Home > Article > Backend Development > How to Read Data in Chunks from a `net.Conn` in Go?
In Go, you can access raw network connections using net.Conn.Read, which reads incoming data packets into a byte array. However, when you don't know the exact size of the incoming data, reading into a fixed-size array can lead to data truncation or unnecessary buffering.
To handle this, you can employ a more flexible approach using the bufio package or alternative techniques.
The bufio package provides the Reader type, which allows you to read data in chunks. You can create a Reader object from your net.Conn connection, and then use the ReadSlice or ReadBytes methods to read data until a specific delimiter is encountered or the end of the input is reached. For instance, to read data until the end of the packet, you could use the following code:
package main import ( "bufio" "fmt" "net" ) func main() { conn, err := net.Dial("tcp", "google.com:80") if err != nil { fmt.Println("dial error:", err) return } defer conn.Close() // Create a bufio.Reader from the net.Conn reader := bufio.NewReader(conn) // Read data in chunks until the end of the packet buf := []byte{} for { chunk, err := reader.ReadSlice('\n') if err != nil { if err != io.EOF { fmt.Println("read error:", err) } break } buf = append(buf, chunk...) } fmt.Println("total size:", len(buf)) // fmt.Println(string(buf)) }
Alternatively, you can use the bytes.Buffer type to append incoming data chunks and accumulate the total size:
package main import ( "bytes" "fmt" "io" "net" ) func main() { conn, err := net.Dial("tcp", "google.com:80") if err != nil { fmt.Println("dial error:", err) return } defer conn.Close() // Create a bytes.Buffer to accumulate incoming data var buf bytes.Buffer // Copy data from the net.Conn to the Buffer if _, err = io.Copy(&buf, conn); err != nil { fmt.Println("copy error:", err) } fmt.Println("total size:", buf.Len()) }
By using one of these approaches, you can handle varying data lengths without data truncation or excessive buffering, ensuring efficient data transfer over network connections in Go.
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