http_listener: pre-allocate buffer for reading request body

Fixes: #1823 and #1856

plugins/inputs/http_listener/http_listener.go

@@ -1,12 +1,13 @@
 package http_listener
 
 import (
-	"bufio"
 	"bytes"
+	"compress/gzip"
 	"fmt"
 	"log"
 	"net"
 	"net/http"
+	"strconv"
 	"sync"
 	"time"
 
@@ -117,31 +118,52 @@ func (t *HttpListener) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 	switch req.URL.Path {
 	case "/write":
 		var http400msg bytes.Buffer
-		var partial string
-		scanner := bufio.NewScanner(req.Body)
-		scanner.Buffer([]byte(""), 128*1024)
-		for scanner.Scan() {
-			metrics, err := t.parser.Parse(scanner.Bytes())
-			if err == nil {
-				for _, m := range metrics {
-					t.acc.AddFields(m.Name(), m.Fields(), m.Tags(), m.Time())
-				}
-				partial = "partial write: "
-			} else {
+		defer func() {
+			if http400msg.Len() > 0 {
+				res.Header().Set("Content-Type", "application/json")
+				res.Header().Set("X-Influxdb-Version", "1.0")
+				res.WriteHeader(http.StatusBadRequest)
+				res.Write([]byte(fmt.Sprintf(`{"error":"%s"}`, http400msg.String())))
+			}
+		}()
+
+		body := req.Body
+		if req.Header.Get("Content-Encoding") == "gzip" {
+			b, err := gzip.NewReader(req.Body)
+			if err != nil {
 				http400msg.WriteString(err.Error() + " ")
+				return
+			}
+			defer b.Close()
+			body = b
+		}
+
+		var bs []byte
+		if cl := req.Header.Get("Content-length"); cl != "" {
+			if l, err := strconv.Atoi(cl); err == nil {
+				bs = make([]byte, 0, l)
 			}
 		}
 
-		if err := scanner.Err(); err != nil {
-			http.Error(res, "Internal server error: "+err.Error(), http.StatusInternalServerError)
-		} else if http400msg.Len() > 0 {
-			res.Header().Set("Content-Type", "application/json")
-			res.Header().Set("X-Influxdb-Version", "1.0")
-			res.WriteHeader(http.StatusBadRequest)
-			res.Write([]byte(fmt.Sprintf(`{"error":"%s%s"}`, partial, http400msg.String())))
-		} else {
-			res.WriteHeader(http.StatusNoContent)
+		buf := bytes.NewBuffer(bs)
+		_, err := buf.ReadFrom(body)
+		if err != nil {
+			log.Printf("E! HttpListener unable to read request body. data: [%s], error: %s\n", string(buf.Bytes()), err.Error())
+			http400msg.WriteString("HttpHandler unable to read from request body: " + err.Error())
+			return
 		}
+
+		metrics, err := t.parser.Parse(buf.Bytes())
+		if err != nil {
+			log.Printf("E! HttpListener unable to parse metrics. data: [%s], error: %s \n", string(buf.Bytes()), err.Error())
+			http400msg.WriteString("Error while parsing metrics: " + err.Error())
+			return
+		}
+
+		for _, m := range metrics {
+			t.acc.AddFields(m.Name(), m.Fields(), m.Tags(), m.Time())
+		}
+		res.WriteHeader(http.StatusNoContent)
 	case "/query":
 		// Deliver a dummy response to the query endpoint, as some InfluxDB
 		// clients test endpoint availability with a query