Iosxr telnet implementation (#19)

* Implemented the feature iosxr_telnet

* Update iosxr_telnet.tf

---------

Co-authored-by: Praveen Matanam <pmatanam@cisco.com>

Author: praveenmatanam

README.md

@@ -72,6 +72,7 @@ module "iosxr" {
 | [iosxr_service_timestamps.service_timestamps](https://registry.terraform.io/providers/CiscoDevNet/iosxr/latest/docs/resources/service_timestamps) | resource |
 | [iosxr_snmp_server_mib.snmp_server_mib](https://registry.terraform.io/providers/CiscoDevNet/iosxr/latest/docs/resources/snmp_server_mib) | resource |
 | [iosxr_snmp_server_view.snmp_server_view](https://registry.terraform.io/providers/CiscoDevNet/iosxr/latest/docs/resources/snmp_server_view) | resource |
+| [iosxr_telnet.telnet](https://registry.terraform.io/providers/CiscoDevNet/iosxr/latest/docs/resources/telnet) | resource |
 | [local_sensitive_file.defaults](https://registry.terraform.io/providers/hashicorp/local/latest/docs/resources/sensitive_file) | resource |
 | [terraform_data.validation](https://registry.terraform.io/providers/hashicorp/terraform/latest/docs/resources/data) | resource |
 ## Modules

iosxr_telnet.tf

@@ -0,0 +1,40 @@
+locals {
+  device_telnet_configs = flatten([
+    for device in local.devices : [
+      {
+        device_name = device.name
+        key         = "${device.name}-telnet"
+
+        ipv4_client_source_interface = try(local.device_config[device.name].telnet.ipv4_client_source_interface, local.defaults.iosxr.configuration.telnet.ipv4_client_source_interface, null)
+        ipv6_client_source_interface = try(local.device_config[device.name].telnet.ipv6_client_source_interface, local.defaults.iosxr.configuration.telnet.ipv6_client_source_interface, null)
+
+        vrfs = [
+          for vrf in try(local.device_config[device.name].telnet.vrfs, local.defaults.iosxr.configuration.telnet.vrfs, []) : {
+            vrf_name                = try(vrf.vrf_name, null)
+            ipv4_server_max_servers = try(vrf.ipv4_server_max_servers, null)
+            ipv4_server_access_list = try(vrf.ipv4_server_access_list, null)
+            ipv6_server_max_servers = try(vrf.ipv6_server_max_servers, null)
+            ipv6_server_access_list = try(vrf.ipv6_server_access_list, null)
+          }
+        ]
+
+        vrfs_dscp = [
+          for vrf_dscp in try(local.device_config[device.name].telnet.vrfs_dscp, local.defaults.iosxr.configuration.telnet.vrfs_dscp, []) : {
+            vrf_name  = try(vrf_dscp.vrf_name, null)
+            ipv4_dscp = try(vrf_dscp.ipv4_dscp, null)
+          }
+        ]
+      }
+    ] if try(local.device_config[device.name].telnet, null) != null || try(local.defaults.iosxr.configuration.telnet, null) != null
+  ])
+}
+
+resource "iosxr_telnet" "telnet" {
+  for_each = { for telnet_config in local.device_telnet_configs : telnet_config.key => telnet_config }
+  device   = each.value.device_name
+
+  ipv4_client_source_interface = each.value.ipv4_client_source_interface
+  ipv6_client_source_interface = each.value.ipv6_client_source_interface
+  vrfs                         = each.value.vrfs
+  vrfs_dscp                    = each.value.vrfs_dscp
+}