github.com/containerd/nerdctl/v2@v2.0.0-beta.5.0.20240520001846-b5758f54fa28/pkg/portutil/procnet/procnet.go (about)

     1  /*
     2     Copyright The containerd Authors.
     3  
     4     Licensed under the Apache License, Version 2.0 (the "License");
     5     you may not use this file except in compliance with the License.
     6     You may obtain a copy of the License at
     7  
     8         http://www.apache.org/licenses/LICENSE-2.0
     9  
    10     Unless required by applicable law or agreed to in writing, software
    11     distributed under the License is distributed on an "AS IS" BASIS,
    12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13     See the License for the specific language governing permissions and
    14     limitations under the License.
    15  */
    16  
    17  package procnet
    18  
    19  import (
    20  	"encoding/hex"
    21  	"fmt"
    22  	"net"
    23  	"strconv"
    24  	"strings"
    25  )
    26  
    27  type NetworkDetail struct {
    28  	LocalIP   net.IP
    29  	LocalPort uint64
    30  }
    31  
    32  func Parse(data []string) (results []NetworkDetail) {
    33  	temp := removeEmpty(data)
    34  	for _, value := range temp {
    35  		lineData := removeEmpty(strings.Split(strings.TrimSpace(value), " "))
    36  		ip, port, err := ParseAddress(lineData[1])
    37  		if err != nil {
    38  			continue
    39  		}
    40  		results = append(results, NetworkDetail{
    41  			LocalIP:   ip,
    42  			LocalPort: uint64(port),
    43  		})
    44  	}
    45  	return results
    46  }
    47  
    48  func removeEmpty(array []string) (results []string) {
    49  	for _, i := range array {
    50  		if i != "" {
    51  			results = append(results, i)
    52  		}
    53  	}
    54  	return results
    55  }
    56  
    57  // ParseAddress parses a string, e.g.,Akihiro Suda, 10 months ago: • initial commit
    58  // "0100007F:0050"                         (127.0.0.1:80)
    59  // "000080FE00000000FF57A6705DC771FE:0050" ([fe80::70a6:57ff:fe71:c75d]:80)
    60  // "00000000000000000000000000000000:0050" (0.0.0.0:80)
    61  //
    62  // See https://serverfault.com/questions/592574/why-does-proc-net-tcp6-represents-1-as-1000
    63  //
    64  // ParseAddress is expected to be used for /proc/net/{tcp,tcp6} entries on
    65  // little endian machines.
    66  // Not sure how those entries look like on big endian machines.
    67  // All the code below is copied from the lima project in https://github.com/lima-vm/lima/blob/v0.8.3/pkg/guestagent/procnettcp/procnettcp.go#L95-L137
    68  // and is licensed under the Apache License, Version 2.0
    69  func ParseAddress(s string) (net.IP, uint16, error) {
    70  	split := strings.SplitN(s, ":", 2)
    71  	if len(split) != 2 {
    72  		return nil, 0, fmt.Errorf("unparsable address %q", s)
    73  	}
    74  	switch l := len(split[0]); l {
    75  	case 8, 32:
    76  	default:
    77  		return nil, 0, fmt.Errorf("unparsable address %q, expected length of %q to be 8 or 32, got %d",
    78  			s, split[0], l)
    79  	}
    80  
    81  	ipBytes := make([]byte, len(split[0])/2) // 4 bytes (8 chars) or 16 bytes (32 chars)
    82  	for i := 0; i < len(split[0])/8; i++ {
    83  		quartet := split[0][8*i : 8*(i+1)]
    84  		quartetLE, err := hex.DecodeString(quartet) // surprisingly little endian, per 4 bytes
    85  		if err != nil {
    86  			return nil, 0, fmt.Errorf("unparsable address %q: unparsable quartet %q: %w", s, quartet, err)
    87  		}
    88  		for j := 0; j < len(quartetLE); j++ {
    89  			ipBytes[4*i+len(quartetLE)-1-j] = quartetLE[j]
    90  		}
    91  	}
    92  	ip := net.IP(ipBytes)
    93  
    94  	port64, err := strconv.ParseUint(split[1], 16, 16)
    95  	if err != nil {
    96  		return nil, 0, fmt.Errorf("unparsable address %q: unparsable port %q", s, split[1])
    97  	}
    98  	port := uint16(port64)
    99  
   100  	return ip, port, nil
   101  }