string_matcher.go

Documentation: google.golang.org/grpc/internal/xds/matcher

     1  /*
     2   *
     3   * Copyright 2021 gRPC authors.
     4   *
     5   * Licensed under the Apache License, Version 2.0 (the "License");
     6   * you may not use this file except in compliance with the License.
     7   * You may obtain a copy of the License at
     8   *
     9   *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   *
    17   */
    18  
    19  // Package matcher contains types that need to be shared between code under
    20  // google.golang.org/grpc/xds/... and the rest of gRPC.
    21  package matcher
    22  
    23  import (
    24  	"errors"
    25  	"fmt"
    26  	"regexp"
    27  	"strings"
    28  
    29  	v3matcherpb "github.com/envoyproxy/go-control-plane/envoy/type/matcher/v3"
    30  	"google.golang.org/grpc/internal/grpcutil"
    31  )
    32  
    33  // StringMatcher contains match criteria for matching a string, and is an
    34  // internal representation of the `StringMatcher` proto defined at
    35  // https://github.com/envoyproxy/envoy/blob/main/api/envoy/type/matcher/v3/string.proto.
    36  type StringMatcher struct {
    37  	// Since these match fields are part of a `oneof` in the corresponding xDS
    38  	// proto, only one of them is expected to be set.
    39  	exactMatch    *string
    40  	prefixMatch   *string
    41  	suffixMatch   *string
    42  	regexMatch    *regexp.Regexp
    43  	containsMatch *string
    44  	// If true, indicates the exact/prefix/suffix/contains matching should be
    45  	// case insensitive. This has no effect on the regex match.
    46  	ignoreCase bool
    47  }
    48  
    49  // Match returns true if input matches the criteria in the given StringMatcher.
    50  func (sm StringMatcher) Match(input string) bool {
    51  	if sm.ignoreCase {
    52  		input = strings.ToLower(input)
    53  	}
    54  	switch {
    55  	case sm.exactMatch != nil:
    56  		return input == *sm.exactMatch
    57  	case sm.prefixMatch != nil:
    58  		return strings.HasPrefix(input, *sm.prefixMatch)
    59  	case sm.suffixMatch != nil:
    60  		return strings.HasSuffix(input, *sm.suffixMatch)
    61  	case sm.regexMatch != nil:
    62  		return grpcutil.FullMatchWithRegex(sm.regexMatch, input)
    63  	case sm.containsMatch != nil:
    64  		return strings.Contains(input, *sm.containsMatch)
    65  	}
    66  	return false
    67  }
    68  
    69  // StringMatcherFromProto is a helper function to create a StringMatcher from
    70  // the corresponding StringMatcher proto.
    71  //
    72  // Returns a non-nil error if matcherProto is invalid.
    73  func StringMatcherFromProto(matcherProto *v3matcherpb.StringMatcher) (StringMatcher, error) {
    74  	if matcherProto == nil {
    75  		return StringMatcher{}, errors.New("input StringMatcher proto is nil")
    76  	}
    77  
    78  	matcher := StringMatcher{ignoreCase: matcherProto.GetIgnoreCase()}
    79  	switch mt := matcherProto.GetMatchPattern().(type) {
    80  	case *v3matcherpb.StringMatcher_Exact:
    81  		matcher.exactMatch = &mt.Exact
    82  		if matcher.ignoreCase {
    83  			*matcher.exactMatch = strings.ToLower(*matcher.exactMatch)
    84  		}
    85  	case *v3matcherpb.StringMatcher_Prefix:
    86  		if matcherProto.GetPrefix() == "" {
    87  			return StringMatcher{}, errors.New("empty prefix is not allowed in StringMatcher")
    88  		}
    89  		matcher.prefixMatch = &mt.Prefix
    90  		if matcher.ignoreCase {
    91  			*matcher.prefixMatch = strings.ToLower(*matcher.prefixMatch)
    92  		}
    93  	case *v3matcherpb.StringMatcher_Suffix:
    94  		if matcherProto.GetSuffix() == "" {
    95  			return StringMatcher{}, errors.New("empty suffix is not allowed in StringMatcher")
    96  		}
    97  		matcher.suffixMatch = &mt.Suffix
    98  		if matcher.ignoreCase {
    99  			*matcher.suffixMatch = strings.ToLower(*matcher.suffixMatch)
   100  		}
   101  	case *v3matcherpb.StringMatcher_SafeRegex:
   102  		regex := matcherProto.GetSafeRegex().GetRegex()
   103  		re, err := regexp.Compile(regex)
   104  		if err != nil {
   105  			return StringMatcher{}, fmt.Errorf("safe_regex matcher %q is invalid", regex)
   106  		}
   107  		matcher.regexMatch = re
   108  	case *v3matcherpb.StringMatcher_Contains:
   109  		if matcherProto.GetContains() == "" {
   110  			return StringMatcher{}, errors.New("empty contains is not allowed in StringMatcher")
   111  		}
   112  		matcher.containsMatch = &mt.Contains
   113  		if matcher.ignoreCase {
   114  			*matcher.containsMatch = strings.ToLower(*matcher.containsMatch)
   115  		}
   116  	default:
   117  		return StringMatcher{}, fmt.Errorf("unrecognized string matcher: %+v", matcherProto)
   118  	}
   119  	return matcher, nil
   120  }
   121  
   122  // StringMatcherForTesting is a helper function to create a StringMatcher based
   123  // on the given arguments. Intended only for testing purposes.
   124  func StringMatcherForTesting(exact, prefix, suffix, contains *string, regex *regexp.Regexp, ignoreCase bool) StringMatcher {
   125  	sm := StringMatcher{
   126  		exactMatch:    exact,
   127  		prefixMatch:   prefix,
   128  		suffixMatch:   suffix,
   129  		regexMatch:    regex,
   130  		containsMatch: contains,
   131  		ignoreCase:    ignoreCase,
   132  	}
   133  	if ignoreCase {
   134  		switch {
   135  		case sm.exactMatch != nil:
   136  			*sm.exactMatch = strings.ToLower(*exact)
   137  		case sm.prefixMatch != nil:
   138  			*sm.prefixMatch = strings.ToLower(*prefix)
   139  		case sm.suffixMatch != nil:
   140  			*sm.suffixMatch = strings.ToLower(*suffix)
   141  		case sm.containsMatch != nil:
   142  			*sm.containsMatch = strings.ToLower(*contains)
   143  		}
   144  	}
   145  	return sm
   146  }
   147  
   148  // ExactMatch returns the value of the configured exact match or an empty string
   149  // if exact match criteria was not specified.
   150  func (sm StringMatcher) ExactMatch() string {
   151  	if sm.exactMatch != nil {
   152  		return *sm.exactMatch
   153  	}
   154  	return ""
   155  }
   156  
   157  // Equal returns true if other and sm are equivalent to each other.
   158  func (sm StringMatcher) Equal(other StringMatcher) bool {
   159  	if sm.ignoreCase != other.ignoreCase {
   160  		return false
   161  	}
   162  
   163  	if (sm.exactMatch != nil) != (other.exactMatch != nil) ||
   164  		(sm.prefixMatch != nil) != (other.prefixMatch != nil) ||
   165  		(sm.suffixMatch != nil) != (other.suffixMatch != nil) ||
   166  		(sm.regexMatch != nil) != (other.regexMatch != nil) ||
   167  		(sm.containsMatch != nil) != (other.containsMatch != nil) {
   168  		return false
   169  	}
   170  
   171  	switch {
   172  	case sm.exactMatch != nil:
   173  		return *sm.exactMatch == *other.exactMatch
   174  	case sm.prefixMatch != nil:
   175  		return *sm.prefixMatch == *other.prefixMatch
   176  	case sm.suffixMatch != nil:
   177  		return *sm.suffixMatch == *other.suffixMatch
   178  	case sm.regexMatch != nil:
   179  		return sm.regexMatch.String() == other.regexMatch.String()
   180  	case sm.containsMatch != nil:
   181  		return *sm.containsMatch == *other.containsMatch
   182  	}
   183  	return true
   184  }
   185
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