298 lines
7.3 KiB
C++
298 lines
7.3 KiB
C++
// This file Copyright © 2022-2023 Mnemosyne LLC.
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// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
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// or any future license endorsed by Mnemosyne LLC.
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// License text can be found in the licenses/ folder.
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#pragma once
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#include <algorithm> // for std::copy_n
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#include <cstddef>
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#include <iterator>
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#include <limits>
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#include <string>
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#include <string_view>
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#include <small/vector.hpp>
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#include "error.h"
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#include "net.h" // tr_socket_t
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#include "utils.h" // for tr_htonll(), tr_ntohll()
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namespace libtransmission
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{
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template<typename value_type>
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class BufferReader
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{
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public:
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virtual ~BufferReader() = default;
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virtual void drain(size_t n_bytes) = 0;
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[[nodiscard]] virtual size_t size() const noexcept = 0;
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[[nodiscard]] virtual value_type const* data() const noexcept = 0;
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[[nodiscard]] auto empty() const noexcept
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{
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return size() == 0;
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}
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[[nodiscard]] auto const* begin() const noexcept
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{
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return data();
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}
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[[nodiscard]] auto const* end() const noexcept
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{
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return begin() + size();
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}
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template<typename T>
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[[nodiscard]] TR_CONSTEXPR20 bool starts_with(T const& needle) const
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{
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auto const n_bytes = std::size(needle);
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auto const needle_begin = reinterpret_cast<value_type const*>(std::data(needle));
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auto const needle_end = needle_begin + n_bytes;
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return n_bytes <= size() && std::equal(needle_begin, needle_end, data());
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}
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[[nodiscard]] auto to_string_view() const
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{
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return std::string_view{ reinterpret_cast<char const*>(data()), size() };
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}
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[[nodiscard]] auto to_string() const
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{
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return std::string{ to_string_view() };
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}
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void to_buf(void* tgt, size_t n_bytes)
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{
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n_bytes = std::min(n_bytes, size());
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std::copy_n(data(), n_bytes, static_cast<value_type*>(tgt));
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drain(n_bytes);
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}
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[[nodiscard]] auto to_uint8()
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{
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auto tmp = uint8_t{};
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to_buf(&tmp, sizeof(tmp));
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return tmp;
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}
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[[nodiscard]] uint16_t to_uint16()
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{
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auto tmp = uint16_t{};
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to_buf(&tmp, sizeof(tmp));
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return ntohs(tmp);
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}
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[[nodiscard]] uint32_t to_uint32()
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{
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auto tmp = uint32_t{};
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to_buf(&tmp, sizeof(tmp));
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return ntohl(tmp);
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}
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[[nodiscard]] uint64_t to_uint64()
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{
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auto tmp = uint64_t{};
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to_buf(&tmp, sizeof(tmp));
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return tr_ntohll(tmp);
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}
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// Returns the number of bytes written. Check `error` for error.
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size_t to_socket(tr_socket_t sockfd, size_t n_bytes, tr_error** error = nullptr)
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{
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n_bytes = std::min(n_bytes, size());
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if (n_bytes == 0U)
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{
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return {};
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}
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if (auto const n_sent = send(sockfd, reinterpret_cast<char const*>(data()), n_bytes, 0); n_sent >= 0U)
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{
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drain(n_sent);
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return n_sent;
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}
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auto const err = sockerrno;
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tr_error_set(error, err, tr_net_strerror(err));
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return {};
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}
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void clear()
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{
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drain(size());
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}
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};
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template<typename value_type>
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class BufferWriter
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{
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public:
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virtual ~BufferWriter() = default;
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virtual std::pair<value_type*, size_t> reserve_space(size_t n_bytes) = 0;
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virtual void commit_space(size_t n_bytes) = 0;
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void add(void const* span_begin, size_t span_len)
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{
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auto [buf, buflen] = reserve_space(span_len);
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std::copy_n(reinterpret_cast<value_type const*>(span_begin), span_len, buf);
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commit_space(span_len);
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}
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template<typename ContiguousContainer>
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void add(ContiguousContainer const& container)
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{
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add(std::data(container), std::size(container));
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}
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template<typename OneByteType>
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void push_back(OneByteType ch)
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{
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add(&ch, 1);
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}
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void add_uint8(uint8_t uch)
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{
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add(&uch, 1);
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}
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void add_uint16(uint16_t hs)
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{
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uint16_t const ns = htons(hs);
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add(&ns, sizeof(ns));
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}
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void add_hton16(uint16_t hs)
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{
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add_uint16(hs);
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}
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void add_uint32(uint32_t hl)
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{
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uint32_t const nl = htonl(hl);
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add(&nl, sizeof(nl));
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}
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void eadd_hton32(uint32_t hl)
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{
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add_uint32(hl);
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}
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void add_uint64(uint64_t hll)
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{
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uint64_t const nll = tr_htonll(hll);
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add(&nll, sizeof(nll));
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}
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void add_hton64(uint64_t hll)
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{
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add_uint64(hll);
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}
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void add_port(tr_port port)
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{
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auto nport = port.network();
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add(&nport, sizeof(nport));
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}
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size_t add_socket(tr_socket_t sockfd, size_t n_bytes, tr_error** error = nullptr)
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{
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auto const [buf, buflen] = reserve_space(n_bytes);
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auto const n_read = recv(sockfd, reinterpret_cast<char*>(buf), std::min(n_bytes, buflen), 0);
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auto const err = sockerrno;
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if (n_read > 0)
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{
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commit_space(n_read);
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return static_cast<size_t>(n_read);
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}
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// When a stream socket peer has performed an orderly shutdown,
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// the return value will be 0 (the traditional "end-of-file" return).
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if (n_read == 0)
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{
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tr_error_set_from_errno(error, ENOTCONN);
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}
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else
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{
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tr_error_set(error, err, tr_net_strerror(err));
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}
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return {};
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}
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};
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template<size_t N, typename value_type = std::byte, typename GrowthFactor = std::ratio<3, 2>>
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class StackBuffer final
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: public BufferReader<value_type>
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, public BufferWriter<value_type>
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{
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public:
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StackBuffer() = default;
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StackBuffer(StackBuffer&&) = delete;
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StackBuffer(StackBuffer const&) = delete;
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StackBuffer& operator=(StackBuffer&&) = delete;
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StackBuffer& operator=(StackBuffer const&) = delete;
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template<typename ContiguousContainer>
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explicit StackBuffer(ContiguousContainer const& data)
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{
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BufferWriter<value_type>::add(data);
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}
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[[nodiscard]] size_t size() const noexcept override
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{
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return end_pos_ - begin_pos_;
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}
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[[nodiscard]] value_type const* data() const noexcept override
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{
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return std::data(buf_) + begin_pos_;
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}
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void drain(size_t n_bytes) override
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{
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begin_pos_ += std::min(n_bytes, size());
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if (begin_pos_ == end_pos_) // empty; reuse the buf
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{
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begin_pos_ = end_pos_ = 0U;
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}
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}
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std::pair<value_type*, size_t> reserve_space(size_t n_bytes) override
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{
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if (auto const free_at_end = buf_.size() - end_pos_; free_at_end < n_bytes)
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{
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if (auto const total_free = begin_pos_ + free_at_end; total_free >= n_bytes)
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{
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// move data so that all free space is at the end
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auto const size = this->size();
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std::copy(data(), data() + size, std::data(buf_));
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begin_pos_ = 0;
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end_pos_ = size;
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}
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else // even `total_free` is not enough, so resize
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{
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buf_.resize(end_pos_ + n_bytes);
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}
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}
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return { buf_.data() + end_pos_, n_bytes };
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}
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void commit_space(size_t n_bytes) override
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{
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end_pos_ += n_bytes;
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}
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private:
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small::vector<value_type, N, std::allocator<value_type>, std::true_type, size_t, GrowthFactor> buf_ = {};
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size_t begin_pos_ = {};
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size_t end_pos_ = {};
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};
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} // namespace libtransmission
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