message.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build darwin || dragonfly || freebsd || netbsd || openbsd
     6  // +build darwin dragonfly freebsd netbsd openbsd
     7  
     8  package route
     9  
    10  // A Message represents a routing message.
    11  type Message interface {
    12  	// Sys returns operating system-specific information.
    13  	Sys() []Sys
    14  }
    15  
    16  // A Sys reprensents operating system-specific information.
    17  type Sys interface {
    18  	// SysType returns a type of operating system-specific
    19  	// information.
    20  	SysType() SysType
    21  }
    22  
    23  // A SysType represents a type of operating system-specific
    24  // information.
    25  type SysType int
    26  
    27  const (
    28  	SysMetrics SysType = iota
    29  	SysStats
    30  )
    31  
    32  // ParseRIB parses b as a routing information base and returns a list
    33  // of routing messages.
    34  func ParseRIB(typ RIBType, b []byte) ([]Message, error) {
    35  	if !typ.parseable() {
    36  		return nil, errUnsupportedMessage
    37  	}
    38  	var msgs []Message
    39  	nmsgs, nskips := 0, 0
    40  	for len(b) > 4 {
    41  		nmsgs++
    42  		l := int(nativeEndian.Uint16(b[:2]))
    43  		if l == 0 {
    44  			return nil, errInvalidMessage
    45  		}
    46  		if len(b) < l {
    47  			return nil, errMessageTooShort
    48  		}
    49  		if b[2] != rtmVersion {
    50  			b = b[l:]
    51  			continue
    52  		}
    53  		if w, ok := wireFormats[int(b[3])]; !ok {
    54  			nskips++
    55  		} else {
    56  			m, err := w.parse(typ, b[:l])
    57  			if err != nil {
    58  				return nil, err
    59  			}
    60  			if m == nil {
    61  				nskips++
    62  			} else {
    63  				msgs = append(msgs, m)
    64  			}
    65  		}
    66  		b = b[l:]
    67  	}
    68  	// We failed to parse any of the messages - version mismatch?
    69  	if nmsgs != len(msgs)+nskips {
    70  		return nil, errMessageMismatch
    71  	}
    72  	return msgs, nil
    73  }
    74
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