1 files changed, 75 insertions, 0 deletions
diff --git a/src/authentication_request.zig b/src/authentication_request.zig
new file mode 100644
index 0000000..549a26b
--- /dev/null
+++ b/src/authentication_request.zig
@@ -0,0 +1,75 @@
+const std = @import("std");
+const log = std.log.scoped(.pgz);
+const ByteArrayList = std.ArrayList(u8);
+const ProtocolError = @import("main.zig").ProtocolError;
+const ClientError = @import("main.zig").ClientError;
+const enum_from_int = @import("main.zig").enum_from_int;
+
+pub const Tag: u8 = 'R';
+
+const AuthenticationRequest = @This();
+
+pub const InnerAuthRequestType = enum(u32) {
+    AuthRequestTypeOk = 0,
+    AuthRequestTypeCleartextPassword = 3,
+};
+pub const InnerAuthRequest = union{
+    ok: AuthRequestOk,
+    cleartext_password: AuthRequestCleartextPassword,
+};
+pub const AuthRequestOk = struct {};
+pub const AuthRequestCleartextPassword = struct {};
+
+// Authentication requests have multiple subtypes.
+// It's not possible to have a tagged union with a custom backing integer, so do it the long way
+inner_type: InnerAuthRequestType,
+inner: InnerAuthRequest,
+
+pub fn read(_: std.mem.Allocator, b: []const u8) !AuthenticationRequest {
+    if (b.len != 4) {
+        log.err("invalid message length, expected 4 got {}",.{b.len});
+        return ProtocolError.InvalidMessageLength;
+    }
+    const inner_type = enum_from_int(InnerAuthRequestType, std.mem.readIntBig(u32, b[0..4])) orelse return ClientError.UnsupportedAuthType;
+    var inner: InnerAuthRequest = switch (inner_type) {
+        .AuthRequestTypeOk => .{.ok = AuthRequestOk{}},
+        .AuthRequestTypeCleartextPassword => .{.cleartext_password = AuthRequestCleartextPassword{}},
+    };
+    return .{
+        .inner_type = inner_type,
+        .inner = inner,
+    };
+}
+
+pub fn write(self: AuthenticationRequest, _: std.mem.Allocator, stream_writer: anytype) !void {
+    try stream_writer.writeByte(Tag);
+    try stream_writer.writeIntBig(u32, 8);
+    try stream_writer.writeIntBig(u32, @intFromEnum(self.inner_type));
+}
+
+pub fn deinit(_: *AuthenticationRequest, _: std.mem.Allocator) void {}
+
+test "round trip" {
+    const allocator = std.testing.allocator;
+    var sm = AuthenticationRequest{
+        .inner_type = .AuthRequestTypeOk,
+        .inner = .{.ok = AuthRequestOk{}},
+    };
+    defer sm.deinit(allocator);
+
+    var bal = ByteArrayList.init(allocator);
+    defer bal.deinit();
+    try sm.write(allocator, bal.writer());
+
+    var fbs = std.io.fixedBufferStream(bal.items);
+    var reader = fbs.reader();
+    const tag = try reader.readByte();
+    try std.testing.expectEqual(Tag, tag);
+    const len = try reader.readIntBig(u32);
+    const buf = try allocator.alloc(u8, len - 4);
+    defer allocator.free(buf);
+    try reader.readNoEof(buf);
+    var sm2 = try AuthenticationRequest.read(allocator, buf);
+    defer sm2.deinit(allocator);
+    try std.testing.expectEqual(InnerAuthRequestType.AuthRequestTypeOk, sm2.inner_type);
+}