classic.c

/*
  Copyright 2024 Northern.tech AS

  This file is part of CFEngine 3 - written and maintained by Northern.tech AS.

  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; version 3.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA

  To the extent this program is licensed as part of the Enterprise
  versions of CFEngine, the applicable Commercial Open Source License
  (COSL) may apply to this file if you as a licensee so wish it. See
  included file COSL.txt.
*/


#include <classic.h>

#include <logging.h>
#include <misc_lib.h>

static bool LastRecvTimedOut(void)
{
#ifndef __MINGW32__
    if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
    {
        return true;
    }
#else
    int lasterror = GetLastError();

    if (lasterror == EAGAIN || lasterror == WSAEWOULDBLOCK)
    {
        return true;
    }
#endif

    return false;
}

/**
 * @brief Receive up to #toget bytes, plus a '\0', into buffer from sd.
 * @param sd Socket descriptor
 * @param buffer Buffer into which to read data
 * @param toget Number of bytes to read; a '\0' shall be written after
 *        the data; buffer must have space for that.
 *
 * @note Writes up to buffer[toget] (toget + 1 bytes total)
 * @return number of bytes actually received, must be equal to #toget
 *         -1  in case of timeout or error - socket is unusable
 *         0   connection was closed (not an error, that's how clients
 *             normally terminate)
 *         <toget  NEVER
 */
int RecvSocketStream(int sd, char *buffer, int toget)
{
    int already, got;

    // This function used to take char buffer[CF_BUFSIZE]
    // Since it only writes up to (toget + 1) bytes I changed the function
    // signature
    if (toget > CF_BUFSIZE - 1 || toget <= 0)
    {
        Log(LOG_LEVEL_ERR, "Bad software request to receive %d bytes", toget);
        return -1;
    }

    /* Repeat recv() until we get "toget" bytes. */
    for (already = 0; already < toget; already += got)
    {
        got = recv(sd, buffer + already, toget - already, 0);

        if (got == -1)
        {
            if (errno != EINTR)           /* recv() again in case of signal */
            {
                if (LastRecvTimedOut())
                {
                    Log(LOG_LEVEL_ERR, "Receive timeout"
                        " (received=%dB, expecting=%dB) (recv: %s)",
                        already, toget, GetErrorStr());
                    Log(LOG_LEVEL_VERBOSE,
                        "Consider increasing body agent control"
                        " \"default_timeout\" setting");

                    /* Shutdown() TCP connection despite of EAGAIN error, in
                     * order to avoid receiving this delayed response later on
                     * (Redmine #6027). */
                    shutdown(sd, SHUT_RDWR);
                }
                else
                {
                    Log(LOG_LEVEL_ERR, "Couldn't receive (recv: %s)",
                        GetErrorStr());
                }
                return -1;
            }
        }
        else if (got == 0)
        {
            Log(LOG_LEVEL_VERBOSE, "Peer has closed the connection");
            buffer[already] = '\0';
            return 0;
        }
    }
    assert(already == toget);

    buffer[already] = '\0';
    return already;
}

/*************************************************************************/

/**
 * @brief Send #tosend bytes from buffer to sd.
 * @param sd Socket descriptor
 * @param buffer Buffer from which to read data
 * @param tosend Number of bytes to write.
 *
 * @return number of bytes actually sent, must be equal to #tosend
 *         -1  in case of timeout or error - socket is unusable
 *         -1  also in case of early proper connection close
 *         0        NEVER
 *         <tosend  NEVER
 */
int SendSocketStream(int sd, const char buffer[CF_BUFSIZE], int tosend)
{
    int sent, already = 0;

    if (tosend <= 0)
    {
        Log(LOG_LEVEL_ERR, "Bad software request to send %d bytes",
            tosend);
        return -1;
    }

    EnforceBwLimit(tosend);

    do
    {
        sent = send(sd, buffer + already, tosend - already, 0);

        if ((sent == -1) && (errno == EINTR))
        {
            continue;
        }

        if (sent == -1)
        {
            Log(LOG_LEVEL_ERR, "Couldn't send. (send: %s)", GetErrorStr());
            return -1;
        }

        already += sent;
    } while (already < tosend);
    assert(already == tosend);

    return already;
}