libssh/src/misc.c

/*
 * misc.c - useful client functions
 *
 * This file is part of the SSH Library
 *
 * Copyright (c) 2003-2009 by Aris Adamantiadis
 * Copyright (c) 2008-2009 by Andreas Schneider <mail@cynapses.org>
 *
 * The SSH Library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 *
 * The SSH Library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the SSH Library; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

#include "config.h"

#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <ctype.h>

#ifdef _WIN32
#define _WIN32_IE 0x0501 //SHGetSpecialFolderPath
#include <winsock2.h> // Must be the first to include
#include <ws2tcpip.h>
#include <shlobj.h>
#include <direct.h>
#if _MSC_VER >= 1400
#include <io.h>
#endif /* _MSC_VER */
#else /* _WIN32 */
/* This is needed for a standard getpwuid_r on opensolaris */
#define _POSIX_PTHREAD_SEMANTICS
#include <pwd.h>
#include <arpa/inet.h>
#endif /* _WIN32 */

#include "libssh/priv.h"
#include "libssh/misc.h"
#include "libssh/session.h"

#ifdef HAVE_LIBGCRYPT
#define GCRYPT_STRING "/gnutls"
#else
#define GCRYPT_STRING ""
#endif

#ifdef HAVE_LIBCRYPTO
#define CRYPTO_STRING "/openssl"
#else
#define CRYPTO_STRING ""
#endif

#if defined(HAVE_LIBZ) && defined(WITH_LIBZ)
#define LIBZ_STRING "/zlib"
#else
#define LIBZ_STRING ""
#endif

/**
 * @defgroup libssh_misc The SSH helper functions.
 * @ingroup libssh
 *
 * Different helper functions used in the SSH Library.
 *
 * @{
 */

#ifdef _WIN32
char *ssh_get_user_home_dir(void) {
  char tmp[MAX_PATH] = {0};
  char *szPath = NULL;

  if (SHGetSpecialFolderPathA(NULL, tmp, CSIDL_PROFILE, TRUE)) {
    szPath = malloc(strlen(tmp) + 1);
    if (szPath == NULL) {
      return NULL;
    }

    strcpy(szPath, tmp);
    return szPath;
  }

  return NULL;
}

/* we have read access on file */
int ssh_file_readaccess_ok(const char *file) {
  if (_access(file, 4) < 0) {
    return 0;
  }

  return 1;
}

#define SSH_USEC_IN_SEC         1000000LL
#define SSH_SECONDS_SINCE_1601  11644473600LL

int gettimeofday(struct timeval *__p, void *__t) {
  union {
    unsigned long long ns100; /* time since 1 Jan 1601 in 100ns units */
    FILETIME ft;
  } now;

  GetSystemTimeAsFileTime (&now.ft);
  __p->tv_usec = (long) ((now.ns100 / 10LL) % SSH_USEC_IN_SEC);
  __p->tv_sec  = (long)(((now.ns100 / 10LL ) / SSH_USEC_IN_SEC) - SSH_SECONDS_SINCE_1601);

  return (0);
}

char *ssh_get_local_username(ssh_session session) {
  DWORD size = 0;
  char *user;

  /* get the size */
  GetUserName(NULL, &size);

  user = malloc(size);
  if (user == NULL) {
    ssh_set_error_oom(session);
    return NULL;
  }

  if (GetUserName(user, &size)) {
    return user;
  }

  return NULL;
}
#else /* _WIN32 */

#ifndef NSS_BUFLEN_PASSWD
#define NSS_BUFLEN_PASSWD 4096
#endif /* NSS_BUFLEN_PASSWD */

char *ssh_get_user_home_dir(void) {
  char *szPath = NULL;
  struct passwd pwd;
  struct passwd *pwdbuf;
  char buf[NSS_BUFLEN_PASSWD];
  int rc;

  rc = getpwuid_r(getuid(), &pwd, buf, NSS_BUFLEN_PASSWD, &pwdbuf);
  if (rc != 0) {
    return NULL;
  }

  szPath = strdup(pwd.pw_dir);

  return szPath;
}

/* we have read access on file */
int ssh_file_readaccess_ok(const char *file) {
  if (access(file, R_OK) < 0) {
    return 0;
  }

  return 1;
}

char *ssh_get_local_username(ssh_session session) {
    struct passwd pwd;
    struct passwd *pwdbuf;
    char buf[NSS_BUFLEN_PASSWD];
    char *name;
    int rc;

    rc = getpwuid_r(getuid(), &pwd, buf, NSS_BUFLEN_PASSWD, &pwdbuf);
    if (rc != 0) {
        ssh_set_error(session, SSH_FATAL,
            "Couldn't retrieve information for current user!");
        return NULL;
    }

    name = strdup(pwd.pw_name);

    if (name == NULL) {
      ssh_set_error_oom(session);
      return NULL;
    }

    return name;
}
#endif /* _WIN32 */

uint64_t ntohll(uint64_t a) {
#ifdef WORDS_BIGENDIAN
  return a;
#else
  uint32_t low = (uint32_t)(a & 0xffffffff);
  uint32_t high = (uint32_t)(a >> 32);
  low = ntohl(low);
  high = ntohl(high);

  return ((((uint64_t) low) << 32) | ( high));
#endif
}

char *ssh_lowercase(const char* str) {
  char *new, *p;

  if (str == NULL) {
    return NULL;
  }

  new = strdup(str);
  if (new == NULL) {
    return NULL;
  }

  for (p = new; *p; p++) {
    *p = tolower(*p);
  }

  return new;
}

char *ssh_hostport(const char *host, int port){
    char *dest;
    size_t len;
    if(host==NULL)
        return NULL;
    /* 3 for []:, 5 for 65536 and 1 for nul */
    len=strlen(host) + 3 + 5 + 1;
    dest=malloc(len);
    if(dest==NULL)
        return NULL;
    snprintf(dest,len,"[%s]:%d",host,port);
    return dest;
}

/**
 * @brief Check if libssh is the required version or get the version
 * string.
 *
 * @param[in]  req_version The version required.
 *
 * @return              If the version of libssh is newer than the version
 *                      required it will return a version string.
 *                      NULL if the version is older.
 *
 * Example:
 *
 * @code
 *  if (ssh_version(SSH_VERSION_INT(0,2,1)) == NULL) {
 *    fprintf(stderr, "libssh version is too old!\n");
 *    exit(1);
 *  }
 *
 *  if (debug) {
 *    printf("libssh %s\n", ssh_version(0));
 *  }
 * @endcode
 */
const char *ssh_version(int req_version) {
  if (req_version <= LIBSSH_VERSION_INT) {
    return SSH_STRINGIFY(LIBSSH_VERSION) GCRYPT_STRING CRYPTO_STRING
      LIBZ_STRING;
  }

  return NULL;
}

struct ssh_list *ssh_list_new(){
  struct ssh_list *ret=malloc(sizeof(struct ssh_list));
  if(!ret)
    return NULL;
  ret->root=ret->end=NULL;
  return ret;
}

void ssh_list_free(struct ssh_list *list){
  struct ssh_iterator *ptr,*next;
  ptr=list->root;
  while(ptr){
    next=ptr->next;
    SAFE_FREE(ptr);
    ptr=next;
  }
  SAFE_FREE(list);
}

struct ssh_iterator *ssh_list_get_iterator(const struct ssh_list *list){
  return list->root;
}

static struct ssh_iterator *ssh_iterator_new(const void *data){
  struct ssh_iterator *iterator=malloc(sizeof(struct ssh_iterator));
  if(!iterator)
    return NULL;
  iterator->next=NULL;
  iterator->data=data;
  return iterator;
}

int ssh_list_append(struct ssh_list *list,const void *data){
  struct ssh_iterator *iterator=ssh_iterator_new(data);
  if(!iterator)
    return SSH_ERROR;
  if(!list->end){
    /* list is empty */
    list->root=list->end=iterator;
  } else {
    /* put it on end of list */
    list->end->next=iterator;
    list->end=iterator;
  }
  return SSH_OK;
}

int ssh_list_prepend(struct ssh_list *list, const void *data){
  struct ssh_iterator *it = ssh_iterator_new(data);

  if (it == NULL) {
    return SSH_ERROR;
  }

  if (list->end == NULL) {
    /* list is empty */
    list->root = list->end = it;
  } else {
    /* set as new root */
    it->next = list->root;
    list->root = it;
  }

  return SSH_OK;
}

void ssh_list_remove(struct ssh_list *list, struct ssh_iterator *iterator){
  struct ssh_iterator *ptr,*prev;
  prev=NULL;
  ptr=list->root;
  while(ptr && ptr != iterator){
    prev=ptr;
    ptr=ptr->next;
  }
  if(!ptr){
    /* we did not find the element */
    return;
  }
  /* unlink it */
  if(prev)
    prev->next=ptr->next;
  /* if iterator was the head */
  if(list->root == iterator)
    list->root=iterator->next;
  /* if iterator was the tail */
  if(list->end == iterator)
    list->end = prev;
  SAFE_FREE(iterator);
}

/**
 * @internal
 *
 * @brief Removes the top element of the list and returns the data value
 * attached to it.
 *
 * @param[in[  list     The ssh_list to remove the element.
 *
 * @returns             A pointer to the element being stored in head, or NULL
 *                      if the list is empty.
 */
const void *_ssh_list_pop_head(struct ssh_list *list){
  struct ssh_iterator *iterator=list->root;
  const void *data;
  if(!list->root)
    return NULL;
  data=iterator->data;
  list->root=iterator->next;
  if(list->end==iterator)
    list->end=NULL;
  SAFE_FREE(iterator);
  return data;
}

/**
 * @brief Parse directory component.
 *
 * dirname breaks a null-terminated pathname string into a directory component.
 * In the usual case, ssh_dirname() returns the string up to, but not including,
 * the final '/'. Trailing '/' characters are  not  counted as part of the
 * pathname. The caller must free the memory.
 *
 * @param[in]  path     The path to parse.
 *
 * @return              The dirname of path or NULL if we can't allocate memory.
 *                      If path does not contain a slash, c_dirname() returns
 *                      the string ".".  If path is the string "/", it returns
 *                      the string "/". If path is NULL or an empty string,
 *                      "." is returned.
 */
char *ssh_dirname (const char *path) {
  char *new = NULL;
  unsigned int len;

  if (path == NULL || *path == '\0') {
    return strdup(".");
  }

  len = strlen(path);

  /* Remove trailing slashes */
  while(len > 0 && path[len - 1] == '/') --len;

  /* We have only slashes */
  if (len == 0) {
    return strdup("/");
  }

  /* goto next slash */
  while(len > 0 && path[len - 1] != '/') --len;

  if (len == 0) {
    return strdup(".");
  } else if (len == 1) {
    return strdup("/");
  }

  /* Remove slashes again */
  while(len > 0 && path[len - 1] == '/') --len;

  new = malloc(len + 1);
  if (new == NULL) {
    return NULL;
  }

  strncpy(new, path, len);
  new[len] = '\0';

  return new;
}

/**
 * @brief basename - parse filename component.
 *
 * basename breaks a null-terminated pathname string into a filename component.
 * ssh_basename() returns the component following the final '/'.  Trailing '/'
 * characters are not counted as part of the pathname.
 *
 * @param[in]  path     The path to parse.
 *
 * @return              The filename of path or NULL if we can't allocate
 *                      memory. If path is a the string "/", basename returns
 *                      the string "/". If path is NULL or an empty string,
 *                      "." is returned.
 */
char *ssh_basename (const char *path) {
  char *new = NULL;
  const char *s;
  unsigned int len;

  if (path == NULL || *path == '\0') {
    return strdup(".");
  }

  len = strlen(path);
  /* Remove trailing slashes */
  while(len > 0 && path[len - 1] == '/') --len;

  /* We have only slashes */
  if (len == 0) {
    return strdup("/");
  }

  while(len > 0 && path[len - 1] != '/') --len;

  if (len > 0) {
    s = path + len;
    len = strlen(s);

    while(len > 0 && s[len - 1] == '/') --len;
  } else {
    return strdup(path);
  }

  new = malloc(len + 1);
  if (new == NULL) {
    return NULL;
  }

  strncpy(new, s, len);
  new[len] = '\0';

  return new;
}

/**
 * @brief Attempts to create a directory with the given pathname.
 *
 * This is the portable version of mkdir, mode is ignored on Windows systems.
 *
 * @param[in]  pathname The path name to create the directory.
 *
 * @param[in]  mode     The permissions to use.
 *
 * @return              0 on success, < 0 on error with errno set.
 */
int ssh_mkdir(const char *pathname, mode_t mode) {
  int r;

#ifdef _WIN32
  r = _mkdir(pathname);
#else
  r = mkdir(pathname, mode);
#endif

  return r;
}

/**
 * @brief Expand a directory starting with a tilde '~'
 *
 * @param[in]  d        The directory to expand.
 *
 * @return              The expanded directory, NULL on error.
 */
char *ssh_path_expand_tilde(const char *d) {
    char *h = NULL, *r;
    const char *p;
    size_t ld;
    size_t lh = 0;

    if (d[0] != '~') {
        return strdup(d);
    }
    d++;

    /* handle ~user/path */
    p = strchr(d, '/');
    if (p != NULL && p > d) {
#ifdef _WIN32
        return strdup(d);
#else
        struct passwd *pw;
        size_t s = p - d;
        char u[128];

        if (s > sizeof(u)) {
            return NULL;
        }
        memcpy(u, d, s);
        u[s] = '\0';
        pw = getpwnam(u);
        if (pw == NULL) {
            return NULL;
        }
        ld = strlen(p);
        h = strdup(pw->pw_dir);
#endif
    } else {
        ld = strlen(d);
        p = (char *) d;
        h = ssh_get_user_home_dir();
    }
    if (h == NULL) {
        return NULL;
    }
    lh = strlen(h);

    r = malloc(ld + lh + 1);
    if (r == NULL) {
        return NULL;
    }

    if (lh > 0) {
        memcpy(r, h, lh);
        SAFE_FREE(h);
    }
    memcpy(r + lh, p, ld + 1);

    return r;
}

char *ssh_path_expand_escape(ssh_session session, const char *s) {
#define MAX_BUF_SIZE 4096
    char host[NI_MAXHOST];
    char buf[MAX_BUF_SIZE];
    char *r, *x = NULL;
    const char *p;
    size_t i, l;

    r = ssh_path_expand_tilde(s);
    if (r == NULL) {
        ssh_set_error_oom(session);
        return NULL;
    }

    if (strlen(r) > MAX_BUF_SIZE) {
        ssh_set_error(session, SSH_FATAL, "string to expand too long");
        free(r);
        return NULL;
    }

    p = r;
    buf[0] = '\0';

    for (i = 0; *p != '\0'; p++) {
        if (*p != '%') {
            buf[i] = *p;
            i++;
            if (i > MAX_BUF_SIZE) {
                return NULL;
            }
            buf[i] = '\0';
            continue;
        }

        p++;
        if (*p == '\0') {
            break;
        }

        switch (*p) {
            case 'd':
                x = strdup(session->sshdir);
                break;
            case 'u':
                x = ssh_get_local_username(session);
                break;
            case 'l':
                if (gethostname(host, sizeof(host) == 0)) {
                    x = strdup(host);
                }
                break;
            case 'h':
                x = strdup(session->host);
                break;
            case 'r':
                x = strdup(session->username);
                break;
            case 'p':
                if (session->port < 65536) {
                    char tmp[6];

                    snprintf(tmp, sizeof(tmp), "%u", session->port);
                    x = strdup(tmp);
                }
                break;
            default:
                ssh_set_error(session, SSH_FATAL,
                        "Wrong escape sequence detected");
                return NULL;
        }

        if (x == NULL) {
            ssh_set_error_oom(session);
            return NULL;
        }

        i += strlen(x);
        if (i > MAX_BUF_SIZE) {
            ssh_set_error(session, SSH_FATAL,
                    "String too long");
            return NULL;
        }
        l = strlen(buf);
        strcat(buf + l, x);
        buf[i] = '\0';
        SAFE_FREE(x);
    }

    free(r);
    return strdup(buf);
#undef MAX_BUF_SIZE
}

/**
 * @internal
 *
 * @brief Analyze the SSH banner to find out if we have a SSHv1 or SSHv2
 * server.
 *
 * @param  session      The session to analyze the banner from.
 * @param  ssh1         The variable which is set if it is a SSHv1 server.
 * @param  ssh2         The variable which is set if it is a SSHv2 server.
 *
 * @return 0 on success, < 0 on error.
 *
 * @see ssh_get_banner()
 */
int ssh_analyze_banner(ssh_session session, int *ssh1, int *ssh2) {
  const char *banner = session->clientbanner;
  const char *openssh;


  if (banner == NULL ||
      strlen(banner) <= 4 ||
      strncmp(banner, "SSH-", 4) != 0) {
    ssh_set_error(session, SSH_FATAL, "Protocol mismatch: %s", banner);
    return -1;
  }

  ssh_log(session, SSH_LOG_RARE, "Analyzing banner: %s", banner);

  /*
   * Typical banners e.g. are:
   * SSH-1.5-blah
   * SSH-1.99-blah
   * SSH-2.0-blah
   */
  switch(banner[4]) {
    case '1':
      *ssh1 = 1;
      if (banner[6] == '9') {
        *ssh2 = 1;
      } else {
        *ssh2 = 0;
      }
      break;
    case '2':
      *ssh1 = 0;
      *ssh2 = 1;
      break;
    default:
      ssh_set_error(session, SSH_FATAL, "Protocol mismatch: %s", banner);
      return -1;
  }

  openssh = strstr(banner, "OpenSSH");
  if (openssh != NULL) {
    int major, minor;
    major = strtol(openssh + 8, (char **) NULL, 10);
    minor = strtol(openssh + 10, (char **) NULL, 10);
    session->openssh = SSH_VERSION_INT(major, minor, 0);
    ssh_log(session, SSH_LOG_RARE,
        "We are talking to an OpenSSH client version: %d.%d (%x)",
        major, minor, session->openssh);
  }

  return 0;
}

/** @} */

/* vim: set ts=4 sw=4 et cindent: */