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  
     7  package routebsd
     8  
     9  // A Message represents a routing message.
    10  type Message interface {
    11  	message()
    12  }
    13  
    14  // parseRIB parses b as a routing information base and returns a list
    15  // of routing messages.
    16  func parseRIB(b []byte) ([]Message, error) {
    17  	var msgs []Message
    18  	nmsgs, nskips := 0, 0
    19  	for len(b) > 4 {
    20  		nmsgs++
    21  		l := int(nativeEndian.Uint16(b[:2]))
    22  		if l == 0 {
    23  			return nil, errInvalidMessage
    24  		}
    25  		if len(b) < l {
    26  			return nil, errMessageTooShort
    27  		}
    28  		if b[2] != rtmVersion {
    29  			b = b[l:]
    30  			continue
    31  		}
    32  		if w, ok := wireFormats[int(b[3])]; !ok {
    33  			nskips++
    34  		} else {
    35  			m, err := w.parse(b[:l])
    36  			if err != nil {
    37  				return nil, err
    38  			}
    39  			if m == nil {
    40  				nskips++
    41  			} else {
    42  				msgs = append(msgs, m)
    43  			}
    44  		}
    45  		b = b[l:]
    46  	}
    47  
    48  	// We failed to parse any of the messages - version mismatch?
    49  	if nmsgs != len(msgs)+nskips {
    50  		return nil, errMessageMismatch
    51  	}
    52  	return msgs, nil
    53  }
    54
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