49 lines
1.4 KiB
C++
49 lines
1.4 KiB
C++
#pragma once
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#include <cstdint>
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#include <span>
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#include "eth.h"
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#include "ipv4.h"
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#include "net.h"
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#include "span_writer.h"
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namespace udp {
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struct __attribute__((packed)) header {
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uint16_t src_port;
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uint16_t dst_port;
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uint16_t length;
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uint16_t checksum;
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};
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static_assert(sizeof(header) == 8);
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struct address {
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// mac is carried here until we grow an ARP cache; once we do, a
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// destination mac comes from resolving ip and this field goes away.
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eth::mac_addr mac;
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ipv4::ip4_addr ip;
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uint16_t port;
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};
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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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ipv4::ip4_addr src_ip, ipv4::ip4_addr dst_ip,
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uint16_t src_port, uint16_t dst_port,
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size_t payload_len, uint8_t ttl = 64) {
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auto* u = buf.template prepend<header>();
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u->src_port = src_port;
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u->dst_port = dst_port;
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u->length = __builtin_bswap16(sizeof(header) + payload_len);
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u->checksum = 0;
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ipv4::prepend(buf, dst_mac, src_mac, src_ip, dst_ip, 17, sizeof(header) + payload_len, ttl);
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}
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void handle(std::span<const uint8_t> frame, span_writer& tx);
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namespace client {
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// Defined by the higher layer (dispatch) to receive decoded UDP payloads
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// addressed to PICOMAP_PORT_BE. Resolved at link time.
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void handler(std::span<const uint8_t> payload, const address& from);
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} // namespace client
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} // namespace udp
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