1 files changed, 284 insertions, 0 deletions
diff --git a/comp3331/server/src/shared/net.cc b/comp3331/server/src/shared/net.cc
new file mode 100644
index 0000000..b71170a
--- /dev/null
+++ b/comp3331/server/src/shared/net.cc
@@ -0,0 +1,284 @@
+#include "shared/net.hh"
+
+namespace shared {
+
+static std::string get_errno_str() noexcept { return strerror(errno); }
+
+addrinfo_t make_addrinfo(const char* const address, const char* const port,
+                         const addrinfo&& hints) {
+    addrinfo* info = nullptr;
+    if (int status = getaddrinfo(address, port, &hints, &info)) {
+        throw std::runtime_error{gai_strerror(status)};
+    }
+    return addrinfo_t{info, [](const auto& p) { freeaddrinfo(p); }};
+}
+
+socket_t make_socket(const addrinfo_t& info) {
+    const int sock =
+        socket(info->ai_family, info->ai_socktype, info->ai_protocol);
+    if (sock == -1) {
+        throw std::runtime_error{get_errno_str()};
+    }
+
+    // to avoid annoying binding timeouts
+    const int enable = 1;
+    setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &enable, sizeof(int));
+    setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int));
+    return sock;
+}
+
+socket_t accept_socket(const socket_t& lsock) {
+    sockaddr_in in{};
+    socklen_t size = sizeof(in);
+
+    const shared::socket_t sock =
+        accept(lsock, reinterpret_cast<sockaddr*>(&in), &size);
+    if (sock == -1) {
+        throw std::runtime_error(get_errno_str());
+    }
+    return sock;
+}
+
+void bind_socket(const socket_t sock, const addrinfo_t& info) {
+    // bind to first we can
+    for (const addrinfo* i = info.get(); i != nullptr; i = i->ai_next) {
+        if (bind(sock, info->ai_addr, info->ai_addrlen) == -1) {
+            continue;
+        }
+        return;
+    }
+    throw std::runtime_error{get_errno_str()};
+}
+
+void connect_socket(const socket_t sock, const addrinfo_t& info) {
+    if (connect(sock, info->ai_addr, info->ai_addrlen) == -1) {
+        throw std::runtime_error{get_errno_str()};
+    }
+}
+
+void listen_socket(const socket_t sock) {
+    if (listen(sock, SOMAXCONN) == -1) {
+        throw std::runtime_error{get_errno_str()};
+    }
+}
+
+void close_socket(const socket_t sock) {
+    if (close(sock) == -1) {
+        throw std::runtime_error{get_errno_str()};
+    }
+}
+
+packet contents_to_packet(const contents_t& contents,
+                          const char* const command) {
+    packet ret{};
+    std::memset(&ret.header, 0, sizeof(ret.header)); // 0init padding bytes
+
+    std::uint32_t size = 0;
+    for (const auto& keyvalue : contents) {
+        const auto& key = keyvalue.first; // no structured bindings :(
+        const auto& value = keyvalue.second;
+
+        const auto contents_size = static_cast<std::uint32_t>(value.size());
+
+        decltype(ret.contents) addition;
+        // Copy the size, name and data as expected, then push it.
+        std::copy(reinterpret_cast<const char* const>(&contents_size),
+                  reinterpret_cast<const char* const>(&contents_size) +
+                      sizeof(contents_size),
+                  std::back_inserter(addition));
+        std::copy(key.c_str(), key.c_str() + key.size() + 1,
+                  std::back_inserter(addition));
+        std::copy(value.c_str(), value.c_str() + value.size(),
+                  std::back_inserter(addition));
+
+        size += addition.size(); // update size before moving
+        std::copy(std::make_move_iterator(std::begin(addition)),
+                  std::make_move_iterator(std::end(addition)),
+                  std::back_inserter(ret.contents));
+    }
+
+    // fill in expected header values
+    ret.header.size = size + sizeof(packet::header);
+    std::memcpy(ret.header.command, command, 3);
+
+    return ret;
+}
+
+contents_t packet_to_contents(const packet& packet) {
+    contents_t ret{};
+
+    // Extract the data as described in the header file.
+    for (auto i = 0u; i < packet.contents.size();) {
+        const char* const data = packet.contents.data() + i;
+
+        const std::uint32_t contents_size = [&]() {
+            std::uint32_t contents_size;
+            std::memcpy(&contents_size,
+                        reinterpret_cast<const std::uint32_t* const>(data),
+                        sizeof(std::uint32_t));
+            return contents_size;
+        }();
+
+        const auto size_size = sizeof(std::uint32_t);
+        const std::string name = data + size_size;
+        const char* const contents = data + size_size + name.length() + 1;
+
+        ret.emplace(name, std::string{contents, contents + contents_size});
+        i += size_size + name.size() + 1 + contents_size;
+    }
+    return ret;
+}
+
+static std::vector<char> packet_to_data(const packet& packet) noexcept {
+    std::vector<char> data{};
+    // data.reserve(sizeof(struct packet) + packet.contents.size());
+    std::copy(reinterpret_cast<const char* const>(&packet.header),
+              reinterpret_cast<const char* const>(&packet.header) +
+                  sizeof(packet::header),
+              std::back_inserter(data));
+    std::copy(std::begin(packet.contents), std::end(packet.contents),
+              std::back_inserter(data));
+    return data;
+}
+
+void send_packet(const packet& packet, const socket_t& sock,
+                 const sockaddr_in& dest) {
+    const std::vector<char> data = packet_to_data(packet);
+
+    if (sendto(sock, data.data(), data.size(), 0, (sockaddr*)&dest,
+               sizeof(sockaddr_in)) == -1) {
+        throw std::runtime_error{get_errno_str()};
+    }
+}
+
+void send_packet(const packet& packet, const socket_t& sock) {
+    const std::vector<char> data = packet_to_data(packet);
+
+    const auto total_size = data.size();
+    for (unsigned sent = 0; sent < data.size();) {
+        const ssize_t res =
+            send(sock, data.data() + sent, total_size - sent, 0);
+        if (res != -1) {
+            sent += res;
+            continue;
+        }
+
+        if (errno == EAGAIN || errno == EWOULDBLOCK) {
+            std::this_thread::sleep_for(std::chrono::milliseconds(1));
+            continue;
+        }
+
+        throw std::runtime_error{get_errno_str()};
+    }
+}
+
+static std::size_t get_backlog_size(const socket_t& socket) noexcept {
+    size_t size = 0;
+    if (ioctl(socket, FIONREAD, &size) == -1) {
+        throw std::runtime_error{get_errno_str()};
+    }
+    return size;
+}
+
+std::shared_ptr<recv_packet_ret> maybe_urecv_packet(const socket_t& sock) {
+    const auto packet_size = get_backlog_size(sock);
+    if (packet_size <= 0) {
+        return nullptr;
+    }
+
+    recv_packet_ret ret;
+    unsigned int origin_len = sizeof(ret.origin);
+
+    std::vector<char> buffer;
+    buffer.reserve(packet_size);
+    if (recvfrom(sock, buffer.data(), packet_size, 0, (sockaddr*)&ret.origin,
+                 &origin_len) == -1) {
+        throw std::runtime_error(get_errno_str());
+    }
+
+    std::memcpy(&ret.packet.header, buffer.data(), sizeof(packet::header));
+    ret.packet.contents.reserve(ret.packet.header.size -
+                                sizeof(packet::header));
+    std::copy(buffer.data() + sizeof(packet::header),
+              buffer.data() + ret.packet.header.size,
+              std::back_inserter(ret.packet.contents));
+
+    return std::make_shared<recv_packet_ret>(std::move(ret));
+}
+
+// true when finished reading as our stream packets may be very large
+static bool maybe_rrecv_packet(const socket_t& sock, packet& packet) {
+
+    auto backlog_size = get_backlog_size(sock);
+    if (backlog_size <= 0) {
+        return false;
+    }
+
+    auto& target_size = packet.header.size;
+    if (!target_size) {                      // header read required
+        if (backlog_size < sizeof(header)) { // no header, try again later
+            return false;
+        }
+
+        if (read(sock, &packet.header, sizeof(header)) == -1) {
+            throw std::runtime_error{get_errno_str()};
+        }
+        backlog_size -= sizeof(header);
+    }
+
+    const auto read_size =
+        std::min(backlog_size, static_cast<unsigned long>(target_size));
+    std::vector<char> buffer;
+    buffer.reserve(read_size);
+    if (read(sock, buffer.data(), read_size) == -1) {
+        throw std::runtime_error{get_errno_str()};
+    }
+
+    std::copy(buffer.data(), buffer.data() + read_size,
+              std::back_inserter(packet.contents));
+    if (packet.contents.size() < packet.header.size - sizeof(header)) {
+        return false; // more data to read, do again
+    }
+
+    return true;
+}
+
+static const auto ms_timeout = std::chrono::seconds(30);
+std::shared_ptr<recv_packet_ret> urecv_packet(const socket_t& rsock,
+                                              const bool& timeout) {
+    // poll our non-blocking sockets
+    const auto start = std::chrono::steady_clock::now();
+    while (!shared::should_exit) {
+        const auto pkt = maybe_urecv_packet(rsock);
+        if (pkt != nullptr) {
+            return pkt;
+        }
+        if (timeout && std::chrono::steady_clock::now() > start + ms_timeout) {
+            throw std::runtime_error("urecv timeout elapsed");
+        }
+        std::this_thread::sleep_for(std::chrono::milliseconds(1));
+    }
+    throw should_exit_exception();
+}
+
+std::shared_ptr<packet> rrecv_packet(const socket_t& rsock,
+                                     const bool& timeout) {
+    packet packet{};
+    auto last = std::chrono::steady_clock::now();
+    while (!shared::should_exit) {
+        const auto prev_size = packet.contents.size();
+        if (maybe_rrecv_packet(rsock, packet)) {
+            return std::make_shared<struct packet>(std::move(packet));
+        }
+        if (prev_size != packet.contents.size()) {
+            last = std::chrono::steady_clock::now();
+        }
+        if (timeout && std::chrono::steady_clock::now() > last + ms_timeout) {
+            throw std::runtime_error("rrecv timeout elapsed");
+        }
+        std::this_thread::sleep_for(std::chrono::milliseconds(1));
+    }
+    throw should_exit_exception();
+}
+
+} // namespace shared