95 lines
2.2 KiB
Go
95 lines
2.2 KiB
Go
package upgrade
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import (
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"crypto/sha1"
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"encoding/base64"
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"fmt"
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"io"
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)
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// HTTPVersion constant
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const HTTPVersion = "1.1"
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// UsedWSVersion constant websocket version
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const UsedWSVersion = 13
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// WSSalt constant websocket salt
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const WSSalt = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
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// Response represents an HTTP Upgrade Response
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type Response struct {
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code StatusCode // status code
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accept []byte // processed from Sec-WebSocket-Key
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protocol []byte // set from Sec-WebSocket-Protocol or none if not received
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}
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// SetStatusCode sets the status code
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func (r *Response) SetStatusCode(sc StatusCode) {
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r.code = sc
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}
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// SetProtocol sets the protocols
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func (r *Response) SetProtocol(p []byte) {
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r.protocol = p
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}
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// ProcessKey processes the accept token according
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// to the rfc from the Sec-WebSocket-Key
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func (r *Response) ProcessKey(k []byte) {
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// do nothing for empty key
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if k == nil || len(k) == 0 {
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r.accept = nil
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return
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}
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// 1. Concat with constant salt
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mix := append(k, []byte(WSSalt)...)
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// 2. Hash with sha1 algorithm
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digest := sha1.Sum(mix)
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// 3. Base64 encode it
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r.accept = []byte(base64.StdEncoding.EncodeToString(digest[:sha1.Size]))
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}
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// Send sends the response through an io.Writer
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// typically a socket
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func (r Response) Send(w io.Writer) (int, error) {
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// 1. Build response line
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responseLine := fmt.Sprintf("HTTP/%s %d %s\r\n", HTTPVersion, r.code, r.code)
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// 2. Build headers
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optionalProtocol := ""
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if len(r.protocol) > 0 {
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optionalProtocol = fmt.Sprintf("Sec-WebSocket-Protocol: %s\r\n", r.protocol)
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}
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headers := fmt.Sprintf("Upgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Version: %d\r\n%s", UsedWSVersion, optionalProtocol)
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if r.accept != nil {
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headers = fmt.Sprintf("%sSec-WebSocket-Accept: %s\r\n", headers, r.accept)
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}
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headers = fmt.Sprintf("%s\r\n", headers)
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// 3. Build all
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raw := []byte(fmt.Sprintf("%s%s", responseLine, headers))
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// 4. Write
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written, err := w.Write(raw)
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return written, err
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}
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// GetProtocol returns the choosen protocol if set, else nil
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func (r Response) GetProtocol() []byte {
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return r.protocol
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}
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// GetStatusCode returns the response status code
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func (r Response) GetStatusCode() StatusCode {
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return r.code
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}
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