065e07da4b
for convenience. Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja> git-svn-id: file:///srv/svn/repo/suika/trunk@822 f0ae65fe-ee39-954e-97ec-027ff2717ef4
244 lines
6.9 KiB
Go
244 lines
6.9 KiB
Go
package proxyproto
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import (
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"bufio"
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"bytes"
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"fmt"
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"net"
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"net/netip"
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"strconv"
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"strings"
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)
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const (
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crlf = "\r\n"
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separator = " "
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)
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func initVersion1() *Header {
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header := new(Header)
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header.Version = 1
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// Command doesn't exist in v1
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header.Command = PROXY
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return header
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}
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func parseVersion1(reader *bufio.Reader) (*Header, error) {
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//The header cannot be more than 107 bytes long. Per spec:
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//
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// (...)
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// - worst case (optional fields set to 0xff) :
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// "PROXY UNKNOWN ffff:f...f:ffff ffff:f...f:ffff 65535 65535\r\n"
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// => 5 + 1 + 7 + 1 + 39 + 1 + 39 + 1 + 5 + 1 + 5 + 2 = 107 chars
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//
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// So a 108-byte buffer is always enough to store all the line and a
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// trailing zero for string processing.
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//
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// It must also be CRLF terminated, as above. The header does not otherwise
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// contain a CR or LF byte.
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//
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// ISSUE #69
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// We can't use Peek here as it will block trying to fill the buffer, which
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// will never happen if the header is TCP4 or TCP6 (max. 56 and 104 bytes
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// respectively) and the server is expected to speak first.
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//
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// Similarly, we can't use ReadString or ReadBytes as these will keep reading
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// until the delimiter is found; an abusive client could easily disrupt a
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// server by sending a large amount of data that do not contain a LF byte.
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// Another means of attack would be to start connections and simply not send
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// data after the initial PROXY signature bytes, accumulating a large
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// number of blocked goroutines on the server. ReadSlice will also block for
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// a delimiter when the internal buffer does not fill up.
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//
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// A plain Read is also problematic since we risk reading past the end of the
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// header without being able to easily put the excess bytes back into the reader's
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// buffer (with the current implementation's design).
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//
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// So we use a ReadByte loop, which solves the overflow problem and avoids
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// reading beyond the end of the header. However, we need one more trick to harden
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// against partial header attacks (slow loris) - per spec:
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//
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// (..) The sender must always ensure that the header is sent at once, so that
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// the transport layer maintains atomicity along the path to the receiver. The
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// receiver may be tolerant to partial headers or may simply drop the connection
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// when receiving a partial header. Recommendation is to be tolerant, but
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// implementation constraints may not always easily permit this.
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//
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// We are subject to such implementation constraints. So we return an error if
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// the header cannot be fully extracted with a single read of the underlying
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// reader.
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buf := make([]byte, 0, 107)
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for {
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b, err := reader.ReadByte()
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if err != nil {
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return nil, fmt.Errorf(ErrCantReadVersion1Header.Error()+": %v", err)
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}
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buf = append(buf, b)
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if b == '\n' {
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// End of header found
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break
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}
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if len(buf) == 107 {
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// No delimiter in first 107 bytes
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return nil, ErrVersion1HeaderTooLong
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}
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if reader.Buffered() == 0 {
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// Header was not buffered in a single read. Since we can't
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// differentiate between genuine slow writers and DoS agents,
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// we abort. On healthy networks, this should never happen.
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return nil, ErrCantReadVersion1Header
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}
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}
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// Check for CR before LF.
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if len(buf) < 2 || buf[len(buf)-2] != '\r' {
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return nil, ErrLineMustEndWithCrlf
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}
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// Check full signature.
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tokens := strings.Split(string(buf[:len(buf)-2]), separator)
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// Expect at least 2 tokens: "PROXY" and the transport protocol.
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if len(tokens) < 2 {
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return nil, ErrCantReadAddressFamilyAndProtocol
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}
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// Read address family and protocol
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var transportProtocol AddressFamilyAndProtocol
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switch tokens[1] {
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case "TCP4":
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transportProtocol = TCPv4
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case "TCP6":
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transportProtocol = TCPv6
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case "UNKNOWN":
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transportProtocol = UNSPEC // doesn't exist in v1 but fits UNKNOWN
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default:
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return nil, ErrCantReadAddressFamilyAndProtocol
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}
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// Expect 6 tokens only when UNKNOWN is not present.
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if transportProtocol != UNSPEC && len(tokens) < 6 {
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return nil, ErrCantReadAddressFamilyAndProtocol
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}
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// When a signature is found, allocate a v1 header with Command set to PROXY.
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// Command doesn't exist in v1 but set it for other parts of this library
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// to rely on it for determining connection details.
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header := initVersion1()
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// Transport protocol has been processed already.
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header.TransportProtocol = transportProtocol
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// When UNKNOWN, set the command to LOCAL and return early
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if header.TransportProtocol == UNSPEC {
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header.Command = LOCAL
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return header, nil
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}
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// Otherwise, continue to read addresses and ports
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sourceIP, err := parseV1IPAddress(header.TransportProtocol, tokens[2])
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if err != nil {
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return nil, err
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}
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destIP, err := parseV1IPAddress(header.TransportProtocol, tokens[3])
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if err != nil {
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return nil, err
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}
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sourcePort, err := parseV1PortNumber(tokens[4])
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if err != nil {
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return nil, err
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}
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destPort, err := parseV1PortNumber(tokens[5])
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if err != nil {
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return nil, err
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}
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header.SourceAddr = &net.TCPAddr{
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IP: sourceIP,
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Port: sourcePort,
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}
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header.DestinationAddr = &net.TCPAddr{
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IP: destIP,
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Port: destPort,
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}
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return header, nil
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}
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func (header *Header) formatVersion1() ([]byte, error) {
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// As of version 1, only "TCP4" ( \x54 \x43 \x50 \x34 ) for TCP over IPv4,
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// and "TCP6" ( \x54 \x43 \x50 \x36 ) for TCP over IPv6 are allowed.
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var proto string
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switch header.TransportProtocol {
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case TCPv4:
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proto = "TCP4"
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case TCPv6:
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proto = "TCP6"
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default:
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// Unknown connection (short form)
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return []byte("PROXY UNKNOWN" + crlf), nil
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}
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sourceAddr, sourceOK := header.SourceAddr.(*net.TCPAddr)
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destAddr, destOK := header.DestinationAddr.(*net.TCPAddr)
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if !sourceOK || !destOK {
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return nil, ErrInvalidAddress
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}
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sourceIP, destIP := sourceAddr.IP, destAddr.IP
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switch header.TransportProtocol {
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case TCPv4:
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sourceIP = sourceIP.To4()
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destIP = destIP.To4()
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case TCPv6:
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sourceIP = sourceIP.To16()
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destIP = destIP.To16()
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}
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if sourceIP == nil || destIP == nil {
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return nil, ErrInvalidAddress
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}
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buf := bytes.NewBuffer(make([]byte, 0, 108))
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buf.Write(SIGV1)
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buf.WriteString(separator)
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buf.WriteString(proto)
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buf.WriteString(separator)
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buf.WriteString(sourceIP.String())
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buf.WriteString(separator)
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buf.WriteString(destIP.String())
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buf.WriteString(separator)
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buf.WriteString(strconv.Itoa(sourceAddr.Port))
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buf.WriteString(separator)
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buf.WriteString(strconv.Itoa(destAddr.Port))
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buf.WriteString(crlf)
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return buf.Bytes(), nil
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}
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func parseV1PortNumber(portStr string) (int, error) {
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port, err := strconv.Atoi(portStr)
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if err != nil || port < 0 || port > 65535 {
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return 0, ErrInvalidPortNumber
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}
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return port, nil
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}
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func parseV1IPAddress(protocol AddressFamilyAndProtocol, addrStr string) (net.IP, error) {
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addr, err := netip.ParseAddr(addrStr)
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if err != nil {
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return nil, ErrInvalidAddress
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}
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switch protocol {
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case TCPv4:
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if addr.Is4() {
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return net.IP(addr.AsSlice()), nil
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}
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case TCPv6:
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if addr.Is6() || addr.Is4In6() {
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return net.IP(addr.AsSlice()), nil
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}
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}
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return nil, ErrInvalidAddress
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}
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