Update schema proto file

This commit updates the schema protocol to use the latest version
present on [mafintosh/simple-hypercore-protocol](https://github.com/mafintosh/simple-hypercore-protocol/blob/d577298a47479630d0e340190273db4a22d3c793/schema.proto).

This includes the NOISE protocol handshake as part of the file, and it
is not backward compatible with DAT <= 7. Due to that, a major bump has
been proposed.

It uses a simplified single file/single namespace proposal, to help to
keep it up to date instead of checking multiple files to see if the
fields are updated, which could be split if needed.

README.md

@@ -4,6 +4,8 @@
 
 Dat Network Protocol protobuf definitions.
 
+Includes a Noise handshake, and is not backwards compatible with Hypercore <= 7
+
 ## Installation
 ```sh
 $ cargo add dat-network-protocol

build.rs

@@ -1,24 +1,12 @@
 // Uncomment method below for like local builds.
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-  // protobuf_codegen_pure::run(protobuf_codegen_pure::Args {
-  //   out_dir: "src",
-  //   input: &[
-  //     "protos/cancel.proto",
-  //     "protos/data.proto",
-  //     "protos/data.proto",
-  //     "protos/feed.proto",
-  //     "protos/handshake.proto",
-  //     "protos/have.proto",
-  //     "protos/info.proto",
-  //     "protos/request.proto",
-  //     "protos/unhave.proto",
-  //     "protos/unwant.proto",
-  //     "protos/want.proto",
-  //   ],
-  //   customize: protobuf_codegen_pure::Customize {
-  //     ..Default::default()
-  //   },
-  //   includes: &["protos"],
-  // })?;
+  //  protobuf_codegen_pure::run(protobuf_codegen_pure::Args {
+  //    out_dir: "src",
+  //    input: &["protos/lib.proto"],
+  //    customize: protobuf_codegen_pure::Customize {
+  //      ..Default::default()
+  //    },
+  //    includes: &["protos"],
+  //  })?;
   Ok(())
 }

protos/lib.proto

@@ -0,0 +1,87 @@
+syntax = "proto2";
+
+// Sent as part of the noise protocol.
+message NoisePayload {
+  required bytes nonce = 1;
+}
+
+// type=0
+message Open {
+  required bytes discoveryKey = 1;
+  optional bytes capability = 2;
+}
+
+// type=1, overall feed options. can be sent multiple times
+message Options {
+  repeated string extensions = 1; // Should be sorted lexicographically
+  optional bool ack = 2; // Should all blocks be explicitly acknowledged?
+}
+
+// type=2, message indicating state changes etc.
+// initial state for uploading/downloading is true
+message Status {
+  optional bool uploading = 1;
+  optional bool downloading = 2;
+}
+
+// type=3, what do we have?
+message Have {
+  required uint64 start = 1;
+  optional uint64 length = 2 [default = 1]; // defaults to 1
+  optional bytes bitfield = 3;
+  optional bool ack = 4; // when true, this Have message is an acknowledgement
+}
+
+// type=4, what did we lose?
+message Unhave {
+  required uint64 start = 1;
+  optional uint64 length = 2 [default = 1]; // defaults to 1
+}
+
+// type=5, what do we want? remote should start sending have messages in this range
+message Want {
+  required uint64 start = 1;
+  optional uint64 length = 2; // defaults to Infinity or feed.length (if not live)
+}
+
+// type=6, what don't we want anymore?
+message Unwant {
+  required uint64 start = 1;
+  optional uint64 length = 2; // defaults to Infinity or feed.length (if not live)
+}
+
+// type=7, ask for data
+message Request {
+  required uint64 index = 1;
+  optional uint64 bytes = 2;
+  optional bool hash = 3;
+  optional uint64 nodes = 4;
+}
+
+// type=8, cancel a request
+message Cancel {
+  required uint64 index = 1;
+  optional uint64 bytes = 2;
+  optional bool hash = 3;
+}
+
+// type=9, get some data
+message Data {
+  message Node {
+    required uint64 index = 1;
+    required bytes hash = 2;
+    required uint64 size = 3;
+  }
+
+  required uint64 index = 1;
+  optional bytes value = 2;
+  repeated Node nodes = 3;
+  optional bytes signature = 4;
+}
+
+// type=10, explicitly close a channel.
+message Close {
+  optional bytes discoveryKey = 1; // only send this if you did not do an open
+}
+
+// type=15, extension message