package PVE::Corosync;

use strict;
use warnings;

use Clone 'clone';
use Digest::SHA;
use Net::IP qw(ip_is_ipv6);
use Scalar::Util qw(weaken);
use Socket qw(AF_INET AF_INET6 inet_ntop);

use PVE::Cluster;
use PVE::JSONSchema;
use PVE::Tools;
use PVE::Tools qw($IPV4RE $IPV6RE);

my $basedir = "/etc/pve";
our $link_addr_re = qw/^(ring|link)(\d+)_addr$/;

my $conf_array_sections = {
    node => 1,
    interface => 1,
};

my $corosync_link_format = {
    address => {
        default_key => 1,
        type => 'string',
        format => 'address',
        format_description => 'IP',
        description => "Hostname (or IP) of this corosync link address.",
    },
    priority => {
        optional => 1,
        type => 'integer',
        minimum => 0,
        maximum => 255,
        default => 0,
        description => "The priority for the link when knet is used in 'passive'"
            . " mode (default). Lower value means higher priority. Only"
            . " valid for cluster create, ignored on node add.",
    },
};
my $corosync_link_desc = {
    type => 'string',
    format => $corosync_link_format,
    description => "Address and priority information of a single corosync link."
        . " (up to 8 links supported; link0..link7)",
    optional => 1,
};
PVE::JSONSchema::register_standard_option("corosync-link", $corosync_link_desc);

sub parse_corosync_link {
    my ($value) = @_;

    return undef if !defined($value);

    return PVE::JSONSchema::parse_property_string($corosync_link_format, $value);
}

sub print_corosync_link {
    my ($link) = @_;

    return undef if !defined($link);

    return PVE::JSONSchema::print_property_string($link, $corosync_link_format);
}

use constant MAX_LINK_INDEX => 7;

sub add_corosync_link_properties {
    my ($prop) = @_;

    for my $lnum (0 .. MAX_LINK_INDEX) {
        $prop->{"link$lnum"} = PVE::JSONSchema::get_standard_option("corosync-link");
    }

    return $prop;
}

sub extract_corosync_link_args {
    my ($args) = @_;

    my $links = {};
    for my $lnum (0 .. MAX_LINK_INDEX) {
        $links->{$lnum} = parse_corosync_link($args->{"link$lnum"})
            if $args->{"link$lnum"};
    }

    return $links;
}

# a very simply parser ...
sub parse_conf {
    my ($filename, $raw) = @_;

    return {} if !$raw;

    my $digest = Digest::SHA::sha1_hex(defined($raw) ? $raw : '');

    $raw =~ s/#.*$//mg;
    $raw =~ s/\r?\n/ /g;
    $raw =~ s/\s+/ /g;
    $raw =~ s/^\s+//;
    $raw =~ s/\s*$//;

    my @tokens = split(/\s/, $raw);

    my $conf = { 'main' => {} };

    my $stack = [];
    my $section = $conf->{main};

    while (defined(my $token = shift @tokens)) {
        my $nexttok = $tokens[0];

        if ($nexttok && ($nexttok eq '{')) {
            shift @tokens; # skip '{'
            my $new_section = {};
            if ($conf_array_sections->{$token}) {
                $section->{$token} = [] if !defined($section->{$token});
                push @{ $section->{$token} }, $new_section;
            } elsif (!defined($section->{$token})) {
                $section->{$token} = $new_section;
            } else {
                die "section '$token' already exists and not marked as array!\n";
            }
            push @$stack, $section;
            $section = $new_section;
            next;
        }

        if ($token eq '}') {
            $section = pop @$stack;
            die "parse error - uncexpected '}'\n" if !$section;
            next;
        }

        my $key = $token;
        die "missing ':' after key '$key'\n" if !($key =~ s/:$//);

        die "parse error - no value for '$key'\n" if !defined($nexttok);
        my $value = shift @tokens;

        $section->{$key} = $value;
    }

    # make working with the config way easier
    my ($totem, $nodelist) = $conf->{main}->@{ "totem", "nodelist" };

    $nodelist->{node} = {
        map {
            $_->{name} // $_->{ring0_addr} => $_
        } @{ $nodelist->{node} }
    };
    $totem->{interface} = {
        map {
            $_->{linknumber} // $_->{ringnumber} => $_
        } @{ $totem->{interface} }
    };

    $conf->{digest} = $digest;

    return $conf;
}

sub write_conf {
    my ($filename, $conf) = @_;

    my $c = clone($conf->{main}) // die "no main section";

    # retransform back for easier dumping
    my $hash_to_array = sub {
        my ($hash) = @_;
        return [$hash->@{ sort keys %$hash }];
    };

    $c->{nodelist}->{node} = &$hash_to_array($c->{nodelist}->{node});
    $c->{totem}->{interface} = &$hash_to_array($c->{totem}->{interface});

    my $dump_section_weak;
    $dump_section_weak = sub {
        my ($section, $prefix) = @_;

        my $raw = '';

        foreach my $k (sort keys %$section) {
            my $v = $section->{$k};
            if (ref($v) eq 'HASH') {
                $raw .= $prefix . "$k {\n";
                $raw .= $dump_section_weak->($v, "$prefix  ");
                $raw .= $prefix . "}\n";
                $raw .= "\n" if !$prefix; # add extra newline at 1st level only
            } elsif (ref($v) eq 'ARRAY') {
                foreach my $child (@$v) {
                    $raw .= $prefix . "$k {\n";
                    $raw .= $dump_section_weak->($child, "$prefix  ");
                    $raw .= $prefix . "}\n";
                }
            } elsif (!ref($v)) {
                die "got undefined value for key '$k'!\n" if !defined($v);
                $raw .= $prefix . "$k: $v\n";
            } else {
                die "unexpected reference in config hash: $k => " . ref($v) . "\n";
            }
        }

        return $raw;
    };
    my $dump_section = $dump_section_weak;
    weaken($dump_section_weak);

    my $raw = $dump_section->($c, '');

    return $raw;
}

# read only - use atomic_write_conf method to write
PVE::Cluster::cfs_register_file('corosync.conf', \&parse_conf);
# this is read/write
PVE::Cluster::cfs_register_file('corosync.conf.new', \&parse_conf, \&write_conf);

sub check_conf_exists {
    my ($noerr) = @_;

    my $exists = -f "$basedir/corosync.conf";

    die
        "Error: Corosync config '$basedir/corosync.conf' does not exist - is this node part of a cluster?\n"
        if !$noerr && !$exists;

    return $exists;
}

sub update_nodelist {
    my ($conf, $nodelist) = @_;

    $conf->{main}->{nodelist}->{node} = $nodelist;

    atomic_write_conf($conf);
}

sub nodelist {
    my ($conf) = @_;
    return clone($conf->{main}->{nodelist}->{node});
}

sub totem_config {
    my ($conf) = @_;
    return clone($conf->{main}->{totem});
}

# caller must hold corosync.conf cfs lock if used in read-modify-write cycle
sub atomic_write_conf {
    my ($conf, $no_increase_version) = @_;

    if (!$no_increase_version) {
        die "invalid corosync config: unable to read config version\n"
            if !defined($conf->{main}->{totem}->{config_version});
        $conf->{main}->{totem}->{config_version}++;
    }

    PVE::Cluster::cfs_write_file("corosync.conf.new", $conf);

    rename("/etc/pve/corosync.conf.new", "/etc/pve/corosync.conf")
        || die "activating corosync.conf.new failed - $!\n";
}

# for creating a new cluster with the current node
# params are those from the API/CLI cluster create call
sub create_conf {
    my ($nodename, $param) = @_;

    my $clustername = $param->{clustername};
    my $nodeid = $param->{nodeid} || 1;
    my $votes = $param->{votes} || 1;
    my $token_coefficient = $param->{'token-coefficient'};

    my $local_ip_address = PVE::Cluster::remote_node_ip($nodename);

    my $links = extract_corosync_link_args($param);

    # if no links given, fall back to local IP as link0
    $links->{0} = { address => $local_ip_address }
        if !%$links;

    my $conf = {
        totem => {
            version => 2, # protocol version
            secauth => 'on',
            cluster_name => $clustername,
            config_version => 0,
            ip_version => 'ipv4-6',
            link_mode => 'passive',
            interface => {},
        },
        nodelist => {
            node => {
                $nodename => {
                    name => $nodename,
                    nodeid => $nodeid,
                    quorum_votes => $votes,
                },
            },
        },
        quorum => {
            provider => 'corosync_votequorum',
        },
        logging => {
            to_syslog => 'yes',
            debug => 'off',
        },
    };
    my $totem = $conf->{totem};
    my $node = $conf->{nodelist}->{node}->{$nodename};

    foreach my $lnum (keys %$links) {
        my $link = $links->{$lnum};

        $totem->{interface}->{$lnum} = { linknumber => $lnum };

        my $prio = $link->{priority};
        $totem->{interface}->{$lnum}->{knet_link_priority} = $prio if $prio;

        $node->{"ring${lnum}_addr"} = $link->{address};
    }

    $totem->{token_coefficient} = $token_coefficient if defined($token_coefficient);

    return { main => $conf };
}

# returns (\@errors, \@warnings) to the caller, does *not* 'die' or 'warn'
# verification was successful if \@errors is empty
sub verify_conf {
    my ($conf) = @_;

    my @errors = ();
    my @warnings = ();

    my $nodelist = nodelist($conf);
    if (!$nodelist) {
        push @errors, "no nodes found";
        return (\@errors, \@warnings);
    }

    my $totem = $conf->{main}->{totem};
    if (!$totem) {
        push @errors, "no totem found";
        return (\@errors, \@warnings);
    }

    if (
        (!defined($totem->{secauth}) || $totem->{secauth} ne 'on')
        && (!defined($totem->{crypto_cipher}) || $totem->{crypto_cipher} eq 'none')
    ) {
        push @warnings, "warning: authentication/encryption is not explicitly enabled"
            . " (secauth / crypto_cipher / crypto_hash)";
    }

    my $interfaces = $totem->{interface};

    my $verify_link_ip = sub {
        my ($key, $link, $node) = @_;
        my ($resolved_ip, undef) = resolve_hostname_like_corosync($link, $conf);
        if (!defined($resolved_ip)) {
            push @warnings,
                "warning: unable to resolve $key '$link' for node '$node'"
                . " to an IP address according to Corosync's resolve strategy -"
                . " cluster could fail on restart!";
        } elsif ($resolved_ip ne $link) {
            push @warnings,
                "warning: $key '$link' for node '$node' resolves to"
                . " '$resolved_ip' - consider replacing it with the currently"
                . " resolved IP address for stability";
        }
    };

    # sort for output order stability
    my @node_names = sort keys %$nodelist;

    my $node_links = {};
    foreach my $node (@node_names) {
        my $options = $nodelist->{$node};
        foreach my $opt (keys %$options) {
            my ($linktype, $linkid) = parse_link_entry($opt);
            next if !defined($linktype);
            $node_links->{$node}->{$linkid} = {
                name => "${linktype}${linkid}_addr",
                addr => $options->{$opt},
            };
        }
    }

    if (%$interfaces) {
        # if interfaces are defined, *all* links must have a matching interface
        # definition, and vice versa
        for my $link (0 .. MAX_LINK_INDEX) {
            my $have_interface = defined($interfaces->{$link});
            foreach my $node (@node_names) {
                my $linkdef = $node_links->{$node}->{$link};
                if (defined($linkdef)) {
                    $verify_link_ip->($linkdef->{name}, $linkdef->{addr}, $node);
                    if (!$have_interface) {
                        push @errors, "node '$node' has '$linkdef->{name}', but"
                            . " there is no interface number $link configured";
                    }
                } else {
                    if ($have_interface) {
                        push @errors,
                            "node '$node' is missing address for" . "interface number $link";
                    }
                }
            }
        }
    } else {
        # without interfaces, only check that links are consistent among nodes
        for my $link (0 .. MAX_LINK_INDEX) {
            my $nodes_with_link = {};
            foreach my $node (@node_names) {
                my $linkdef = $node_links->{$node}->{$link};
                if (defined($linkdef)) {
                    $verify_link_ip->($linkdef->{name}, $linkdef->{addr}, $node);
                    $nodes_with_link->{$node} = 1;
                }
            }

            if (%$nodes_with_link) {
                foreach my $node (@node_names) {
                    if (!defined($nodes_with_link->{$node})) {
                        push @errors, "node '$node' is missing link $link,"
                            . " which is configured on other nodes";
                    }
                }
            }
        }
    }

    return (\@errors, \@warnings);
}

# returns ($linktype, $linkid) with $linktype being 'ring' for now, and possibly
# 'link' with upcoming corosync versions
sub parse_link_entry {
    my ($opt) = @_;
    return (undef, undef) if $opt !~ $link_addr_re;
    return ($1, $2);
}

sub for_all_corosync_addresses {
    my ($corosync_conf, $ip_version, $func) = @_;

    my $nodelist = nodelist($corosync_conf);
    return if !defined($nodelist);

    # iterate sorted to make rules deterministic (for change detection)
    foreach my $node_name (sort keys %$nodelist) {
        my $node_config = $nodelist->{$node_name};
        foreach my $node_key (sort keys %$node_config) {
            if ($node_key =~ $link_addr_re) {
                my $node_address = $node_config->{$node_key};

                my ($ip, $version) = resolve_hostname_like_corosync($node_address, $corosync_conf);
                next if !defined($ip);
                next if defined($version) && defined($ip_version) && $version != $ip_version;

                $func->($node_name, $ip, $version, $node_key);
            }
        }
    }
}

# NOTE: Corosync actually only resolves on startup or config change, but we
# currently do not have an easy way to synchronize our behaviour to that.
sub resolve_hostname_like_corosync {
    my ($hostname, $corosync_conf) = @_;

    my $corosync_strategy = $corosync_conf->{main}->{totem}->{ip_version};
    $corosync_strategy = lc($corosync_strategy // "ipv6-4");

    my $match_ip_and_version = sub {
        my ($addr) = @_;

        return undef if !defined($addr);

        if ($addr =~ m/^$IPV4RE$/) {
            return ($addr, 4);
        } elsif ($addr =~ m/^$IPV6RE$/) {
            return ($addr, 6);
        }

        return undef;
    };

    my ($resolved_ip, $ip_version) = $match_ip_and_version->($hostname);

    return ($resolved_ip, $ip_version) if defined($resolved_ip);

    my $resolved_ip4;
    my $resolved_ip6;

    my @resolved_raw;
    eval { @resolved_raw = PVE::Tools::getaddrinfo_all($hostname); };

    return undef if ($@ || !@resolved_raw);

    foreach my $socket_info (@resolved_raw) {
        next if !$socket_info->{addr};

        my ($family, undef, $host) = PVE::Tools::unpack_sockaddr_in46($socket_info->{addr});

        if ($family == AF_INET && !defined($resolved_ip4)) {
            $resolved_ip4 = inet_ntop(AF_INET, $host);
        } elsif ($family == AF_INET6 && !defined($resolved_ip6)) {
            $resolved_ip6 = inet_ntop(AF_INET6, $host);
        }

        last if defined($resolved_ip4) && defined($resolved_ip6);
    }

    # corosync_strategy specifies the order in which IP addresses are resolved
    # by corosync. We need to match that order, to ensure we create firewall
    # rules for the correct address family.
    if ($corosync_strategy eq "ipv4") {
        $resolved_ip = $resolved_ip4;
    } elsif ($corosync_strategy eq "ipv6") {
        $resolved_ip = $resolved_ip6;
    } elsif ($corosync_strategy eq "ipv6-4") {
        $resolved_ip = $resolved_ip6 // $resolved_ip4;
    } elsif ($corosync_strategy eq "ipv4-6") {
        $resolved_ip = $resolved_ip4 // $resolved_ip6;
    }

    return $match_ip_and_version->($resolved_ip);
}

1;