3 files changed, 107 insertions, 0 deletions
diff --git a/pkg/server/module/alpha.go b/pkg/server/module/alpha.go
new file mode 100644
index 0000000..be9032c
--- /dev/null
+++ b/pkg/server/module/alpha.go
@@ -0,0 +1,32 @@
+package module
+
+import (
+	"tunnel/pkg/server/queue"
+	"unicode"
+	"bufio"
+	"io"
+)
+
+func alpha(cb func (rune) rune) pipe {
+	return func (rq, wq queue.Q) error {
+		r := bufio.NewReader(rq.Reader())
+
+		for {
+			c, _, err := r.ReadRune()
+			if err != nil {
+				if err == io.EOF {
+					break
+				}
+				return err
+			}
+			wq <- []byte(string(cb(c)))
+		}
+
+		return nil
+	}
+}
+
+func init() {
+	register("lower", alpha(unicode.ToLower))
+	register("upper", alpha(unicode.ToUpper))
+}
diff --git a/pkg/server/module/hex.go b/pkg/server/module/hex.go
new file mode 100644
index 0000000..2ffd1fc
--- /dev/null
+++ b/pkg/server/module/hex.go
@@ -0,0 +1,27 @@
+package module
+
+import (
+	"tunnel/pkg/server/queue"
+	"encoding/hex"
+)
+
+func hexEncoder(rq, wq queue.Q) error {
+	enc := hex.NewEncoder(wq.Writer())
+
+	for b := range rq {
+		enc.Write(b)
+	}
+
+	return nil
+}
+
+func hexDecoder(rq, wq queue.Q) error {
+	r := hex.NewDecoder(rq.Reader())
+	w := wq.Writer()
+	return queue.IoCopy(r, w)
+}
+
+func init() {
+	register("hex", pipe(hexEncoder))
+	register("unhex", pipe(hexDecoder))
+}
diff --git a/pkg/server/module/module.go b/pkg/server/module/module.go
new file mode 100644
index 0000000..768a87b
--- /dev/null
+++ b/pkg/server/module/module.go
@@ -0,0 +1,48 @@
+package module
+
+import (
+	"tunnel/pkg/server/queue"
+	"fmt"
+	"log"
+)
+
+var modules = map[string]M{}
+
+type pipe func (rq, wq queue.Q) error
+
+type M interface {
+	Open() (pipe, pipe)
+}
+
+type reverse struct {
+	M
+}
+
+func Reverse(m M) M {
+	return &reverse{m}
+}
+
+func (r *reverse) Open() (pipe, pipe) {
+	p1, p2 := r.M.Open()
+	return p2, p1
+}
+
+func (p pipe) Open() (pipe, pipe) {
+	return p, nil
+}
+
+func register(name string, m M) {
+	if _, ok := modules[name]; ok {
+		log.Panicf("duplicate module name '%s'", name)
+	}
+
+	modules[name] = m
+}
+
+func New(name string) (M, error) {
+	if m, ok := modules[name]; ok {
+		return m, nil
+	}
+
+	return nil, fmt.Errorf("unknown module '%s'", name)
+}