99 lines
2.9 KiB
Go
99 lines
2.9 KiB
Go
package goricochet
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import (
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"github.com/s-rah/go-ricochet/utils"
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"github.com/s-rah/go-ricochet/connection"
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"io"
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"net"
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"log"
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)
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// Open establishes a protocol session on an established net.Conn, and returns a new
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// OpenConnection instance representing this connection. On error, the connection
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// will be closed. This function blocks until version negotiation has completed.
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// The application should call Process() on the returned OpenConnection to continue
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// handling protocol messages.
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func Open(remoteHostname string) (*connection.Connection, error) {
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networkResolver := utils.NetworkResolver{}
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log.Printf("Connecting...")
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conn, remoteHostname, err := networkResolver.Resolve(remoteHostname)
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if err != nil {
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return nil, err
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}
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log.Printf("Connected...negotiating version")
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rc, err := negotiateVersion(conn, remoteHostname)
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if err != nil {
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conn.Close()
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return nil, err
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}
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log.Printf("Connected...negotiated version")
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return rc, nil
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}
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// negotiate version takes an open network connection and executes
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// the ricochet version negotiation procedure.
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func negotiateVersion(conn net.Conn, remoteHostname string) (*connection.Connection, error) {
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versions := []byte{0x49, 0x4D, 0x01, 0x01}
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if n, err := conn.Write(versions); err != nil || n < len(versions) {
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return nil, utils.VersionNegotiationError
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}
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res := make([]byte, 1)
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if _, err := io.ReadAtLeast(conn, res, len(res)); err != nil {
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return nil, utils.VersionNegotiationError
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}
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if res[0] != 0x01 {
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return nil, utils.VersionNegotiationFailed
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}
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rc := connection.NewOutboundConnection(conn,remoteHostname)
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return rc, nil
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}
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// NegotiateVersionInbound takes in a connection and performs version negotiation
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// as if that connection was a client. Returns a ricochet connection if successful
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// error otherwise.
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func NegotiateVersionInbound(conn net.Conn) (*connection.Connection, error) {
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versions := []byte{0x49, 0x4D, 0x01, 0x01}
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// Read version response header
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header := make([]byte, 3)
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if _, err := io.ReadAtLeast(conn, header, len(header)); err != nil {
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return nil, err
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}
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if header[0] != versions[0] || header[1] != versions[1] || header[2] < 1 {
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return nil, utils.VersionNegotiationError
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}
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// Read list of supported versions (which is header[2] bytes long)
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versionList := make([]byte, header[2])
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if _, err := io.ReadAtLeast(conn, versionList, len(versionList)); err != nil {
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return nil, utils.VersionNegotiationError
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}
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selectedVersion := byte(0xff)
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for _, v := range versionList {
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if v == 0x01 {
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selectedVersion = v
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break
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}
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}
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if n, err := conn.Write([]byte{selectedVersion}); err != nil || n < 1 {
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return nil, utils.VersionNegotiationFailed
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}
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if selectedVersion == 0xff {
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return nil, utils.VersionNegotiationFailed
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}
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rc := connection.NewInboundConnection(conn)
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return rc, nil
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}
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