apq.go

Documentation: github.com/99designs/gqlgen/graphql/handler/extension

     1  package extension
     2  
     3  import (
     4  	"context"
     5  	"crypto/sha256"
     6  	"encoding/hex"
     7  	"fmt"
     8  
     9  	"github.com/mitchellh/mapstructure"
    10  	"github.com/vektah/gqlparser/v2/gqlerror"
    11  
    12  	"github.com/99designs/gqlgen/graphql"
    13  	"github.com/99designs/gqlgen/graphql/errcode"
    14  )
    15  
    16  const (
    17  	errPersistedQueryNotFound     = "PersistedQueryNotFound"
    18  	errPersistedQueryNotFoundCode = "PERSISTED_QUERY_NOT_FOUND"
    19  )
    20  
    21  // AutomaticPersistedQuery saves client upload by optimistically sending only the hashes of queries, if the server
    22  // does not yet know what the query is for the hash it will respond telling the client to send the query along with the
    23  // hash in the next request.
    24  // see https://github.com/apollographql/apollo-link-persisted-queries
    25  type AutomaticPersistedQuery struct {
    26  	Cache graphql.Cache
    27  }
    28  
    29  type ApqStats struct {
    30  	// The hash of the incoming query
    31  	Hash string
    32  
    33  	// SentQuery is true if the incoming request sent the full query
    34  	SentQuery bool
    35  }
    36  
    37  const apqExtension = "APQ"
    38  
    39  var _ interface {
    40  	graphql.OperationParameterMutator
    41  	graphql.HandlerExtension
    42  } = AutomaticPersistedQuery{}
    43  
    44  func (a AutomaticPersistedQuery) ExtensionName() string {
    45  	return "AutomaticPersistedQuery"
    46  }
    47  
    48  func (a AutomaticPersistedQuery) Validate(schema graphql.ExecutableSchema) error {
    49  	if a.Cache == nil {
    50  		return fmt.Errorf("AutomaticPersistedQuery.Cache can not be nil")
    51  	}
    52  	return nil
    53  }
    54  
    55  func (a AutomaticPersistedQuery) MutateOperationParameters(ctx context.Context, rawParams *graphql.RawParams) *gqlerror.Error {
    56  	if rawParams.Extensions["persistedQuery"] == nil {
    57  		return nil
    58  	}
    59  
    60  	var extension struct {
    61  		Sha256  string `mapstructure:"sha256Hash"`
    62  		Version int64  `mapstructure:"version"`
    63  	}
    64  
    65  	if err := mapstructure.Decode(rawParams.Extensions["persistedQuery"], &extension); err != nil {
    66  		return gqlerror.Errorf("invalid APQ extension data")
    67  	}
    68  
    69  	if extension.Version != 1 {
    70  		return gqlerror.Errorf("unsupported APQ version")
    71  	}
    72  
    73  	fullQuery := false
    74  	if rawParams.Query == "" {
    75  		// client sent optimistic query hash without query string, get it from the cache
    76  		query, ok := a.Cache.Get(ctx, extension.Sha256)
    77  		if !ok {
    78  			err := gqlerror.Errorf(errPersistedQueryNotFound)
    79  			errcode.Set(err, errPersistedQueryNotFoundCode)
    80  			return err
    81  		}
    82  		rawParams.Query = query.(string)
    83  	} else {
    84  		// client sent optimistic query hash with query string, verify and store it
    85  		if computeQueryHash(rawParams.Query) != extension.Sha256 {
    86  			return gqlerror.Errorf("provided APQ hash does not match query")
    87  		}
    88  		a.Cache.Add(ctx, extension.Sha256, rawParams.Query)
    89  		fullQuery = true
    90  	}
    91  
    92  	graphql.GetOperationContext(ctx).Stats.SetExtension(apqExtension, &ApqStats{
    93  		Hash:      extension.Sha256,
    94  		SentQuery: fullQuery,
    95  	})
    96  
    97  	return nil
    98  }
    99  
   100  func GetApqStats(ctx context.Context) *ApqStats {
   101  	rc := graphql.GetOperationContext(ctx)
   102  	if rc == nil {
   103  		return nil
   104  	}
   105  
   106  	s, _ := rc.Stats.GetExtension(apqExtension).(*ApqStats)
   107  	return s
   108  }
   109  
   110  func computeQueryHash(query string) string {
   111  	b := sha256.Sum256([]byte(query))
   112  	return hex.EncodeToString(b[:])
   113  }
   114
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