dgramoverstream.cpp

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#include <string.h>
#include <unistd.h>
#include <string>

/*
   The committers of the libsocket project, all rights reserved
   (c) 2016, dermesser <lbo@spheniscida.de>

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

   1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

   THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS “AS IS” AND ANY
   EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
   DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

#include <dgramoverstream.hpp>
#include <exception.hpp>

namespace libsocket {

dgram_over_stream::dgram_over_stream(stream_client_socket socket)
    : inner(std::unique_ptr<stream_client_socket>(
          new stream_client_socket(std::move(socket)))) {
    enable_nagle(false);
}

dgram_over_stream::dgram_over_stream(
    std::unique_ptr<stream_client_socket> inner_)
    : inner(std::move(inner_)) {
    enable_nagle(false);
}

void dgram_over_stream::enable_nagle(bool enabled) const {
    int enabled_ = int(!enabled);
    inner->set_sock_opt(IPPROTO_TCP, TCP_NODELAY, (const char*)&enabled_,
                        sizeof(int));
}

ssize_t dgram_over_stream::sndmsg(const std::string& msg) {
    return sndmsg(msg.c_str(), msg.size());
}

ssize_t dgram_over_stream::rcvmsg(std::string* dst) {
    uint32_t expected = receive_header();

    if (expected <= dst->size()) dst->resize(expected);

    size_t to_receive = dst->size();
    size_t received = 0;

    while (received < to_receive) {
        ssize_t result = receive_bytes(to_receive - received);

        if (result < 0)
            throw socket_exception(
                __FILE__, __LINE__,
                "dgram_over_stream::rcvmsg(): Could not receive message!",
                false);

        dst->replace(received, result, RECV_BUF);

        received += (size_t)result;
    }

    // Consume remaining frame that doesn't fit into dst.
    ssize_t rest = expected - to_receive;
    while (rest > 0) {
        rest -= receive_bytes(rest);
    }

    return received;
}

ssize_t dgram_over_stream::sndmsg(const std::vector<uint8_t>& msg) {
    return sndmsg(static_cast<const void*>(msg.data()), msg.size());
}

ssize_t dgram_over_stream::rcvmsg(std::vector<uint8_t>* dst) {
    uint32_t expected = receive_header();

    if (expected <= dst->size()) dst->resize(expected);

    size_t to_receive = dst->size();
    size_t received = 0;
    std::vector<uint8_t>::iterator dst_iter = dst->begin();

    while (received < to_receive) {
        ssize_t result = receive_bytes(to_receive - received);

        if (result < 0)
            throw socket_exception(
                __FILE__, __LINE__,
                "dgram_over_stream::rcvmsg(): Could not receive message!",
                false);

        for (ssize_t i = 0; i < result; i++, dst_iter++)
            *dst_iter = RECV_BUF[i];

        received += result;
    }

    // Consume remaining frame that doesn't fit into dst.
    ssize_t rest = expected - to_receive;
    while (rest > 0) {
        rest -= receive_bytes(rest);
    }

    return received;
}

ssize_t dgram_over_stream::sndmsg(const void* buf, size_t len) {
    encode_uint32(uint32_t(len), prefix_buffer);
    ssize_t result = inner->snd(prefix_buffer, FRAMING_PREFIX_LENGTH, 0);

    if (result < 0) return result;

    result = inner->snd(buf, len, 0);

    if (result < 0) return result;

    return result;
}

ssize_t dgram_over_stream::rcvmsg(void* dst, size_t len) {
    uint32_t expected = receive_header();

    size_t to_receive = len < expected ? len : expected;
    size_t received = 0;

    while (received < to_receive) {
        ssize_t result = receive_bytes(to_receive - received);

        if (result < 0)
            throw socket_exception(
                __FILE__, __LINE__,
                "dgram_over_stream::rcvmsg(): Could not receive message!",
                false);

        memcpy(dst, RECV_BUF, result);
        dst = static_cast<void*>(static_cast<char*>(dst) + result);
        received += result;
    }

    // Consume remaining frame that doesn't fit into dst.
    ssize_t rest = expected - to_receive;
    while (rest > 0) {
        rest -= receive_bytes(rest);
    }
    return received;
}

// Places up to n bytes into this->RECV_BUF.
ssize_t dgram_over_stream::receive_bytes(size_t n) {
    if (n == 0) return 0;

    // Ignore rest of message.
    ssize_t rest_len = n > RECV_BUF_SIZE ? RECV_BUF_SIZE : n;
    size_t pos = 0;

    while (rest_len > 0) {
        ssize_t recvd = inner->rcv(RECV_BUF + pos, rest_len, 0);

        if (recvd <= 0) return n - rest_len;

        rest_len -= recvd;
        pos += recvd;
    }

    return pos;
}

uint32_t dgram_over_stream::receive_header(void) {
    ssize_t pos = 0;

    do {
        ssize_t result =
            inner->rcv(prefix_buffer + pos, FRAMING_PREFIX_LENGTH, 0);

        if (result < 0)
            throw socket_exception(__FILE__, __LINE__,
                                   "dgram_over_stream::receive_header(): Could "
                                   "not receive length prefix!",
                                   false);

        pos += result;
    } while (pos < 4);

    return decode_uint32(prefix_buffer);
}
}  // namespace libsocket