Add new windows module: win_hosts (ansible#46450)

* Add win_hosts module

added win_hosts module for easier manipulation of hosts entries in "%windir%\system32\drivers\etc\hosts" for windows systems

* Update win_hosts.py

* Add alias support to win_hosts module (#1)

* win_hosts supports aliases

added support for adding / removing aliases from a host entry, rather than adding a new entry

added ability for win_hosts to detect aliases:
`192.168.1.1 alias1 alias2 alias3`
```
win_hosts:
  host_name: alias2
  ip_address: 192.168.1.1
```
will result in `192.168.1.1 alias1 alias3`

also includes `replace` and `add` as options for `ip_action` (`replace` is default)

for example:
```
192.168.1.1 my_reused_alias
192.168.1.2 my_reused_alias
```
with
```
win_hosts:
  host_name: my_reused_alias
  ip_address: 192.168.1.3
  ip_action: add
```
the result will be
```
192.168.1.1 my_reused_alias
192.168.1.2 my_reused_alias
```
but with `ip_action=replace` the result would be
```
192.168.1.3 my_reused_alias
```

* fixed metadata version and version added

* fix line endings

* upload fixed line endings

try to upload the file with the fixed line endings

* aliases and canonical names are separate entities. added IPv4 and IPv6 validation

* only makes changes if "check_mode" is false

* improved behavior for duplicate aliases/entries.

* adding tests

* missing aliases file

* fix trailing whitespace and uses explicit paths

* Tweak tests to copy and restore original hosts file

lib/ansible/modules/windows/win_hosts.ps1

@@ -0,0 +1,298 @@
+#!powershell
+
+# Copyright: (c) 2018, Micah Hunsberger (@mhunsber)
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+#Requires -Module Ansible.ModuleUtils.Legacy
+
+Set-StrictMode -Version 2
+$ErrorActionPreference = "Stop"
+
+$params = Parse-Args -arguments $args -supports_check_mode $true
+$check_mode = Get-AnsibleParam -obj $params -name "_ansible_check_mode" -type "bool" -default $false
+$diff_mode = Get-AnsibleParam -obj $params -name "_ansible_diff" -type "bool" -default $false
+
+$state = Get-AnsibleParam -obj $params -name "state" -type "str" -default "present" -validateset "absent","present"
+$aliases = Get-AnsibleParam -obj $params -name "aliases" -type "list" -failifempty $false
+$canonical_name = Get-AnsibleParam -obj $params -name "canonical_name" -type "str" -failifempty ($state -eq 'present')
+$ip_address = Get-AnsibleParam -obj $params -name "ip_address" -type "str" -default "" -failifempty ($state -eq 'present')
+$action = Get-AnsibleParam -obj $params -name "action" -type "str" -default "set" -validateset "add","remove","set"
+
+$tmp = [ipaddress]::None
+if($ip_address -and -not [ipaddress]::TryParse($ip_address, [ref]$tmp)){
+    Fail-Json -obj @{} -message "win_hosts: Argument ip_address needs to be a valid ip address, but was $ip_address"
+}
+$ip_address_type = $tmp.AddressFamily
+
+$hosts_file = Get-Item -LiteralPath "$env:SystemRoot\System32\drivers\etc\hosts"
+
+$result = @{
+    changed = $false
+    diff = @{
+        prepared = ""
+    }
+}
+
+Function Get-CommentIndex($line) {
+    $c_index = $line.IndexOf('#')
+    if($c_index -lt 0) {
+        $c_index = $line.Length
+    }
+    return $c_index
+}
+
+Function Get-HostEntryParts($line) {
+    $success = $true
+    $c_index = Get-CommentIndex -line $line
+    $pure_line = $line.Substring(0,$c_index).Trim()
+    $bits = $pure_line -split "\s+"
+    if($bits.Length -lt 2){
+        return @{
+            success = $false
+            ip_address = ""
+            ip_type = ""
+            canonical_name = ""
+            aliases = @()
+        }
+    }
+    $ip_obj = [ipaddress]::None
+    if(-not [ipaddress]::TryParse($bits[0], [ref]$ip_obj) ){
+        $success = $false
+    }
+    $cname = $bits[1]
+    $als = New-Object string[] ($bits.Length - 2)
+    [array]::Copy($bits, 2, $als, 0, $als.Length)
+    return @{
+        success = $success
+        ip_address = $ip_obj.IPAddressToString
+        ip_type = $ip_obj.AddressFamily
+        canonical_name = $cname
+        aliases = $als
+    }
+}
+
+Function Find-HostName($line, $name) {
+    $c_idx = Get-CommentIndex -line $line
+    $re = New-Object regex ("\s+$($name.Replace('.',"\."))(\s|$)", [System.Text.RegularExpressions.RegexOptions]::IgnoreCase)
+    $match = $re.Match($line, 0, $c_idx)
+    return $match
+}
+
+Function Remove-HostEntry($list, $idx) {
+    $result.changed = $true
+    $removed = $false
+
+    if($diff_mode) {
+        $result.diff.prepared += "`n-[$($list[$idx])]`n"
+    }
+
+    if(-not $check_mode) {
+        $list.RemoveAt($idx)
+        $removed = $true
+    }
+
+    return $removed
+}
+
+Function Add-HostEntry($list, $cname, $aliases, $ip) {
+    $result.changed = $true
+    $line = "$ip $cname $($aliases -join ' ')"
+    if($diff_mode) {
+        $result.diff.prepared += "`n+[$line]`n"
+    }
+    if(-not $check_mode) {
+        $list.Add($line) | Out-Null
+    }
+}
+
+Function Remove-HostnamesFromEntry($list, $idx, $aliases) {
+    $line = $list[$idx]
+    $line_removed = $false
+
+    foreach($name in $aliases){
+        $match = Find-HostName -line $line -name $name
+        if($match.Success){
+            $line = $line.Remove($match.Index + 1, $match.Length -1)
+            # was this the last alias? (check for space characters after trimming)
+            if($line.Substring(0,(Get-CommentIndex -line $line)).Trim() -inotmatch "\s") {
+                if($diff_mode){
+                    $result.diff.prepared += "`n-[$($list[$idx])]`n"
+                }
+                if(-not $check_mode) {
+                    $list.RemoveAt($idx)
+                    $line_removed = $true
+                }
+                # we're done
+                return @{
+                    line_removed = $line_removed
+                }
+            }
+        }
+    }
+    if($line -ne $list[$idx]){
+        $result.changed = $true
+        if($diff_mode) {
+            $result.diff.prepared += "`n-[$($list[$idx])]`n+[$line]`n"
+        }
+        if(-not $check_mode) {
+            $list[$idx] = $line
+        }
+    }
+    return @{
+        line_removed = $line_removed
+    }
+}
+
+Function Add-AliasesToEntry($list, $idx, $aliases) {
+    $line = $list[$idx]
+    foreach($name in $aliases){
+        $match = Find-HostName -line $line -name $name
+        if(-not $match.Success) {
+            # just add the alias before the comment
+            $line = $line.Insert((Get-CommentIndex -line $line), " $name ")
+        }
+    }
+    if($line -ne $list[$idx]){
+        $result.changed = $true
+        if($diff_mode) {
+            $result.diff.prepared += "`n-[$($list[$idx])]`n+[$line]`n"
+        }
+        if(-not $check_mode) {
+            $list[$idx] = $line
+        }
+    }
+}
+
+$hosts_lines = New-Object System.Collections.ArrayList
+
+Get-Content -LiteralPath $hosts_file.FullName | ForEach-Object { $hosts_lines.Add($_) } | Out-Null
+
+if ($state -eq 'absent') {
+    # go through and remove canonical_name and ip
+    for($idx = 0; $idx -lt $hosts_lines.Count; $idx++) {
+        $entry = $hosts_lines[$idx]
+         # skip comment lines
+         if(-not $entry.Trim().StartsWith('#')) {
+            $entry_parts = Get-HostEntryParts -line $entry
+            if($entry_parts.success) {
+                if(-not $ip_address -or $entry_parts.ip_address -eq $ip_address) {
+                    if(-not $canonical_name -or $entry_parts.canonical_name -eq $canonical_name) {
+                        if(Remove-HostEntry -list $hosts_lines -idx $idx){
+                            # keep index correct if we removed the line
+                            $idx = $idx - 1
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+if($state -eq 'present') {
+    $entry_idx = -1
+    $aliases_to_keep = @()
+    # go through lines, find the entry and determine what to remove based on action
+    for($idx = 0; $idx -lt $hosts_lines.Count; $idx++) {
+        $entry = $hosts_lines[$idx]
+         # skip comment lines
+         if(-not $entry.Trim().StartsWith('#')) {
+            $entry_parts = Get-HostEntryParts -line $entry
+            if($entry_parts.success) {
+                $aliases_to_remove = @()
+                if($entry_parts.ip_address -eq $ip_address) {
+                    if($entry_parts.canonical_name -eq $canonical_name) {
+                        # don't need to worry about line being removed since canonical_name is present
+                        $entry_idx = $idx
+
+                        if($action -eq 'set') {
+                            # remove the entry's aliases that are not in $aliases
+                            $aliases_to_remove = $entry_parts.aliases | Where-Object { $aliases -notcontains $_ }
+                        } elseif($action -eq 'remove') {
+                            $aliases_to_remove = $aliases
+                        }
+                    } else {
+                        # this is the right ip_address, but not the cname we were looking for.
+                        # we need to make sure none of aliases or canonical_name exist for this entry
+                        # since the given canonical_name should be an A/AAAA record,
+                        # and aliases should be cname records for the canonical_name.
+                        $aliases_to_remove = $aliases + $canonical_name
+                    }
+                } else {
+                    # this is not the ip_address we are looking for
+                    if ($ip_address_type -eq $entry_parts.ip_type) {
+                        if ($entry_parts.canonical_name -eq $canonical_name) {
+                            # remove the entry
+                            if (Remove-HostEntry -list $hosts_lines -idx $idx){
+                                # keep index correct if we removed the line
+                                $idx = $idx - 1
+                            }
+                            if ($action -ne "set") {
+                                # keep old aliases intact
+                                $aliases_to_keep += $entry_parts.aliases | Where-Object { ($aliases + $aliases_to_keep + $canonical_name) -notcontains $_ }
+                            }
+                        } elseif ($action -eq "remove") {
+                            # just remove canonical_name. user may want alias(es) mapped to this canonical name
+                            $aliases_to_remove = $canonical_name
+                        } elseif ($aliases -contains $entry_parts.canonical_name) {
+                            # remove the entry
+                            if (Remove-HostEntry -list $hosts_lines -idx $idx) {
+                                # keep index correct if we removed the line
+                                $idx = $idx - 1
+                            }
+                            if ($action -eq "add") {
+                                # keep old aliases intact
+                                $aliases_to_keep += $entry_parts.aliases | Where-Object { ($aliases + $aliases_to_keep + $canonical_name) -notcontains $_ }
+                            }
+                        } else {
+                            # ensure canonical_name and aliases removed from this entry
+                            $aliases_to_remove = $aliases + $canonical_name
+                        }
+                    } else {
+                        # Just ignore if the types don't match.
+                        # TODO: Better ipv6 support. There is odd behavior for when an alias can be used for both ipv6 and ipv4
+                    }
+                }
+
+                if($aliases_to_remove) {
+                    if((Remove-HostnamesFromEntry -list $hosts_lines -idx $idx -aliases $aliases_to_remove).line_removed) {
+                        # keep index correct if we removed the line
+                        $idx = $idx - 1
+                    }
+                }
+            }
+        }
+    }
+
+    if($entry_idx -ge 0) {
+        # we found the entry
+        $aliases_to_add = @()
+        $entry_parts = Get-HostEntryParts -line $hosts_lines[$entry_idx]
+        if($action -eq 'remove') {
+            # just preserve any previously removed aliases
+            $aliases_to_add = $aliases_to_keep | Where-Object { $entry_parts.aliases -notcontains $_ }
+        } else {
+            # we want to add provided aliases and previously removed aliases that are not already in the list
+            $aliases_to_add = ($aliases + $aliases_to_keep) | Where-Object { $entry_parts.aliases -notcontains $_ }
+        }
+
+        if($aliases_to_add) {
+            Add-AliasesToEntry -list $hosts_lines -idx $entry_idx -aliases $aliases_to_add
+        }
+    } else {
+        # add the entry at the end
+        if($action -eq 'remove') {
+            if($aliases_to_keep) {
+                Add-HostEntry -list $hosts_lines -ip $ip_address -cname $canonical_name -aliases $aliases_to_keep
+            } else {
+                Add-HostEntry -list $hosts_lines -ip $ip_address -cname $canonical_name
+            }
+        } else {
+            Add-HostEntry -list $hosts_lines -ip $ip_address -cname $canonical_name -aliases ($aliases + $aliases_to_keep)
+        }
+    }
+}
+
+if( $result.changed -and -not $check_mode ) {
+    Set-Content -LiteralPath $hosts_file.FullName -Value $hosts_lines
+}
+
+Exit-Json $result