localrpc: Add a package for local RPC over UNIX sockets

This patch adds a new package for doing local lightweight RPC calls over UNIX
sockets. This will be used in later patches for communication between chasquid
and chasquid-util.

internal/localrpc/server_test.go

@@ -0,0 +1,66 @@
+package localrpc
+
+import (
+	"bufio"
+	"bytes"
+	"net"
+	"net/textproto"
+	"strings"
+	"testing"
+
+	"blitiri.com.ar/go/chasquid/internal/trace"
+)
+
+func TestListenError(t *testing.T) {
+	server := NewServer()
+	err := server.ListenAndServe("/dev/null")
+	if err == nil {
+		t.Errorf("ListenAndServe(/dev/null) = nil, want error")
+	}
+}
+
+// Test that the server can handle a broken client sending a bad request.
+func TestServerBadRequest(t *testing.T) {
+	server := NewServer()
+	server.Register("Echo", Echo)
+
+	srvConn, cliConn := net.Pipe()
+	defer srvConn.Close()
+	defer cliConn.Close()
+
+	// Client sends an invalid request.
+	go cliConn.Write([]byte("Echo this is an ; invalid ; query\n"))
+
+	// Servers will handle the connection, and should return an error.
+	tr := trace.New("test", "TestBadRequest")
+	defer tr.Finish()
+	go server.handleConn(tr, srvConn)
+
+	// Read the error that the server should have sent.
+	code, msg, err := textproto.NewConn(cliConn).ReadResponse(0)
+	if err != nil {
+		t.Errorf("ReadResponse error: %q", err)
+	}
+	if code != 500 {
+		t.Errorf("ReadResponse code %d, expected 500", code)
+	}
+	if !strings.Contains(msg, "invalid semicolon separator") {
+		t.Errorf("ReadResponse message %q, does not contain 'invalid semicolon separator'", msg)
+	}
+}
+
+func TestShortReadRequest(t *testing.T) {
+	// This request is too short, it does not have any arguments.
+	// This does not happen with the real client, but just in case.
+	buf := bufio.NewReader(bytes.NewReader([]byte("Method\n")))
+	method, args, err := readRequest(textproto.NewReader(buf))
+	if err != nil {
+		t.Errorf("readRequest error: %v", err)
+	}
+	if method != "Method" {
+		t.Errorf("readRequest method %q, expected 'Method'", method)
+	}
+	if args != "" {
+		t.Errorf("readRequest args %q, expected ''", args)
+	}
+}