Bech32m Support (#50)

* Bech32m encode / decode support

This breaks the API by requiring a `variant` parameter in a few places,
which instructs the library whether to use Bech32 or Bech32m.

Test cases from BIP-0350

* Update fuzzer for Bech32m

* Revert Self idiom (stabilized in Rust 1.32)

* Bump version to 0.8.0

* Switch to GitHub Actions for CI

.github/workflows/rust.yml

@@ -0,0 +1,65 @@
+on: [pull_request]
+
+name: Continuous Integration
+
+jobs:
+  test:
+    name: Test Suite
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust:
+          - 1.29.0
+          - stable
+          - nightly
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --verbose --features strict
+
+  fmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust:
+          - stable
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          override: true
+      - run: rustup component add rustfmt
+      - uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust:
+          - stable
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          override: true
+      - run: rustup component add clippy
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: -- -D warnings

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "bech32"
-version = "0.7.3"
+version = "0.8.0"
 authors = ["Clark Moody"]
 repository = "https://github.com/rust-bitcoin/rust-bech32"
 description = "Encodes and decodes the Bech32 format"

clippy.toml

@@ -0,0 +1 @@
+msrv = "1.29.0"

fuzz/fuzz_targets/decode_rnd.rs

@@ -10,7 +10,7 @@ fn do_test(data: &[u8]) {
         Err(_) => return,
     };
 
-    assert_eq!(bech32::encode(&b32.0, b32.1).unwrap(), data_str);
+    assert_eq!(bech32::encode(&b32.0, b32.1, b32.2).unwrap(), data_str);
 }
 
 #[cfg(feature = "afl")]
@@ -23,7 +23,8 @@ fn main() {
 }
 
 #[cfg(feature = "honggfuzz")]
-#[macro_use] extern crate honggfuzz;
+#[macro_use]
+extern crate honggfuzz;
 #[cfg(feature = "honggfuzz")]
 fn main() {
     loop {

fuzz/fuzz_targets/encode_decode.rs

@@ -13,18 +13,26 @@ fn do_test(data: &[u8]) {
         return;
     }
 
-    let hrp = String::from_utf8_lossy(&data[1..hrp_end]).to_lowercase().to_string();
+    let hrp = String::from_utf8_lossy(&data[1..hrp_end])
+        .to_lowercase()
+        .to_string();
 
     let dp = data[hrp_end..]
         .iter()
         .map(|b| bech32::u5::try_from_u8(b % 32).unwrap())
         .collect::<Vec<_>>();
 
-    if let Ok(data_str) = bech32::encode(&hrp, &dp).map(|b32| b32.to_string()) {
+    let variant = if data[0] > 0x0f {
+        bech32::Variant::Bech32m
+    } else {
+        bech32::Variant::Bech32
+    };
+
+    if let Ok(data_str) = bech32::encode(&hrp, &dp, variant).map(|b32| b32.to_string()) {
         let decoded = bech32::decode(&data_str);
         let b32 = decoded.expect("should be able to decode own encoding");
 
-        assert_eq!(bech32::encode(&b32.0, &b32.1).unwrap(), data_str);
+        assert_eq!(bech32::encode(&b32.0, &b32.1, b32.2).unwrap(), data_str);
     }
 }
 
@@ -38,7 +46,8 @@ fn main() {
 }
 
 #[cfg(feature = "honggfuzz")]
-#[macro_use] extern crate honggfuzz;
+#[macro_use]
+extern crate honggfuzz;
 #[cfg(feature = "honggfuzz")]
 fn main() {
     loop {