/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ 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 2 of the License.                      │
│                                                                              │
│ 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., 51 Franklin Street, Fifth Floor, Boston, MA                │
│ 02110-1301 USA                                                               │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/nt/winsock.h"
#include "libc/sock/internal.h"
#include "libc/sock/sock.h"
#include "libc/sysv/consts/so.h"
#include "libc/sysv/errfuns.h"

static bool setsockopt_polyfill(int *optname) {
  if (errno == ENOPROTOOPT && *optname == SO_REUSEPORT /* RHEL5 */) {
    *optname = SO_REUSEADDR; /* close enough */
    return true;             /* fudges errno */
  }
  return false;
}

static textwindows int setsockopt$nt(struct Fd *fd, int level, int optname,
                                     const void *optval, uint32_t optlen) {
  if (__setsockopt$nt(fd->handle, level, optname, optval, optlen) != -1) {
    return 0;
  } else {
    return winsockerr();
  }
}

/**
 * Modifies socket settings.
 *
 * This function is the ultimate rabbit hole. Basic usage:
 *
 *   int yes = 1;
 *   setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &yes, sizeof(yes));
 *
 * @param level can be SOL_SOCKET, SOL_IP, SOL_TCP, etc.
 * @param optname can be SO_{REUSE{PORT,ADDR},KEEPALIVE,etc.} etc.
 * @return 0 on success, or -1 w/ errno
 * @error ENOPROTOOPT for unknown (level,optname)
 * @see libc/sysv/consts.sh for tuning catalogue
 * @see getsockopt()
 */
int setsockopt(int fd, int level, int optname, const void *optval,
               uint32_t optlen) {
  if (!optval) return efault();
  if (!level || !optname) return enoprotoopt(); /* our sysvconsts definition */
  if (optname == -1) return 0;                  /* our sysvconsts definition */
  if (!IsWindows()) {
    do {
      if (setsockopt$sysv(fd, level, optname, optval, optlen) != -1) {
        return 0;
      }
    } while (setsockopt_polyfill(&optname));
    return -1;
  } else if (isfdkind(fd, kFdSocket)) {
    return setsockopt$nt(&g_fds.p[fd], level, optname, optval, optlen);
  } else {
    return ebadf();
  }
}
