# Authors: Simo Sorce <ssorce@redhat.com>
#
# Copyright (C) 2007    Red Hat
# see file 'COPYING' for use and warranty information
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#

import logging
import socket
import errno
import getpass
import os
import re
import fileinput
import sys
import struct
import fcntl
import netaddr
import time
import tempfile
import shutil
from ConfigParser import SafeConfigParser

from ipapython import ipautil, dnsclient, sysrestore

# Used to determine install status
IPA_MODULES = ['httpd', 'kadmin', 'dirsrv', 'pki-cad', 'pkids', 'install', 'krb5kdc', 'ntpd', 'named']

class BadHostError(Exception):
    pass

class HostLookupError(BadHostError):
    pass

class HostForwardLookupError(HostLookupError):
    pass

class HostReverseLookupError(HostLookupError):
    pass

class HostnameLocalhost(HostLookupError):
    pass

class ReplicaConfig:
    def __init__(self):
        self.realm_name = ""
        self.domain_name = ""
        self.master_host_name = ""
        self.dirman_password = ""
        self.host_name = ""
        self.dir = ""
        self.subject_base = ""
        self.setup_ca = False

def get_fqdn():
    fqdn = ""
    try:
        fqdn = socket.getfqdn()
    except:
        try:
            fqdn = socket.gethostname()
        except:
            fqdn = ""
    return fqdn

def verify_dns_records(host_name, responses, resaddr, family):
    familykw = { 'ipv4' : {
                             'dns_type' : dnsclient.DNS_T_A,
                             'socket_family' : socket.AF_INET,
                          },
                 'ipv6' : {
                             'dns_type' : dnsclient.DNS_T_AAAA,
                             'socket_family' : socket.AF_INET6,
                          },
               }

    family = family.lower()
    if family not in familykw.keys():
        raise RuntimeError("Unknown faimily %s\n" % family)

    rec = None
    for rsn in responses:
        if rsn.dns_type == familykw[family]['dns_type']:
            rec = rsn
            break

    if rec == None:
        raise IOError(errno.ENOENT,
                      "Warning: Hostname (%s) not found in DNS" % host_name)

    if family == 'ipv4':
        familykw[family]['address'] = socket.inet_ntop(socket.AF_INET,
                                                       struct.pack('!L',rec.rdata.address))
    else:
        familykw[family]['address'] = socket.inet_ntop(socket.AF_INET6,
                                                       struct.pack('!16B', *rec.rdata.address))

    # Check that DNS address is the same is address returned via standard glibc calls
    dns_addr = netaddr.IPAddress(familykw[family]['address'])
    if dns_addr.format() != resaddr:
        raise RuntimeError("The network address %s does not match the DNS lookup %s. Check /etc/hosts and ensure that %s is the IP address for %s" % (dns_addr.format(), resaddr, dns_addr.format(), host_name))

    rs = dnsclient.query(dns_addr.reverse_dns, dnsclient.DNS_C_IN, dnsclient.DNS_T_PTR)
    if len(rs) == 0:
        raise RuntimeError("Cannot find Reverse Address for %s (%s)" % (host_name, dns_addr.format()))

    rev = None
    for rsn in rs:
        if rsn.dns_type == dnsclient.DNS_T_PTR:
            rev = rsn
            break

    if rev == None:
        raise RuntimeError("Cannot find Reverse Address for %s (%s)" % (host_name, dns_addr.format()))

    if rec.dns_name != rev.rdata.ptrdname:
        raise RuntimeError("The DNS forward record %s does not match the reverse address %s" % (rec.dns_name, rev.rdata.ptrdname))


def verify_fqdn(host_name, no_host_dns=False, local_hostname=True):
    """
    Run fqdn checks for given host:
        - test hostname format
        - test that hostname is fully qualified
        - test forward and reverse hostname DNS lookup

    Raises `BadHostError` or derived Exceptions if there is an error

    :param host_name: The host name to verify.
    :param no_host_dns: If true, skip DNS resolution tests of the host name.
    :param local_hostname: If true, run additional checks for local hostnames
    """
    if len(host_name.split(".")) < 2 or host_name == "localhost.localdomain":
        raise BadHostError("Invalid hostname '%s', must be fully-qualified." % host_name)

    if host_name != host_name.lower():
        raise BadHostError("Invalid hostname '%s', must be lower-case." % host_name)

    if ipautil.valid_ip(host_name):
        raise BadHostError("IP address not allowed as a hostname")

    if local_hostname:
        try:
            ex_name = socket.gethostbyaddr(host_name)
            if host_name != ex_name[0]:
                raise HostLookupError("The host name %s does not match the primary host name %s. "\
                        "Please check /etc/hosts or DNS name resolution" % (host_name, ex_name[0]))
        except socket.gaierror:
            pass

    if no_host_dns:
        print "Warning: skipping DNS resolution of host", host_name
        return

    try:
        hostaddr = socket.getaddrinfo(host_name, None)
    except:
        raise HostForwardLookupError("Unable to resolve host name, check /etc/hosts or DNS name resolution")

    if len(hostaddr) == 0:
        raise HostForwardLookupError("Unable to resolve host name, check /etc/hosts or DNS name resolution")

    for a in hostaddr:
        if a[4][0] == '127.0.0.1' or a[4][0] == '::1':
            raise HostForwardLookupError("The IPA Server hostname must not resolve to localhost (%s). A routable IP address must be used. Check /etc/hosts to see if %s is an alias for %s" % (a[4][0], host_name, a[4][0]))
        try:
            resaddr = a[4][0]
            revname = socket.gethostbyaddr(a[4][0])[0]
        except:
            raise HostReverseLookupError("Unable to resolve the reverse ip address, check /etc/hosts or DNS name resolution")
        if revname != host_name:
            raise HostReverseLookupError("The host name %s does not match the reverse lookup %s" % (host_name, revname))

    # Verify this is NOT a CNAME
    rs = dnsclient.query(host_name+".", dnsclient.DNS_C_IN, dnsclient.DNS_T_CNAME)
    if len(rs) != 0:
        for rsn in rs:
            if rsn.dns_type == dnsclient.DNS_T_CNAME:
                raise HostReverseLookupError("The IPA Server Hostname cannot be a CNAME, only A and AAAA names are allowed.")

    # Verify that it is a DNS A or AAAA record
    rs = dnsclient.query(host_name+".", dnsclient.DNS_C_IN, dnsclient.DNS_T_A)
    if len([ rec for rec in rs if rec.dns_type is not dnsclient.DNS_T_SOA ]) > 0:
        verify_dns_records(host_name, rs, resaddr, 'ipv4')
        return

    rs = dnsclient.query(host_name+".", dnsclient.DNS_C_IN, dnsclient.DNS_T_AAAA)
    if len([ rec for rec in rs if rec.dns_type is not dnsclient.DNS_T_SOA ]) > 0:
        verify_dns_records(host_name, rs, resaddr, 'ipv6')
        return
    else:
        print "Warning: Hostname (%s) not found in DNS" % host_name

def record_in_hosts(ip, host_name, file="/etc/hosts"):
    hosts = open(file, 'r').readlines()
    for line in hosts:
        line = line.rstrip('\n')
        fields = line.partition('#')[0].split()
        if len(fields) == 0:
            continue

        try:
            hosts_ip = fields[0]
            names = fields[1:]

            if hosts_ip != ip:
                continue
            if host_name in names:
                return True
        except IndexError:
            print "Warning: Erroneous line '%s' in %s" % (line, file)
            continue

    return False

def add_record_to_hosts(ip, host_name, file="/etc/hosts"):
    hosts_fd = open(file, 'r+')
    hosts_fd.seek(0, 2)
    hosts_fd.write(ip+'\t'+host_name+' '+host_name.split('.')[0]+'\n')
    hosts_fd.close()

def read_ip_address(host_name, fstore):
    while True:
        ip = ipautil.user_input("Please provide the IP address to be used for this host name", allow_empty = False)
        try:
            ip_parsed = ipautil.CheckedIPAddress(ip, match_local=True)
        except Exception, e:
            print "Error: Invalid IP Address %s: %s" % (ip, e)
            continue
        else:
            break

    ip = str(ip_parsed)
    print "Adding ["+ip+" "+host_name+"] to your /etc/hosts file"
    fstore.backup_file("/etc/hosts")
    add_record_to_hosts(ip, host_name)

    return ip_parsed

def read_dns_forwarders():
    addrs = []
    if ipautil.user_input("Do you want to configure DNS forwarders?", True):
        print "Enter the IP address of DNS forwarder to use, or press Enter to finish."

        while True:
            ip = ipautil.user_input("Enter IP address for a DNS forwarder",
                                    allow_empty=True)
            if not ip:
                break
            try:
                ip_parsed = ipautil.CheckedIPAddress(ip, parse_netmask=False)
            except Exception, e:
                print "Error: Invalid IP Address %s: %s" % (ip, e)
                print "DNS forwarder %s not added" % ip
                continue

            print "DNS forwarder %s added" % ip
            addrs.append(str(ip_parsed))

    if not addrs:
        print "No DNS forwarders configured"

    return addrs

def port_available(port):
    """Try to bind to a port on the wildcard host
       Return 1 if the port is available
       Return 0 if the port is in use
    """
    rv = 1

    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        fcntl.fcntl(s, fcntl.F_SETFD, fcntl.FD_CLOEXEC)
        s.bind(('', port))
        s.close()
    except socket.error, e:
        if e[0] == errno.EADDRINUSE:
            rv = 0

    if rv:
        try:
            s = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
            s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
            fcntl.fcntl(s, fcntl.F_SETFD, fcntl.FD_CLOEXEC)
            s.bind(('', port))
            s.close()
        except socket.error, e:
            if e[0] == errno.EADDRINUSE:
                rv = 0

    return rv

def standard_logging_setup(log_filename, debug=False, filemode='w'):
    old_umask = os.umask(077)
    # Always log everything (i.e., DEBUG) to the log
    # file.
    logging.basicConfig(level=logging.DEBUG,
                        format='%(asctime)s %(levelname)s %(message)s',
                        filename=log_filename,
                        filemode=filemode)
    os.umask(old_umask)

    console = logging.StreamHandler()
    # If the debug option is set, also log debug messages to the console
    if debug:
        console.setLevel(logging.DEBUG)
    else:
        # Otherwise, log critical and error messages
        console.setLevel(logging.ERROR)
    formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')
    console.setFormatter(formatter)
    logging.getLogger('').addHandler(console)

def get_password(prompt):
    if os.isatty(sys.stdin.fileno()):
        return getpass.getpass(prompt)
    else:
        return sys.stdin.readline().rstrip()

def _read_password_default_validator(password):
    if len(password) < 8:
        raise ValueError("Password must be at least 8 characters long")

def read_password(user, confirm=True, validate=True, retry=True, validator=_read_password_default_validator):
    correct = False
    pwd = None
    try:
        while not correct:
            if not retry:
                correct = True
            pwd = get_password(user + " password: ")
            if not pwd:
                continue
            if validate:
                try:
                    validator(pwd)
                except ValueError, e:
                    print str(e)
                    pwd = None
                    continue
            if not confirm:
                correct = True
                continue
            pwd_confirm = get_password("Password (confirm): ")
            if pwd != pwd_confirm:
                print "Password mismatch!"
                print ""
                pwd = None
            else:
                correct = True
    except EOFError:
        return None
    print ""
    return pwd

def update_file(filename, orig, subst):
    if os.path.exists(filename):
        st = os.stat(filename)
        pattern = "%s" % re.escape(orig)
        p = re.compile(pattern)
        for line in fileinput.input(filename, inplace=1):
            if not p.search(line):
                sys.stdout.write(line)
            else:
                sys.stdout.write(p.sub(subst, line))
        fileinput.close()
        os.chown(filename, st.st_uid, st.st_gid) # reset perms
        return 0
    else:
        print "File %s doesn't exist." % filename
        return 1

def set_directive(filename, directive, value, quotes=True, separator=' '):
    """Set a name/value pair directive in a configuration file.

       A value of None means to drop the directive.

       This has only been tested with nss.conf
    """
    valueset = False
    st = os.stat(filename)
    fd = open(filename)
    newfile = []
    for line in fd:
        if directive in line:
            valueset = True
            if value is not None:
                if quotes:
                    newfile.append('%s%s"%s"\n' % (directive, separator, value))
                else:
                    newfile.append('%s%s%s\n' % (directive, separator, value))
        else:
            newfile.append(line)
    fd.close()
    if not valueset:
        if value is not None:
            if quotes:
                newfile.append('%s%s"%s"\n' % (directive, separator, value))
            else:
                newfile.append('%s%s%s\n' % (directive, separator, value))

    fd = open(filename, "w")
    fd.write("".join(newfile))
    fd.close()
    os.chown(filename, st.st_uid, st.st_gid) # reset perms

def get_directive(filename, directive, separator=' '):
    """
    A rather inefficient way to get a configuration directive.
    """
    fd = open(filename, "r")
    for line in fd:
        if directive in line:
            line = line.strip()
            result = line.split(separator, 1)[1]
            result = result.strip('"')
            result = result.strip(' ')
            fd.close()
            return result
    fd.close()
    return None

def kadmin(command):
    ipautil.run(["kadmin.local", "-q", command,
                                 "-x", "ipa-setup-override-restrictions"])

def kadmin_addprinc(principal):
    kadmin("addprinc -randkey " + principal)

def kadmin_modprinc(principal, options):
    kadmin("modprinc " + options + " " + principal)

def create_keytab(path, principal):
    try:
        if ipautil.file_exists(path):
            os.remove(path)
    except os.error:
        logging.critical("Failed to remove %s." % path)

    kadmin("ktadd -k " + path + " " + principal)

def wait_for_open_ports(host, ports, timeout=0):
    """
    Wait until the specified port(s) on the remote host are open. Timeout
    in seconds may be specified to limit the wait.
    """
    if not isinstance(ports, (tuple, list)):
        ports = [ports]

    op_timeout = time.time() + timeout
    ipv6_failover = False

    for port in ports:
        while True:
            try:
                if ipv6_failover:
                    s = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
                else:
                    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                s.connect((host, port))
                s.close()
                break;
            except socket.error, e:
                if e.errno == 111:  # 111: Connection refused
                    if timeout and time.time() > op_timeout: # timeout exceeded
                        raise e
                    time.sleep(1)
                elif not ipv6_failover: # fallback to IPv6 connection
                    ipv6_failover = True
                else:
                    raise e

def wait_for_open_socket(socket_name, timeout=0):
    """
    Wait until the specified socket on the local host is open. Timeout
    in seconds may be specified to limit the wait.
    """
    op_timeout = time.time() + timeout

    while True:
        try:
            s = socket.socket(socket.AF_UNIX)
            s.connect(socket_name)
            s.close()
            break;
        except socket.error, e:
            if e.errno == 111:  # 111: Connection refused
                if timeout and time.time() > op_timeout: # timeout exceeded
                    raise e
                time.sleep(1)
            else:
                raise e

def resolve_host(host_name):
    try:
        addrinfos = socket.getaddrinfo(host_name, None,
                                       socket.AF_UNSPEC, socket.SOCK_STREAM)
        for ai in addrinfos:
            ip = ai[4][0]
            if ip == "127.0.0.1" or ip == "::1":
                raise HostnameLocalhost("The hostname resolves to the localhost address")

        return addrinfos[0][4][0]
    except:
        return None

def get_host_name(no_host_dns):
    """
    Get the current FQDN from the socket and verify that it is valid.

    no_host_dns is a boolean that determines whether we enforce that the
    hostname is resolvable.

    Will raise a RuntimeError on error, returns hostname on success
    """
    hostname = get_fqdn()
    verify_fqdn(hostname, no_host_dns)
    return hostname

def expand_replica_info(filename, password):
    """
    Decrypt and expand a replica installation file into a temporary
    location. The caller is responsible to remove this directory.
    """
    top_dir = tempfile.mkdtemp("ipa")
    tarfile = top_dir+"/files.tar"
    dir = top_dir + "/realm_info"
    ipautil.decrypt_file(filename, tarfile, password, top_dir)
    ipautil.run(["tar", "xf", tarfile, "-C", top_dir])
    os.remove(tarfile)

    return top_dir, dir

def read_replica_info(dir, rconfig):
    """
    Read the contents of a replica installation file.

    rconfig is a ReplicaConfig object
    """
    filename = dir + "/realm_info"
    fd = open(filename)
    config = SafeConfigParser()
    config.readfp(fd)

    rconfig.realm_name = config.get("realm", "realm_name")
    rconfig.master_host_name = config.get("realm", "master_host_name")
    rconfig.domain_name = config.get("realm", "domain_name")
    rconfig.host_name = config.get("realm", "destination_host")
    rconfig.subject_base = config.get("realm", "subject_base")

def check_server_configuration():
    """
    Check if IPA server is configured on the system.

    This is done by checking if there are system restore (uninstall) files
    present on the system. Note that this check can only be run with root
    privileges.

    When IPA is not configured, this function raises a RuntimeError exception.
    Most convenient use case for the function is in install tools that require
    configured IPA for its function.
    """
    server_fstore = sysrestore.FileStore('/var/lib/ipa/sysrestore')
    if not server_fstore.has_files():
        raise RuntimeError("IPA is not configured on this system.")

def remove_file(filename):
    """
    Remove a file and log any exceptions raised.
    """
    try:
        if os.path.exists(filename):
            os.unlink(filename)
    except Exception, e:
        logging.error('Error removing %s: %s' % (filename, str(e)))

def rmtree(path):
    """
    Remove a directory structure and log any exceptions raised.
    """
    try:
        if os.path.exists(path):
            shutil.rmtree(path)
    except Exception, e:
        logging.error('Error removing %s: %s' % (path, str(e)))

def is_ipa_configured():
    """
    Using the state and index install files determine if IPA is already
    configured.
    """
    installed = False

    sstore = sysrestore.StateFile('/var/lib/ipa/sysrestore')
    fstore = sysrestore.FileStore('/var/lib/ipa/sysrestore')

    for module in IPA_MODULES:
        if sstore.has_state(module):
            logging.debug('%s is configured' % module)
            installed = True
        else:
            logging.debug('%s is not configured' % module)

    if fstore.has_files():
        logging.debug('filestore has files')
        installed = True
    else:
        logging.debug('filestore is tracking no files')

    return installed