From c71d73ccc1115482aaca1a6ccaf6d2c0a218f459 Mon Sep 17 00:00:00 2001
From: Azanul <azanulhaque@gmail.com>
Date: Tue, 25 Jul 2023 15:49:12 +0530
Subject: [PATCH] file transfer fully functional

Signed-off-by: Azanul <azanulhaque@gmail.com>
---
 oldNode.go       | 15 ++++++---
 pkg/util/util.go | 87 +++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 89 insertions(+), 13 deletions(-)

diff --git a/oldNode.go b/oldNode.go
index 3555449..0b5fcce 100644
--- a/oldNode.go
+++ b/oldNode.go
@@ -147,15 +147,22 @@ func receiveFile(ctx context.Context, nodeName string) {
 		// Create a buffer stream for non blocking read and write.
 		rw := bufio.NewReader(stream)
 
-		f, err := os.Create("nodes/saveFilePath.txt")
+		generatedName := fmt.Sprintf("nodes/%s.part", util.RandString(10))
+		f, err := os.Create(generatedName)
 		if err != nil {
 			log.Println(err)
 			return
 		}
 
-		go util.StreamToFile(rw, f)
-
-		// 'stream' will stay open until you close it (or the other side closes it).
+		receivedName := util.StreamToFile(rw, f)
+		log.Println(receivedName)
+		if receivedName != "" {
+			receivedName = filepath.Base(receivedName)
+			err = os.Rename(generatedName, "nodes/"+receivedName)
+			if err != nil {
+				log.Println(err)
+			}
+		}
 	})
 
 	f, err := os.Open(nodeDir)
diff --git a/pkg/util/util.go b/pkg/util/util.go
index 23559fd..65f398b 100644
--- a/pkg/util/util.go
+++ b/pkg/util/util.go
@@ -2,10 +2,14 @@ package util
 
 import (
 	"bufio"
+	"encoding/binary"
 	"fmt"
 	"io"
 	"log"
+	"math/rand"
 	"os"
+	"time"
+	"unsafe"
 
 	"github.com/Azanul/peer-pressure/pkg/pressure/pb"
 	"google.golang.org/protobuf/proto"
@@ -32,17 +36,28 @@ func AppendStringToFile(path string, content string) {
 	}
 }
 
-func StreamToFile(rw *bufio.Reader, file *os.File) {
+func StreamToFile(rw *bufio.Reader, file *os.File) (filename string) {
 	writer := bufio.NewWriter(file)
+	lenBytes := make([]byte, 4)
 	for {
-		str, err := io.ReadAll(rw)
-		if err == io.EOF || len(str) == 0 {
+		n, err := rw.Read(lenBytes)
+		if err == io.EOF || n == 0 {
 			log.Printf("%s done writing", file.Name())
 			break
 		} else if err != nil {
 			fmt.Println("Error reading from buffer")
 			panic(err)
 		}
+		messageSize := binary.BigEndian.Uint32(lenBytes)
+
+		str := make([]byte, messageSize)
+		_, err = io.ReadFull(rw, str)
+		if err != nil {
+			fmt.Println("Error reading from buffer")
+			panic(err)
+		}
+		log.Println(n, len(str), str)
+
 		chunk := pb.Chunk{}
 		err = proto.Unmarshal(str, &chunk)
 		if err != nil {
@@ -50,10 +65,21 @@ func StreamToFile(rw *bufio.Reader, file *os.File) {
 			panic(err)
 		}
 
-		log.Println(str)
 		log.Println(chunk.Data)
+		log.Println(*chunk.Len)
+		log.Println(*chunk.Filename)
 		log.Println()
-		_, err = writer.Write(chunk.Data)
+		if chunk.Filename != nil {
+			filename = *chunk.Filename
+		}
+
+		var data []byte
+		if chunk.Len == nil {
+			data = chunk.Data
+		} else {
+			data = chunk.Data[:*chunk.Len]
+		}
+		_, err = writer.Write(data)
 		if err != nil {
 			log.Println(err)
 		}
@@ -62,14 +88,17 @@ func StreamToFile(rw *bufio.Reader, file *os.File) {
 	if err != nil {
 		log.Panic(err)
 	}
+	return
 }
 
 func FileToStream(rw *bufio.Writer, file *os.File) {
 	data := make([]byte, chunkSize)
+	filename := file.Name()
 
 	var partNum int32 = 0
 	for {
-		_, err := file.Read(data)
+		n, err := file.Read(data)
+		lenData := int32(n)
 		if err == io.EOF {
 			break
 		} else if err != nil {
@@ -79,20 +108,33 @@ func FileToStream(rw *bufio.Writer, file *os.File) {
 
 		partNum++
 		chunk := &pb.Chunk{
-			Index: partNum,
-			Data:  data,
+			Index:    partNum,
+			Data:     data,
+			Filename: &filename,
+			Len:      &lenData,
 		}
 		sendData, err := proto.Marshal(chunk)
 		if err != nil {
 			log.Println("Error marshaling proto chunk")
 			panic(err)
 		}
+
+		messageSize := uint32(len(sendData))
+		messageSizeBytes := make([]byte, 4)
+		binary.BigEndian.PutUint32(messageSizeBytes, messageSize)
+
+		_, err = rw.Write(messageSizeBytes)
+		if err != nil {
+			log.Println("Error writing size prefix to buffer")
+			panic(err)
+		}
+
 		_, err = rw.Write(sendData)
 		if err != nil {
 			log.Println("Error writing to buffer")
 			panic(err)
 		}
-		log.Println(rw.Available())
+		log.Println(lenData, len(sendData), sendData)
 		err = rw.Flush()
 		if err != nil {
 			log.Println("Error flushing buffer")
@@ -100,3 +142,30 @@ func FileToStream(rw *bufio.Writer, file *os.File) {
 		}
 	}
 }
+
+const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+const (
+	letterIdxBits = 6                    // 6 bits to represent a letter index
+	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
+	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
+)
+
+var src = rand.NewSource(time.Now().UnixNano())
+
+func RandString(n int) string {
+	b := make([]byte, n)
+	// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
+	for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
+		if remain == 0 {
+			cache, remain = src.Int63(), letterIdxMax
+		}
+		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
+			b[i] = letterBytes[idx]
+			i--
+		}
+		cache >>= letterIdxBits
+		remain--
+	}
+
+	return *(*string)(unsafe.Pointer(&b))
+}