Add parameter type sensitivity to type encoding

This requires recording the response to parsing to know what types are
expected for parameters, and then passing that information to the type
encoder.

Signed-off-by: Daniel Farina <daniel@heroku.com>

buf.go

@@ -13,6 +13,12 @@ func (b *readBuf) int32() (n int) {
 	return
 }
 
+func (b *readBuf) oid() (n oid) {
+	n = oid(binary.BigEndian.Uint32(*b))
+	*b = (*b)[4:]
+	return
+}
+
 func (b *readBuf) int16() (n int) {
 	n = int(binary.BigEndian.Uint16(*b))
 	*b = (*b)[2:]

conn.go

@@ -191,14 +191,19 @@ func (cn *conn) prepareTo(q, stmtName string) (_ driver.Stmt, err error) {
 		case '1', '2', 'N':
 		case 't':
 			st.nparams = int(r.int16())
+			st.paramTyps = make([]oid, st.nparams, st.nparams)
+
+			for i := 0; i < st.nparams; i += 1 {
+				st.paramTyps[i] = r.oid()
+			}
 		case 'T':
 			n := r.int16()
 			st.cols = make([]string, n)
-			st.ooid = make([]int, n)
+			st.rowTyps = make([]oid, n)
 			for i := range st.cols {
 				st.cols[i] = r.string()
 				r.next(6)
-				st.ooid[i] = r.int32()
+				st.rowTyps[i] = r.oid()
 				r.next(8)
 			}
 		case 'n':
@@ -390,14 +395,17 @@ func (cn *conn) auth(r *readBuf, o Values) {
 	}
 }
 
+type oid uint32
+
 type stmt struct {
-	cn      *conn
-	name    string
-	query   string
-	cols    []string
-	nparams int
-	ooid    []int
-	closed  bool
+	cn        *conn
+	name      string
+	query     string
+	cols      []string
+	nparams   int
+	rowTyps   []oid
+	paramTyps []oid
+	closed    bool
 }
 
 func (st *stmt) Close() (err error) {
@@ -470,11 +478,11 @@ func (st *stmt) exec(v []driver.Value) {
 	w.string(st.name)
 	w.int16(0)
 	w.int16(len(v))
-	for _, x := range v {
+	for i, x := range v {
 		if x == nil {
 			w.int32(-1)
 		} else {
-			b := encode(x)
+			b := encode(x, st.paramTyps[i])
 			w.int32(len(b))
 			w.bytes(b)
 		}
@@ -584,7 +592,7 @@ func (rs *rows) Next(dest []driver.Value) (err error) {
 					dest[i] = nil
 					continue
 				}
-				dest[i] = decode(r.next(l), rs.st.ooid[i])
+				dest[i] = decode(r.next(l), rs.st.rowTyps[i])
 			}
 			return
 		default:

encode.go

@@ -8,15 +8,23 @@ import (
 	"time"
 )
 
-func encode(x interface{}) []byte {
+func encode(x interface{}, pgtypoid oid) []byte {
 	switch v := x.(type) {
 	case int64:
 		return []byte(fmt.Sprintf("%d", v))
 	case float32, float64:
 		return []byte(fmt.Sprintf("%f", v))
 	case []byte:
-		return []byte(fmt.Sprintf("\\x%x", v))
+		if pgtypoid == t_bytea {
+			return []byte(fmt.Sprintf("\\x%x", v))
+		}
+
+		return v
 	case string:
+		if pgtypoid == t_bytea {
+			return []byte(fmt.Sprintf("\\x%x", v))
+		}
+
 		return []byte(v)
 	case bool:
 		return []byte(fmt.Sprintf("%t", v))
@@ -29,7 +37,7 @@ func encode(x interface{}) []byte {
 	panic("not reached")
 }
 
-func decode(s []byte, typ int) interface{} {
+func decode(s []byte, typ oid) interface{} {
 	switch typ {
 	case t_bytea:
 		s = s[2:] // trim off "\\x"

encode_test.go

@@ -100,3 +100,21 @@ func TestStringWithNul(t *testing.T) {
 			"injection attacks may be plausible")
 	}
 }
+
+func TestByteToText(t *testing.T) {
+	db := openTestConn(t)
+	defer db.Close()
+
+	b := []byte("hello world")
+	row := db.QueryRow("SELECT $1::text", b)
+
+	var result []byte
+	err := row.Scan(&result)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if string(result) != string(b) {
+		t.Fatalf("expected %v but got %v", b, result)
+	}
+}