istio.io/istio@v0.0.0-20240520182934-d79c90f27776/tools/istio-iptables/pkg/dependencies/stub.go (about)

     1  // Copyright Istio Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package dependencies
    16  
    17  import (
    18  	"bufio"
    19  	"fmt"
    20  	"io"
    21  	"os"
    22  	"strings"
    23  
    24  	"istio.io/istio/pkg/env"
    25  	"istio.io/istio/tools/istio-iptables/pkg/constants"
    26  )
    27  
    28  var DryRunFilePath = env.Register("DRY_RUN_FILE_PATH", "", "If provided, StdoutStubDependencies will write the input from stdin to the given file.")
    29  
    30  // TODO BML replace DIY mocks/state with something better
    31  type DependenciesStub struct {
    32  	ExecutedNormally []string
    33  	ExecutedQuietly  []string
    34  	ExecutedStdin    []string
    35  	ExecutedAll      []string
    36  }
    37  
    38  func (s *DependenciesStub) Run(cmd constants.IptablesCmd, iptVer *IptablesVersion, stdin io.ReadSeeker, args ...string) error {
    39  	s.execute(false /*quietly*/, cmd, iptVer, stdin, args...)
    40  	_ = s.writeAllToDryRunPath()
    41  	return nil
    42  }
    43  
    44  func (s *DependenciesStub) RunQuietlyAndIgnore(cmd constants.IptablesCmd, iptVer *IptablesVersion, stdin io.ReadSeeker, args ...string) {
    45  	s.execute(true /*quietly*/, cmd, iptVer, stdin, args...)
    46  	_ = s.writeAllToDryRunPath()
    47  }
    48  
    49  func (s *DependenciesStub) DetectIptablesVersion(ipV6 bool) (IptablesVersion, error) {
    50  	if ipV6 {
    51  		return IptablesVersion{
    52  			DetectedBinary:        "ip6tables",
    53  			DetectedSaveBinary:    "ip6tables-save",
    54  			DetectedRestoreBinary: "ip6tables-restore",
    55  		}, nil
    56  	}
    57  	return IptablesVersion{
    58  		DetectedBinary:        "iptables",
    59  		DetectedSaveBinary:    "iptables-save",
    60  		DetectedRestoreBinary: "iptables-restore",
    61  	}, nil
    62  }
    63  
    64  func (s *DependenciesStub) execute(quietly bool, cmd constants.IptablesCmd, iptVer *IptablesVersion, stdin io.ReadSeeker, args ...string) {
    65  	// We are either getting iptables rules as a `stdin` blob in `iptables-save` format (if this is a restore)
    66  	if stdin != nil {
    67  		buf := bufio.NewScanner(stdin)
    68  		for buf.Scan() {
    69  			stdincmd := buf.Text()
    70  			s.ExecutedAll = append(s.ExecutedAll, stdincmd)
    71  			s.ExecutedStdin = append(s.ExecutedStdin, stdincmd)
    72  		}
    73  	} else {
    74  		// ...or as discrete individual commands
    75  		cmdline := strings.Join(append([]string{iptVer.CmdToString(cmd)}, args...), " ")
    76  		s.ExecutedAll = append(s.ExecutedAll, cmdline)
    77  		if quietly {
    78  			s.ExecutedQuietly = append(s.ExecutedQuietly, cmdline)
    79  		} else {
    80  			s.ExecutedNormally = append(s.ExecutedNormally, cmdline)
    81  		}
    82  	}
    83  }
    84  
    85  // TODO BML this is more than a stub actually needs to do, we should be able to drop this testing hack
    86  // and skip writing to a file, but some tests are not *actually* doing unit testing and need this.
    87  func (s *DependenciesStub) writeAllToDryRunPath() error {
    88  	path := DryRunFilePath.Get()
    89  	if path != "" {
    90  		// Print the input into the given output file.
    91  		f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0o644)
    92  		if err != nil {
    93  			return fmt.Errorf("unable to open dry run output file %v: %v", path, err)
    94  		}
    95  
    96  		defer f.Close()
    97  
    98  		for _, line := range s.ExecutedAll {
    99  			_, err := f.WriteString(line + "\n")
   100  			if err != nil {
   101  				return fmt.Errorf("unable to write lines to dry run output file %v: %v", path, err)
   102  			}
   103  		}
   104  	}
   105  	return nil
   106  }