Implement operator 'sctp'

doc/Makefile

@@ -35,7 +35,8 @@ EXAMPLES = \
 	decnet-src-10.15.md \
 	decnet-host-10.15.md \
 	l1.md \
-	icmp6.md
+	icmp6.md \
+	sctp.md
 
 PFLUA = \
 	../src/pf.lua \
@@ -157,3 +158,6 @@ l1.md: $(PFLUA)
 
 icmp6.md: $(PFLUA)
 	../tools/dump-markdown "icmp6" > $@.tmp && mv $@.tmp $@
+
+sctp.md: $(PFLUA)
+	../tools/dump-markdown "sctp" > $@.tmp && mv $@.tmp $@

doc/sctp.md

@@ -0,0 +1,72 @@
+# sctp
+
+
+## BPF
+
+```
+000: A = P[12:2]
+001: if (A == 34525) goto 2 else goto 7
+002: A = P[20:1]
+003: if (A == 132) goto 10 else goto 4
+004: if (A == 44) goto 5 else goto 11
+005: A = P[54:1]
+006: if (A == 132) goto 10 else goto 11
+007: if (A == 2048) goto 8 else goto 11
+008: A = P[23:1]
+009: if (A == 132) goto 10 else goto 11
+010: return 65535
+011: return 0
+```
+
+
+## BPF cross-compiled to Lua
+
+```
+return function (P, length)
+   local A = 0
+   if 14 > length then return false end
+   A = bit.bor(bit.lshift(P[12], 8), P[12+1])
+   if not (A==34525) then goto L6 end
+   if 21 > length then return false end
+   A = P[20]
+   if (A==132) then goto L9 end
+   if not (A==44) then goto L10 end
+   if 55 > length then return false end
+   A = P[54]
+   if (A==132) then goto L9 end
+   goto L10
+   ::L6::
+   if not (A==2048) then goto L10 end
+   if 24 > length then return false end
+   A = P[23]
+   if not (A==132) then goto L10 end
+   ::L9::
+   do return true end
+   ::L10::
+   do return false end
+   error("end of bpf")
+end
+```
+
+
+## Direct pflang compilation
+
+```
+local cast = require("ffi").cast
+return function(P,length)
+   if length < 34 then return false end
+   local var1 = cast("uint16_t*", P+12)[0]
+   if var1 == 8 then
+      return P[23] == 132
+   end
+   if length < 54 then return false end
+   if var1 ~= 56710 then return false end
+   local var4 = P[20]
+   if var4 == 132 then return true end
+   if length < 55 then return false end
+   if var4 ~= 44 then return false end
+   return P[54] == 132
+end
+
+```
+

src/pf/expand.lua

@@ -874,6 +874,7 @@ local primitive_expanders = {
    ah = function(expr) return has_ip_protocol(PROTO_AH) end,
    esp = function(expr) return has_ip_protocol(PROTO_ESP) end,
    vrrp = function(expr) return has_ip_protocol(PROTO_VRRP) end,
+   sctp = function(expr) return has_ip_protocol(PROTO_SCTP) end,
    protochain = expand_ip_protochain,
    arp = expand_arp,
    arp_host = expand_arp_host,

src/pf/parse.lua

@@ -761,6 +761,7 @@ local primitives = {
    ah = nullary(),
    esp = nullary(),
    vrrp = nullary(),
+   sctp = nullary(),
    protochain = unary(parse_proto_arg),
    arp = table_parser(arp_types, nullary()),
    rarp = table_parser(rarp_types, nullary()),