feat: initial webssh tooling

agent/internal/sshutil/handler.go

@@ -0,0 +1,56 @@
+package sshutil
+
+import (
+	"io"
+
+	"github.com/tale/headplane/agent/internal/util"
+)
+
+func StartInputReader(fd3 io.Reader) {
+	log := util.GetLogger();
+
+	log.Info("Starting SSH fd3 input reader")
+	go func() {
+		buffer := make([]byte, 8192)
+		for {
+			n, err := fd3.Read(buffer)
+			if err != nil {
+				log.Error("fd3 read error: %v", err)
+				return
+			}
+			offset := 0
+			for offset < n {
+				id, payload, ok := decodeFrame(buffer[offset:n])
+				if !ok {
+					break // Wait for more data
+				}
+				offset += 1 + len(id) + 4 + len(payload)
+
+				sessionsMu.RLock()
+				sess, ok := sessions[id]
+				sessionsMu.RUnlock()
+				if !ok {
+					log.Error("invalid session id: %s", id)
+					continue
+				}
+				_, err := sess.Stdin.Write(payload)
+				if err != nil {
+					log.Error("failed to write to session stdin: %v", err)
+					continue
+				}
+			}
+		}
+	}()
+}
+
+func streamSSHOutput(id string, r io.Reader, fd4 io.Writer) {
+	buf := make([]byte, 1024)
+	for {
+		n, err := r.Read(buf)
+		if err != nil {
+			break
+		}
+		frame, _ := encodeFrame(id, buf[:n])
+		fd4.Write(frame)
+	}
+}