/src/openssh/misc.c

Source (jump to first uncovered line)
/* $OpenBSD: misc.c,v 1.181 2023/03/03 02:37:58 dtucker Exp $ */
/*
 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
 * Copyright (c) 2005-2020 Damien Miller.  All rights reserved.
 * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */


#include "includes.h"

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/un.h>

#include <limits.h>
#ifdef HAVE_LIBGEN_H
# include <libgen.h>
#endif
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#ifdef HAVE_PATHS_H
# include <paths.h>
#include <pwd.h>
#include <grp.h>
#endif
#ifdef SSH_TUN_OPENBSD
#include <net/if.h>
#endif

#include "xmalloc.h"
#include "misc.h"
#include "log.h"
#include "ssh.h"
#include "sshbuf.h"
#include "ssherr.h"
#include "platform.h"

/* remove newline at end of string */
char *
chop(char *s)
{
  char *t = s;
  while (*t) {
    if (*t == '\n' || *t == '\r') {
      *t = '\0';
      return s;
    }
    t++;
  }
  return s;

}

/* remove whitespace from end of string */
void
rtrim(char *s)
{
  size_t i;

  if ((i = strlen(s)) == 0)
    return;
  for (i--; i > 0; i--) {
    if (isspace((unsigned char)s[i]))
      s[i] = '\0';
  }
}

/* set/unset filedescriptor to non-blocking */
int
set_nonblock(int fd)
{
  int val;

  val = fcntl(fd, F_GETFL);
  if (val == -1) {
    error("fcntl(%d, F_GETFL): %s", fd, strerror(errno));
    return (-1);
  }
  if (val & O_NONBLOCK) {
    debug3("fd %d is O_NONBLOCK", fd);
    return (0);
  }
  debug2("fd %d setting O_NONBLOCK", fd);
  val |= O_NONBLOCK;
  if (fcntl(fd, F_SETFL, val) == -1) {
    debug("fcntl(%d, F_SETFL, O_NONBLOCK): %s", fd,
        strerror(errno));
    return (-1);
  }
  return (0);
}

int
unset_nonblock(int fd)
{
  int val;

  val = fcntl(fd, F_GETFL);
  if (val == -1) {
    error("fcntl(%d, F_GETFL): %s", fd, strerror(errno));
    return (-1);
  }
  if (!(val & O_NONBLOCK)) {
    debug3("fd %d is not O_NONBLOCK", fd);
    return (0);
  }
  debug("fd %d clearing O_NONBLOCK", fd);
  val &= ~O_NONBLOCK;
  if (fcntl(fd, F_SETFL, val) == -1) {
    debug("fcntl(%d, F_SETFL, ~O_NONBLOCK): %s",
        fd, strerror(errno));
    return (-1);
  }
  return (0);
}

const char *
ssh_gai_strerror(int gaierr)
{
  if (gaierr == EAI_SYSTEM && errno != 0)
    return strerror(errno);
  return gai_strerror(gaierr);
}

/* disable nagle on socket */
void
set_nodelay(int fd)
{
  int opt;
  socklen_t optlen;

  optlen = sizeof opt;
  if (getsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, &optlen) == -1) {
    debug("getsockopt TCP_NODELAY: %.100s", strerror(errno));
    return;
  }
  if (opt == 1) {
    debug2("fd %d is TCP_NODELAY", fd);
    return;
  }
  opt = 1;
  debug2("fd %d setting TCP_NODELAY", fd);
  if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof opt) == -1)
    error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
}

/* Allow local port reuse in TIME_WAIT */
int
set_reuseaddr(int fd)
{
  int on = 1;

  if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1) {
    error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
    return -1;
  }
  return 0;
}

/* Get/set routing domain */
char *
get_rdomain(int fd)
{
#if defined(HAVE_SYS_GET_RDOMAIN)
  return sys_get_rdomain(fd);
#elif defined(__OpenBSD__)
  int rtable;
  char *ret;
  socklen_t len = sizeof(rtable);

  if (getsockopt(fd, SOL_SOCKET, SO_RTABLE, &rtable, &len) == -1) {
    error("Failed to get routing domain for fd %d: %s",
        fd, strerror(errno));
    return NULL;
  }
  xasprintf(&ret, "%d", rtable);
  return ret;
#else /* defined(__OpenBSD__) */
  return NULL;
#endif
}

int
set_rdomain(int fd, const char *name)
{
#if defined(HAVE_SYS_SET_RDOMAIN)
  return sys_set_rdomain(fd, name);
#elif defined(__OpenBSD__)
  int rtable;
  const char *errstr;

  if (name == NULL)
    return 0; /* default table */

  rtable = (int)strtonum(name, 0, 255, &errstr);
  if (errstr != NULL) {
    /* Shouldn't happen */
    error("Invalid routing domain \"%s\": %s", name, errstr);
    return -1;
  }
  if (setsockopt(fd, SOL_SOCKET, SO_RTABLE,
      &rtable, sizeof(rtable)) == -1) {
    error("Failed to set routing domain %d on fd %d: %s",
        rtable, fd, strerror(errno));
    return -1;
  }
  return 0;
#else /* defined(__OpenBSD__) */
  error("Setting routing domain is not supported on this platform");
  return -1;
#endif
}

int
get_sock_af(int fd)
{
  struct sockaddr_storage to;
  socklen_t tolen = sizeof(to);

  memset(&to, 0, sizeof(to));
  if (getsockname(fd, (struct sockaddr *)&to, &tolen) == -1)
    return -1;
#ifdef IPV4_IN_IPV6
  if (to.ss_family == AF_INET6 &&
      IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
    return AF_INET;
#endif
  return to.ss_family;
}

void
set_sock_tos(int fd, int tos)
{
#ifndef IP_TOS_IS_BROKEN
  int af;

  switch ((af = get_sock_af(fd))) {
  case -1:
    /* assume not a socket */
    break;
  case AF_INET:
# ifdef IP_TOS
    debug3_f("set socket %d IP_TOS 0x%02x", fd, tos);
    if (setsockopt(fd, IPPROTO_IP, IP_TOS,
        &tos, sizeof(tos)) == -1) {
      error("setsockopt socket %d IP_TOS %d: %s",
          fd, tos, strerror(errno));
    }
# endif /* IP_TOS */
    break;
  case AF_INET6:
# ifdef IPV6_TCLASS
    debug3_f("set socket %d IPV6_TCLASS 0x%02x", fd, tos);
    if (setsockopt(fd, IPPROTO_IPV6, IPV6_TCLASS,
        &tos, sizeof(tos)) == -1) {
      error("setsockopt socket %d IPV6_TCLASS %d: %s",
          fd, tos, strerror(errno));
    }
# endif /* IPV6_TCLASS */
    break;
  default:
    debug2_f("unsupported socket family %d", af);
    break;
  }
#endif /* IP_TOS_IS_BROKEN */
}

/*
 * Wait up to *timeoutp milliseconds for events on fd. Updates
 * *timeoutp with time remaining.
 * Returns 0 if fd ready or -1 on timeout or error (see errno).
 */
static int
waitfd(int fd, int *timeoutp, short events)
{
  struct pollfd pfd;
  struct timeval t_start;
  int oerrno, r;

  pfd.fd = fd;
  pfd.events = events;
  for (; *timeoutp >= 0;) {
    monotime_tv(&t_start);
    r = poll(&pfd, 1, *timeoutp);
    oerrno = errno;
    ms_subtract_diff(&t_start, timeoutp);
    errno = oerrno;
    if (r > 0)
      return 0;
    else if (r == -1 && errno != EAGAIN && errno != EINTR)
      return -1;
    else if (r == 0)
      break;
  }
  /* timeout */
  errno = ETIMEDOUT;
  return -1;
}

/*
 * Wait up to *timeoutp milliseconds for fd to be readable. Updates
 * *timeoutp with time remaining.
 * Returns 0 if fd ready or -1 on timeout or error (see errno).
 */
int
waitrfd(int fd, int *timeoutp) {
  return waitfd(fd, timeoutp, POLLIN);
}

/*
 * Attempt a non-blocking connect(2) to the specified address, waiting up to
 * *timeoutp milliseconds for the connection to complete. If the timeout is
 * <=0, then wait indefinitely.
 *
 * Returns 0 on success or -1 on failure.
 */
int
timeout_connect(int sockfd, const struct sockaddr *serv_addr,
    socklen_t addrlen, int *timeoutp)
{
  int optval = 0;
  socklen_t optlen = sizeof(optval);

  /* No timeout: just do a blocking connect() */
  if (timeoutp == NULL || *timeoutp <= 0)
    return connect(sockfd, serv_addr, addrlen);

  set_nonblock(sockfd);
  for (;;) {
    if (connect(sockfd, serv_addr, addrlen) == 0) {
      /* Succeeded already? */
      unset_nonblock(sockfd);
      return 0;
    } else if (errno == EINTR)
      continue;
    else if (errno != EINPROGRESS)
      return -1;
    break;
  }

  if (waitfd(sockfd, timeoutp, POLLIN | POLLOUT) == -1)
    return -1;

  /* Completed or failed */
  if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
    debug("getsockopt: %s", strerror(errno));
    return -1;
  }
  if (optval != 0) {
    errno = optval;
    return -1;
  }
  unset_nonblock(sockfd);
  return 0;
}

/* Characters considered whitespace in strsep calls. */
#define WHITESPACE " \t\r\n"
#define QUOTE "\""

/* return next token in configuration line */
static char *
strdelim_internal(char **s, int split_equals)
{
  char *old;
  int wspace = 0;

  if (*s == NULL)
    return NULL;

  old = *s;

  *s = strpbrk(*s,
      split_equals ? WHITESPACE QUOTE "=" : WHITESPACE QUOTE);
  if (*s == NULL)
    return (old);

  if (*s[0] == '\"') {
    memmove(*s, *s + 1, strlen(*s)); /* move nul too */
    /* Find matching quote */
    if ((*s = strpbrk(*s, QUOTE)) == NULL) {
      return (NULL);    /* no matching quote */
    } else {
      *s[0] = '\0';
      *s += strspn(*s + 1, WHITESPACE) + 1;
      return (old);
    }
  }

  /* Allow only one '=' to be skipped */
  if (split_equals && *s[0] == '=')
    wspace = 1;
  *s[0] = '\0';

  /* Skip any extra whitespace after first token */
  *s += strspn(*s + 1, WHITESPACE) + 1;
  if (split_equals && *s[0] == '=' && !wspace)
    *s += strspn(*s + 1, WHITESPACE) + 1;

  return (old);
}

/*
 * Return next token in configuration line; splts on whitespace or a
 * single '=' character.
 */
char *
strdelim(char **s)
{
  return strdelim_internal(s, 1);
}

/*
 * Return next token in configuration line; splts on whitespace only.
 */
char *
strdelimw(char **s)
{
  return strdelim_internal(s, 0);
}

struct passwd *
pwcopy(struct passwd *pw)
{
  struct passwd *copy = xcalloc(1, sizeof(*copy));

  copy->pw_name = xstrdup(pw->pw_name);
  copy->pw_passwd = xstrdup(pw->pw_passwd == NULL ? "*" : pw->pw_passwd);
#ifdef HAVE_STRUCT_PASSWD_PW_GECOS
  copy->pw_gecos = xstrdup(pw->pw_gecos);
#endif
  copy->pw_uid = pw->pw_uid;
  copy->pw_gid = pw->pw_gid;
#ifdef HAVE_STRUCT_PASSWD_PW_EXPIRE
  copy->pw_expire = pw->pw_expire;
#endif
#ifdef HAVE_STRUCT_PASSWD_PW_CHANGE
  copy->pw_change = pw->pw_change;
#endif
#ifdef HAVE_STRUCT_PASSWD_PW_CLASS
  copy->pw_class = xstrdup(pw->pw_class);
#endif
  copy->pw_dir = xstrdup(pw->pw_dir);
  copy->pw_shell = xstrdup(pw->pw_shell);
  return copy;
}

/*
 * Convert ASCII string to TCP/IP port number.
 * Port must be >=0 and <=65535.
 * Return -1 if invalid.
 */
int
a2port(const char *s)
{
  struct servent *se;
  long long port;
  const char *errstr;

  port = strtonum(s, 0, 65535, &errstr);
  if (errstr == NULL)
    return (int)port;
  if ((se = getservbyname(s, "tcp")) != NULL)
    return ntohs(se->s_port);
  return -1;
}

int
a2tun(const char *s, int *remote)
{
  const char *errstr = NULL;
  char *sp, *ep;
  int tun;

  if (remote != NULL) {
    *remote = SSH_TUNID_ANY;
    sp = xstrdup(s);
    if ((ep = strchr(sp, ':')) == NULL) {
      free(sp);
      return (a2tun(s, NULL));
    }
    ep[0] = '\0'; ep++;
    *remote = a2tun(ep, NULL);
    tun = a2tun(sp, NULL);
    free(sp);
    return (*remote == SSH_TUNID_ERR ? *remote : tun);
  }

  if (strcasecmp(s, "any") == 0)
    return (SSH_TUNID_ANY);

  tun = strtonum(s, 0, SSH_TUNID_MAX, &errstr);
  if (errstr != NULL)
    return (SSH_TUNID_ERR);

  return (tun);
}

#define SECONDS   1
#define MINUTES   (SECONDS * 60)
#define HOURS   (MINUTES * 60)
#define DAYS    (HOURS * 24)
#define WEEKS   (DAYS * 7)

/*
 * Convert a time string into seconds; format is
 * a sequence of:
 *      time[qualifier]
 *
 * Valid time qualifiers are:
 *      <none>  seconds
 *      s|S     seconds
 *      m|M     minutes
 *      h|H     hours
 *      d|D     days
 *      w|W     weeks
 *
 * Examples:
 *      90m     90 minutes
 *      1h30m   90 minutes
 *      2d      2 days
 *      1w      1 week
 *
 * Return -1 if time string is invalid.
 */
int
convtime(const char *s)
{
  long total, secs, multiplier;
  const char *p;
  char *endp;

  errno = 0;
  total = 0;
  p = s;

  if (p == NULL || *p == '\0')
    return -1;

  while (*p) {
    secs = strtol(p, &endp, 10);
    if (p == endp ||
        (errno == ERANGE && (secs == INT_MIN || secs == INT_MAX)) ||
        secs < 0)
      return -1;

    multiplier = 1;
    switch (*endp++) {
    case '\0':
      endp--;
      break;
    case 's':
    case 'S':
      break;
    case 'm':
    case 'M':
      multiplier = MINUTES;
      break;
    case 'h':
    case 'H':
      multiplier = HOURS;
      break;
    case 'd':
    case 'D':
      multiplier = DAYS;
      break;
    case 'w':
    case 'W':
      multiplier = WEEKS;
      break;
    default:
      return -1;
    }
    if (secs > INT_MAX / multiplier)
      return -1;
    secs *= multiplier;
    if  (total > INT_MAX - secs)
      return -1;
    total += secs;
    if (total < 0)
      return -1;
    p = endp;
  }

  return total;
}

#define TF_BUFS 8
#define TF_LEN  9

const char *
fmt_timeframe(time_t t)
{
  char    *buf;
  static char  tfbuf[TF_BUFS][TF_LEN];  /* ring buffer */
  static int   idx = 0;
  unsigned int   sec, min, hrs, day;
  unsigned long long  week;

  buf = tfbuf[idx++];
  if (idx == TF_BUFS)
    idx = 0;

  week = t;

  sec = week % 60;
  week /= 60;
  min = week % 60;
  week /= 60;
  hrs = week % 24;
  week /= 24;
  day = week % 7;
  week /= 7;

  if (week > 0)
    snprintf(buf, TF_LEN, "%02lluw%01ud%02uh", week, day, hrs);
  else if (day > 0)
    snprintf(buf, TF_LEN, "%01ud%02uh%02um", day, hrs, min);
  else
    snprintf(buf, TF_LEN, "%02u:%02u:%02u", hrs, min, sec);

  return (buf);
}

/*
 * Returns a standardized host+port identifier string.
 * Caller must free returned string.
 */
char *
put_host_port(const char *host, u_short port)
{
  char *hoststr;

  if (port == 0 || port == SSH_DEFAULT_PORT)
    return(xstrdup(host));
  if (asprintf(&hoststr, "[%s]:%d", host, (int)port) == -1)
    fatal("put_host_port: asprintf: %s", strerror(errno));
  debug3("put_host_port: %s", hoststr);
  return hoststr;
}

/*
 * Search for next delimiter between hostnames/addresses and ports.
 * Argument may be modified (for termination).
 * Returns *cp if parsing succeeds.
 * *cp is set to the start of the next field, if one was found.
 * The delimiter char, if present, is stored in delim.
 * If this is the last field, *cp is set to NULL.
 */
char *
hpdelim2(char **cp, char *delim)
{
  char *s, *old;

  if (cp == NULL || *cp == NULL)
    return NULL;

  old = s = *cp;
  if (*s == '[') {
    if ((s = strchr(s, ']')) == NULL)
      return NULL;
    else
      s++;
  } else if ((s = strpbrk(s, ":/")) == NULL)
    s = *cp + strlen(*cp); /* skip to end (see first case below) */

  switch (*s) {
  case '\0':
    *cp = NULL; /* no more fields*/
    break;

  case ':':
  case '/':
    if (delim != NULL)
      *delim = *s;
    *s = '\0';  /* terminate */
    *cp = s + 1;
    break;

  default:
    return NULL;
  }

  return old;
}

/* The common case: only accept colon as delimiter. */
char *
hpdelim(char **cp)
{
  char *r, delim = '\0';

  r =  hpdelim2(cp, &delim);
  if (delim == '/')
    return NULL;
  return r;
}

char *
cleanhostname(char *host)
{
  if (*host == '[' && host[strlen(host) - 1] == ']') {
    host[strlen(host) - 1] = '\0';
    return (host + 1);
  } else
    return host;
}

char *
colon(char *cp)
{
  int flag = 0;

  if (*cp == ':')   /* Leading colon is part of file name. */
    return NULL;
  if (*cp == '[')
    flag = 1;

  for (; *cp; ++cp) {
    if (*cp == '@' && *(cp+1) == '[')
      flag = 1;
    if (*cp == ']' && *(cp+1) == ':' && flag)
      return (cp+1);
    if (*cp == ':' && !flag)
      return (cp);
    if (*cp == '/')
      return NULL;
  }
  return NULL;
}

/*
 * Parse a [user@]host:[path] string.
 * Caller must free returned user, host and path.
 * Any of the pointer return arguments may be NULL (useful for syntax checking).
 * If user was not specified then *userp will be set to NULL.
 * If host was not specified then *hostp will be set to NULL.
 * If path was not specified then *pathp will be set to ".".
 * Returns 0 on success, -1 on failure.
 */
int
parse_user_host_path(const char *s, char **userp, char **hostp, char **pathp)
{
  char *user = NULL, *host = NULL, *path = NULL;
  char *sdup, *tmp;
  int ret = -1;

  if (userp != NULL)
    *userp = NULL;
  if (hostp != NULL)
    *hostp = NULL;
  if (pathp != NULL)
    *pathp = NULL;

  sdup = xstrdup(s);

  /* Check for remote syntax: [user@]host:[path] */
  if ((tmp = colon(sdup)) == NULL)
    goto out;

  /* Extract optional path */
  *tmp++ = '\0';
  if (*tmp == '\0')
    tmp = ".";
  path = xstrdup(tmp);

  /* Extract optional user and mandatory host */
  tmp = strrchr(sdup, '@');
  if (tmp != NULL) {
    *tmp++ = '\0';
    host = xstrdup(cleanhostname(tmp));
    if (*sdup != '\0')
      user = xstrdup(sdup);
  } else {
    host = xstrdup(cleanhostname(sdup));
    user = NULL;
  }

  /* Success */
  if (userp != NULL) {
    *userp = user;
    user = NULL;
  }
  if (hostp != NULL) {
    *hostp = host;
    host = NULL;
  }
  if (pathp != NULL) {
    *pathp = path;
    path = NULL;
  }
  ret = 0;
out:
  free(sdup);
  free(user);
  free(host);
  free(path);
  return ret;
}

/*
 * Parse a [user@]host[:port] string.
 * Caller must free returned user and host.
 * Any of the pointer return arguments may be NULL (useful for syntax checking).
 * If user was not specified then *userp will be set to NULL.
 * If port was not specified then *portp will be -1.
 * Returns 0 on success, -1 on failure.
 */
int
parse_user_host_port(const char *s, char **userp, char **hostp, int *portp)
{
  char *sdup, *cp, *tmp;
  char *user = NULL, *host = NULL;
  int port = -1, ret = -1;

  if (userp != NULL)
    *userp = NULL;
  if (hostp != NULL)
    *hostp = NULL;
  if (portp != NULL)
    *portp = -1;

  if ((sdup = tmp = strdup(s)) == NULL)
    return -1;
  /* Extract optional username */
  if ((cp = strrchr(tmp, '@')) != NULL) {
    *cp = '\0';
    if (*tmp == '\0')
      goto out;
    if ((user = strdup(tmp)) == NULL)
      goto out;
    tmp = cp + 1;
  }
  /* Extract mandatory hostname */
  if ((cp = hpdelim(&tmp)) == NULL || *cp == '\0')
    goto out;
  host = xstrdup(cleanhostname(cp));
  /* Convert and verify optional port */
  if (tmp != NULL && *tmp != '\0') {
    if ((port = a2port(tmp)) <= 0)
      goto out;
  }
  /* Success */
  if (userp != NULL) {
    *userp = user;
    user = NULL;
  }
  if (hostp != NULL) {
    *hostp = host;
    host = NULL;
  }
  if (portp != NULL)
    *portp = port;
  ret = 0;
 out:
  free(sdup);
  free(user);
  free(host);
  return ret;
}

/*
 * Converts a two-byte hex string to decimal.
 * Returns the decimal value or -1 for invalid input.
 */
static int
hexchar(const char *s)
{
  unsigned char result[2];
  int i;

  for (i = 0; i < 2; i++) {
    if (s[i] >= '0' && s[i] <= '9')
      result[i] = (unsigned char)(s[i] - '0');
    else if (s[i] >= 'a' && s[i] <= 'f')
      result[i] = (unsigned char)(s[i] - 'a') + 10;
    else if (s[i] >= 'A' && s[i] <= 'F')
      result[i] = (unsigned char)(s[i] - 'A') + 10;
    else
      return -1;
  }
  return (result[0] << 4) | result[1];
}

/*
 * Decode an url-encoded string.
 * Returns a newly allocated string on success or NULL on failure.
 */
static char *
urldecode(const char *src)
{
  char *ret, *dst;
  int ch;

  ret = xmalloc(strlen(src) + 1);
  for (dst = ret; *src != '\0'; src++) {
    switch (*src) {
    case '+':
      *dst++ = ' ';
      break;
    case '%':
      if (!isxdigit((unsigned char)src[1]) ||
          !isxdigit((unsigned char)src[2]) ||
          (ch = hexchar(src + 1)) == -1) {
        free(ret);
        return NULL;
      }
      *dst++ = ch;
      src += 2;
      break;
    default:
      *dst++ = *src;
      break;
    }
  }
  *dst = '\0';

  return ret;
}

/*
 * Parse an (scp|ssh|sftp)://[user@]host[:port][/path] URI.
 * See https://tools.ietf.org/html/draft-ietf-secsh-scp-sftp-ssh-uri-04
 * Either user or path may be url-encoded (but not host or port).
 * Caller must free returned user, host and path.
 * Any of the pointer return arguments may be NULL (useful for syntax checking)
 * but the scheme must always be specified.
 * If user was not specified then *userp will be set to NULL.
 * If port was not specified then *portp will be -1.
 * If path was not specified then *pathp will be set to NULL.
 * Returns 0 on success, 1 if non-uri/wrong scheme, -1 on error/invalid uri.
 */
int
parse_uri(const char *scheme, const char *uri, char **userp, char **hostp,
    int *portp, char **pathp)
{
  char *uridup, *cp, *tmp, ch;
  char *user = NULL, *host = NULL, *path = NULL;
  int port = -1, ret = -1;
  size_t len;

  len = strlen(scheme);
  if (strncmp(uri, scheme, len) != 0 || strncmp(uri + len, "://", 3) != 0)
    return 1;
  uri += len + 3;

  if (userp != NULL)
    *userp = NULL;
  if (hostp != NULL)
    *hostp = NULL;
  if (portp != NULL)
    *portp = -1;
  if (pathp != NULL)
    *pathp = NULL;

  uridup = tmp = xstrdup(uri);

  /* Extract optional ssh-info (username + connection params) */
  if ((cp = strchr(tmp, '@')) != NULL) {
    char *delim;

    *cp = '\0';
    /* Extract username and connection params */
    if ((delim = strchr(tmp, ';')) != NULL) {
      /* Just ignore connection params for now */
      *delim = '\0';
    }
    if (*tmp == '\0') {
      /* Empty username */
      goto out;
    }
    if ((user = urldecode(tmp)) == NULL)
      goto out;
    tmp = cp + 1;
  }

  /* Extract mandatory hostname */
  if ((cp = hpdelim2(&tmp, &ch)) == NULL || *cp == '\0')
    goto out;
  host = xstrdup(cleanhostname(cp));
  if (!valid_domain(host, 0, NULL))
    goto out;

  if (tmp != NULL && *tmp != '\0') {
    if (ch == ':') {
      /* Convert and verify port. */
      if ((cp = strchr(tmp, '/')) != NULL)
        *cp = '\0';
      if ((port = a2port(tmp)) <= 0)
        goto out;
      tmp = cp ? cp + 1 : NULL;
    }
    if (tmp != NULL && *tmp != '\0') {
      /* Extract optional path */
      if ((path = urldecode(tmp)) == NULL)
        goto out;
    }
  }

  /* Success */
  if (userp != NULL) {
    *userp = user;
    user = NULL;
  }
  if (hostp != NULL) {
    *hostp = host;
    host = NULL;
  }
  if (portp != NULL)
    *portp = port;
  if (pathp != NULL) {
    *pathp = path;
    path = NULL;
  }
  ret = 0;
 out:
  free(uridup);
  free(user);
  free(host);
  free(path);
  return ret;
}

/* function to assist building execv() arguments */
void
addargs(arglist *args, char *fmt, ...)
{
  va_list ap;
  char *cp;
  u_int nalloc;
  int r;

  va_start(ap, fmt);
  r = vasprintf(&cp, fmt, ap);
  va_end(ap);
  if (r == -1)
    fatal_f("argument too long");

  nalloc = args->nalloc;
  if (args->list == NULL) {
    nalloc = 32;
    args->num = 0;
  } else if (args->num > (256 * 1024))
    fatal_f("too many arguments");
  else if (args->num >= args->nalloc)
    fatal_f("arglist corrupt");
  else if (args->num+2 >= nalloc)
    nalloc *= 2;

  args->list = xrecallocarray(args->list, args->nalloc,
      nalloc, sizeof(char *));
  args->nalloc = nalloc;
  args->list[args->num++] = cp;
  args->list[args->num] = NULL;
}

void
replacearg(arglist *args, u_int which, char *fmt, ...)
{
  va_list ap;
  char *cp;
  int r;

  va_start(ap, fmt);
  r = vasprintf(&cp, fmt, ap);
  va_end(ap);
  if (r == -1)
    fatal_f("argument too long");
  if (args->list == NULL || args->num >= args->nalloc)
    fatal_f("arglist corrupt");

  if (which >= args->num)
    fatal_f("tried to replace invalid arg %d >= %d",
        which, args->num);
  free(args->list[which]);
  args->list[which] = cp;
}

void
freeargs(arglist *args)
{
  u_int i;

  if (args == NULL)
    return;
  if (args->list != NULL && args->num < args->nalloc) {
    for (i = 0; i < args->num; i++)
      free(args->list[i]);
    free(args->list);
  }
  args->nalloc = args->num = 0;
  args->list = NULL;
}

/*
 * Expands tildes in the file name.  Returns data allocated by xmalloc.
 * Warning: this calls getpw*.
 */
int
tilde_expand(const char *filename, uid_t uid, char **retp)
{
  char *ocopy = NULL, *copy, *s = NULL;
  const char *path = NULL, *user = NULL;
  struct passwd *pw;
  size_t len;
  int ret = -1, r, slash;

  *retp = NULL;
  if (*filename != '~') {
    *retp = xstrdup(filename);
    return 0;
  }
  ocopy = copy = xstrdup(filename + 1);

  if (*copy == '\0')       /* ~ */
    path = NULL;
  else if (*copy == '/') {
    copy += strspn(copy, "/");
    if (*copy == '\0')
      path = NULL;     /* ~/ */
    else
      path = copy;     /* ~/path */
  } else {
    user = copy;
    if ((path = strchr(copy, '/')) != NULL) {
      copy[path - copy] = '\0';
      path++;
      path += strspn(path, "/");
      if (*path == '\0')   /* ~user/ */
        path = NULL;
      /* else        ~user/path */
    }
    /* else         ~user */
  }
  if (user != NULL) {
    if ((pw = getpwnam(user)) == NULL) {
      error_f("No such user %s", user);
      goto out;
    }
  } else if ((pw = getpwuid(uid)) == NULL) {
    error_f("No such uid %ld", (long)uid);
    goto out;
  }

  /* Make sure directory has a trailing '/' */
  slash = (len = strlen(pw->pw_dir)) == 0 || pw->pw_dir[len - 1] != '/';

  if ((r = xasprintf(&s, "%s%s%s", pw->pw_dir,
      slash ? "/" : "", path != NULL ? path : "")) <= 0) {
    error_f("xasprintf failed");
    goto out;
  }
  if (r >= PATH_MAX) {
    error_f("Path too long");
    goto out;
  }
  /* success */
  ret = 0;
  *retp = s;
  s = NULL;
 out:
  free(s);
  free(ocopy);
  return ret;
}

char *
tilde_expand_filename(const char *filename, uid_t uid)
{
  char *ret;

  if (tilde_expand(filename, uid, &ret) != 0)
    cleanup_exit(255);
  return ret;
}

/*
 * Expand a string with a set of %[char] escapes and/or ${ENVIRONMENT}
 * substitutions.  A number of escapes may be specified as
 * (char *escape_chars, char *replacement) pairs. The list must be terminated
 * by a NULL escape_char. Returns replaced string in memory allocated by
 * xmalloc which the caller must free.
 */
static char *
vdollar_percent_expand(int *parseerror, int dollar, int percent,
    const char *string, va_list ap)
{
#define EXPAND_MAX_KEYS 16
  u_int num_keys = 0, i;
  struct {
    const char *key;
    const char *repl;
  } keys[EXPAND_MAX_KEYS];
  struct sshbuf *buf;
  int r, missingvar = 0;
  char *ret = NULL, *var, *varend, *val;
  size_t len;

  if ((buf = sshbuf_new()) == NULL)
    fatal_f("sshbuf_new failed");
  if (parseerror == NULL)
    fatal_f("null parseerror arg");
  *parseerror = 1;

  /* Gather keys if we're doing percent expansion. */
  if (percent) {
    for (num_keys = 0; num_keys < EXPAND_MAX_KEYS; num_keys++) {
      keys[num_keys].key = va_arg(ap, char *);
      if (keys[num_keys].key == NULL)
        break;
      keys[num_keys].repl = va_arg(ap, char *);
      if (keys[num_keys].repl == NULL) {
        fatal_f("NULL replacement for token %s",
            keys[num_keys].key);
      }
    }
    if (num_keys == EXPAND_MAX_KEYS && va_arg(ap, char *) != NULL)
      fatal_f("too many keys");
    if (num_keys == 0)
      fatal_f("percent expansion without token list");
  }

  /* Expand string */
  for (i = 0; *string != '\0'; string++) {
    /* Optionally process ${ENVIRONMENT} expansions. */
    if (dollar && string[0] == '$' && string[1] == '{') {
      string += 2;  /* skip over '${' */
      if ((varend = strchr(string, '}')) == NULL) {
        error_f("environment variable '%s' missing "
            "closing '}'", string);
        goto out;
      }
      len = varend - string;
      if (len == 0) {
        error_f("zero-length environment variable");
        goto out;
      }
      var = xmalloc(len + 1);
      (void)strlcpy(var, string, len + 1);
      if ((val = getenv(var)) == NULL) {
        error_f("env var ${%s} has no value", var);
        missingvar = 1;
      } else {
        debug3_f("expand ${%s} -> '%s'", var, val);
        if ((r = sshbuf_put(buf, val, strlen(val))) !=0)
          fatal_fr(r, "sshbuf_put ${}");
      }
      free(var);
      string += len;
      continue;
    }

    /*
     * Process percent expansions if we have a list of TOKENs.
     * If we're not doing percent expansion everything just gets
     * appended here.
     */
    if (*string != '%' || !percent) {
 append:
      if ((r = sshbuf_put_u8(buf, *string)) != 0)
        fatal_fr(r, "sshbuf_put_u8 %%");
      continue;
    }
    string++;
    /* %% case */
    if (*string == '%')
      goto append;
    if (*string == '\0') {
      error_f("invalid format");
      goto out;
    }
    for (i = 0; i < num_keys; i++) {
      if (strchr(keys[i].key, *string) != NULL) {
        if ((r = sshbuf_put(buf, keys[i].repl,
            strlen(keys[i].repl))) != 0)
          fatal_fr(r, "sshbuf_put %%-repl");
        break;
      }
    }
    if (i >= num_keys) {
      error_f("unknown key %%%c", *string);
      goto out;
    }
  }
  if (!missingvar && (ret = sshbuf_dup_string(buf)) == NULL)
    fatal_f("sshbuf_dup_string failed");
  *parseerror = 0;
 out:
  sshbuf_free(buf);
  return *parseerror ? NULL : ret;
#undef EXPAND_MAX_KEYS
}

/*
 * Expand only environment variables.
 * Note that although this function is variadic like the other similar
 * functions, any such arguments will be unused.
 */

char *
dollar_expand(int *parseerr, const char *string, ...)
{
  char *ret;
  int err;
  va_list ap;

  va_start(ap, string);
  ret = vdollar_percent_expand(&err, 1, 0, string, ap);
  va_end(ap);
  if (parseerr != NULL)
    *parseerr = err;
  return ret;
}

/*
 * Returns expanded string or NULL if a specified environment variable is
 * not defined, or calls fatal if the string is invalid.
 */
char *
percent_expand(const char *string, ...)
{
  char *ret;
  int err;
  va_list ap;

  va_start(ap, string);
  ret = vdollar_percent_expand(&err, 0, 1, string, ap);
  va_end(ap);
  if (err)
    fatal_f("failed");
  return ret;
}

/*
 * Returns expanded string or NULL if a specified environment variable is
 * not defined, or calls fatal if the string is invalid.
 */
char *
percent_dollar_expand(const char *string, ...)
{
  char *ret;
  int err;
  va_list ap;

  va_start(ap, string);
  ret = vdollar_percent_expand(&err, 1, 1, string, ap);
  va_end(ap);
  if (err)
    fatal_f("failed");
  return ret;
}

int
tun_open(int tun, int mode, char **ifname)
{
#if defined(CUSTOM_SYS_TUN_OPEN)
  return (sys_tun_open(tun, mode, ifname));
#elif defined(SSH_TUN_OPENBSD)
  struct ifreq ifr;
  char name[100];
  int fd = -1, sock;
  const char *tunbase = "tun";

  if (ifname != NULL)
    *ifname = NULL;

  if (mode == SSH_TUNMODE_ETHERNET)
    tunbase = "tap";

  /* Open the tunnel device */
  if (tun <= SSH_TUNID_MAX) {
    snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
    fd = open(name, O_RDWR);
  } else if (tun == SSH_TUNID_ANY) {
    for (tun = 100; tun >= 0; tun--) {
      snprintf(name, sizeof(name), "/dev/%s%d",
          tunbase, tun);
      if ((fd = open(name, O_RDWR)) >= 0)
        break;
    }
  } else {
    debug_f("invalid tunnel %u", tun);
    return -1;
  }

  if (fd == -1) {
    debug_f("%s open: %s", name, strerror(errno));
    return -1;
  }

  debug_f("%s mode %d fd %d", name, mode, fd);

  /* Bring interface up if it is not already */
  snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
  if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
    goto failed;

  if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1) {
    debug_f("get interface %s flags: %s", ifr.ifr_name,
        strerror(errno));
    goto failed;
  }

  if (!(ifr.ifr_flags & IFF_UP)) {
    ifr.ifr_flags |= IFF_UP;
    if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1) {
      debug_f("activate interface %s: %s", ifr.ifr_name,
          strerror(errno));
      goto failed;
    }
  }

  if (ifname != NULL)
    *ifname = xstrdup(ifr.ifr_name);

  close(sock);
  return fd;

 failed:
  if (fd >= 0)
    close(fd);
  if (sock >= 0)
    close(sock);
  return -1;
#else
  error("Tunnel interfaces are not supported on this platform");
  return (-1);
#endif
}

void
sanitise_stdfd(void)
{
  int nullfd, dupfd;

  if ((nullfd = dupfd = open(_PATH_DEVNULL, O_RDWR)) == -1) {
    fprintf(stderr, "Couldn't open /dev/null: %s\n",
        strerror(errno));
    exit(1);
  }
  while (++dupfd <= STDERR_FILENO) {
    /* Only populate closed fds. */
    if (fcntl(dupfd, F_GETFL) == -1 && errno == EBADF) {
      if (dup2(nullfd, dupfd) == -1) {
        fprintf(stderr, "dup2: %s\n", strerror(errno));
        exit(1);
      }
    }
  }
  if (nullfd > STDERR_FILENO)
    close(nullfd);
}

char *
tohex(const void *vp, size_t l)
{
  const u_char *p = (const u_char *)vp;
  char b[3], *r;
  size_t i, hl;

  if (l > 65536)
    return xstrdup("tohex: length > 65536");

  hl = l * 2 + 1;
  r = xcalloc(1, hl);
  for (i = 0; i < l; i++) {
    snprintf(b, sizeof(b), "%02x", p[i]);
    strlcat(r, b, hl);
  }
  return (r);
}

/*
 * Extend string *sp by the specified format. If *sp is not NULL (or empty),
 * then the separator 'sep' will be prepended before the formatted arguments.
 * Extended strings are heap allocated.
 */
void
xextendf(char **sp, const char *sep, const char *fmt, ...)
{
  va_list ap;
  char *tmp1, *tmp2;

  va_start(ap, fmt);
  xvasprintf(&tmp1, fmt, ap);
  va_end(ap);

  if (*sp == NULL || **sp == '\0') {
    free(*sp);
    *sp = tmp1;
    return;
  }
  xasprintf(&tmp2, "%s%s%s", *sp, sep == NULL ? "" : sep, tmp1);
  free(tmp1);
  free(*sp);
  *sp = tmp2;
}


u_int64_t
get_u64(const void *vp)
{
  const u_char *p = (const u_char *)vp;
  u_int64_t v;

  v  = (u_int64_t)p[0] << 56;
  v |= (u_int64_t)p[1] << 48;
  v |= (u_int64_t)p[2] << 40;
  v |= (u_int64_t)p[3] << 32;
  v |= (u_int64_t)p[4] << 24;
  v |= (u_int64_t)p[5] << 16;
  v |= (u_int64_t)p[6] << 8;
  v |= (u_int64_t)p[7];

  return (v);
}

u_int32_t
get_u32(const void *vp)
{
  const u_char *p = (const u_char *)vp;
  u_int32_t v;

  v  = (u_int32_t)p[0] << 24;
  v |= (u_int32_t)p[1] << 16;
  v |= (u_int32_t)p[2] << 8;
  v |= (u_int32_t)p[3];

  return (v);
}

u_int32_t
get_u32_le(const void *vp)
{
  const u_char *p = (const u_char *)vp;
  u_int32_t v;

  v  = (u_int32_t)p[0];
  v |= (u_int32_t)p[1] << 8;
  v |= (u_int32_t)p[2] << 16;
  v |= (u_int32_t)p[3] << 24;

  return (v);
}

u_int16_t
get_u16(const void *vp)
{
  const u_char *p = (const u_char *)vp;
  u_int16_t v;

  v  = (u_int16_t)p[0] << 8;
  v |= (u_int16_t)p[1];

  return (v);
}

void
put_u64(void *vp, u_int64_t v)
{
  u_char *p = (u_char *)vp;

  p[0] = (u_char)(v >> 56) & 0xff;
  p[1] = (u_char)(v >> 48) & 0xff;
  p[2] = (u_char)(v >> 40) & 0xff;
  p[3] = (u_char)(v >> 32) & 0xff;
  p[4] = (u_char)(v >> 24) & 0xff;
  p[5] = (u_char)(v >> 16) & 0xff;
  p[6] = (u_char)(v >> 8) & 0xff;
  p[7] = (u_char)v & 0xff;
}

void
put_u32(void *vp, u_int32_t v)
{
  u_char *p = (u_char *)vp;

  p[0] = (u_char)(v >> 24) & 0xff;
  p[1] = (u_char)(v >> 16) & 0xff;
  p[2] = (u_char)(v >> 8) & 0xff;
  p[3] = (u_char)v & 0xff;
}

void
put_u32_le(void *vp, u_int32_t v)
{
  u_char *p = (u_char *)vp;

  p[0] = (u_char)v & 0xff;
  p[1] = (u_char)(v >> 8) & 0xff;
  p[2] = (u_char)(v >> 16) & 0xff;
  p[3] = (u_char)(v >> 24) & 0xff;
}

void
put_u16(void *vp, u_int16_t v)
{
  u_char *p = (u_char *)vp;

  p[0] = (u_char)(v >> 8) & 0xff;
  p[1] = (u_char)v & 0xff;
}

void
ms_subtract_diff(struct timeval *start, int *ms)
{
  struct timeval diff, finish;

  monotime_tv(&finish);
  timersub(&finish, start, &diff);
  *ms -= (diff.tv_sec * 1000) + (diff.tv_usec / 1000);
}

void
ms_to_timespec(struct timespec *ts, int ms)
{
  if (ms < 0)
    ms = 0;
  ts->tv_sec = ms / 1000;
  ts->tv_nsec = (ms % 1000) * 1000 * 1000;
}

void
monotime_ts(struct timespec *ts)
{
  struct timeval tv;
#if defined(HAVE_CLOCK_GETTIME) && (defined(CLOCK_BOOTTIME) || \
    defined(CLOCK_MONOTONIC) || defined(CLOCK_REALTIME))
  static int gettime_failed = 0;

  if (!gettime_failed) {
# ifdef CLOCK_BOOTTIME
    if (clock_gettime(CLOCK_BOOTTIME, ts) == 0)
      return;
# endif /* CLOCK_BOOTTIME */
# ifdef CLOCK_MONOTONIC
    if (clock_gettime(CLOCK_MONOTONIC, ts) == 0)
      return;
# endif /* CLOCK_MONOTONIC */
# ifdef CLOCK_REALTIME
    /* Not monotonic, but we're almost out of options here. */
    if (clock_gettime(CLOCK_REALTIME, ts) == 0)
      return;
# endif /* CLOCK_REALTIME */
    debug3("clock_gettime: %s", strerror(errno));
    gettime_failed = 1;
  }
#endif /* HAVE_CLOCK_GETTIME && (BOOTTIME || MONOTONIC || REALTIME) */
  gettimeofday(&tv, NULL);
  ts->tv_sec = tv.tv_sec;
  ts->tv_nsec = (long)tv.tv_usec * 1000;
}

void
monotime_tv(struct timeval *tv)
{
  struct timespec ts;

  monotime_ts(&ts);
  tv->tv_sec = ts.tv_sec;
  tv->tv_usec = ts.tv_nsec / 1000;
}

time_t
monotime(void)
{
  struct timespec ts;

  monotime_ts(&ts);
  return ts.tv_sec;
}

double
monotime_double(void)
{
  struct timespec ts;

  monotime_ts(&ts);
  return ts.tv_sec + ((double)ts.tv_nsec / 1000000000);
}

void
bandwidth_limit_init(struct bwlimit *bw, u_int64_t kbps, size_t buflen)
{
  bw->buflen = buflen;
  bw->rate = kbps;
  bw->thresh = buflen;
  bw->lamt = 0;
  timerclear(&bw->bwstart);
  timerclear(&bw->bwend);
}

/* Callback from read/write loop to insert bandwidth-limiting delays */
void
bandwidth_limit(struct bwlimit *bw, size_t read_len)
{
  u_int64_t waitlen;
  struct timespec ts, rm;

  bw->lamt += read_len;
  if (!timerisset(&bw->bwstart)) {
    monotime_tv(&bw->bwstart);
    return;
  }
  if (bw->lamt < bw->thresh)
    return;

  monotime_tv(&bw->bwend);
  timersub(&bw->bwend, &bw->bwstart, &bw->bwend);
  if (!timerisset(&bw->bwend))
    return;

  bw->lamt *= 8;
  waitlen = (double)1000000L * bw->lamt / bw->rate;

  bw->bwstart.tv_sec = waitlen / 1000000L;
  bw->bwstart.tv_usec = waitlen % 1000000L;

  if (timercmp(&bw->bwstart, &bw->bwend, >)) {
    timersub(&bw->bwstart, &bw->bwend, &bw->bwend);

    /* Adjust the wait time */
    if (bw->bwend.tv_sec) {
      bw->thresh /= 2;
      if (bw->thresh < bw->buflen / 4)
        bw->thresh = bw->buflen / 4;
    } else if (bw->bwend.tv_usec < 10000) {
      bw->thresh *= 2;
      if (bw->thresh > bw->buflen * 8)
        bw->thresh = bw->buflen * 8;
    }

    TIMEVAL_TO_TIMESPEC(&bw->bwend, &ts);
    while (nanosleep(&ts, &rm) == -1) {
      if (errno != EINTR)
        break;
      ts = rm;
    }
  }

  bw->lamt = 0;
  monotime_tv(&bw->bwstart);
}

/* Make a template filename for mk[sd]temp() */
void
mktemp_proto(char *s, size_t len)
{
  const char *tmpdir;
  int r;

  if ((tmpdir = getenv("TMPDIR")) != NULL) {
    r = snprintf(s, len, "%s/ssh-XXXXXXXXXXXX", tmpdir);
    if (r > 0 && (size_t)r < len)
      return;
  }
  r = snprintf(s, len, "/tmp/ssh-XXXXXXXXXXXX");
  if (r < 0 || (size_t)r >= len)
    fatal_f("template string too short");
}

static const struct {
  const char *name;
  int value;
} ipqos[] = {
  { "none", INT_MAX },    /* can't use 0 here; that's CS0 */
  { "af11", IPTOS_DSCP_AF11 },
  { "af12", IPTOS_DSCP_AF12 },
  { "af13", IPTOS_DSCP_AF13 },
  { "af21", IPTOS_DSCP_AF21 },
  { "af22", IPTOS_DSCP_AF22 },
  { "af23", IPTOS_DSCP_AF23 },
  { "af31", IPTOS_DSCP_AF31 },
  { "af32", IPTOS_DSCP_AF32 },
  { "af33", IPTOS_DSCP_AF33 },
  { "af41", IPTOS_DSCP_AF41 },
  { "af42", IPTOS_DSCP_AF42 },
  { "af43", IPTOS_DSCP_AF43 },
  { "cs0", IPTOS_DSCP_CS0 },
  { "cs1", IPTOS_DSCP_CS1 },
  { "cs2", IPTOS_DSCP_CS2 },
  { "cs3", IPTOS_DSCP_CS3 },
  { "cs4", IPTOS_DSCP_CS4 },
  { "cs5", IPTOS_DSCP_CS5 },
  { "cs6", IPTOS_DSCP_CS6 },
  { "cs7", IPTOS_DSCP_CS7 },
  { "ef", IPTOS_DSCP_EF },
  { "le", IPTOS_DSCP_LE },
  { "lowdelay", IPTOS_LOWDELAY },
  { "throughput", IPTOS_THROUGHPUT },
  { "reliability", IPTOS_RELIABILITY },
  { NULL, -1 }
};

int
parse_ipqos(const char *cp)
{
  u_int i;
  char *ep;
  long val;

  if (cp == NULL)
    return -1;
  for (i = 0; ipqos[i].name != NULL; i++) {
    if (strcasecmp(cp, ipqos[i].name) == 0)
      return ipqos[i].value;
  }
  /* Try parsing as an integer */
  val = strtol(cp, &ep, 0);
  if (*cp == '\0' || *ep != '\0' || val < 0 || val > 255)
    return -1;
  return val;
}

const char *
iptos2str(int iptos)
{
  int i;
  static char iptos_str[sizeof "0xff"];

  for (i = 0; ipqos[i].name != NULL; i++) {
    if (ipqos[i].value == iptos)
      return ipqos[i].name;
  }
  snprintf(iptos_str, sizeof iptos_str, "0x%02x", iptos);
  return iptos_str;
}

void
lowercase(char *s)
{
  for (; *s; s++)
    *s = tolower((u_char)*s);
}

int
unix_listener(const char *path, int backlog, int unlink_first)
{
  struct sockaddr_un sunaddr;
  int saved_errno, sock;

  memset(&sunaddr, 0, sizeof(sunaddr));
  sunaddr.sun_family = AF_UNIX;
  if (strlcpy(sunaddr.sun_path, path,
      sizeof(sunaddr.sun_path)) >= sizeof(sunaddr.sun_path)) {
    error_f("path \"%s\" too long for Unix domain socket", path);
    errno = ENAMETOOLONG;
    return -1;
  }

  sock = socket(PF_UNIX, SOCK_STREAM, 0);
  if (sock == -1) {
    saved_errno = errno;
    error_f("socket: %.100s", strerror(errno));
    errno = saved_errno;
    return -1;
  }
  if (unlink_first == 1) {
    if (unlink(path) != 0 && errno != ENOENT)
      error("unlink(%s): %.100s", path, strerror(errno));
  }
  if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1) {
    saved_errno = errno;
    error_f("cannot bind to path %s: %s", path, strerror(errno));
    close(sock);
    errno = saved_errno;
    return -1;
  }
  if (listen(sock, backlog) == -1) {
    saved_errno = errno;
    error_f("cannot listen on path %s: %s", path, strerror(errno));
    close(sock);
    unlink(path);
    errno = saved_errno;
    return -1;
  }
  return sock;
}

void
sock_set_v6only(int s)
{
#if defined(IPV6_V6ONLY) && !defined(__OpenBSD__)
  int on = 1;

  debug3("%s: set socket %d IPV6_V6ONLY", __func__, s);
  if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) == -1)
    error("setsockopt IPV6_V6ONLY: %s", strerror(errno));
#endif
}

/*
 * Compares two strings that maybe be NULL. Returns non-zero if strings
 * are both NULL or are identical, returns zero otherwise.
 */
static int
strcmp_maybe_null(const char *a, const char *b)
{
  if ((a == NULL && b != NULL) || (a != NULL && b == NULL))
    return 0;
  if (a != NULL && strcmp(a, b) != 0)
    return 0;
  return 1;
}

/*
 * Compare two forwards, returning non-zero if they are identical or
 * zero otherwise.
 */
int
forward_equals(const struct Forward *a, const struct Forward *b)
{
  if (strcmp_maybe_null(a->listen_host, b->listen_host) == 0)
    return 0;
  if (a->listen_port != b->listen_port)
    return 0;
  if (strcmp_maybe_null(a->listen_path, b->listen_path) == 0)
    return 0;
  if (strcmp_maybe_null(a->connect_host, b->connect_host) == 0)
    return 0;
  if (a->connect_port != b->connect_port)
    return 0;
  if (strcmp_maybe_null(a->connect_path, b->connect_path) == 0)
    return 0;
  /* allocated_port and handle are not checked */
  return 1;
}

/* returns 1 if process is already daemonized, 0 otherwise */
int
daemonized(void)
{
  int fd;

  if ((fd = open(_PATH_TTY, O_RDONLY | O_NOCTTY)) >= 0) {
    close(fd);
    return 0; /* have controlling terminal */
  }
  if (getppid() != 1)
    return 0; /* parent is not init */
  if (getsid(0) != getpid())
    return 0; /* not session leader */
  debug3("already daemonized");
  return 1;
}

/*
 * Splits 's' into an argument vector. Handles quoted string and basic
 * escape characters (\\, \", \'). Caller must free the argument vector
 * and its members.
 */
int
argv_split(const char *s, int *argcp, char ***argvp, int terminate_on_comment)
{
  int r = SSH_ERR_INTERNAL_ERROR;
  int argc = 0, quote, i, j;
  char *arg, **argv = xcalloc(1, sizeof(*argv));

  *argvp = NULL;
  *argcp = 0;

  for (i = 0; s[i] != '\0'; i++) {
    /* Skip leading whitespace */
    if (s[i] == ' ' || s[i] == '\t')
      continue;
    if (terminate_on_comment && s[i] == '#')
      break;
    /* Start of a token */
    quote = 0;

    argv = xreallocarray(argv, (argc + 2), sizeof(*argv));
    arg = argv[argc++] = xcalloc(1, strlen(s + i) + 1);
    argv[argc] = NULL;

    /* Copy the token in, removing escapes */
    for (j = 0; s[i] != '\0'; i++) {
      if (s[i] == '\\') {
        if (s[i + 1] == '\'' ||
            s[i + 1] == '\"' ||
            s[i + 1] == '\\' ||
            (quote == 0 && s[i + 1] == ' ')) {
          i++; /* Skip '\' */
          arg[j++] = s[i];
        } else {
          /* Unrecognised escape */
          arg[j++] = s[i];
        }
      } else if (quote == 0 && (s[i] == ' ' || s[i] == '\t'))
        break; /* done */
      else if (quote == 0 && (s[i] == '\"' || s[i] == '\''))
        quote = s[i]; /* quote start */
      else if (quote != 0 && s[i] == quote)
        quote = 0; /* quote end */
      else
        arg[j++] = s[i];
    }
    if (s[i] == '\0') {
      if (quote != 0) {
        /* Ran out of string looking for close quote */
        r = SSH_ERR_INVALID_FORMAT;
        goto out;
      }
      break;
    }
  }
  /* Success */
  *argcp = argc;
  *argvp = argv;
  argc = 0;
  argv = NULL;
  r = 0;
 out:
  if (argc != 0 && argv != NULL) {
    for (i = 0; i < argc; i++)
      free(argv[i]);
    free(argv);
  }
  return r;
}

/*
 * Reassemble an argument vector into a string, quoting and escaping as
 * necessary. Caller must free returned string.
 */
char *
argv_assemble(int argc, char **argv)
{
  int i, j, ws, r;
  char c, *ret;
  struct sshbuf *buf, *arg;

  if ((buf = sshbuf_new()) == NULL || (arg = sshbuf_new()) == NULL)
    fatal_f("sshbuf_new failed");

  for (i = 0; i < argc; i++) {
    ws = 0;
    sshbuf_reset(arg);
    for (j = 0; argv[i][j] != '\0'; j++) {
      r = 0;
      c = argv[i][j];
      switch (c) {
      case ' ':
      case '\t':
        ws = 1;
        r = sshbuf_put_u8(arg, c);
        break;
      case '\\':
      case '\'':
      case '"':
        if ((r = sshbuf_put_u8(arg, '\\')) != 0)
          break;
        /* FALLTHROUGH */
      default:
        r = sshbuf_put_u8(arg, c);
        break;
      }
      if (r != 0)
        fatal_fr(r, "sshbuf_put_u8");
    }
    if ((i != 0 && (r = sshbuf_put_u8(buf, ' ')) != 0) ||
        (ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0) ||
        (r = sshbuf_putb(buf, arg)) != 0 ||
        (ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0))
      fatal_fr(r, "assemble");
  }
  if ((ret = malloc(sshbuf_len(buf) + 1)) == NULL)
    fatal_f("malloc failed");
  memcpy(ret, sshbuf_ptr(buf), sshbuf_len(buf));
  ret[sshbuf_len(buf)] = '\0';
  sshbuf_free(buf);
  sshbuf_free(arg);
  return ret;
}

char *
argv_next(int *argcp, char ***argvp)
{
  char *ret = (*argvp)[0];

  if (*argcp > 0 && ret != NULL) {
    (*argcp)--;
    (*argvp)++;
  }
  return ret;
}

void
argv_consume(int *argcp)
{
  *argcp = 0;
}

void
argv_free(char **av, int ac)
{
  int i;

  if (av == NULL)
    return;
  for (i = 0; i < ac; i++)
    free(av[i]);
  free(av);
}

/* Returns 0 if pid exited cleanly, non-zero otherwise */
int
exited_cleanly(pid_t pid, const char *tag, const char *cmd, int quiet)
{
  int status;

  while (waitpid(pid, &status, 0) == -1) {
    if (errno != EINTR) {
      error("%s waitpid: %s", tag, strerror(errno));
      return -1;
    }
  }
  if (WIFSIGNALED(status)) {
    error("%s %s exited on signal %d", tag, cmd, WTERMSIG(status));
    return -1;
  } else if (WEXITSTATUS(status) != 0) {
    do_log2(quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_INFO,
        "%s %s failed, status %d", tag, cmd, WEXITSTATUS(status));
    return -1;
  }
  return 0;
}

/*
 * Check a given path for security. This is defined as all components
 * of the path to the file must be owned by either the owner of
 * of the file or root and no directories must be group or world writable.
 *
 * XXX Should any specific check be done for sym links ?
 *
 * Takes a file name, its stat information (preferably from fstat() to
 * avoid races), the uid of the expected owner, their home directory and an
 * error buffer plus max size as arguments.
 *
 * Returns 0 on success and -1 on failure
 */
int
safe_path(const char *name, struct stat *stp, const char *pw_dir,
    uid_t uid, char *err, size_t errlen)
{
  char buf[PATH_MAX], homedir[PATH_MAX];
  char *cp;
  int comparehome = 0;
  struct stat st;

  if (realpath(name, buf) == NULL) {
    snprintf(err, errlen, "realpath %s failed: %s", name,
        strerror(errno));
    return -1;
  }
  if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
    comparehome = 1;

  if (!S_ISREG(stp->st_mode)) {
    snprintf(err, errlen, "%s is not a regular file", buf);
    return -1;
  }
  if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
      (stp->st_mode & 022) != 0) {
    snprintf(err, errlen, "bad ownership or modes for file %s",
        buf);
    return -1;
  }

  /* for each component of the canonical path, walking upwards */
  for (;;) {
    if ((cp = dirname(buf)) == NULL) {
      snprintf(err, errlen, "dirname() failed");
      return -1;
    }
    strlcpy(buf, cp, sizeof(buf));

    if (stat(buf, &st) == -1 ||
        (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
        (st.st_mode & 022) != 0) {
      snprintf(err, errlen,
          "bad ownership or modes for directory %s", buf);
      return -1;
    }

    /* If are past the homedir then we can stop */
    if (comparehome && strcmp(homedir, buf) == 0)
      break;

    /*
     * dirname should always complete with a "/" path,
     * but we can be paranoid and check for "." too
     */
    if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
      break;
  }
  return 0;
}

/*
 * Version of safe_path() that accepts an open file descriptor to
 * avoid races.
 *
 * Returns 0 on success and -1 on failure
 */
int
safe_path_fd(int fd, const char *file, struct passwd *pw,
    char *err, size_t errlen)
{
  struct stat st;

  /* check the open file to avoid races */
  if (fstat(fd, &st) == -1) {
    snprintf(err, errlen, "cannot stat file %s: %s",
        file, strerror(errno));
    return -1;
  }
  return safe_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
}

/*
 * Sets the value of the given variable in the environment.  If the variable
 * already exists, its value is overridden.
 */
void
child_set_env(char ***envp, u_int *envsizep, const char *name,
  const char *value)
{
  char **env;
  u_int envsize;
  u_int i, namelen;

  if (strchr(name, '=') != NULL) {
    error("Invalid environment variable \"%.100s\"", name);
    return;
  }

  /*
   * If we're passed an uninitialized list, allocate a single null
   * entry before continuing.
   */
  if ((*envp == NULL) != (*envsizep == 0))
    fatal_f("environment size mismatch");
  if (*envp == NULL && *envsizep == 0) {
    *envp = xmalloc(sizeof(char *));
    *envp[0] = NULL;
    *envsizep = 1;
  }

  /*
   * Find the slot where the value should be stored.  If the variable
   * already exists, we reuse the slot; otherwise we append a new slot
   * at the end of the array, expanding if necessary.
   */
  env = *envp;
  namelen = strlen(name);
  for (i = 0; env[i]; i++)
    if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
      break;
  if (env[i]) {
    /* Reuse the slot. */
    free(env[i]);
  } else {
    /* New variable.  Expand if necessary. */
    envsize = *envsizep;
    if (i >= envsize - 1) {
      if (envsize >= 1000)
        fatal("child_set_env: too many env vars");
      envsize += 50;
      env = (*envp) = xreallocarray(env, envsize, sizeof(char *));
      *envsizep = envsize;
    }
    /* Need to set the NULL pointer at end of array beyond the new slot. */
    env[i + 1] = NULL;
  }

  /* Allocate space and format the variable in the appropriate slot. */
  /* XXX xasprintf */
  env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
  snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
}

/*
 * Check and optionally lowercase a domain name, also removes trailing '.'
 * Returns 1 on success and 0 on failure, storing an error message in errstr.
 */
int
valid_domain(char *name, int makelower, const char **errstr)
{
  size_t i, l = strlen(name);
  u_char c, last = '\0';
  static char errbuf[256];

  if (l == 0) {
    strlcpy(errbuf, "empty domain name", sizeof(errbuf));
    goto bad;
  }
  if (!isalpha((u_char)name[0]) && !isdigit((u_char)name[0])) {
    snprintf(errbuf, sizeof(errbuf), "domain name \"%.100s\" "
        "starts with invalid character", name);
    goto bad;
  }
  for (i = 0; i < l; i++) {
    c = tolower((u_char)name[i]);
    if (makelower)
      name[i] = (char)c;
    if (last == '.' && c == '.') {
      snprintf(errbuf, sizeof(errbuf), "domain name "
          "\"%.100s\" contains consecutive separators", name);
      goto bad;
    }
    if (c != '.' && c != '-' && !isalnum(c) &&
        c != '_') /* technically invalid, but common */ {
      snprintf(errbuf, sizeof(errbuf), "domain name "
          "\"%.100s\" contains invalid characters", name);
      goto bad;
    }
    last = c;
  }
  if (name[l - 1] == '.')
    name[l - 1] = '\0';
  if (errstr != NULL)
    *errstr = NULL;
  return 1;
bad:
  if (errstr != NULL)
    *errstr = errbuf;
  return 0;
}

/*
 * Verify that a environment variable name (not including initial '$') is
 * valid; consisting of one or more alphanumeric or underscore characters only.
 * Returns 1 on valid, 0 otherwise.
 */
int
valid_env_name(const char *name)
{
  const char *cp;

  if (name[0] == '\0')
    return 0;
  for (cp = name; *cp != '\0'; cp++) {
    if (!isalnum((u_char)*cp) && *cp != '_')
      return 0;
  }
  return 1;
}

const char *
atoi_err(const char *nptr, int *val)
{
  const char *errstr = NULL;
  long long num;

  if (nptr == NULL || *nptr == '\0')
    return "missing";
  num = strtonum(nptr, 0, INT_MAX, &errstr);
  if (errstr == NULL)
    *val = (int)num;
  return errstr;
}

int
parse_absolute_time(const char *s, uint64_t *tp)
{
  struct tm tm;
  time_t tt;
  char buf[32], *fmt;
  const char *cp;
  size_t l;
  int is_utc = 0;

  *tp = 0;

  l = strlen(s);
  if (l > 1 && strcasecmp(s + l - 1, "Z") == 0) {
    is_utc = 1;
    l--;
  } else if (l > 3 && strcasecmp(s + l - 3, "UTC") == 0) {
    is_utc = 1;
    l -= 3;
  }
  /*
   * POSIX strptime says "The application shall ensure that there
   * is white-space or other non-alphanumeric characters between
   * any two conversion specifications" so arrange things this way.
   */
  switch (l) {
  case 8: /* YYYYMMDD */
    fmt = "%Y-%m-%d";
    snprintf(buf, sizeof(buf), "%.4s-%.2s-%.2s", s, s + 4, s + 6);
    break;
  case 12: /* YYYYMMDDHHMM */
    fmt = "%Y-%m-%dT%H:%M";
    snprintf(buf, sizeof(buf), "%.4s-%.2s-%.2sT%.2s:%.2s",
        s, s + 4, s + 6, s + 8, s + 10);
    break;
  case 14: /* YYYYMMDDHHMMSS */
    fmt = "%Y-%m-%dT%H:%M:%S";
    snprintf(buf, sizeof(buf), "%.4s-%.2s-%.2sT%.2s:%.2s:%.2s",
        s, s + 4, s + 6, s + 8, s + 10, s + 12);
    break;
  default:
    return SSH_ERR_INVALID_FORMAT;
  }

  memset(&tm, 0, sizeof(tm));
  if ((cp = strptime(buf, fmt, &tm)) == NULL || *cp != '\0')
    return SSH_ERR_INVALID_FORMAT;
  if (is_utc) {
    if ((tt = timegm(&tm)) < 0)
      return SSH_ERR_INVALID_FORMAT;
  } else {
    if ((tt = mktime(&tm)) < 0)
      return SSH_ERR_INVALID_FORMAT;
  }
  /* success */
  *tp = (uint64_t)tt;
  return 0;
}

void
format_absolute_time(uint64_t t, char *buf, size_t len)
{
  time_t tt = t > SSH_TIME_T_MAX ? SSH_TIME_T_MAX : t;
  struct tm tm;

  localtime_r(&tt, &tm);
  strftime(buf, len, "%Y-%m-%dT%H:%M:%S", &tm);
}

/* check if path is absolute */
int
path_absolute(const char *path)
{
  return (*path == '/') ? 1 : 0;
}

void
skip_space(char **cpp)
{
  char *cp;

  for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
    ;
  *cpp = cp;
}

/* authorized_key-style options parsing helpers */

/*
 * Match flag 'opt' in *optsp, and if allow_negate is set then also match
 * 'no-opt'. Returns -1 if option not matched, 1 if option matches or 0
 * if negated option matches.
 * If the option or negated option matches, then *optsp is updated to
 * point to the first character after the option.
 */
int
opt_flag(const char *opt, int allow_negate, const char **optsp)
{
  size_t opt_len = strlen(opt);
  const char *opts = *optsp;
  int negate = 0;

  if (allow_negate && strncasecmp(opts, "no-", 3) == 0) {
    opts += 3;
    negate = 1;
  }
  if (strncasecmp(opts, opt, opt_len) == 0) {
    *optsp = opts + opt_len;
    return negate ? 0 : 1;
  }
  return -1;
}

char *
opt_dequote(const char **sp, const char **errstrp)
{
  const char *s = *sp;
  char *ret;
  size_t i;

  *errstrp = NULL;
  if (*s != '"') {
    *errstrp = "missing start quote";
    return NULL;
  }
  s++;
  if ((ret = malloc(strlen((s)) + 1)) == NULL) {
    *errstrp = "memory allocation failed";
    return NULL;
  }
  for (i = 0; *s != '\0' && *s != '"';) {
    if (s[0] == '\\' && s[1] == '"')
      s++;
    ret[i++] = *s++;
  }
  if (*s == '\0') {
    *errstrp = "missing end quote";
    free(ret);
    return NULL;
  }
  ret[i] = '\0';
  s++;
  *sp = s;
  return ret;
}

int
opt_match(const char **opts, const char *term)
{
  if (strncasecmp((*opts), term, strlen(term)) == 0 &&
      (*opts)[strlen(term)] == '=') {
    *opts += strlen(term) + 1;
    return 1;
  }
  return 0;
}

void
opt_array_append2(const char *file, const int line, const char *directive,
    char ***array, int **iarray, u_int *lp, const char *s, int i)
{

  if (*lp >= INT_MAX)
    fatal("%s line %d: Too many %s entries", file, line, directive);

  if (iarray != NULL) {
    *iarray = xrecallocarray(*iarray, *lp, *lp + 1,
        sizeof(**iarray));
    (*iarray)[*lp] = i;
  }

  *array = xrecallocarray(*array, *lp, *lp + 1, sizeof(**array));
  (*array)[*lp] = xstrdup(s);
  (*lp)++;
}

void
opt_array_append(const char *file, const int line, const char *directive,
    char ***array, u_int *lp, const char *s)
{
  opt_array_append2(file, line, directive, array, NULL, lp, s, 0);
}

sshsig_t
ssh_signal(int signum, sshsig_t handler)
{
  struct sigaction sa, osa;

  /* mask all other signals while in handler */
  memset(&sa, 0, sizeof(sa));
  sa.sa_handler = handler;
  sigfillset(&sa.sa_mask);
#if defined(SA_RESTART) && !defined(NO_SA_RESTART)
  if (signum != SIGALRM)
    sa.sa_flags = SA_RESTART;
#endif
  if (sigaction(signum, &sa, &osa) == -1) {
    debug3("sigaction(%s): %s", strsignal(signum), strerror(errno));
    return SIG_ERR;
  }
  return osa.sa_handler;
}

int
stdfd_devnull(int do_stdin, int do_stdout, int do_stderr)
{
  int devnull, ret = 0;

  if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
    error_f("open %s: %s", _PATH_DEVNULL,
        strerror(errno));
    return -1;
  }
  if ((do_stdin && dup2(devnull, STDIN_FILENO) == -1) ||
      (do_stdout && dup2(devnull, STDOUT_FILENO) == -1) ||
      (do_stderr && dup2(devnull, STDERR_FILENO) == -1)) {
    error_f("dup2: %s", strerror(errno));
    ret = -1;
  }
  if (devnull > STDERR_FILENO)
    close(devnull);
  return ret;
}

/*
 * Runs command in a subprocess with a minimal environment.
 * Returns pid on success, 0 on failure.
 * The child stdout and stderr maybe captured, left attached or sent to
 * /dev/null depending on the contents of flags.
 * "tag" is prepended to log messages.
 * NB. "command" is only used for logging; the actual command executed is
 * av[0].
 */
pid_t
subprocess(const char *tag, const char *command,
    int ac, char **av, FILE **child, u_int flags,
    struct passwd *pw, privdrop_fn *drop_privs, privrestore_fn *restore_privs)
{
  FILE *f = NULL;
  struct stat st;
  int fd, devnull, p[2], i;
  pid_t pid;
  char *cp, errmsg[512];
  u_int nenv = 0;
  char **env = NULL;

  /* If dropping privs, then must specify user and restore function */
  if (drop_privs != NULL && (pw == NULL || restore_privs == NULL)) {
    error("%s: inconsistent arguments", tag); /* XXX fatal? */
    return 0;
  }
  if (pw == NULL && (pw = getpwuid(getuid())) == NULL) {
    error("%s: no user for current uid", tag);
    return 0;
  }
  if (child != NULL)
    *child = NULL;

  debug3_f("%s command \"%s\" running as %s (flags 0x%x)",
      tag, command, pw->pw_name, flags);

  /* Check consistency */
  if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
      (flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) {
    error_f("inconsistent flags");
    return 0;
  }
  if (((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) != (child == NULL)) {
    error_f("inconsistent flags/output");
    return 0;
  }

  /*
   * If executing an explicit binary, then verify the it exists
   * and appears safe-ish to execute
   */
  if (!path_absolute(av[0])) {
    error("%s path is not absolute", tag);
    return 0;
  }
  if (drop_privs != NULL)
    drop_privs(pw);
  if (stat(av[0], &st) == -1) {
    error("Could not stat %s \"%s\": %s", tag,
        av[0], strerror(errno));
    goto restore_return;
  }
  if ((flags & SSH_SUBPROCESS_UNSAFE_PATH) == 0 &&
      safe_path(av[0], &st, NULL, 0, errmsg, sizeof(errmsg)) != 0) {
    error("Unsafe %s \"%s\": %s", tag, av[0], errmsg);
    goto restore_return;
  }
  /* Prepare to keep the child's stdout if requested */
  if (pipe(p) == -1) {
    error("%s: pipe: %s", tag, strerror(errno));
 restore_return:
    if (restore_privs != NULL)
      restore_privs();
    return 0;
  }
  if (restore_privs != NULL)
    restore_privs();

  switch ((pid = fork())) {
  case -1: /* error */
    error("%s: fork: %s", tag, strerror(errno));
    close(p[0]);
    close(p[1]);
    return 0;
  case 0: /* child */
    /* Prepare a minimal environment for the child. */
    if ((flags & SSH_SUBPROCESS_PRESERVE_ENV) == 0) {
      nenv = 5;
      env = xcalloc(sizeof(*env), nenv);
      child_set_env(&env, &nenv, "PATH", _PATH_STDPATH);
      child_set_env(&env, &nenv, "USER", pw->pw_name);
      child_set_env(&env, &nenv, "LOGNAME", pw->pw_name);
      child_set_env(&env, &nenv, "HOME", pw->pw_dir);
      if ((cp = getenv("LANG")) != NULL)
        child_set_env(&env, &nenv, "LANG", cp);
    }

    for (i = 1; i < NSIG; i++)
      ssh_signal(i, SIG_DFL);

    if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
      error("%s: open %s: %s", tag, _PATH_DEVNULL,
          strerror(errno));
      _exit(1);
    }
    if (dup2(devnull, STDIN_FILENO) == -1) {
      error("%s: dup2: %s", tag, strerror(errno));
      _exit(1);
    }

    /* Set up stdout as requested; leave stderr in place for now. */
    fd = -1;
    if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0)
      fd = p[1];
    else if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0)
      fd = devnull;
    if (fd != -1 && dup2(fd, STDOUT_FILENO) == -1) {
      error("%s: dup2: %s", tag, strerror(errno));
      _exit(1);
    }
    closefrom(STDERR_FILENO + 1);

    if (geteuid() == 0 &&
        initgroups(pw->pw_name, pw->pw_gid) == -1) {
      error("%s: initgroups(%s, %u): %s", tag,
          pw->pw_name, (u_int)pw->pw_gid, strerror(errno));
      _exit(1);
    }
    if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1) {
      error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid,
          strerror(errno));
      _exit(1);
    }
    if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1) {
      error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid,
          strerror(errno));
      _exit(1);
    }
    /* stdin is pointed to /dev/null at this point */
    if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
        dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
      error("%s: dup2: %s", tag, strerror(errno));
      _exit(1);
    }
    if (env != NULL)
      execve(av[0], av, env);
    else
      execv(av[0], av);
    error("%s %s \"%s\": %s", tag, env == NULL ? "execv" : "execve",
        command, strerror(errno));
    _exit(127);
  default: /* parent */
    break;
  }

  close(p[1]);
  if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0)
    close(p[0]);
  else if ((f = fdopen(p[0], "r")) == NULL) {
    error("%s: fdopen: %s", tag, strerror(errno));
    close(p[0]);
    /* Don't leave zombie child */
    kill(pid, SIGTERM);
    while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
      ;
    return 0;
  }
  /* Success */
  debug3_f("%s pid %ld", tag, (long)pid);
  if (child != NULL)
    *child = f;
  return pid;
}

const char *
lookup_env_in_list(const char *env, char * const *envs, size_t nenvs)
{
  size_t i, envlen;

  envlen = strlen(env);
  for (i = 0; i < nenvs; i++) {
    if (strncmp(envs[i], env, envlen) == 0 &&
        envs[i][envlen] == '=') {
      return envs[i] + envlen + 1;
    }
  }
  return NULL;
}

const char *
lookup_setenv_in_list(const char *env, char * const *envs, size_t nenvs)
{
  char *name, *cp;
  const char *ret;

  name = xstrdup(env);
  if ((cp = strchr(name, '=')) == NULL) {
    free(name);
    return NULL; /* not env=val */
  }
  *cp = '\0';
  ret = lookup_env_in_list(name, envs, nenvs);
  free(name);
  return ret;
}

/*
 * Helpers for managing poll(2)/ppoll(2) timeouts
 * Will remember the earliest deadline and return it for use in poll/ppoll.
 */

/* Initialise a poll/ppoll timeout with an indefinite deadline */
void
ptimeout_init(struct timespec *pt)
{
  /*
   * Deliberately invalid for ppoll(2).
   * Will be converted to NULL in ptimeout_get_tspec() later.
   */
  pt->tv_sec = -1;
  pt->tv_nsec = 0;
}

/* Specify a poll/ppoll deadline of at most 'sec' seconds */
void
ptimeout_deadline_sec(struct timespec *pt, long sec)
{
  if (pt->tv_sec == -1 || pt->tv_sec >= sec) {
    pt->tv_sec = sec;
    pt->tv_nsec = 0;
  }
}

/* Specify a poll/ppoll deadline of at most 'p' (timespec) */
static void
ptimeout_deadline_tsp(struct timespec *pt, struct timespec *p)
{
  if (pt->tv_sec == -1 || timespeccmp(pt, p, >=))
    *pt = *p;
}

/* Specify a poll/ppoll deadline of at most 'ms' milliseconds */
void
ptimeout_deadline_ms(struct timespec *pt, long ms)
{
  struct timespec p;

  p.tv_sec = ms / 1000;
  p.tv_nsec = (ms % 1000) * 1000000;
  ptimeout_deadline_tsp(pt, &p);
}

/* Specify a poll/ppoll deadline at wall clock monotime 'when' */
void
ptimeout_deadline_monotime(struct timespec *pt, time_t when)
{
  struct timespec now, t;

  t.tv_sec = when;
  t.tv_nsec = 0;
  monotime_ts(&now);

  if (timespeccmp(&now, &t, >=))
    ptimeout_deadline_sec(pt, 0);
  else {
    timespecsub(&t, &now, &t);
    ptimeout_deadline_tsp(pt, &t);
  }
}

/* Get a poll(2) timeout value in milliseconds */
int
ptimeout_get_ms(struct timespec *pt)
{
  if (pt->tv_sec == -1)
    return -1;
  if (pt->tv_sec >= (INT_MAX - (pt->tv_nsec / 1000000)) / 1000)
    return INT_MAX;
  return (pt->tv_sec * 1000) + (pt->tv_nsec / 1000000);
}

/* Get a ppoll(2) timeout value as a timespec pointer */
struct timespec *
ptimeout_get_tsp(struct timespec *pt)
{
  return pt->tv_sec == -1 ? NULL : pt;
}

/* Returns non-zero if a timeout has been set (i.e. is not indefinite) */
int
ptimeout_isset(struct timespec *pt)
{
  return pt->tv_sec != -1;
}

Coverage Report

Created: 2023-06-07 07:08