Validate the response from InfluxDB after writing/creating a database to avoid json parsing panics/errors (#8775)

* Validate the response from InfluxDB after writing/creating a database to avoid json parsing panics.

* Testing windows signing - ignore

* Update config.yml

* adding signing to workflow - test

* Updated config.yml

* Updated config.yml

* Updated config.yml

* Updated config.yml

* revert circleci test changes

* Various updates

plugins/outputs/influxdb/http.go

@@ -1,9 +1,11 @@
 package influxdb
 
 import (
+	"bytes"
 	"context"
 	"crypto/tls"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -216,8 +218,19 @@ func (c *httpClient) CreateDatabase(ctx context.Context, database string) error
 	}
 	defer resp.Body.Close()
 
+	body, err := c.validateResponse(resp.Body)
+
+	// Check for poorly formatted response (can't be decoded)
+	if err != nil {
+		return &APIError{
+			StatusCode:  resp.StatusCode,
+			Title:       resp.Status,
+			Description: "An error response was received while attempting to create the following database: " + database + ". Error: " + err.Error(),
+		}
+	}
+
 	queryResp := &QueryResponse{}
-	dec := json.NewDecoder(resp.Body)
+	dec := json.NewDecoder(body)
 	err = dec.Decode(queryResp)
 
 	if err != nil {
@@ -341,8 +354,19 @@ func (c *httpClient) writeBatch(ctx context.Context, db, rp string, metrics []te
 		return nil
 	}
 
+	body, err := c.validateResponse(resp.Body)
+
+	// Check for poorly formatted response (can't be decoded)
+	if err != nil {
+		return &APIError{
+			StatusCode:  resp.StatusCode,
+			Title:       resp.Status,
+			Description: "An error response was received while attempting to write metrics. Error: " + err.Error(),
+		}
+	}
+
 	writeResp := &WriteResponse{}
-	dec := json.NewDecoder(resp.Body)
+	dec := json.NewDecoder(body)
 
 	var desc string
 	err = dec.Decode(writeResp)
@@ -466,6 +490,27 @@ func (c *httpClient) addHeaders(req *http.Request) {
 	}
 }
 
+func (c *httpClient) validateResponse(response io.ReadCloser) (io.ReadCloser, error) {
+	bodyBytes, err := ioutil.ReadAll(response)
+	if err != nil {
+		return nil, err
+	}
+	defer response.Close()
+
+	originalResponse := ioutil.NopCloser(bytes.NewBuffer(bodyBytes))
+
+	// Empty response is valid.
+	if response == http.NoBody || len(bodyBytes) == 0 || bodyBytes == nil {
+		return originalResponse, nil
+	}
+
+	if valid := json.Valid(bodyBytes); !valid {
+		err = errors.New(string(bodyBytes))
+	}
+
+	return originalResponse, err
+}
+
 func makeWriteURL(loc *url.URL, db, rp, consistency string) (string, error) {
 	params := url.Values{}
 	params.Set("db", db)

plugins/outputs/influxdb/http_test.go

@@ -212,6 +212,26 @@ func TestHTTP_CreateDatabase(t *testing.T) {
 				w.WriteHeader(http.StatusOK)
 			},
 		},
+		{
+			name: "invalid json response is handled",
+			config: influxdb.HTTPConfig{
+				URL:      u,
+				Database: `database`,
+			},
+			queryHandlerFunc: func(t *testing.T, w http.ResponseWriter, r *http.Request) {
+				w.WriteHeader(http.StatusBadRequest)
+				w.Write([]byte(`invalid response`))
+			},
+			errFunc: func(t *testing.T, err error) {
+				expected := &influxdb.APIError{
+					StatusCode:  400,
+					Title:       "400 Bad Request",
+					Description: "An error response was received while attempting to create the following database: database. Error: invalid response",
+				}
+
+				require.Equal(t, expected, err)
+			},
+		},
 	}
 
 	for _, tt := range tests {