block.c: rename (DIS)ALLOW to BPF_(DIS)ALLOW

Makes things clearer.
Prep work for a better shared bpf_net_helpers.h header file.

Generated via:
  sed -i -r 's@ ALLOW@ BPF_ALLOW@' block.c
  sed -i -r 's@ DISALLOW@ BPF_DISALLOW@' block.c

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I089a730d8881d62871ce2daff64e79caccd41a00
diff --git a/bpf_progs/block.c b/bpf_progs/block.c
index 152dda6..127ec4e 100644
--- a/bpf_progs/block.c
+++ b/bpf_progs/block.c
@@ -24,14 +24,14 @@
 
 #include "bpf_helpers.h"
 
-static const int ALLOW = 1;
-static const int DISALLOW = 0;
+static const int BPF_ALLOW = 1;
+static const int BPF_DISALLOW = 0;
 
 DEFINE_BPF_MAP_GRW(blocked_ports_map, ARRAY, int, uint64_t,
         1024 /* 64K ports -> 1024 u64s */, AID_SYSTEM)
 
 static inline __always_inline int block_port(struct bpf_sock_addr *ctx) {
-    if (!ctx->user_port) return ALLOW;
+    if (!ctx->user_port) return BPF_ALLOW;
 
     switch (ctx->protocol) {
         case IPPROTO_TCP:
@@ -42,7 +42,7 @@
         case IPPROTO_SCTP:
             break;
         default:
-            return ALLOW; // unknown protocols are allowed
+            return BPF_ALLOW; // unknown protocols are allowed
     }
 
     int key = ctx->user_port >> 6;
@@ -51,10 +51,10 @@
     uint64_t *val = bpf_blocked_ports_map_lookup_elem(&key);
     // Lookup should never fail in reality, but if it does return here to keep the
     // BPF verifier happy.
-    if (!val) return ALLOW;
+    if (!val) return BPF_ALLOW;
 
-    if ((*val >> shift) & 1) return DISALLOW;
-    return ALLOW;
+    if ((*val >> shift) & 1) return BPF_DISALLOW;
+    return BPF_ALLOW;
 }
 
 // the program need to be accessible/loadable by netd (from netd updatable plugin)