fix: Use variable length byte to encode the subscription ID (#74)

The length of the package was already properly calculated. Only the
value itself wasn't properly encoded in the packet.

Closes #73

src/v5/codec/encode.rs

@@ -272,7 +272,7 @@ pub(super) fn reduce_limit(limit: u32, reduction: usize) -> u32 {
 #[cfg(test)]
 mod tests {
     use ntex::util::Bytes;
-    use std::num::NonZeroU16;
+    use std::num::{NonZeroU16, NonZeroU32};
 
     use super::*;
     use crate::types::{QoS, MAX_PACKET_SIZE};
@@ -411,6 +411,22 @@ mod tests {
             }),
             b"\x30\x0c\x00\x05topic\x00data",
         );
+
+        assert_encode_packet(
+            &Packet::Publish(Publish {
+                dup: false,
+                retain: false,
+                qos: QoS::AtMostOnce,
+                topic: ByteString::from_static("topic"),
+                packet_id: None,
+                payload: Bytes::from_static(b"data"),
+                properties: PublishProperties {
+                    subscription_ids: Some(vec![NonZeroU32::new(1).unwrap()]),
+                    ..Default::default()
+                },
+            }),
+            b"\x30\x0e\x00\x05topic\x02\x0b\x01data",
+        );
     }
 
     #[test]
@@ -444,6 +460,35 @@ mod tests {
             b"\x82\x13\x12\x34\x00\x00\x04test\x01\x00\x06filter\x02",
         );
 
+        assert_encode_packet(
+            &Packet::Subscribe(Subscribe {
+                packet_id: packet_id(0x1234),
+                id: Some(NonZeroU32::new(1).unwrap()),
+                user_properties: Vec::new(),
+                topic_filters: vec![
+                    (
+                        ByteString::from_static("test"),
+                        SubscriptionOptions {
+                            qos: QoS::AtLeastOnce,
+                            no_local: false,
+                            retain_as_published: false,
+                            retain_handling: RetainHandling::AtSubscribe,
+                        },
+                    ),
+                    (
+                        ByteString::from_static("filter"),
+                        SubscriptionOptions {
+                            qos: QoS::ExactlyOnce,
+                            no_local: false,
+                            retain_as_published: false,
+                            retain_handling: RetainHandling::AtSubscribe,
+                        },
+                    ),
+                ],
+            }),
+            b"\x82\x14\x12\x34\x01\x0b\x01\x00\x04test\x01\x00\x06filter\x02",
+        );
+
         assert_encode_packet(
             &Packet::SubscribeAck(SubscribeAck {
                 packet_id: packet_id(0x1234),

src/v5/codec/packet/publish.rs

@@ -3,7 +3,7 @@ use std::{convert::TryFrom, fmt, num::NonZeroU16, num::NonZeroU32};
 
 use crate::error::{DecodeError, EncodeError};
 use crate::types::QoS;
-use crate::utils::{self, Decode, Encode, Property};
+use crate::utils::{self, write_variable_length, Decode, Encode, Property};
 use crate::v5::codec::{encode::*, property_type as pt, UserProperties};
 
 /// PUBLISH message
@@ -183,7 +183,7 @@ impl EncodeLtd for PublishProperties {
         if let Some(sub_ids) = self.subscription_ids.as_ref() {
             for sub_id in sub_ids.iter() {
                 buf.put_u8(pt::SUB_ID);
-                sub_id.encode(buf)?;
+                write_variable_length(sub_id.get(), buf);
             }
         }
         self.user_properties.encode(buf)

src/v5/codec/packet/subscribe.rs

@@ -5,7 +5,7 @@ use std::num::{NonZeroU16, NonZeroU32};
 use super::ack_props;
 use crate::error::{DecodeError, EncodeError};
 use crate::types::QoS;
-use crate::utils::{self, Decode, Encode};
+use crate::utils::{self, write_variable_length, Decode, Encode};
 use crate::v5::codec::{encode::*, property_type as pt, UserProperties, UserProperty};
 
 /// Represents SUBSCRIBE packet
@@ -191,7 +191,12 @@ impl EncodeLtd for Subscribe {
         let prop_len = self.id.map_or(0, |v| var_int_len(v.get() as usize))
             + self.user_properties.encoded_size() as u32; // safe: size was already checked against maximum
         utils::write_variable_length(prop_len, buf);
-        encode_property(&self.id, pt::SUB_ID, buf)?;
+
+        if let Some(id) = self.id {
+            buf.put_u8(pt::SUB_ID);
+            write_variable_length(id.get(), buf);
+        }
+
         for (filter, opts) in self.topic_filters.iter() {
             filter.encode(buf)?;
             opts.encode(buf)?;