74 lines
1.9 KiB
C++
74 lines
1.9 KiB
C++
#pragma once
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#include <array>
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#include <cstdint>
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#include <cstdio>
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#include <span>
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#include <string>
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#include "eth.h"
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#include "span_writer.h"
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namespace ipv4 {
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using ip4_addr = std::array<uint8_t, 4>;
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inline std::string to_string(const ip4_addr& ip) {
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char buf[16];
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snprintf(buf, sizeof(buf), "%u.%u.%u.%u", ip[0], ip[1], ip[2], ip[3]);
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return buf;
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}
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struct __attribute__((packed)) header {
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uint8_t ver_ihl;
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uint8_t dscp_ecn;
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uint16_t total_len;
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uint16_t identification;
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uint16_t flags_frag;
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uint8_t ttl;
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uint8_t protocol;
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uint16_t checksum;
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ip4_addr src;
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ip4_addr dst;
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size_t header_len() const { return (ver_ihl & 0x0F) * 4; }
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size_t total() const { return __builtin_bswap16(total_len); }
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};
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static_assert(sizeof(header) == 20);
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uint16_t checksum(const void* data, size_t len);
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static constexpr ip4_addr SUBNET_BROADCAST = {169, 254, 255, 255};
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template <typename Buf>
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void prepend(Buf& buf, const eth::mac_addr& dst_mac, const eth::mac_addr& src_mac,
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ip4_addr src_ip, ip4_addr dst_ip, uint8_t protocol,
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size_t payload_len, uint8_t ttl = 64) {
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auto* h = buf.template prepend<header>();
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h->ver_ihl = 0x45;
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h->dscp_ecn = 0;
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h->total_len = __builtin_bswap16(sizeof(header) + payload_len);
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h->identification = 0;
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h->flags_frag = 0;
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h->ttl = ttl;
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h->protocol = protocol;
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h->checksum = 0;
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h->src = src_ip;
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h->dst = dst_ip;
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h->checksum = checksum(h, sizeof(header));
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eth::prepend(buf, dst_mac, src_mac, eth::ETH_IPV4);
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}
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void handle(std::span<const uint8_t> frame, span_writer& tx);
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void init();
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const ip4_addr& get_ip();
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bool addressed_to_us(ip4_addr dst);
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using protocol_handler = void (*)(std::span<const uint8_t> frame, span_writer& tx);
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void register_protocol(uint8_t protocol, protocol_handler fn);
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using addr_filter = bool (*)(const ip4_addr& dst);
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void register_addr_filter(addr_filter fn);
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} // namespace ipv4
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