| // Package jsonrpc provides a JSON-RPC 2.0 client that sends JSON-RPC requests and receives JSON-RPC responses using HTTP. |
| package jsonrpc |
| |
| import ( |
| "bytes" |
| "encoding/json" |
| "errors" |
| "fmt" |
| "net/http" |
| "reflect" |
| "strconv" |
| ) |
| |
| const ( |
| jsonrpcVersion = "2.0" |
| ) |
| |
| // RPCClient sends JSON-RPC requests over HTTP to the provided JSON-RPC backend. |
| // |
| // RPCClient is created using the factory function NewClient(). |
| type RPCClient interface { |
| // Call is used to send a JSON-RPC request to the server endpoint. |
| // |
| // The spec states, that params can only be an array or an object, no primitive values. |
| // So there are a few simple rules to notice: |
| // |
| // 1. no params: params field is omitted. e.g. Call("getinfo") |
| // |
| // 2. single params primitive value: value is wrapped in array. e.g. Call("getByID", 1423) |
| // |
| // 3. single params value array or object: value is unchanged. e.g. Call("storePerson", &Person{Name: "Alex"}) |
| // |
| // 4. multiple params values: always wrapped in array. e.g. Call("setDetails", "Alex, 35, "Germany", true) |
| // |
| // Examples: |
| // Call("getinfo") -> {"method": "getinfo"} |
| // Call("getPersonId", 123) -> {"method": "getPersonId", "params": [123]} |
| // Call("setName", "Alex") -> {"method": "setName", "params": ["Alex"]} |
| // Call("setMale", true) -> {"method": "setMale", "params": [true]} |
| // Call("setNumbers", []int{1, 2, 3}) -> {"method": "setNumbers", "params": [1, 2, 3]} |
| // Call("setNumbers", 1, 2, 3) -> {"method": "setNumbers", "params": [1, 2, 3]} |
| // Call("savePerson", &Person{Name: "Alex", Age: 35}) -> {"method": "savePerson", "params": {"name": "Alex", "age": 35}} |
| // Call("setPersonDetails", "Alex", 35, "Germany") -> {"method": "setPersonDetails", "params": ["Alex", 35, "Germany"}} |
| // |
| // for more information, see the examples or the unit tests |
| Call(method string, params ...interface{}) (*RPCResponse, error) |
| |
| // CallRaw is like Call() but without magic in the requests.Params field. |
| // The RPCRequest object is sent exactly as you provide it. |
| // See docs: NewRequest, RPCRequest, Params() |
| // |
| // It is recommended to first consider Call() and CallFor() |
| CallRaw(request *RPCRequest) (*RPCResponse, error) |
| |
| // CallFor is a very handy function to send a JSON-RPC request to the server endpoint |
| // and directly specify an object to store the response. |
| // |
| // out: will store the unmarshaled object, if request was successful. |
| // should always be provided by references. can be nil even on success. |
| // the behaviour is the same as expected from json.Unmarshal() |
| // |
| // method and params: see Call() function |
| // |
| // if the request was not successful (network, http error) or the rpc response returns an error, |
| // an error is returned. if it was an JSON-RPC error it can be casted |
| // to *RPCError. |
| // |
| CallFor(out interface{}, method string, params ...interface{}) error |
| |
| // CallBatch invokes a list of RPCRequests in a single batch request. |
| // |
| // Most convenient is to use the following form: |
| // CallBatch(RPCRequests{ |
| // Batch("myMethod1", 1, 2, 3), |
| // Batch("myMethod2), "Test"), |
| // }) |
| // |
| // You can create the []*RPCRequest array yourself, but it is not recommended and you should notice the following: |
| // - field Params is sent as provided, so Params: 2 forms an invalid json (correct would be Params: []int{2}) |
| // - you can use the helper function Params(1, 2, 3) to use the same format as in Call() |
| // - field JSONRPC is overwritten and set to value: "2.0" |
| // - field ID is overwritten and set incrementally and maps to the array position (e.g. requests[5].ID == 5) |
| // |
| // |
| // Returns RPCResponses that is of type []*RPCResponse |
| // - note that a list of RPCResponses can be received unordered so it can happen that: responses[i] != responses[i].ID |
| // - RPCPersponses is enriched with helper functions e.g.: responses.HasError() returns true if one of the responses holds an RPCError |
| CallBatch(requests RPCRequests) (RPCResponses, error) |
| |
| // CallBatchRaw invokes a list of RPCRequests in a single batch request. |
| // It sends the RPCRequests parameter is it passed (no magic, no id autoincrement). |
| // |
| // Consider to use CallBatch() instead except you have some good reason not to. |
| // |
| // CallBatchRaw(RPCRequests{ |
| // &RPCRequest{ |
| // ID: 123, // this won't be replaced in CallBatchRaw |
| // JSONRPC: "wrong", // this won't be replaced in CallBatchRaw |
| // Method: "myMethod1", |
| // Params: []int{1}, // there is no magic, be sure to only use array or object |
| // }, |
| // &RPCRequest{ |
| // ID: 612, |
| // JSONRPC: "2.0", |
| // Method: "myMethod2", |
| // Params: Params("Alex", 35, true), // you can use helper function Params() (see doc) |
| // }, |
| // }) |
| // |
| // Returns RPCResponses that is of type []*RPCResponse |
| // - note that a list of RPCResponses can be received unordered |
| // - the id's must be mapped against the id's you provided |
| // - RPCPersponses is enriched with helper functions e.g.: responses.HasError() returns true if one of the responses holds an RPCError |
| CallBatchRaw(requests RPCRequests) (RPCResponses, error) |
| } |
| |
| // RPCRequest represents a JSON-RPC request object. |
| // |
| // Method: string containing the method to be invoked |
| // |
| // Params: can be nil. if not must be an json array or object |
| // |
| // ID: may always set to 1 for single requests. Should be unique for every request in one batch request. |
| // |
| // JSONRPC: must always be set to "2.0" for JSON-RPC version 2.0 |
| // |
| // See: http://www.jsonrpc.org/specification#request_object |
| // |
| // Most of the time you shouldn't create the RPCRequest object yourself. |
| // The following functions do that for you: |
| // Call(), CallFor(), NewRequest() |
| // |
| // If you want to create it yourself (e.g. in batch or CallRaw()), consider using Params(). |
| // Params() is a helper function that uses the same parameter syntax as Call(). |
| // |
| // e.g. to manually create an RPCRequest object: |
| // request := &RPCRequest{ |
| // Method: "myMethod", |
| // Params: Params("Alex", 35, true), |
| // } |
| // |
| // If you know what you are doing you can omit the Params() call to avoid some reflection but potentially create incorrect rpc requests: |
| //request := &RPCRequest{ |
| // Method: "myMethod", |
| // Params: 2, <-- invalid since a single primitive value must be wrapped in an array --> no magic without Params() |
| // } |
| // |
| // correct: |
| // request := &RPCRequest{ |
| // Method: "myMethod", |
| // Params: []int{2}, <-- invalid since a single primitive value must be wrapped in an array |
| // } |
| type RPCRequest struct { |
| Method string `json:"method"` |
| Params interface{} `json:"params,omitempty"` |
| ID int `json:"id"` |
| JSONRPC string `json:"jsonrpc"` |
| } |
| |
| // NewRequest returns a new RPCRequest that can be created using the same convenient parameter syntax as Call() |
| // |
| // e.g. NewRequest("myMethod", "Alex", 35, true) |
| func NewRequest(method string, params ...interface{}) *RPCRequest { |
| request := &RPCRequest{ |
| Method: method, |
| Params: Params(params...), |
| JSONRPC: jsonrpcVersion, |
| } |
| |
| return request |
| } |
| |
| // RPCResponse represents a JSON-RPC response object. |
| // |
| // Result: holds the result of the rpc call if no error occurred, nil otherwise. can be nil even on success. |
| // |
| // Error: holds an RPCError object if an error occurred. must be nil on success. |
| // |
| // ID: may always be 0 for single requests. is unique for each request in a batch call (see CallBatch()) |
| // |
| // JSONRPC: must always be set to "2.0" for JSON-RPC version 2.0 |
| // |
| // See: http://www.jsonrpc.org/specification#response_object |
| type RPCResponse struct { |
| JSONRPC string `json:"jsonrpc"` |
| Result interface{} `json:"result,omitempty"` |
| Error *RPCError `json:"error,omitempty"` |
| ID int `json:"id"` |
| } |
| |
| // RPCError represents a JSON-RPC error object if an RPC error occurred. |
| // |
| // Code: holds the error code |
| // |
| // Message: holds a short error message |
| // |
| // Data: holds additional error data, may be nil |
| // |
| // See: http://www.jsonrpc.org/specification#error_object |
| type RPCError struct { |
| Code int `json:"code"` |
| Message string `json:"message"` |
| Data interface{} `json:"data,omitempty"` |
| } |
| |
| // Error function is provided to be used as error object. |
| func (e *RPCError) Error() string { |
| return strconv.Itoa(e.Code) + ":" + e.Message |
| } |
| |
| // HTTPError represents a error that occurred on HTTP level. |
| // |
| // An error of type HTTPError is returned when a HTTP error occurred (status code) |
| // and the body could not be parsed to a valid RPCResponse object that holds a RPCError. |
| // |
| // Otherwise a RPCResponse object is returned with a RPCError field that is not nil. |
| type HTTPError struct { |
| Code int |
| err error |
| } |
| |
| // Error function is provided to be used as error object. |
| func (e *HTTPError) Error() string { |
| return e.err.Error() |
| } |
| |
| type rpcClient struct { |
| endpoint string |
| httpClient *http.Client |
| customHeaders map[string]string |
| } |
| |
| // RPCClientOpts can be provided to NewClientWithOpts() to change configuration of RPCClient. |
| // |
| // HTTPClient: provide a custom http.Client (e.g. to set a proxy, or tls options) |
| // |
| // CustomHeaders: provide custom headers, e.g. to set BasicAuth |
| type RPCClientOpts struct { |
| HTTPClient *http.Client |
| CustomHeaders map[string]string |
| } |
| |
| // RPCResponses is of type []*RPCResponse. |
| // This type is used to provide helper functions on the result list |
| type RPCResponses []*RPCResponse |
| |
| // AsMap returns the responses as map with response id as key. |
| func (res RPCResponses) AsMap() map[int]*RPCResponse { |
| resMap := make(map[int]*RPCResponse, 0) |
| for _, r := range res { |
| resMap[r.ID] = r |
| } |
| |
| return resMap |
| } |
| |
| // GetByID returns the response object of the given id, nil if it does not exist. |
| func (res RPCResponses) GetByID(id int) *RPCResponse { |
| for _, r := range res { |
| if r.ID == id { |
| return r |
| } |
| } |
| |
| return nil |
| } |
| |
| // HasError returns true if one of the response objects has Error field != nil |
| func (res RPCResponses) HasError() bool { |
| for _, res := range res { |
| if res.Error != nil { |
| return true |
| } |
| } |
| return false |
| } |
| |
| // RPCRequests is of type []*RPCRequest. |
| // This type is used to provide helper functions on the request list |
| type RPCRequests []*RPCRequest |
| |
| // NewClient returns a new RPCClient instance with default configuration. |
| // |
| // endpoint: JSON-RPC service URL to which JSON-RPC requests are sent. |
| func NewClient(endpoint string) RPCClient { |
| return NewClientWithOpts(endpoint, nil) |
| } |
| |
| // NewClientWithOpts returns a new RPCClient instance with custom configuration. |
| // |
| // endpoint: JSON-RPC service URL to which JSON-RPC requests are sent. |
| // |
| // opts: RPCClientOpts provide custom configuration |
| func NewClientWithOpts(endpoint string, opts *RPCClientOpts) RPCClient { |
| rpcClient := &rpcClient{ |
| endpoint: endpoint, |
| httpClient: &http.Client{}, |
| customHeaders: make(map[string]string), |
| } |
| |
| if opts == nil { |
| return rpcClient |
| } |
| |
| if opts.HTTPClient != nil { |
| rpcClient.httpClient = opts.HTTPClient |
| } |
| |
| if opts.CustomHeaders != nil { |
| for k, v := range opts.CustomHeaders { |
| rpcClient.customHeaders[k] = v |
| } |
| } |
| |
| return rpcClient |
| } |
| |
| func (client *rpcClient) Call(method string, params ...interface{}) (*RPCResponse, error) { |
| |
| request := &RPCRequest{ |
| Method: method, |
| Params: Params(params...), |
| JSONRPC: jsonrpcVersion, |
| } |
| |
| return client.doCall(request) |
| } |
| |
| func (client *rpcClient) CallRaw(request *RPCRequest) (*RPCResponse, error) { |
| |
| return client.doCall(request) |
| } |
| |
| func (client *rpcClient) CallFor(out interface{}, method string, params ...interface{}) error { |
| rpcResponse, err := client.Call(method, params...) |
| if err != nil { |
| return err |
| } |
| |
| if rpcResponse.Error != nil { |
| return rpcResponse.Error |
| } |
| |
| return rpcResponse.GetObject(out) |
| } |
| |
| func (client *rpcClient) CallBatch(requests RPCRequests) (RPCResponses, error) { |
| if len(requests) == 0 { |
| return nil, errors.New("empty request list") |
| } |
| |
| for i, req := range requests { |
| req.ID = i |
| req.JSONRPC = jsonrpcVersion |
| } |
| |
| return client.doBatchCall(requests) |
| } |
| |
| func (client *rpcClient) CallBatchRaw(requests RPCRequests) (RPCResponses, error) { |
| if len(requests) == 0 { |
| return nil, errors.New("empty request list") |
| } |
| |
| return client.doBatchCall(requests) |
| } |
| |
| func (client *rpcClient) newRequest(req interface{}) (*http.Request, error) { |
| |
| body, err := json.Marshal(req) |
| if err != nil { |
| return nil, err |
| } |
| |
| request, err := http.NewRequest("POST", client.endpoint, bytes.NewReader(body)) |
| if err != nil { |
| return nil, err |
| } |
| |
| request.Header.Set("Content-Type", "application/json") |
| request.Header.Set("Accept", "application/json") |
| |
| // set default headers first, so that even content type and accept can be overwritten |
| for k, v := range client.customHeaders { |
| request.Header.Set(k, v) |
| } |
| |
| return request, nil |
| } |
| |
| func (client *rpcClient) doCall(RPCRequest *RPCRequest) (*RPCResponse, error) { |
| |
| httpRequest, err := client.newRequest(RPCRequest) |
| if err != nil { |
| return nil, fmt.Errorf("rpc call %v() on %v: %v", RPCRequest.Method, httpRequest.URL.String(), err.Error()) |
| } |
| httpResponse, err := client.httpClient.Do(httpRequest) |
| if err != nil { |
| return nil, fmt.Errorf("rpc call %v() on %v: %v", RPCRequest.Method, httpRequest.URL.String(), err.Error()) |
| } |
| defer httpResponse.Body.Close() |
| |
| var rpcResponse *RPCResponse |
| decoder := json.NewDecoder(httpResponse.Body) |
| decoder.DisallowUnknownFields() |
| decoder.UseNumber() |
| err = decoder.Decode(&rpcResponse) |
| |
| // parsing error |
| if err != nil { |
| // if we have some http error, return it |
| if httpResponse.StatusCode >= 400 { |
| return nil, &HTTPError{ |
| Code: httpResponse.StatusCode, |
| err: fmt.Errorf("rpc call %v() on %v status code: %v. could not decode body to rpc response: %v", RPCRequest.Method, httpRequest.URL.String(), httpResponse.StatusCode, err.Error()), |
| } |
| } |
| return nil, fmt.Errorf("rpc call %v() on %v status code: %v. could not decode body to rpc response: %v", RPCRequest.Method, httpRequest.URL.String(), httpResponse.StatusCode, err.Error()) |
| } |
| |
| // response body empty |
| if rpcResponse == nil { |
| // if we have some http error, return it |
| if httpResponse.StatusCode >= 400 { |
| return nil, &HTTPError{ |
| Code: httpResponse.StatusCode, |
| err: fmt.Errorf("rpc call %v() on %v status code: %v. rpc response missing", RPCRequest.Method, httpRequest.URL.String(), httpResponse.StatusCode), |
| } |
| } |
| return nil, fmt.Errorf("rpc call %v() on %v status code: %v. rpc response missing", RPCRequest.Method, httpRequest.URL.String(), httpResponse.StatusCode) |
| } |
| |
| return rpcResponse, nil |
| } |
| |
| func (client *rpcClient) doBatchCall(rpcRequest []*RPCRequest) ([]*RPCResponse, error) { |
| httpRequest, err := client.newRequest(rpcRequest) |
| if err != nil { |
| return nil, fmt.Errorf("rpc batch call on %v: %v", httpRequest.URL.String(), err.Error()) |
| } |
| httpResponse, err := client.httpClient.Do(httpRequest) |
| if err != nil { |
| return nil, fmt.Errorf("rpc batch call on %v: %v", httpRequest.URL.String(), err.Error()) |
| } |
| defer httpResponse.Body.Close() |
| |
| var rpcResponse RPCResponses |
| decoder := json.NewDecoder(httpResponse.Body) |
| decoder.DisallowUnknownFields() |
| decoder.UseNumber() |
| err = decoder.Decode(&rpcResponse) |
| |
| // parsing error |
| if err != nil { |
| // if we have some http error, return it |
| if httpResponse.StatusCode >= 400 { |
| return nil, &HTTPError{ |
| Code: httpResponse.StatusCode, |
| err: fmt.Errorf("rpc batch call on %v status code: %v. could not decode body to rpc response: %v", httpRequest.URL.String(), httpResponse.StatusCode, err.Error()), |
| } |
| } |
| return nil, fmt.Errorf("rpc batch call on %v status code: %v. could not decode body to rpc response: %v", httpRequest.URL.String(), httpResponse.StatusCode, err.Error()) |
| } |
| |
| // response body empty |
| if rpcResponse == nil || len(rpcResponse) == 0 { |
| // if we have some http error, return it |
| if httpResponse.StatusCode >= 400 { |
| return nil, &HTTPError{ |
| Code: httpResponse.StatusCode, |
| err: fmt.Errorf("rpc batch call on %v status code: %v. rpc response missing", httpRequest.URL.String(), httpResponse.StatusCode), |
| } |
| } |
| return nil, fmt.Errorf("rpc batch call on %v status code: %v. rpc response missing", httpRequest.URL.String(), httpResponse.StatusCode) |
| } |
| |
| return rpcResponse, nil |
| } |
| |
| // Params is a helper function that uses the same parameter syntax as Call(). |
| // But you should consider to always use NewRequest() instead. |
| // |
| // e.g. to manually create an RPCRequest object: |
| // request := &RPCRequest{ |
| // Method: "myMethod", |
| // Params: Params("Alex", 35, true), |
| // } |
| // |
| // same with new request: |
| // request := NewRequest("myMethod", "Alex", 35, true) |
| // |
| // If you know what you are doing you can omit the Params() call but potentially create incorrect rpc requests: |
| //request := &RPCRequest{ |
| // Method: "myMethod", |
| // Params: 2, <-- invalid since a single primitive value must be wrapped in an array --> no magic without Params() |
| // } |
| // |
| // correct: |
| // request := &RPCRequest{ |
| // Method: "myMethod", |
| // Params: []int{2}, <-- invalid since a single primitive value must be wrapped in an array |
| // } |
| func Params(params ...interface{}) interface{} { |
| var finalParams interface{} |
| |
| // if params was nil skip this and p stays nil |
| if params != nil { |
| switch len(params) { |
| case 0: // no parameters were provided, do nothing so finalParam is nil and will be omitted |
| case 1: // one param was provided, use it directly as is, or wrap primitive types in array |
| if params[0] != nil { |
| var typeOf reflect.Type |
| |
| // traverse until nil or not a pointer type |
| for typeOf = reflect.TypeOf(params[0]); typeOf != nil && typeOf.Kind() == reflect.Ptr; typeOf = typeOf.Elem() { |
| } |
| |
| if typeOf != nil { |
| // now check if we can directly marshal the type or if it must be wrapped in an array |
| switch typeOf.Kind() { |
| // for these types we just do nothing, since value of p is already unwrapped from the array params |
| case reflect.Struct: |
| finalParams = params[0] |
| case reflect.Array: |
| finalParams = params[0] |
| case reflect.Slice: |
| finalParams = params[0] |
| case reflect.Interface: |
| finalParams = params[0] |
| case reflect.Map: |
| finalParams = params[0] |
| default: // everything else must stay in an array (int, string, etc) |
| finalParams = params |
| } |
| } |
| } else { |
| finalParams = params |
| } |
| default: // if more than one parameter was provided it should be treated as an array |
| finalParams = params |
| } |
| } |
| |
| return finalParams |
| } |
| |
| // GetInt converts the rpc response to an int64 and returns it. |
| // |
| // If result was not an integer an error is returned. |
| func (RPCResponse *RPCResponse) GetInt() (int64, error) { |
| val, ok := RPCResponse.Result.(json.Number) |
| if !ok { |
| return 0, fmt.Errorf("could not parse int64 from %s", RPCResponse.Result) |
| } |
| |
| i, err := val.Int64() |
| if err != nil { |
| return 0, err |
| } |
| |
| return i, nil |
| } |
| |
| // GetFloat converts the rpc response to float64 and returns it. |
| // |
| // If result was not an float64 an error is returned. |
| func (RPCResponse *RPCResponse) GetFloat() (float64, error) { |
| val, ok := RPCResponse.Result.(json.Number) |
| if !ok { |
| return 0, fmt.Errorf("could not parse float64 from %s", RPCResponse.Result) |
| } |
| |
| f, err := val.Float64() |
| if err != nil { |
| return 0, err |
| } |
| |
| return f, nil |
| } |
| |
| // GetBool converts the rpc response to a bool and returns it. |
| // |
| // If result was not a bool an error is returned. |
| func (RPCResponse *RPCResponse) GetBool() (bool, error) { |
| val, ok := RPCResponse.Result.(bool) |
| if !ok { |
| return false, fmt.Errorf("could not parse bool from %s", RPCResponse.Result) |
| } |
| |
| return val, nil |
| } |
| |
| // GetString converts the rpc response to a string and returns it. |
| // |
| // If result was not a string an error is returned. |
| func (RPCResponse *RPCResponse) GetString() (string, error) { |
| val, ok := RPCResponse.Result.(string) |
| if !ok { |
| return "", fmt.Errorf("could not parse string from %s", RPCResponse.Result) |
| } |
| |
| return val, nil |
| } |
| |
| // GetObject converts the rpc response to an arbitrary type. |
| // |
| // The function works as you would expect it from json.Unmarshal() |
| func (RPCResponse *RPCResponse) GetObject(toType interface{}) error { |
| js, err := json.Marshal(RPCResponse.Result) |
| if err != nil { |
| return err |
| } |
| |
| err = json.Unmarshal(js, toType) |
| if err != nil { |
| return err |
| } |
| |
| return nil |
| } |