google.golang.org/grpc@v1.62.1/internal/metadata/metadata.go (about)

     1  /*
     2   *
     3   * Copyright 2020 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 metadata contains functions to set and get metadata from addresses.
    20  //
    21  // This package is experimental.
    22  package metadata
    23  
    24  import (
    25  	"fmt"
    26  	"strings"
    27  
    28  	"google.golang.org/grpc/metadata"
    29  	"google.golang.org/grpc/resolver"
    30  )
    31  
    32  type mdKeyType string
    33  
    34  const mdKey = mdKeyType("grpc.internal.address.metadata")
    35  
    36  type mdValue metadata.MD
    37  
    38  func (m mdValue) Equal(o any) bool {
    39  	om, ok := o.(mdValue)
    40  	if !ok {
    41  		return false
    42  	}
    43  	if len(m) != len(om) {
    44  		return false
    45  	}
    46  	for k, v := range m {
    47  		ov := om[k]
    48  		if len(ov) != len(v) {
    49  			return false
    50  		}
    51  		for i, ve := range v {
    52  			if ov[i] != ve {
    53  				return false
    54  			}
    55  		}
    56  	}
    57  	return true
    58  }
    59  
    60  // Get returns the metadata of addr.
    61  func Get(addr resolver.Address) metadata.MD {
    62  	attrs := addr.Attributes
    63  	if attrs == nil {
    64  		return nil
    65  	}
    66  	md, _ := attrs.Value(mdKey).(mdValue)
    67  	return metadata.MD(md)
    68  }
    69  
    70  // Set sets (overrides) the metadata in addr.
    71  //
    72  // When a SubConn is created with this address, the RPCs sent on it will all
    73  // have this metadata.
    74  func Set(addr resolver.Address, md metadata.MD) resolver.Address {
    75  	addr.Attributes = addr.Attributes.WithValue(mdKey, mdValue(md))
    76  	return addr
    77  }
    78  
    79  // Validate validates every pair in md with ValidatePair.
    80  func Validate(md metadata.MD) error {
    81  	for k, vals := range md {
    82  		if err := ValidatePair(k, vals...); err != nil {
    83  			return err
    84  		}
    85  	}
    86  	return nil
    87  }
    88  
    89  // hasNotPrintable return true if msg contains any characters which are not in %x20-%x7E
    90  func hasNotPrintable(msg string) bool {
    91  	// for i that saving a conversion if not using for range
    92  	for i := 0; i < len(msg); i++ {
    93  		if msg[i] < 0x20 || msg[i] > 0x7E {
    94  			return true
    95  		}
    96  	}
    97  	return false
    98  }
    99  
   100  // ValidatePair validate a key-value pair with the following rules (the pseudo-header will be skipped) :
   101  //
   102  // - key must contain one or more characters.
   103  // - the characters in the key must be contained in [0-9 a-z _ - .].
   104  // - if the key ends with a "-bin" suffix, no validation of the corresponding value is performed.
   105  // - the characters in the every value must be printable (in [%x20-%x7E]).
   106  func ValidatePair(key string, vals ...string) error {
   107  	// key should not be empty
   108  	if key == "" {
   109  		return fmt.Errorf("there is an empty key in the header")
   110  	}
   111  	// pseudo-header will be ignored
   112  	if key[0] == ':' {
   113  		return nil
   114  	}
   115  	// check key, for i that saving a conversion if not using for range
   116  	for i := 0; i < len(key); i++ {
   117  		r := key[i]
   118  		if !(r >= 'a' && r <= 'z') && !(r >= '0' && r <= '9') && r != '.' && r != '-' && r != '_' {
   119  			return fmt.Errorf("header key %q contains illegal characters not in [0-9a-z-_.]", key)
   120  		}
   121  	}
   122  	if strings.HasSuffix(key, "-bin") {
   123  		return nil
   124  	}
   125  	// check value
   126  	for _, val := range vals {
   127  		if hasNotPrintable(val) {
   128  			return fmt.Errorf("header key %q contains value with non-printable ASCII characters", key)
   129  		}
   130  	}
   131  	return nil
   132  }