aquatic_http: check info_hash and peer_id len when deserializing

aquatic_http/src/lib/network/mod.rs

@@ -184,6 +184,13 @@ pub fn run_handshake_and_read_requests<'a>(
 
                     debug!("read request, sending to handler");
 
+                    if let Request::Announce(ref request) = request {
+                        for (i, c) in request.info_hash.0.chars().enumerate() {
+                            debug!("{}: {}", i, c.escape_unicode());
+                        }
+                        debug!("request info hash char count: {}", request.info_hash.0.chars().count());
+                    }
+
                     if let Err(err) = request_channel_sender
                         .send((meta, request))
                     {

aquatic_http/src/lib/protocol/mod.rs

@@ -4,9 +4,9 @@ use serde::{Serialize, Deserialize, Serializer};
 
 use crate::common::Peer;
 
-// mod serde_helpers;
+mod serde_helpers;
 
-// use serde_helpers::*;
+use serde_helpers::*;
 
 
 pub fn serialize_response_peers_compact<S>(
@@ -36,10 +36,9 @@ pub fn serialize_response_peers_compact<S>(
 #[derive(Debug, Clone, Hash, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(transparent)]
 pub struct PeerId(
-    // #[serde(
-    //     deserialize_with = "deserialize_20_bytes",
-    //     serialize_with = "serialize_20_bytes"
-    // )]
+    #[serde(
+        deserialize_with = "deserialize_20_char_string",
+    )]
     pub String
 );
 
@@ -47,10 +46,9 @@ pub struct PeerId(
 #[derive(Debug, Clone, Hash, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(transparent)]
 pub struct InfoHash(
-    // #[serde(
-    //     deserialize_with = "deserialize_20_bytes",
-    //     serialize_with = "serialize_20_bytes"
-    // )]
+    #[serde(
+        deserialize_with = "deserialize_20_char_string",
+    )]
     pub String
 );
 
@@ -129,7 +127,10 @@ pub struct AnnounceResponseFailure {
 
 #[derive(Debug, Clone, Deserialize)]
 pub struct ScrapeRequest {
-    #[serde(rename = "info_hash")]
+    #[serde(
+        rename = "info_hash",
+        deserialize_with = "deserialize_info_hashes" // FIXME: does this work?
+    )]
     pub info_hashes: Vec<InfoHash>,
 }
 

aquatic_http/src/lib/protocol/serde_helpers.rs

@@ -3,71 +3,35 @@ use serde::{Serializer, Deserializer, de::{Visitor, SeqAccess}};
 use super::InfoHash;
 
 
-pub fn serialize_20_bytes<S>(
-    data: &[u8; 20],
-    serializer: S
-) -> Result<S::Ok, S::Error> where S: Serializer {
-    let text: String = data.iter().map(|byte| *byte as char).collect();
+struct TwentyCharStringVisitor;
 
-    serializer.serialize_str(&text)
-}
-
-
-struct TwentyByteVisitor;
-
-impl<'de> Visitor<'de> for TwentyByteVisitor {
-    type Value = [u8; 20];
+impl<'de> Visitor<'de> for TwentyCharStringVisitor {
+    type Value = String;
 
     fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
-        formatter.write_str("string consisting of 20 bytes")
+        formatter.write_str("string consisting of 20 chars")
     }
 
     #[inline]
     fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
         where E: ::serde::de::Error,
     {
-        // Value is encoded in nodejs reference client something as follows:
-        // ```
-        // var infoHash = 'abcd..'; // 40 hexadecimals
-        // Buffer.from(infoHash, 'hex').toString('binary');
-        // ```
-        // As I understand it:
-        // - the code above produces a UTF16 string of 20 chars, each having
-        //   only the "low byte" set (e.g., numeric value ranges from 0-255)
-        // - serde_json decodes this to string of 20 chars (tested), each in
-        //   the aforementioned range (tested), so the bytes can be extracted
-        //   by casting each char to u8.
-
-        let mut arr = [0u8; 20];
-        let mut char_iter = value.chars();
-
-        for a in arr.iter_mut(){
-            if let Some(c) = char_iter.next(){
-                if c as u32 > 255 {
-                    return Err(E::custom(format!(
-                        "character not in single byte range: {:#?}",
-                        c
-                    )));
-                }
-
-                *a = c as u8;
-            } else {
-                return Err(E::custom(format!("not 20 bytes: {:#?}", value)));
-            }
+        if value.chars().count() == 20 {
+            Ok(value.to_string())
+        } else {
+            Err(E::custom(format!("not 20 chars: {:#?}", value)))
         }
-
-        Ok(arr)
     }
 }
 
 
 #[inline]
-pub fn deserialize_20_bytes<'de, D>(
+pub fn deserialize_20_char_string<'de, D>(
     deserializer: D
-) -> Result<[u8; 20], D::Error>
+) -> Result<String, D::Error>
     where D: Deserializer<'de>
 {
-    deserializer.deserialize_any(TwentyByteVisitor)
+    deserializer.deserialize_any(TwentyCharStringVisitor)
 }
 
 
@@ -85,7 +49,7 @@ impl<'de> Visitor<'de> for InfoHashVecVisitor {
     fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
         where E: ::serde::de::Error,
     {
-        match TwentyByteVisitor::visit_str::<E>(TwentyByteVisitor, value){
+        match TwentyCharStringVisitor::visit_str::<E>(TwentyCharStringVisitor, value){
             Ok(arr) => Ok(vec![InfoHash(arr)]),
             Err(err) => Err(E::custom(format!("got string, but {}", err)))
         }
@@ -98,8 +62,8 @@ impl<'de> Visitor<'de> for InfoHashVecVisitor {
         let mut info_hashes: Self::Value = Vec::new();
 
         while let Ok(Some(value)) = seq.next_element::<&str>(){
-            let arr = TwentyByteVisitor::visit_str(
-                TwentyByteVisitor, value
+            let arr = TwentyCharStringVisitor::visit_str(
+                TwentyCharStringVisitor, value
             )?;
 
             info_hashes.push(InfoHash(arr));