+ mantissa = low_bytes & ((1 << 23) - 1)
+ value = 1.0 + mantissa / (2**23)
+ value *= 2**(exp-127)
+ if ty == "0x8006" or ty == "0x8306":
+ accessor = "rate->rate.sent_bytes"
+ else:
+ accessor = "rate->rate.sent_packets"
+ # Note that int64_t will overflow after 292 years of uptime
+ first_action = "int64_t time = bpf_ktime_get_ns();\n"
+ first_action += "uint64_t allowed_since_last = 0;\n"
+ if ty == "0x8006" or ty == "0x800c":
+ spin_lock = "bpf_spin_lock(&rate->lock);"
+ spin_unlock = "bpf_spin_unlock(&rate->lock);"
+ first_action += f"const uint32_t ratelimitidx = {ratelimitcnt};\n"
+ first_action += "struct ratelimit *rate = bpf_map_lookup_elem(&rate_map, &ratelimitidx);\n"
+ ratelimitcnt += 1
+ else:
+ spin_lock = "/* No locking as we're per-CPU */"
+ spin_unlock = "/* No locking as we're per-CPU */"
+ if proto == 4:
+ if high_byte > 32:
+ continue
+ first_action += f"const uint32_t srcip = ip->saddr & MASK4({high_byte});\n"
+ first_action += f"void *rate_map = &v4_src_rate_{v4persrcratelimitcnt};\n"
+ v4persrcratelimitcnt += 1
+ else:
+ if high_byte > 128:
+ continue
+ first_action += f"const uint128_t srcip = ip6->saddr & MASK6({high_byte});\n"
+ first_action += f"void *rate_map = &v6_src_rate_{v6persrcratelimitcnt};\n"
+ v6persrcratelimitcnt += 1
+ first_action += f"struct percpu_ratelimit *rate = bpf_map_lookup_elem(rate_map, &srcip);\n"
+ first_action += "if (rate) {\n"
+ first_action += f"\t{spin_lock}\n"
+ first_action += f"\tif (likely({accessor} > 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 += f"\t\t\t{accessor} = 0;\n"
+ first_action += "\t\telse if (likely(diff > 0))\n"
+ first_action += f"\t\t\tallowed_since_last = ((uint64_t)diff) * {math.floor(value)} / 1000000000;\n"
+ first_action += "\t}\n"
+ first_action += f"\tif ({accessor} - ((int64_t)allowed_since_last) <= 0)" + " {\n"
+ if ty == "0x8006" or ty == "0x8306":
+ first_action += f"\t\t{accessor} = data_end - pktdata;\n"
+ else:
+ first_action += f"\t\t{accessor} = 1;\n"
+ first_action += "\t\trate->sent_time = time;\n"
+ first_action += f"\t\t{spin_unlock}\n"
+ first_action += "\t} else {\n"
+ first_action += f"\t\t{spin_unlock}\n"
+ first_action += "\t\t{stats_replace}\n"
+ first_action += "\t\treturn XDP_DROP;\n"
+ first_action += "\t}\n"
+ if ty == "0x8306" or ty == "0x830c":
+ first_action += "} else {\n"
+ first_action += "\tstruct percpu_ratelimit new_rate = { .sent_time = time, };\n"
+ first_action += "\trate = &new_rate;\n"
+ if ty == "0x8006" or ty == "0x8306":
+ first_action += f"\t\t{accessor} = data_end - pktdata;\n"
+ else:
+ first_action += f"\t\t{accessor} = 1;\n"
+ first_action += "\tbpf_map_update_elem(rate_map, &srcip, rate, BPF_ANY);\n"
+ first_action += "}\n"