X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=genrules.py;h=a84eacc7af0c6d51760f8bbc0fb171be9cda0faf;hb=0714b6c732880fb8ceabe8102afb305ba5ecf95b;hp=51e547d2d28a12f346aac036cd63f052637b757a;hpb=348583843f9499b0f1c335edc684a077bb2c2710;p=flowspec-xdp

diff --git a/genrules.py b/genrules.py
index 51e547d..a84eacc 100755
--- a/genrules.py
+++ b/genrules.py
@@ -4,6 +4,7 @@ import sys
 import ipaddress
 from enum import Enum
 import argparse
+import math
 
 
 IP_PROTO_ICMP = 1
@@ -288,6 +289,7 @@ with open("rules.h", "w") as out:
     rules4 = ""
     use_v6_frags = False
     rulecnt = 0
+    ratelimitcnt = 0
 
     lastrule = None
     for line in sys.stdin.readlines():
@@ -369,10 +371,49 @@ with open("rules.h", "w") as out:
                 ty = blocks[1].strip()[:6]
                 low_bytes = int(blocks[2].strip(") \n"), 16)
                 if ty == "0x8006":
+                    if first_action is not None:
+                        assert False # Two ratelimit actions?
                     if low_bytes == 0:
                         first_action = "return XDP_DROP;"
                     else:
-                        assert False # Not yet supported
+                        if low_bytes & (1 <<  31) != 0:
+                            assert False # Negative ratelimit?
+                        exp = (low_bytes & (0xff << 23)) >> 23
+                        if exp == 0xff:
+                            assert False # NaN/INF?
+                        if exp <= 127: # < 1
+                            first_action = "return XDP_DROP;"
+                        if exp >= 127 + 63: # The count won't even fit in 64-bits, just accept
+                            first_action = "return XDP_PASS;"
+                        mantissa = low_bytes & ((1 << 23) - 1)
+                        value = 1.0 + mantissa / (2**23)
+                        value *= 2**(exp-127)
+                        # Note that int64_t will overflow after 292 years of uptime
+                        first_action = "int64_t time = bpf_ktime_get_ns();\n"
+                        first_action += f"const uint32_t ratelimitidx = {ratelimitcnt};\n"
+                        first_action += "size_t pktlen = data_end - pktdata;\n"
+                        first_action += "uint64_t extra_bytes = 0;\n"
+                        first_action += "struct ratelimit *rate = bpf_map_lookup_elem(&rate_map, &ratelimitidx);\n"
+                        first_action += "if (rate) {\n"
+                        first_action += "\tbpf_spin_lock(&rate->lock);\n"
+                        first_action += "\tif (likely(rate->sent_bytes > 0)) {\n"
+                        first_action += "\t\tint64_t diff = time - rate->sent_time;\n"
+                        # Unlikely or not, if the flow is slow, take a perf hit (though with the else if branch it doesn't matter)
+                        first_action += "\t\tif (unlikely(diff > 1000000000))\n"
+                        first_action += "\t\t\trate->sent_bytes = 0;\n"
+                        first_action += "\t\telse if (likely(diff > 0))\n"
+                        first_action += f"\t\t\textra_bytes = ((uint64_t)diff) * {math.floor(value)} / 1000000000;\n"
+                        first_action += "\t}\n"
+                        first_action += "\tif (rate->sent_bytes - ((int64_t)extra_bytes) <= 0) {\n"
+                        first_action += "\t\trate->sent_bytes = data_end - pktdata;\n"
+                        first_action += "\t\trate->sent_time = time;\n"
+                        first_action += "\t\tbpf_spin_unlock(&rate->lock);\n"
+                        first_action += "\t} else {\n"
+                        first_action += "\t\tbpf_spin_unlock(&rate->lock);\n"
+                        first_action += "\t\treturn XDP_DROP;\n"
+                        first_action += "\t}\n"
+                        first_action += "}\n"
+                        ratelimitcnt += 1
                 elif ty == "0x8007":
                     if low_bytes & 1 == 0:
                         last_action = "return XDP_PASS;"
@@ -407,6 +448,8 @@ with open("rules.h", "w") as out:
 
     out.write("\n")
     out.write(f"#define RULECNT {rulecnt}\n")
+    if ratelimitcnt != 0:
+        out.write(f"#define RATE_CNT {ratelimitcnt}\n")
     if rules4 != "":
         out.write("#define NEED_V4_PARSE\n")
         out.write("#define RULES4 {\\\n" + rules4 + "}\n")