Fetch all txns in a block

Cargo.toml

@@ -20,7 +20,6 @@ hex = "0.3"
 protobuf = "2"
 rustyline = "5.0.2"
 byteorder = "1"
-rand = "0.5.6"
 json = "0.12.0"
 shellwords = "1.0.0"
 tiny-bip39 = "0.6.2"
@@ -37,6 +36,7 @@ webpki = "0.19.1"
 webpki-roots = "0.16.0"
 tower-h2 = { git = "https://github.com/tower-rs/tower-h2" }
 rust-embed = "5.1.0"
+rand = "0.7.2"
 
 [dependencies.bellman]
 git = "https://github.com/adityapk00/librustzcash.git"
@@ -72,8 +72,7 @@ features = ["ff_derive"]
 [build-dependencies]
 tower-grpc-build = { git = "https://github.com/tower-rs/tower-grpc",  features = ["tower-hyper"]  }
 
-[dev-dependencies]
-rand_core = "0.5.1"
+
 
 [profile.release]
 debug = false

src/grpcconnector.rs

@@ -171,8 +171,8 @@ pub fn get_info(uri: http::Uri, no_cert: bool) -> Result<LightdInfo, String> {
 }
 
 
-pub fn fetch_blocks<F : 'static + std::marker::Send>(uri: &http::Uri, start_height: u64, end_height: u64, no_cert: bool, c: F)
-    where F : Fn(&[u8]) {
+pub fn fetch_blocks<F : 'static + std::marker::Send>(uri: &http::Uri, start_height: u64, end_height: u64, no_cert: bool, mut c: F)
+    where F : FnMut(&[u8], u64) {
     let runner = make_grpc_client!(uri.scheme_str().unwrap(), uri.host().unwrap(), uri.port_part().unwrap(), no_cert)
         .and_then(move |mut client| {
             let bs = BlockId{ height: start_height, hash: vec!()};
@@ -191,7 +191,7 @@ pub fn fetch_blocks<F : 'static + std::marker::Send>(uri: &http::Uri, start_heig
                         let mut encoded_buf = vec![];
 
                         b.encode(&mut encoded_buf).unwrap();
-                        c(&encoded_buf);
+                        c(&encoded_buf, b.height);
 
                         Ok(())
                     })

src/lightclient.rs

@@ -2,7 +2,9 @@ use crate::lightwallet::LightWallet;
 
 use log::{info, warn, error};
 
-use std::sync::{Arc};
+use rand::{rngs::OsRng, seq::SliceRandom};
+
+use std::sync::{Arc, RwLock};
 use std::sync::atomic::{AtomicU64, AtomicI32, AtomicUsize, Ordering};
 use std::path::Path;
 use std::fs::File;
@@ -583,6 +585,11 @@ impl LightClient {
 
         let mut total_reorg = 0;
 
+        // Collect all txns in blocks that we have a tx in. We'll fetch all these
+        // txs along with our own, so that the server doesn't learn which ones
+        // belong to us.
+        let all_new_txs = Arc::new(RwLock::new(vec![]));
+
         // Fetch CompactBlocks in increments
         loop {
             let local_light_wallet = self.wallet.clone();
@@ -599,23 +606,26 @@ impl LightClient {
 
             // Fetch compact blocks
             info!("Fetching blocks {}-{}", start_height, end_height);
-            
+            let all_txs = all_new_txs.clone();
+
             let last_invalid_height = Arc::new(AtomicI32::new(0));
             let last_invalid_height_inner = last_invalid_height.clone();
             fetch_blocks(&self.get_server_uri(), start_height, end_height, self.config.no_cert_verification,
-                move |encoded_block: &[u8]| {
+                move |encoded_block: &[u8], height: u64| {
                     // Process the block only if there were no previous errors
                     if last_invalid_height_inner.load(Ordering::SeqCst) > 0 {
                         return;
                     }
 
                     match local_light_wallet.scan_block(encoded_block) {
-                        Ok(_) => {},
+                        Ok(block_txns) => {
+                            all_txs.write().unwrap().copy_from_slice(&block_txns.iter().map(|txid| (txid.clone(), height as i32)).collect::<Vec<_>>()[..]);
+                        },
                         Err(invalid_height) => {
                             // Block at this height seems to be invalid, so invalidate up till that point
                             last_invalid_height_inner.store(invalid_height, Ordering::SeqCst);
                         }
-                    }
+                    };
 
                     local_bytes_downloaded.fetch_add(encoded_block.len(), Ordering::SeqCst);
             });
@@ -683,12 +693,16 @@ impl LightClient {
 
         // We need to first copy over the Txids from the wallet struct, because
         // we need to free the read lock from here (Because we'll self.wallet.txs later)
-        let txids_to_fetch: Vec<(TxId, i32)> = self.wallet.txs.read().unwrap().values()
+        let mut txids_to_fetch: Vec<(TxId, i32)> = self.wallet.txs.read().unwrap().values()
             .filter(|wtx| wtx.full_tx_scanned == false)
             .map(|wtx| (wtx.txid, wtx.block))
             .collect::<Vec<(TxId, i32)>>();
 
-        info!("Fetching {} new txids", txids_to_fetch.len());
+        info!("Fetching {} new txids, along with {} decoy", txids_to_fetch.len(), all_new_txs.read().unwrap().len());
+        txids_to_fetch.extend_from_slice(&all_new_txs.read().unwrap()[..]);
+        
+        let mut rng = OsRng;        
+        txids_to_fetch.shuffle(&mut rng);
 
         // And go and fetch the txids, getting the full transaction, so we can 
         // read the memos        

src/lightwallet.rs

@@ -5,6 +5,8 @@ use std::collections::{HashMap, HashSet};
 use std::sync::{Arc, RwLock};
 use std::io::{Error, ErrorKind};
 
+use rand::{Rng, rngs::OsRng};
+
 use log::{info, warn, error};
 
 use protobuf::parse_from_bytes;
@@ -165,14 +167,12 @@ impl LightWallet {
     }
 
     pub fn new(seed_phrase: Option<String>, config: &LightClientConfig, latest_block: u64) -> io::Result<Self> {
-        use rand::{FromEntropy, ChaChaRng, Rng};
-
         // This is the source entropy that corresponds to the 24-word seed phrase
         let mut seed_bytes = [0u8; 32];
 
         if seed_phrase.is_none() {
             // Create a random seed. 
-            let mut system_rng = ChaChaRng::from_entropy();
+            let mut system_rng = OsRng;
             system_rng.fill(&mut seed_bytes);
         } else {
             seed_bytes.copy_from_slice(&Mnemonic::from_phrase(seed_phrase.expect("should have a seed phrase"), 
@@ -881,8 +881,8 @@ impl LightWallet {
     }
 
     // Scan a block. Will return an error with the block height that failed to scan
-    pub fn scan_block(&self, block: &[u8]) -> Result<(), i32> {
-        let block: CompactBlock = match parse_from_bytes(block) {
+    pub fn scan_block(&self, block_bytes: &[u8]) -> Result<Vec<TxId>, i32> {
+        let block: CompactBlock = match parse_from_bytes(block_bytes) {
             Ok(block) => block,
             Err(e) => {
                 error!("Could not parse CompactBlock from bytes: {}", e);
@@ -900,7 +900,7 @@ impl LightWallet {
                     return Err(height);
                 }
             }
-            return Ok(())
+            return Ok(vec![]);
         } else if height != (self.last_scanned_height() + 1) {
             error!(
                 "Block is not height-sequential (expected {}, found {})",
@@ -978,7 +978,7 @@ impl LightWallet {
                 .collect();
 
             scan_block(
-                block,
+                block.clone(),
                 &self.extfvks.read().unwrap(),
                 &nf_refs[..],
                 &mut block_data.tree,
@@ -986,6 +986,18 @@ impl LightWallet {
             )
         };
 
+        // If this block had any new Txs, return the list of ALL txids in this block, 
+        // so the wallet can fetch them all as a decoy.
+        let all_txs = if !new_txs.is_empty() {
+            block.vtx.iter().map(|vtx| {
+                let mut t = [0u8; 32];
+                t.copy_from_slice(&vtx.hash[..]);
+                TxId{0: t}
+            }).collect::<Vec<TxId>>()
+        } else {
+            vec![]
+        };
+
         for tx in new_txs {
             // Mark notes as spent.
             let mut total_shielded_value_spent: u64 = 0;
@@ -1023,9 +1035,7 @@ impl LightWallet {
             tx_entry.total_shielded_value_spent = total_shielded_value_spent;
 
             // Save notes.
-            for output in tx
-                .shielded_outputs
-                .into_iter()
+            for output in tx.shielded_outputs
             {
                 info!("Received sapling output");
 
@@ -1059,7 +1069,8 @@ impl LightWallet {
             }
         }
 
-        Ok(())
+
+        Ok(all_txs)
     }
 
     pub fn send_to_address(
@@ -1284,9 +1295,10 @@ impl LightWallet {
 pub mod tests {
     use std::convert::TryInto;
     use std::io::{Error};
+    use rand::{RngCore, rngs::OsRng};
+
     use ff::{Field, PrimeField, PrimeFieldRepr};
     use pairing::bls12_381::Bls12;
-    use rand_core::{RngCore, OsRng};
     use protobuf::{Message, UnknownFields, CachedSize, RepeatedField};
     use zcash_client_backend::{encoding::encode_payment_address,
         proto::compact_formats::{
@@ -1938,7 +1950,8 @@ pub mod tests {
             chain_name: "test".to_string(),
             sapling_activation_height: 0,
             consensus_branch_id: "000000".to_string(),
-            anchor_offset: 0
+            anchor_offset: 0,
+            no_cert_verification: false,
         }
     }
 
@@ -2860,7 +2873,8 @@ pub mod tests {
             chain_name: "main".to_string(),
             sapling_activation_height: 0,
             consensus_branch_id: "000000".to_string(),
-            anchor_offset: 1
+            anchor_offset: 1,
+            no_cert_verification: false,
         };
 
         let seed_phrase = Some("chimney better bulb horror rebuild whisper improve intact letter giraffe brave rib appear bulk aim burst snap salt hill sad merge tennis phrase raise".to_string());