Improve arg parsing somewhat and add flexibility/standardness

[flowspec-xdp] / xdp.c

diff --git a/xdp.c b/xdp.c
index 26a12313097539af3477af65dece5d8945016d98..669d3ebfa365f13feee331258df4b4434e3cc5ab 100644 (file)
--- a/xdp.c
+++ b/xdp.c
@@ -104,8 +104,8 @@ 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)
@@ -143,7 +143,7 @@ int xdp_drop_prog(struct xdp_md *ctx)
                        return XDP_DROP;
                const struct ethhdr *const eth = (void*)(size_t)ctx->data;
 
-#ifdef PARSE_8021Q
+#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;
@@ -156,6 +156,10 @@ int xdp_drop_prog(struct xdp_md *ctx)
 
                        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;
@@ -164,10 +168,6 @@ 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;
@@ -183,13 +183,14 @@ int xdp_drop_prog(struct xdp_md *ctx)
                        return XDP_DROP;
                ip = (struct iphdr*) pktdata;
 
-#ifdef PARSE_IHL
+#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 (unlikely(l4hdr + sizeof(struct tcphdr) > data_end))
                                return XDP_DROP;