@ const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
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}
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/**
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* tap_ip_send() - Send IP packet, with L2 headers, calculating L3/L4 checksums
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* tap_push_l2h() - Build an L2 header for an inbound packet
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* @c: Execution context
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* @src: IPv6 source address, IPv4-mapped for IPv4 sources
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* @proto: L4 protocol number
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* @in: Payload
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* @len: L4 payload length
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* @flow: Flow label for TCP over IPv6
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* @buf: Buffer address at which to generate header
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* @proto: Ethernet protocol number for L3
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*
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* Return: pointer at which to write the packet's payload
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*/
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void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto,
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const char *in, size_t len, uint32_t flow)
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static void *tap_push_l2h(const struct ctx *c, void *buf, uint16_t proto)
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{
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char buf[USHRT_MAX];
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struct ethhdr *eh;
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eh = (struct ethhdr *)buf;
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struct ethhdr *eh = (struct ethhdr *)buf;
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/* TODO: ARP table lookup */
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memcpy(eh->h_dest, c->mac_guest, ETH_ALEN);
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memcpy(eh->h_source, c->mac, ETH_ALEN);
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eh->h_proto = ntohs(proto);
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return eh + 1;
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}
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if (IN6_IS_ADDR_V4MAPPED(src)) {
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struct iphdr *iph = (struct iphdr *)(eh + 1);
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char *data = (char *)(iph + 1);
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/**
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* tap_ip4_send() - Send IPv4 packet, with L2 headers, calculating L3/L4 checksums
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* @c: Execution context
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* @src: IPv4 source address
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* @proto: L4 protocol number
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* @in: Payload
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* @len: L4 payload length
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*/
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void tap_ip4_send(const struct ctx *c, in_addr_t src, uint8_t proto,
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const char *in, size_t len)
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{
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char buf[USHRT_MAX];
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struct iphdr *ip4h = (struct iphdr *)tap_push_l2h(c, buf, ETH_P_IP);
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char *data = (char *)(ip4h + 1);
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eh->h_proto = ntohs(ETH_P_IP);
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ip4h->version = 4;
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ip4h->ihl = sizeof(struct iphdr) / 4;
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ip4h->tos = 0;
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ip4h->tot_len = htons(len + sizeof(*ip4h));
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ip4h->id = 0;
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ip4h->frag_off = 0;
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ip4h->ttl = 255;
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ip4h->protocol = proto;
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ip4h->saddr = src;
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ip4h->daddr = tap_ip4_daddr(c);
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csum_ip4_header(ip4h);
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iph->version = 4;
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iph->ihl = 5;
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iph->tos = 0;
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iph->tot_len = htons(len + 20);
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iph->id = 0;
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iph->frag_off = 0;
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iph->ttl = 255;
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iph->protocol = proto;
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iph->daddr = tap_ip4_daddr(c);
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memcpy(&iph->saddr, &src->s6_addr[12], 4);
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memcpy(data, in, len);
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csum_ip4_header(iph);
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if (ip4h->protocol == IPPROTO_UDP) {
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struct udphdr *uh = (struct udphdr *)(ip4h + 1);
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memcpy(data, in, len);
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if (iph->protocol == IPPROTO_UDP) {
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struct udphdr *uh = (struct udphdr *)(iph + 1);
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csum_udp4(uh, iph->saddr, iph->daddr, uh + 1, len - sizeof(*uh));
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} else if (iph->protocol == IPPROTO_ICMP) {
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struct icmphdr *ih = (struct icmphdr *)(iph + 1);
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csum_icmp4(ih, ih + 1, len - sizeof(*ih));
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}
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if (tap_send(c, buf, len + sizeof(*iph) + sizeof(*eh)) < 0)
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debug("tap: failed to send %lu bytes (IPv4)", len);
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} else {
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struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
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char *data = (char *)(ip6h + 1);
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eh->h_proto = ntohs(ETH_P_IPV6);
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memset(ip6h->flow_lbl, 0, 3);
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ip6h->payload_len = htons(len);
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ip6h->priority = 0;
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ip6h->saddr = *src;
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ip6h->daddr = *tap_ip6_daddr(c, src);
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memcpy(data, in, len);
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ip6h->hop_limit = proto;
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ip6h->version = 0;
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ip6h->nexthdr = 0;
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if (proto == IPPROTO_UDP) {
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struct udphdr *uh = (struct udphdr *)(ip6h + 1);
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csum_udp6(uh, &ip6h->saddr, &ip6h->daddr,
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uh + 1, len - sizeof(*uh));
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} else if (proto == IPPROTO_ICMPV6) {
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struct icmp6hdr *ih = (struct icmp6hdr *)(ip6h + 1);
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csum_icmp6(ih, &ip6h->saddr, &ip6h->daddr,
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ih + 1, len - sizeof(*ih));
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}
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ip6h->version = 6;
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ip6h->nexthdr = proto;
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ip6h->hop_limit = 255;
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if (flow) {
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ip6h->flow_lbl[0] = (flow >> 16) & 0xf;
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ip6h->flow_lbl[1] = (flow >> 8) & 0xff;
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ip6h->flow_lbl[2] = (flow >> 0) & 0xff;
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}
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if (tap_send(c, buf, len + sizeof(*ip6h) + sizeof(*eh)) < 1)
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debug("tap: failed to send %lu bytes (IPv6)", len);
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csum_udp4(uh, ip4h->saddr, ip4h->daddr,
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uh + 1, len - sizeof(*uh));
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} else if (ip4h->protocol == IPPROTO_ICMP) {
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struct icmphdr *ih = (struct icmphdr *)(ip4h + 1);
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csum_icmp4(ih, ih + 1, len - sizeof(*ih));
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}
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if (tap_send(c, buf, len + (data - buf)) < 0)
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debug("tap: failed to send %lu bytes (IPv4)", len);
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}
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/**
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* tap_ip6_send() - Send IPv6 packet, with L2 headers, calculating L3/L4 checksums
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* @c: Execution context
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* @src: IPv6 source address
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* @proto: L4 protocol number
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* @in: Payload
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* @len: L4 payload length
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* @flow: Flow label
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*/
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void tap_ip6_send(const struct ctx *c, const struct in6_addr *src,
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uint8_t proto, const char *in, size_t len, uint32_t flow)
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{
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char buf[USHRT_MAX];
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struct ipv6hdr *ip6h =
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(struct ipv6hdr *)tap_push_l2h(c, buf, ETH_P_IPV6);
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char *data = (char *)(ip6h + 1);
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ip6h->payload_len = htons(len);
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ip6h->priority = 0;
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ip6h->version = 6;
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ip6h->nexthdr = proto;
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ip6h->hop_limit = 255;
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ip6h->saddr = *src;
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ip6h->daddr = *tap_ip6_daddr(c, src);
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ip6h->flow_lbl[0] = (flow >> 16) & 0xf;
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ip6h->flow_lbl[1] = (flow >> 8) & 0xff;
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ip6h->flow_lbl[2] = (flow >> 0) & 0xff;
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memcpy(data, in, len);
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if (proto == IPPROTO_UDP) {
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struct udphdr *uh = (struct udphdr *)(ip6h + 1);
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csum_udp6(uh, &ip6h->saddr, &ip6h->daddr,
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uh + 1, len - sizeof(*uh));
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} else if (proto == IPPROTO_ICMPV6) {
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struct icmp6hdr *ih = (struct icmp6hdr *)(ip6h + 1);
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csum_icmp6(ih, &ip6h->saddr, &ip6h->daddr,
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ih + 1, len - sizeof(*ih));
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}
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if (tap_send(c, buf, len + (data - buf)) < 1)
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debug("tap: failed to send %lu bytes (IPv6)", len);
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}
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PACKET_POOL_DECL(pool_l4, UIO_MAXIOV, pkt_buf);
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6
tap.h
6
tap.h
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@ -9,8 +9,10 @@
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in_addr_t tap_ip4_daddr(const struct ctx *c);
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const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
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const struct in6_addr *src);
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void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto,
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const char *in, size_t len, uint32_t flow);
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void tap_ip4_send(const struct ctx *c, in_addr_t src, uint8_t proto,
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const char *in, size_t len);
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void tap_ip6_send(const struct ctx *c, const struct in6_addr *src,
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uint8_t proto, const char *in, size_t len, uint32_t flow);
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int tap_send(const struct ctx *c, const void *data, size_t len);
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void tap_handler(struct ctx *c, int fd, uint32_t events,
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const struct timespec *now);
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