/*
 * ProFTPD - FTP server daemon
 * Copyright (c) 2003-2020 The ProFTPD Project team
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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, Suite 500, Boston, MA 02110-1335, USA.
 *
 * As a special exemption, the ProFTPD Project team and other respective
 * copyright holders give permission to link this program with OpenSSL, and
 * distribute the resulting executable, without including the source code for
 * OpenSSL in the source distribution.
 */

/* Network ACL routines */

#include "conf.h"

extern int ServerUseReverseDNS;

struct pr_netacl_t {
  pr_netacl_type_t type;
  const char *aclstr;

  char *pattern;
  int negated;
  const pr_netaddr_t *addr;
  unsigned int masklen;
};

static const char *trace_channel = "netacl";

pr_netacl_type_t pr_netacl_get_type(const pr_netacl_t *acl) {
  return acl->type;
}

/* Returns 1 if there was a positive match, -1 if there was a negative
 * match, -2 if there was an error, and zero if there was no match at all.
 */
int pr_netacl_match(const pr_netacl_t *acl, const pr_netaddr_t *addr) {
  pool *tmp_pool;
  int res = 0;

  if (acl == NULL ||
      addr == NULL) {
    errno = EINVAL;
    return -2;
  }

  tmp_pool = make_sub_pool(permanent_pool);

  switch (acl->type) {
    case PR_NETACL_TYPE_ALL:
      pr_trace_msg(trace_channel, 10, "addr '%s' matched rule 'ALL' ('%s')",
        pr_netaddr_get_ipstr(addr), pr_netacl_get_str(tmp_pool, acl));
      res = 1;
      break;

    case PR_NETACL_TYPE_NONE:
      pr_trace_msg(trace_channel, 10, "addr '%s' matched rule 'NONE'",
        pr_netaddr_get_ipstr(addr));
      res = -1;
      break;

    case PR_NETACL_TYPE_IPMASK:
      pr_trace_msg(trace_channel, 10,
        "checking addr '%s' against IP mask rule '%s'",
        pr_netaddr_get_ipstr(addr), acl->aclstr);

      if (pr_netaddr_ncmp(addr, acl->addr, acl->masklen) == 0) {
        pr_trace_msg(trace_channel, 10, "addr '%s' matched IP mask rule '%s'",
          pr_netaddr_get_ipstr(addr), acl->aclstr);

        if (acl->negated) {
          res = -1;

        } else {
          res = 1;
        }

      } else {
        pr_trace_msg(trace_channel, 10,
          "addr '%s' did NOT match IP mask rule '%s'",
          pr_netaddr_get_ipstr(addr), acl->aclstr);

        if (acl->negated) {
          res = 1;
        }
      }
      break;

    case PR_NETACL_TYPE_IPMATCH:
      pr_trace_msg(trace_channel, 10,
        "checking addr '%s' against IP address rule '%s'",
        pr_netaddr_get_ipstr(addr), acl->aclstr);

      if (pr_netaddr_cmp(addr, acl->addr) == 0) {
        pr_trace_msg(trace_channel, 10,
          "addr '%s' matched IP address rule '%s'",
          pr_netaddr_get_ipstr(addr), acl->aclstr);

        if (acl->negated) {
          res = -1;

        } else {
          res = 1;
        }

      } else {
        pr_trace_msg(trace_channel, 10,
          "addr '%s' did NOT match IP address rule '%s'",
          pr_netaddr_get_ipstr(addr), acl->aclstr);

        if (acl->negated) {
          res = 1;
        }
      }
      break;
 
    case PR_NETACL_TYPE_DNSMATCH:
      pr_trace_msg(trace_channel, 10,
        "checking addr '%s' against DNS name rule '%s'",
        pr_netaddr_get_dnsstr(addr), acl->pattern);

      if (strcmp(pr_netaddr_get_dnsstr(addr), acl->pattern) == 0) {
        pr_trace_msg(trace_channel, 10,
          "addr '%s' (%s) matched DNS name rule '%s'",
          pr_netaddr_get_ipstr(addr), pr_netaddr_get_dnsstr(addr),
          acl->aclstr);

        if (acl->negated) {
          res = -1;

        } else {
          res = 1;
        }

      } else {
        pr_trace_msg(trace_channel, 10,
          "addr '%s' (%s) did NOT match DNS name rule '%s'",
          pr_netaddr_get_ipstr(addr), pr_netaddr_get_dnsstr(addr),
          acl->aclstr);

        if (acl->negated) {
          res = 1;
        }
      }
      break;

    case PR_NETACL_TYPE_IPGLOB:
      pr_trace_msg(trace_channel, 10,
        "checking addr '%s' against IP glob rule '%s'",
        pr_netaddr_get_ipstr(addr), acl->aclstr);

      if (pr_netaddr_fnmatch(addr, acl->pattern,
          PR_NETADDR_MATCH_IP) == TRUE) {
        pr_trace_msg(trace_channel, 10,
          "addr '%s' matched IP glob rule '%s'",
          pr_netaddr_get_ipstr(addr), acl->aclstr);

        if (acl->negated) {
          res = -1;

        } else {
          res = 1;
        }

      } else {
        pr_trace_msg(trace_channel, 10,
          "addr '%s' did NOT match IP glob rule '%s'",
          pr_netaddr_get_ipstr(addr), acl->aclstr);

        if (acl->negated) {
          res = 1;
        }
      }
      break;

    case PR_NETACL_TYPE_DNSGLOB:
      if (ServerUseReverseDNS) {
        pr_trace_msg(trace_channel, 10,
          "checking addr '%s' against DNS glob rule '%s'",
          pr_netaddr_get_dnsstr(addr), acl->pattern);

        if (pr_netaddr_fnmatch(addr, acl->pattern,
            PR_NETADDR_MATCH_DNS) == TRUE) {
          pr_trace_msg(trace_channel, 10,
            "addr '%s' (%s) matched DNS glob rule '%s'",
            pr_netaddr_get_ipstr(addr), pr_netaddr_get_dnsstr(addr),
            acl->aclstr);

          if (acl->negated) {
            res = -1;

          } else {
            res = 1;
          }

        } else {
          pr_trace_msg(trace_channel, 10,
            "addr '%s' (%s) did NOT match DNS glob rule '%s'",
            pr_netaddr_get_ipstr(addr), pr_netaddr_get_dnsstr(addr),
            acl->aclstr);

          if (acl->negated) {
            res = 1;
          }
        }

      } else {
        pr_trace_msg(trace_channel, 10,
          "skipping comparing addr '%s' (%s) against DNS glob rule '%s' "
          "because UseReverseDNS is off", pr_netaddr_get_ipstr(addr),
          pr_netaddr_get_dnsstr(addr), acl->aclstr);
      }
      break;
  }

  destroy_pool(tmp_pool);
  return res;
}

pr_netacl_t *pr_netacl_create(pool *p, char *aclstr) {
  pr_netacl_t *acl;
  char *cp, *aclstr_dup;

  if (p == NULL ||
      aclstr == NULL) {
    errno = EINVAL;
    return NULL;
  }

  if (strlen(aclstr) == 0) {
    errno = EINVAL;
    return NULL;
  }

  /* Parse the given rule into a netacl object. */
  acl = pcalloc(p, sizeof(pr_netacl_t));

  aclstr_dup = pstrdup(p, aclstr);

  if (strncasecmp(aclstr, "all", 4) == 0) {
    aclstr_dup = pstrdup(p, "all");
    acl->type = PR_NETACL_TYPE_ALL;

  } else if (strncasecmp(aclstr, "none", 5) == 0) {
    aclstr_dup = pstrdup(p, "none");
    acl->type = PR_NETACL_TYPE_NONE;

  } else if ((cp = strchr(aclstr, '/')) != NULL) {
    char *tmp;

    acl->type = PR_NETACL_TYPE_IPMASK;
    *cp = '\0';

    /* Check if the given rule is negated. */
    if (*aclstr == '!') {
      acl->negated = TRUE;
      aclstr++;
    }

    /* We have some type of IP/mask, either IPv4 or IPv6.  We know that colons
     * will only appear in IPv6 addresses, so...
     */

    if (strspn(aclstr, "0123456789ABCDEFabcdef.:") != strlen(aclstr)) {
      errno = EINVAL;
      return NULL;
    }

    acl->addr = pr_netaddr_get_addr(p, aclstr, NULL);
    if (acl->addr == NULL) {
      return NULL;
    }

    /* Determine what the given bitmask is. */
    acl->masklen = strtol(cp + 1, &tmp, 10);

    if (tmp && *tmp) {
      /* Invalid bitmask syntax. */
      errno = EINVAL;
      return NULL;
    }

    *cp = '/';

    /* Make sure the given mask length is appropriate for the address. */
    switch (pr_netaddr_get_family(acl->addr)) {
      case AF_INET: {
        /* Make sure that the given number of bits is not more than supported
         * for IPv4 addresses (32).
         */
        if (acl->masklen > 32) {
          errno = EINVAL;
          return NULL;
        }

        break;
      }

#ifdef PR_USE_IPV6
      case AF_INET6: {
        if (pr_netaddr_use_ipv6()) {
          if (acl->masklen > 128) {
            errno = EINVAL;
            return NULL;

          } else if (pr_netaddr_is_v4mappedv6(acl->addr) == TRUE &&
                     acl->masklen > 32) {
            /* The admin may be trying to use IPv6-style masks on IPv4-mapped
             * IPv6 addresses, which of course will not work as expected.
             * If the mask is 32 bits or more, warn the admin.
             */
            pr_log_pri(PR_LOG_WARNING, "warning: possibly using IPv6-style netmask on IPv4-mapped IPv6 address, which will not work as expected");
            pr_trace_msg(trace_channel, 1, "possibly using IPv6-style netmask on IPv4-mapped IPv6 address (%s), which will not work as expected", aclstr);

            break;
          }
        }
      }
#endif /* PR_USE_IPV6 */

      default:
        break;
    }

#ifdef PR_USE_IPV6
  } else if (pr_netaddr_use_ipv6() &&
             strspn(aclstr, "0123456789ABCDEFabcdef.:!") != strlen(aclstr)) {
#else
  } else if (strspn(aclstr, "0123456789.!") != strlen(aclstr)) {
#endif /* PR_USE_IPV6 */

    /* Check if the given rule is negated. */
    if (*aclstr == '!') {
      acl->negated = TRUE;
      aclstr++;
    }

    /* If there are any glob characters (e.g. '{', '[', '*', or '?'), or if the
     * first character is a '.', then treat the rule as a glob.
     */
    if (strpbrk(aclstr, "{[*?")) {
      register unsigned int i;
      size_t aclstr_len = strlen(aclstr);
      pr_netacl_type_t netacl_type = PR_NETACL_TYPE_IPGLOB;

      /* Is this a DNS glob, or an IP address glob?  To find out, see if there
       * are any non-IP characters (i.e. alphabetical characters, taking IPv6
       * into account).
       */
      for (i = 0; i < aclstr_len; i++) {
        if (PR_ISALPHA(aclstr[i])) {
#ifdef PR_USE_IPV6
          if (pr_netaddr_use_ipv6()) {
            if (aclstr[i] == 'A' || aclstr[i] == 'a' ||
                aclstr[i] == 'B' || aclstr[i] == 'b' ||
                aclstr[i] == 'C' || aclstr[i] == 'c' ||
                aclstr[i] == 'D' || aclstr[i] == 'd' ||
                aclstr[i] == 'E' || aclstr[i] == 'e' ||
                aclstr[i] == 'F' || aclstr[i] == 'f') {
              continue;
            }

            netacl_type = PR_NETACL_TYPE_DNSGLOB;
            break;

          } else {
            netacl_type = PR_NETACL_TYPE_DNSGLOB;
            break;
          }
#else
          netacl_type = PR_NETACL_TYPE_DNSGLOB;
          break;
#endif /* PR_USE_IPV6 */
        }
      }

      acl->type = netacl_type;
      acl->pattern = pstrdup(p, aclstr);

    } else if (*aclstr == '.') {
      acl->type = PR_NETACL_TYPE_DNSGLOB;
      acl->pattern = pstrcat(p, "*", aclstr, NULL);

    } else {
      acl->type = PR_NETACL_TYPE_DNSMATCH;
      acl->pattern = pstrdup(p, aclstr);
    }

  } else if (strchr(aclstr, '.') == NULL) {
    int use_glob = FALSE, use_dns = FALSE;

    /* Is this a DNS glob, DNS match, or an IPv6 glob/match? */

    /* Check if the given rule is negated. */
    if (*aclstr == '!') {
      acl->negated = TRUE;
      aclstr++;
    }

    /* If there are any glob characters (e.g. '{', '[', '*', or '?'), or if the
     * first character is a '.', then treat the rule as a glob.
     */
    if (strpbrk(aclstr, "{[*?")) {
      use_glob = TRUE;
    }

    /* IPv6 addresses use colons, thus if we do not see any, it's a good
     * bet that this is a DNS glob/match.
     */
    if (strchr(aclstr, ':') == NULL) {
      use_dns = TRUE;

    } else {
#ifdef PR_USE_IPV6
      if (pr_netaddr_use_ipv6() == FALSE) {
        pr_trace_msg(trace_channel, 1, "possibly using IPv6 %s '%s' when "
          "IPv6 support is disabled, which will not work as expected",
          use_glob ? "glob" : "match", aclstr);
        pr_log_pri(PR_LOG_WARNING, "warning: possibly using IPv6 %s '%s' when "
          "IPv6 support is disabled, which will not work as expected",
          use_glob ? "glob" : "match", aclstr);
      }
#else
      pr_trace_msg(trace_channel, 1, "possibly using IPv6 %s '%s' when "
        "IPv6 support is disabled, which will not work as expected",
        use_glob ? "glob" : "match", aclstr);
      pr_log_pri(PR_LOG_WARNING, "warning: possibly using IPv6 %s '%s' when "
        "IPv6 support is disabled, which will not work as expected",
        use_glob ? "glob" : "match", aclstr);
#endif /* PR_USE_IPV6 */
    }

    if (use_dns == TRUE) {
      acl->pattern = pstrdup(p, aclstr);
      acl->type = use_glob ? PR_NETACL_TYPE_DNSGLOB : PR_NETACL_TYPE_DNSMATCH;

    } else {
      acl->addr = pr_netaddr_get_addr(p, aclstr, NULL);
      if (acl->addr == NULL) {
        int xerrno = errno;

        pr_trace_msg(trace_channel, 3, "unable to resolve '%s': %s", aclstr,
          strerror(xerrno));

        errno = xerrno;
        return NULL;
      }

      acl->pattern = pstrdup(p, aclstr);
      acl->type = use_glob ? PR_NETACL_TYPE_IPGLOB : PR_NETACL_TYPE_IPMATCH;
    }

  } else {

    /* Check if the given rule is negated. */
    if (*aclstr == '!') {
      acl->negated = TRUE;
      aclstr++;
    }

    /* If the last character is a '.', then treat the rule as an IP glob. */
    if (aclstr[strlen(aclstr)-1] == '.') {
      acl->type = PR_NETACL_TYPE_IPGLOB;
      acl->pattern = pstrcat(p, aclstr, "*", NULL);

    } else {
      register unsigned int i;
      int use_glob = FALSE, use_dns = FALSE;
      size_t aclstr_len;

      /* Is this a DNS glob, DNS match, IP glob, or IP match?
       *
       * First, check for any glob characters.  After that, determine whether
       * it's a DNS or IP type ACL.
       */

      /* If there are any glob characters (e.g. '{', '[', '*', or '?'), or
       * if the first character is a '.', then treat the rule as a glob.
       */
      use_glob = (strpbrk(aclstr, "{[*?") != NULL);

      aclstr_len = strlen(aclstr);
      for (i = 0; i < aclstr_len; i++) {
        if (PR_ISALPHA(aclstr[i])) {
#ifdef PR_USE_IPV6
          if (pr_netaddr_use_ipv6()) {
            if (aclstr[i] == 'A' || aclstr[i] == 'a' ||
                aclstr[i] == 'B' || aclstr[i] == 'b' ||
                aclstr[i] == 'C' || aclstr[i] == 'c' ||
                aclstr[i] == 'D' || aclstr[i] == 'd' ||
                aclstr[i] == 'E' || aclstr[i] == 'e' ||
                aclstr[i] == 'F' || aclstr[i] == 'f') {
              continue;
            }

            use_dns = TRUE;
            break;

          } else {
            use_dns = TRUE;
            break;
          }
#else
          use_dns = TRUE;
          break;
#endif /* PR_USE_IPV6 */
        }
      }

      if (!use_dns) {
        acl->type = use_glob ? PR_NETACL_TYPE_IPGLOB : PR_NETACL_TYPE_IPMATCH;
        acl->addr = pr_netaddr_get_addr(p, aclstr, NULL);
        if (acl->addr == NULL) {
          return NULL;
        }

      } else {
        if (use_glob) {
          acl->type = PR_NETACL_TYPE_DNSGLOB;
          acl->pattern = pstrdup(p, aclstr);

        } else if (*aclstr == '.') {
          acl->type = PR_NETACL_TYPE_DNSGLOB;
          acl->pattern = pstrcat(p, "*", aclstr, NULL);

        } else {
          acl->type = PR_NETACL_TYPE_DNSMATCH;
          acl->pattern = pstrdup(p, aclstr);
        }
      }
    }
  }

  acl->aclstr = aclstr_dup;
  return acl;
}

pr_netacl_t *pr_netacl_dup(pool *p, const pr_netacl_t *acl) {
  pr_netacl_t *acl2;

  if (p == NULL ||
      acl == NULL) {
    errno = EINVAL;
    return NULL;
  }

  acl2 = pcalloc(p, sizeof(pr_netacl_t));

  /* A simple memcpy(3) won't suffice; we need a deep copy. */
  acl2->type = acl->type;

  if (acl->pattern != NULL) {
    acl2->pattern = pstrdup(p, acl->pattern);
  }

  acl2->negated = acl->negated;

  if (acl->addr != NULL) {
    pr_netaddr_t *addr;

    addr = pr_netaddr_alloc(p);
    pr_netaddr_set_family(addr, pr_netaddr_get_family(acl->addr));
    pr_netaddr_set_sockaddr(addr, pr_netaddr_get_sockaddr(acl->addr));

    acl2->addr = addr;
  }

  acl2->masklen = acl->masklen;

  if (acl->aclstr != NULL) {
    acl2->aclstr = pstrdup(p, acl->aclstr);
  }

  return acl2;
}

int pr_netacl_get_negated(const pr_netacl_t *acl) {
  if (acl == NULL) {
    errno = EINVAL;
    return -1;
  }

  return acl->negated;
}

const char *pr_netacl_get_str2(pool *p, const pr_netacl_t *acl, int flags) {
  char *res = "";

  if (p == NULL ||
      acl == NULL) {
    errno = EINVAL;
    return NULL;
  }

  switch (acl->type) {
    case PR_NETACL_TYPE_ALL:
      res = pstrcat(p, res, acl->aclstr, NULL);
      if (!(flags & PR_NETACL_FL_STR_NO_DESC)) {
        res = pstrcat(p, res, " <all>", NULL);
      }
      return res;

    case PR_NETACL_TYPE_NONE:
      res = pstrcat(p, res, acl->aclstr, NULL);
      if (!(flags & PR_NETACL_FL_STR_NO_DESC)) {
        res = pstrcat(p, res, " <none>", NULL);
      }
      return res;

    case PR_NETACL_TYPE_IPMASK: {
      res = pstrcat(p, res, acl->aclstr, NULL);

      if (!(flags & PR_NETACL_FL_STR_NO_DESC)) {
        char masklenstr[64];

        memset(masklenstr, '\0', sizeof(masklenstr));
        pr_snprintf(masklenstr, sizeof(masklenstr)-1, "%u", acl->masklen);
        res = pstrcat(p, res, " <IP address mask, ", masklenstr, "-bit mask",
          NULL);
      }
      break;
    }

    case PR_NETACL_TYPE_IPMATCH:
      res = pstrcat(p, res, acl->aclstr, NULL);
      if (!(flags & PR_NETACL_FL_STR_NO_DESC)) {
        res = pstrcat(p, res, " <IP address match", NULL);
      }
      break;

    case PR_NETACL_TYPE_DNSMATCH:
      res = pstrcat(p, res, acl->aclstr, NULL);
      if (!(flags & PR_NETACL_FL_STR_NO_DESC)) {
        res = pstrcat(p, res, " <DNS hostname match", NULL);
      }
      break;

    case PR_NETACL_TYPE_IPGLOB:
      res = pstrcat(p, res, acl->pattern, NULL);
      if (!(flags & PR_NETACL_FL_STR_NO_DESC)) {
        res = pstrcat(p, res, " <IP address glob", NULL);
      }
      break;

    case PR_NETACL_TYPE_DNSGLOB:
      res = pstrcat(p, res, acl->pattern, NULL);
      if (!(flags & PR_NETACL_FL_STR_NO_DESC)) {
        res = pstrcat(p, res, " <DNS hostname glob", NULL);
      }
      break;
  }

  if (!(flags & PR_NETACL_FL_STR_NO_DESC)) {
    if (!acl->negated) {
      res = pstrcat(p, res, ">", NULL);

    } else {
      res = pstrcat(p, res, ", inverted>", NULL);
    }
  }

  return res;
}

const char *pr_netacl_get_str(pool *p, const pr_netacl_t *acl) {
  return pr_netacl_get_str2(p, acl, 0);
}