github.com/ethereum/go-ethereum@v1.14.3/graphql/service.go (about)

     1  // Copyright 2019 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package graphql
    18  
    19  import (
    20  	"context"
    21  	"encoding/json"
    22  	"net/http"
    23  	"strconv"
    24  	"sync"
    25  	"time"
    26  
    27  	"github.com/ethereum/go-ethereum/eth/filters"
    28  	"github.com/ethereum/go-ethereum/internal/ethapi"
    29  	"github.com/ethereum/go-ethereum/node"
    30  	"github.com/ethereum/go-ethereum/rpc"
    31  	"github.com/graph-gophers/graphql-go"
    32  	gqlErrors "github.com/graph-gophers/graphql-go/errors"
    33  )
    34  
    35  type handler struct {
    36  	Schema *graphql.Schema
    37  }
    38  
    39  func (h handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    40  	var params struct {
    41  		Query         string                 `json:"query"`
    42  		OperationName string                 `json:"operationName"`
    43  		Variables     map[string]interface{} `json:"variables"`
    44  	}
    45  	if err := json.NewDecoder(r.Body).Decode(&params); err != nil {
    46  		http.Error(w, err.Error(), http.StatusBadRequest)
    47  		return
    48  	}
    49  
    50  	var (
    51  		ctx       = r.Context()
    52  		responded sync.Once
    53  		timer     *time.Timer
    54  		cancel    context.CancelFunc
    55  	)
    56  	ctx, cancel = context.WithCancel(ctx)
    57  	defer cancel()
    58  
    59  	if timeout, ok := rpc.ContextRequestTimeout(ctx); ok {
    60  		timer = time.AfterFunc(timeout, func() {
    61  			responded.Do(func() {
    62  				// Cancel request handling.
    63  				cancel()
    64  
    65  				// Create the timeout response.
    66  				response := &graphql.Response{
    67  					Errors: []*gqlErrors.QueryError{{Message: "request timed out"}},
    68  				}
    69  				responseJSON, err := json.Marshal(response)
    70  				if err != nil {
    71  					http.Error(w, err.Error(), http.StatusInternalServerError)
    72  					return
    73  				}
    74  
    75  				// Setting this disables gzip compression in package node.
    76  				w.Header().Set("Transfer-Encoding", "identity")
    77  
    78  				// Flush the response. Since we are writing close to the response timeout,
    79  				// chunked transfer encoding must be disabled by setting content-length.
    80  				w.Header().Set("Content-Type", "application/json")
    81  				w.Header().Set("Content-Length", strconv.Itoa(len(responseJSON)))
    82  				w.Write(responseJSON)
    83  				if flush, ok := w.(http.Flusher); ok {
    84  					flush.Flush()
    85  				}
    86  			})
    87  		})
    88  	}
    89  
    90  	response := h.Schema.Exec(ctx, params.Query, params.OperationName, params.Variables)
    91  	if timer != nil {
    92  		timer.Stop()
    93  	}
    94  	responded.Do(func() {
    95  		responseJSON, err := json.Marshal(response)
    96  		if err != nil {
    97  			http.Error(w, err.Error(), http.StatusInternalServerError)
    98  			return
    99  		}
   100  		w.Header().Set("Content-Type", "application/json")
   101  		if len(response.Errors) > 0 {
   102  			w.WriteHeader(http.StatusBadRequest)
   103  		}
   104  		w.Write(responseJSON)
   105  	})
   106  }
   107  
   108  // New constructs a new GraphQL service instance.
   109  func New(stack *node.Node, backend ethapi.Backend, filterSystem *filters.FilterSystem, cors, vhosts []string) error {
   110  	_, err := newHandler(stack, backend, filterSystem, cors, vhosts)
   111  	return err
   112  }
   113  
   114  // newHandler returns a new `http.Handler` that will answer GraphQL queries.
   115  // It additionally exports an interactive query browser on the / endpoint.
   116  func newHandler(stack *node.Node, backend ethapi.Backend, filterSystem *filters.FilterSystem, cors, vhosts []string) (*handler, error) {
   117  	q := Resolver{backend, filterSystem}
   118  
   119  	s, err := graphql.ParseSchema(schema, &q)
   120  	if err != nil {
   121  		return nil, err
   122  	}
   123  	h := handler{Schema: s}
   124  	handler := node.NewHTTPHandlerStack(h, cors, vhosts, nil)
   125  
   126  	stack.RegisterHandler("GraphQL UI", "/graphql/ui", GraphiQL{})
   127  	stack.RegisterHandler("GraphQL UI", "/graphql/ui/", GraphiQL{})
   128  	stack.RegisterHandler("GraphQL", "/graphql", handler)
   129  	stack.RegisterHandler("GraphQL", "/graphql/", handler)
   130  
   131  	return &h, nil
   132  }