Only parse v4/v6 if we have relevant rules for them

[flowspec-xdp] / xdp.c

diff --git a/xdp.c b/xdp.c
index 8623af44c1f0cdbb6b0591e7d4c6db148cf05739..b93b16936bdfdde7f72d6e84277a95cda8e501cf 100644 (file)
--- a/xdp.c
+++ b/xdp.c
@@ -104,10 +104,13 @@ struct tcphdr {
 #define MASK6(pfxlen) HTON128(~((((uint128_t)1) << (128 - pfxlen)) - 1))
 #define MASK6_OFFS(offs, pfxlen) HTON128((~((((uint128_t)1) << (128 - pfxlen)) - 1)) & ((((uint128_t)1) << (128 - offs)) - 1))
 
-// Note rules.h may also define PARSE_8021Q and REQ_8021Q
-// Note rules.h may also define PARSE_IHL
+// PARSE is used as a preprocessor flag to indicate parsing fields
+#define PARSE 42
 #include "rules.h"
 
+#define unlikely(a) __builtin_expect(a, 0)
+#define likely(a) __builtin_expect(a, 1)
+
 #ifdef TEST
 // 64 bit version of xdp_md for testing
 struct xdp_md {
@@ -136,23 +139,27 @@ int xdp_drop_prog(struct xdp_md *ctx)
        unsigned short eth_proto;
 
        {
-               if ((void*)(size_t)ctx->data + sizeof(struct ethhdr) > data_end)
+               if (unlikely((void*)(size_t)ctx->data + sizeof(struct ethhdr) > data_end))
                        return XDP_DROP;
                const struct ethhdr *const eth = (void*)(size_t)ctx->data;
 
-#ifdef PARSE_8021Q
-               if (eth->h_proto == BE16(ETH_P_8021Q)) {
-                       if ((void*)(size_t)ctx->data + sizeof(struct ethhdr_vlan) > data_end)
+#if PARSE_8021Q == PARSE
+               if (likely(eth->h_proto == BE16(ETH_P_8021Q))) {
+                       if (unlikely((void*)(size_t)ctx->data + sizeof(struct ethhdr_vlan) > data_end))
                                return XDP_DROP;
                        const struct ethhdr_vlan *const eth_vlan = (void*)(size_t)ctx->data;
 
 #ifdef REQ_8021Q
-                       if ((eth_vlan->tci & BE16(0xfff)) != BE16(REQ_8021Q))
+                       if (unlikely((eth_vlan->tci & BE16(0xfff)) != BE16(REQ_8021Q)))
                                return XDP_DROP;
 #endif
 
                        eth_proto = eth_vlan->h_proto;
                        pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr_vlan);
+#else
+               if (unlikely(eth->h_proto == BE16(ETH_P_8021Q))) {
+                       return PARSE_8021Q;
+#endif
                } else {
 #ifdef REQ_8021Q
                        return XDP_DROP;
@@ -161,47 +168,54 @@ int xdp_drop_prog(struct xdp_md *ctx)
                        eth_proto = eth->h_proto;
 #endif
                }
-#else
-               pktdata = (const void *)(long)ctx->data + sizeof(struct ethhdr);
-               eth_proto = eth->h_proto;
-#endif
        }
 
-       const struct tcphdr *tcp = NULL;
-       const struct udphdr *udp = NULL;
+#ifdef NEED_V4_PARSE
+       const struct iphdr *ip = NULL;
        const struct icmphdr *icmp = NULL;
+#endif
+#ifdef NEED_V6_PARSE
+       const struct ip6hdr *ip6 = NULL;
        const struct icmp6hdr *icmpv6 = NULL;
        const struct ip6_fraghdr *frag6 = NULL;
-       const struct iphdr *ip = NULL;
-       const struct ip6hdr *ip6 = NULL;
+#endif
+
        const void *l4hdr = NULL;
+       const struct tcphdr *tcp = NULL;
+       const struct udphdr *udp = NULL;
+
+#ifdef NEED_V4_PARSE
        if (eth_proto == BE16(ETH_P_IP)) {
-               if (pktdata + sizeof(struct iphdr) > data_end)
+               if (unlikely(pktdata + sizeof(struct iphdr) > data_end))
                        return XDP_DROP;
                ip = (struct iphdr*) pktdata;
 
-#ifdef PARSE_IHL
-               if (ip->ihl < 5) return XDP_DROP;
+#if PARSE_IHL == PARSE
+               if (unlikely(ip->ihl < 5)) return XDP_DROP;
                l4hdr = pktdata + ip->ihl * 4;
 #else
-               if (ip->ihl != 5) return XDP_DROP;
+               if (ip->ihl != 5) return PARSE_IHL;
                l4hdr = pktdata + 5*4;
 #endif
+
                if (ip->protocol == IP_PROTO_TCP) {
-                       if (l4hdr + sizeof(struct tcphdr) > data_end)
+                       if (unlikely(l4hdr + sizeof(struct tcphdr) > data_end))
                                return XDP_DROP;
                        tcp = (struct tcphdr*) l4hdr;
                } else if (ip->protocol == IP_PROTO_UDP) {
-                       if (l4hdr + sizeof(struct udphdr) > data_end)
+                       if (unlikely(l4hdr + sizeof(struct udphdr) > data_end))
                                return XDP_DROP;
                        udp = (struct udphdr*) l4hdr;
                } else if (ip->protocol == IP_PROTO_ICMP) {
-                       if (l4hdr + sizeof(struct icmphdr) > data_end)
+                       if (unlikely(l4hdr + sizeof(struct icmphdr) > data_end))
                                return XDP_DROP;
                        icmp = (struct icmphdr*) l4hdr;
                }
-       } else if (eth_proto == BE16(ETH_P_IPV6)) {
-               if (pktdata + sizeof(struct ip6hdr) > data_end)
+       }
+#endif
+#ifdef NEED_V6_PARSE
+       if (eth_proto == BE16(ETH_P_IPV6)) {
+               if (unlikely(pktdata + sizeof(struct ip6hdr) > data_end))
                        return XDP_DROP;
                ip6 = (struct ip6hdr*) pktdata;
 
@@ -209,7 +223,7 @@ int xdp_drop_prog(struct xdp_md *ctx)
 
                uint8_t v6nexthdr;
                if (ip6->nexthdr == IP6_PROTO_FRAG) {
-                       if (l4hdr + sizeof(struct ip6_fraghdr) > data_end)
+                       if (unlikely(l4hdr + sizeof(struct ip6_fraghdr) > data_end))
                                return XDP_DROP;
                        frag6 = (struct ip6_fraghdr*) l4hdr;
                        l4hdr = l4hdr + sizeof(struct ip6_fraghdr);
@@ -219,22 +233,21 @@ int xdp_drop_prog(struct xdp_md *ctx)
                }
 
                if (v6nexthdr == IP_PROTO_TCP) {
-                       if (l4hdr + sizeof(struct tcphdr) > data_end)
+                       if (unlikely(l4hdr + sizeof(struct tcphdr) > data_end))
                                return XDP_DROP;
                        tcp = (struct tcphdr*) l4hdr;
                } else if (v6nexthdr == IP_PROTO_UDP) {
-                       if (l4hdr + sizeof(struct udphdr) > data_end)
+                       if (unlikely(l4hdr + sizeof(struct udphdr) > data_end))
                                return XDP_DROP;
                        udp = (struct udphdr*) l4hdr;
                } else if (v6nexthdr == IP6_PROTO_ICMPV6) {
-                       if (l4hdr + sizeof(struct icmp6hdr) > data_end)
+                       if (unlikely(l4hdr + sizeof(struct icmp6hdr) > data_end))
                                return XDP_DROP;
                        icmpv6 = (struct icmp6hdr*) l4hdr;
                }
                // TODO: Handle some options?
-       } else {
-               return XDP_PASS;
        }
+#endif
 
        uint16_t sport, dport; // Host Endian! Only valid with tcp || udp
        if (tcp != NULL) {