C++ csum_add函数代码示例

static void ila_csum_do_neutral(struct ila_addr *iaddr,
				struct ila_params *p)
{
	__sum16 *adjust = (__force __sum16 *)&iaddr->ident.v16[3];
	__wsum diff, fval;

	/* Check if checksum adjust value has been cached */
	if (p->locator_match.v64) {
		diff = p->csum_diff;
	} else {
		diff = compute_csum_diff8((__be32 *)iaddr,
					  (__be32 *)&p->locator);
	}

	fval = (__force __wsum)(ila_csum_neutral_set(iaddr->ident) ?
			~CSUM_NEUTRAL_FLAG : CSUM_NEUTRAL_FLAG);

	diff = csum_add(diff, fval);

	*adjust = ~csum_fold(csum_add(diff, csum_unfold(*adjust)));

	/* Flip the csum-neutral bit. Either we are doing a SIR->ILA
	 * translation with ILA_CSUM_NEUTRAL_MAP as the csum_method
	 * and the C-bit is not set, or we are doing an ILA-SIR
	 * tranlsation and the C-bit is set.
	 */
	iaddr->ident.csum_neutral ^= 1;
}

static int ip6t_npt_checkentry(const struct xt_tgchk_param *par)
{
	struct ip6t_npt_tginfo *npt = par->targinfo;
	__wsum src_sum = 0, dst_sum = 0;
	struct in6_addr pfx;
	unsigned int i;

	if (npt->src_pfx_len > 64 || npt->dst_pfx_len > 64)
		return -EINVAL;

	/* Ensure that LSB of prefix is zero */
	ipv6_addr_prefix(&pfx, &npt->src_pfx.in6, npt->src_pfx_len);
	if (!ipv6_addr_equal(&pfx, &npt->src_pfx.in6))
		return -EINVAL;
	ipv6_addr_prefix(&pfx, &npt->dst_pfx.in6, npt->dst_pfx_len);
	if (!ipv6_addr_equal(&pfx, &npt->dst_pfx.in6))
		return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(npt->src_pfx.in6.s6_addr16); i++) {
		src_sum = csum_add(src_sum,
				(__force __wsum)npt->src_pfx.in6.s6_addr16[i]);
		dst_sum = csum_add(dst_sum,
				(__force __wsum)npt->dst_pfx.in6.s6_addr16[i]);
	}

	npt->adjustment = ~csum_fold(csum_sub(src_sum, dst_sum));
	return 0;
}

static int push_mpls(struct sk_buff *skb,
		     const struct ovs_action_push_mpls *mpls)
{
	__be32 *new_mpls_lse;
	struct ethhdr *hdr;

	if (skb_cow_head(skb, MPLS_HLEN) < 0)
		return -ENOMEM;

	skb_push(skb, MPLS_HLEN);
	memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
		skb->mac_len);
	skb_reset_mac_header(skb);

	new_mpls_lse = (__be32 *)mac_header_end(skb);
	*new_mpls_lse = mpls->mpls_lse;

	if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->csum = csum_add(skb->csum, csum_partial(new_mpls_lse,
							     MPLS_HLEN, 0));

	hdr = eth_hdr(skb);
	hdr->h_proto = mpls->mpls_ethertype;
	if (!ovs_skb_get_inner_protocol(skb))
		ovs_skb_set_inner_protocol(skb, skb->protocol);
	skb->protocol = mpls->mpls_ethertype;
	return 0;
}

int bpf_push_vlan(struct bpf_context *pctx, u16 proto, u16 vlan)
{
	struct bpf_dp_context *ctx = container_of(pctx, struct bpf_dp_context,
						  context);
	struct sk_buff *skb = ctx->skb;
	u16 current_tag;

	if (unlikely(!skb))
		return -EINVAL;

	if (vlan_tx_tag_present(skb)) {
		current_tag = vlan_tx_tag_get(skb);

		if (!__vlan_put_tag(skb, skb->vlan_proto, current_tag)) {
			ctx->skb = NULL;
			return -ENOMEM;
		}

		if (skb->ip_summed == CHECKSUM_COMPLETE)
			skb->csum = csum_add(skb->csum, csum_partial(skb->data
					+ (2 * ETH_ALEN), VLAN_HLEN, 0));
		ctx->context.length = skb->len;
	}
	__vlan_hwaccel_put_tag(skb, proto, vlan);
	ctx->context.vlan_tag = vlan;

	return 0;
}

static void lro_update_tcp_ip_header(struct net_lro_desc *lro_desc)
{
	struct iphdr *iph = lro_desc->iph;
	struct tcphdr *tcph = lro_desc->tcph;
	__be32 *p;
	__wsum tcp_hdr_csum;

	tcph->ack_seq = lro_desc->tcp_ack;
	tcph->window = lro_desc->tcp_window;

	if (lro_desc->tcp_saw_tstamp) {
		p = (__be32 *)(tcph + 1);
		*(p+2) = lro_desc->tcp_rcv_tsecr;
	}

	iph->tot_len = htons(lro_desc->ip_tot_len);

	iph->check = 0;
	iph->check = ip_fast_csum((u8 *)lro_desc->iph, iph->ihl);

	tcph->check = 0;
	tcp_hdr_csum = csum_partial((u8 *)tcph, TCP_HDR_LEN(tcph), 0);
	lro_desc->data_csum = csum_add(lro_desc->data_csum, tcp_hdr_csum);
	tcph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
					lro_desc->ip_tot_len -
					IP_HDR_LEN(iph), IPPROTO_TCP,
					lro_desc->data_csum);
}

static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
		     const struct ovs_action_push_mpls *mpls)
{
	__be32 *new_mpls_lse;
	struct ethhdr *hdr;

	/* Networking stack do not allow simultaneous Tunnel and MPLS GSO. */
	if (skb->encapsulation)
		return -ENOTSUPP;

	if (skb_cow_head(skb, MPLS_HLEN) < 0)
		return -ENOMEM;

	skb_push(skb, MPLS_HLEN);
	memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
		skb->mac_len);
	skb_reset_mac_header(skb);

	new_mpls_lse = (__be32 *)skb_mpls_header(skb);
	*new_mpls_lse = mpls->mpls_lse;

	if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->csum = csum_add(skb->csum, csum_partial(new_mpls_lse,
							     MPLS_HLEN, 0));

	hdr = eth_hdr(skb);
	hdr->h_proto = mpls->mpls_ethertype;

	if (!skb->inner_protocol)
		skb_set_inner_protocol(skb, skb->protocol);
	skb->protocol = mpls->mpls_ethertype;

	invalidate_flow_key(key);
	return 0;
}

static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vlan)
{
	if (unlikely(vlan_tx_tag_present(skb))) {
		u16 current_tag;

		/* push down current VLAN tag */
		current_tag = vlan_tx_tag_get(skb);

		if (!__vlan_put_tag(skb, skb->vlan_proto, current_tag))
			return -ENOMEM;

		/* Update mac_len for subsequent MPLS actions */
		skb->mac_len += VLAN_HLEN;

		if (skb->ip_summed == CHECKSUM_COMPLETE)
			skb->csum = csum_add(skb->csum, csum_partial(skb->data
					+ (2 * ETH_ALEN), VLAN_HLEN, 0));

		invalidate_skb_flow_key(skb);
	} else {
		flow_key_set_vlan_tci(skb,  vlan->vlan_tci);
	}
	__vlan_hwaccel_put_tag(skb, vlan->vlan_tpid, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
	return 0;
}

static void udpencap_fix6(struct sk_buff *skb, const struct xt_udpencap_tginfo *info)
{
	struct ipv6hdr *iph = ipv6_hdr(skb);
	bool fix_csum = (skb->ip_summed == CHECKSUM_COMPLETE && !info->encap);
	if (fix_csum)
		skb->csum = csum_sub(skb->csum, csum_partial(&iph->payload_len, 3, 0));
	iph->payload_len = htons(ntohs(iph->payload_len) + (info->encap ? 1 : -1) * sizeof(struct udphdr));
	iph->nexthdr = info->proto;
	if (fix_csum)
		skb->csum = csum_add(skb->csum, csum_partial(&iph->payload_len, 3, 0));
}

static void udpencap_fix4(struct sk_buff *skb, const struct xt_udpencap_tginfo *info)
{
	struct iphdr *iph = ip_hdr(skb);
	bool fix_csum = (skb->ip_summed == CHECKSUM_COMPLETE && !info->encap);
	__be16 newlen = htons(ntohs(iph->tot_len) + (info->encap ? 1 : -1) * sizeof(struct udphdr));
	if (fix_csum) {
		skb->csum = csum_sub(skb->csum, csum_partial(&iph->tot_len, 2, 0));
		skb->csum = csum_sub(skb->csum, csum_partial(&iph->protocol, 3, 0));
	}
	csum_replace2(&iph->check, iph->tot_len, newlen);
	iph->tot_len = newlen;
	if (iph->protocol != info->proto) {
		csum_replace2(&iph->check, htons(iph->protocol), htons(info->proto));
		iph->protocol = info->proto;
	}
	if (fix_csum) {
		skb->csum = csum_add(skb->csum, csum_partial(&iph->tot_len, 2, 0));
		skb->csum = csum_add(skb->csum, csum_partial(&iph->protocol, 3, 0));
	}
}

static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vlan)
{
	if (unlikely(vlan_tx_tag_present(skb))) {
		u16 current_tag;

		/* push down current VLAN tag */
		current_tag = vlan_tx_tag_get(skb);

		if (!__vlan_put_tag(skb, current_tag))
			return -ENOMEM;

		if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
			skb->csum = csum_add(skb->csum, csum_partial(skb->data
					+ ETH_HLEN, VLAN_HLEN, 0));

	}
	__vlan_hwaccel_put_tag(skb, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
	return 0;
}

static int set_eth_addr(struct sk_buff *skb,
			const struct ovs_key_ethernet *eth_key)
{
	int err;
	err = make_writable(skb, ETH_HLEN);
	if (unlikely(err))
		return err;

	if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
		skb->csum = csum_sub(skb->csum, csum_partial(eth_hdr(skb),
							     ETH_ALEN * 2, 0));

	memcpy(eth_hdr(skb)->h_source, eth_key->eth_src, ETH_ALEN);
	memcpy(eth_hdr(skb)->h_dest, eth_key->eth_dst, ETH_ALEN);

	if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
		skb->csum = csum_add(skb->csum, csum_partial(eth_hdr(skb),
							     ETH_ALEN * 2, 0));

	return 0;
}

static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vlan)
{
	if (unlikely(vlan_tx_tag_present(skb))) {
		u16 current_tag;

		/* push down current VLAN tag */
		current_tag = vlan_tx_tag_get(skb);

		skb = vlan_insert_tag_set_proto(skb, skb->vlan_proto,
						current_tag);
		if (!skb)
			return -ENOMEM;

		if (skb->ip_summed == CHECKSUM_COMPLETE)
			skb->csum = csum_add(skb->csum, csum_partial(skb->data
					+ (2 * ETH_ALEN), VLAN_HLEN, 0));

	}
	__vlan_hwaccel_put_tag(skb, vlan->vlan_tpid, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
	return 0;
}

static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt,
			     struct in6_addr *addr)
{
	unsigned int pfx_len;
	unsigned int i, idx;
	__be32 mask;
	__sum16 sum;

	pfx_len = max(npt->src_pfx_len, npt->dst_pfx_len);
	for (i = 0; i < pfx_len; i += 32) {
		if (pfx_len - i >= 32)
			mask = 0;
		else
			mask = htonl((1 << (i - pfx_len + 32)) - 1);

		idx = i / 32;
		addr->s6_addr32[idx] &= mask;
		addr->s6_addr32[idx] |= ~mask & npt->dst_pfx.in6.s6_addr32[idx];
	}

	if (pfx_len <= 48)
		idx = 3;
	else {
		for (idx = 4; idx < ARRAY_SIZE(addr->s6_addr16); idx++) {
			if ((__force __sum16)addr->s6_addr16[idx] !=
			    CSUM_MANGLED_0)
				break;
		}
		if (idx == ARRAY_SIZE(addr->s6_addr16))
			return false;
	}

	sum = ~csum_fold(csum_add(csum_unfold((__force __sum16)addr->s6_addr16[idx]),
				  csum_unfold(npt->adjustment)));
	if (sum == CSUM_MANGLED_0)
		sum = 0;
	*(__force __sum16 *)&addr->s6_addr16[idx] = sum;

	return true;
}

void bpf_store_bits(struct bpf_context *pctx, u32 off, const void *from,
		    u32 len)
{
	struct bpf_dp_context *ctx = container_of(pctx, struct bpf_dp_context,
						  context);
	struct sk_buff *skb = ctx->skb;

	if (unlikely(!skb))
		return;
	if (!pskb_may_pull(skb, off + len))
		return;

	if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->csum = csum_sub(skb->csum,
				     csum_partial(skb->data + off, len, 0));

	memcpy(skb->data + off, from, len);


	if (skb->ip_summed == CHECKSUM_COMPLETE)
		skb->csum = csum_add(skb->csum,
				     csum_partial(skb->data + off, len, 0));
}

static int internal_dev_recv(struct vport *vport, struct sk_buff *skb)
{
	struct net_device *netdev = netdev_vport_priv(vport)->dev;
	int len;

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37)
	if (vlan_tx_tag_present(skb)) {
		if (unlikely(!__vlan_put_tag(skb,
					     skb->vlan_proto,
					     vlan_tx_tag_get(skb))))
			return 0;

		if (skb->ip_summed == CHECKSUM_COMPLETE)
			skb->csum = csum_add(skb->csum,
					     csum_partial(skb->data + (2 * ETH_ALEN),
							  VLAN_HLEN, 0));

		vlan_set_tci(skb, 0);
	}
#endif

	len = skb->len;

	skb_dst_drop(skb);
	nf_reset(skb);
	secpath_reset(skb);

	skb->dev = netdev;
	skb->pkt_type = PACKET_HOST;
	skb->protocol = eth_type_trans(skb, netdev);
	skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);

	netif_rx(skb);

	return len;
}