mirror of
https://github.com/gravitational/teleport.git
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STeve (Xin) Huang
e13d96d4ac
* Split PingConn to PingConn and PingTLSConn * minor name change * require utils.TLSConn * fix typo
132 lines
3.3 KiB
Go
132 lines
3.3 KiB
Go
/*
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Copyright 2023 Gravitational, Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package pingconn
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import (
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"encoding/binary"
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"math"
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"net"
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"sync"
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"github.com/gravitational/trace"
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)
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// New returns a ping connection wrapping the provided net.Conn.
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func New(conn net.Conn) *PingConn {
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return &PingConn{Conn: conn}
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}
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// PingConn wraps a net.Conn and add ping capabilities to it, including the
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// `WritePing` function and `Read` (which excludes ping packets).
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//
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// When using this connection, the packets written will contain an initial data:
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// the packet size. When reading, this information is taken into account, but it
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// is not returned to the caller.
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//
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// Ping messages have a packet size of zero and are produced only when
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// `WritePing` is called. On `Read`, any Ping packet is discarded.
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type PingConn struct {
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net.Conn
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muRead sync.Mutex
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muWrite sync.Mutex
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// currentSize size of bytes of the current packet.
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currentSize uint32
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}
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// Read reads content from the underlying connection, discarding any ping
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// messages it finds.
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func (c *PingConn) Read(p []byte) (int, error) {
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c.muRead.Lock()
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defer c.muRead.Unlock()
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err := c.discardPingReads()
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if err != nil {
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return 0, err
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}
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// Check if the current size is larger than the provided buffer.
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readSize := c.currentSize
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if c.currentSize > uint32(len(p)) {
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readSize = uint32(len(p))
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}
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n, err := c.Conn.Read(p[:readSize])
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c.currentSize -= uint32(n)
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return n, err
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}
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// WritePing writes the ping packet to the connection.
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func (c *PingConn) WritePing() error {
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c.muWrite.Lock()
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defer c.muWrite.Unlock()
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return binary.Write(c.Conn, binary.BigEndian, uint32(0))
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}
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// discardPingReads reads from the wrapped net.Conn until it encounters a
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// non-ping packet.
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func (c *PingConn) discardPingReads() error {
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for c.currentSize == 0 {
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err := binary.Read(c.Conn, binary.BigEndian, &c.currentSize)
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if err != nil {
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return err
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}
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}
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return nil
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}
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// Write writes provided content to the underlying connection with proper
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// protocol fields.
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func (c *PingConn) Write(p []byte) (int, error) {
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c.muWrite.Lock()
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defer c.muWrite.Unlock()
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// Avoid overflow when casting data length. It is only present to avoid
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// panicking if the size cannot be cast. Callers should handle packet length
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// limits, such as protocol implementations and audits.
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if uint64(len(p)) > math.MaxUint32 {
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return 0, trace.BadParameter("invalid content size, max size permitted is %d", uint64(math.MaxUint32))
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}
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size := uint32(len(p))
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if size == 0 {
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return 0, nil
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}
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// Write packet size.
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if err := binary.Write(c.Conn, binary.BigEndian, size); err != nil {
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return 0, trace.Wrap(err)
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}
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// Iterate until everything is written.
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var written int
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for written < len(p) {
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n, err := c.Conn.Write(p)
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written += n
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if err != nil {
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return written, trace.Wrap(err)
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}
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}
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return written, nil
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}
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