Add C API

build.zig

@@ -41,6 +41,23 @@ pub fn build(b: *std.Build) void {
         .target = target,
     });
 
+    // Create static library
+    const lib = b.addLibrary(.{
+        .name = "zaprus",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/c_api.zig"),
+            .target = target,
+            .optimize = optimize,
+            .link_libc = true,
+            .imports = &.{
+                .{ .name = "zaprus", .module = mod },
+            },
+        }),
+    });
+
+    b.installArtifact(lib);
+    lib.installHeader(b.path("include/zaprus.h"), "zaprus.h");
+
     // Here we define an executable. An executable needs to have a root module
     // which needs to expose a `main` function. While we could add a main function
     // to the module defined above, it's sometimes preferable to split business

include/zaprus.h

@@ -0,0 +1,33 @@
+#ifndef ZAPRUS_H
+#define ZAPRUS_H
+
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef void* zaprus_client;
+typedef void* zaprus_connection;
+
+// Returns NULL if there was an error.
+zaprus_client zaprus_init_client(void);
+
+void zaprus_deinit_client(zaprus_client client);
+
+// Returns 0 on success, else returns 1.
+int zaprus_client_send_relay(zaprus_client client, const char* payload, size_t payload_len, const char dest[4]);
+
+// Returns NULL if there was an error.
+// Caller should call zaprus_deinit_connection when done with the connection.
+zaprus_connection zaprus_connect(zaprus_client client, const char* payload, size_t payload_len);
+
+void zaprus_deinit_connection(zaprus_connection connection);
+
+// Capacity is the maximum length of the output buffer.
+// out_len is modified to specify how much of the capacity is used by the response.
+// Blocks until the next message is available, or returns 1 if the underlying socket times out.
+// Returns 0 on success, else returns 1.
+int zaprus_connection_next(zaprus_connection connection, char *out, size_t capacity, size_t *out_len);
+
+// Returns 0 on success, else returns 1.
+int zaprus_connection_send(zaprus_connection connection, const char *payload, size_t payload_len);
+
+#endif // ZAPRUS_H

src/Connection.zig

@@ -12,6 +12,10 @@ pub fn init(socket: RawSocket, headers: EthIpUdp, connection: SaprusMessage) Con
     };
 }
 
+pub fn deinit(self: *Connection) void {
+    self.socket.deinit();
+}
+
 pub fn next(self: Connection, io: Io, buf: []u8) ![]const u8 {
     _ = io;
     log.debug("Awaiting connection message", .{});

src/c_api.zig

@@ -0,0 +1,89 @@
+const std = @import("std");
+const zaprus = @import("zaprus");
+
+// Opaque types for C API
+const ZaprusClient = opaque {};
+const ZaprusConnection = opaque {};
+
+const alloc = std.heap.c_allocator;
+const io = std.Io.Threaded.global_single_threaded.io();
+
+export fn zaprus_init_client() ?*ZaprusClient {
+    const client = alloc.create(zaprus.Client) catch return null;
+    client.* = zaprus.Client.init() catch {
+        alloc.destroy(client);
+        return null;
+    };
+    return @ptrCast(client);
+}
+
+export fn zaprus_deinit_client(client: ?*ZaprusClient) void {
+    const c: ?*zaprus.Client = @ptrCast(@alignCast(client));
+    if (c) |zc| {
+        zc.deinit();
+        alloc.destroy(zc);
+    }
+}
+
+export fn zaprus_client_send_relay(
+    client: ?*ZaprusClient,
+    payload: [*c]const u8,
+    payload_len: usize,
+    dest: [*c]const u8,
+) c_int {
+    const c: ?*zaprus.Client = @ptrCast(@alignCast(client));
+    const zc = c orelse return 1;
+
+    zc.sendRelay(io, payload[0..payload_len], dest[0..4].*) catch return 1;
+    return 0;
+}
+
+export fn zaprus_connect(
+    client: ?*ZaprusClient,
+    payload: [*c]const u8,
+    payload_len: usize,
+) ?*ZaprusConnection {
+    const c: ?*zaprus.Client = @ptrCast(@alignCast(client));
+    const zc = c orelse return null;
+
+    const connection = alloc.create(zaprus.Connection) catch return null;
+    connection.* = zc.connect(io, payload[0..payload_len]) catch {
+        alloc.destroy(connection);
+        return null;
+    };
+    return @ptrCast(connection);
+}
+
+export fn zaprus_deinit_connection(connection: ?*ZaprusConnection) void {
+    const c: ?*zaprus.Connection = @ptrCast(@alignCast(connection));
+    if (c) |zc| {
+        zc.deinit();
+        alloc.destroy(zc);
+    }
+}
+
+export fn zaprus_connection_next(
+    connection: ?*ZaprusConnection,
+    out: [*c]u8,
+    capacity: usize,
+    out_len: *usize,
+) c_int {
+    const c: ?*zaprus.Connection = @ptrCast(@alignCast(connection));
+    const zc = c orelse return 1;
+
+    const result = zc.next(io, out[0..capacity]) catch return 1;
+    out_len.* = result.len;
+    return 0;
+}
+
+export fn zaprus_connection_send(
+    connection: ?*ZaprusConnection,
+    payload: [*c]const u8,
+    payload_len: usize,
+) c_int {
+    const c: ?*zaprus.Connection = @ptrCast(@alignCast(connection));
+    const zc = c orelse return 1;
+
+    zc.send(io, payload[0..payload_len]) catch return 1;
+    return 0;
+}

src/main.zig

@@ -134,6 +134,7 @@ pub fn main(init: std.process.Init) !void {
             var w: Writer = .fixed(&init_con_buf);
             try w.print("{b64}", .{flags.connect.?});
             var connection = try client.connect(init.io, w.buffered());
+            defer connection.deinit();
 
             log.debug("Connection started", .{});