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httpclient.go
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httpclient.go
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/*
* Copyright 2021 Comcast Cable Communications Management, LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* SPDX-License-Identifier: Apache-2.0
*/
package chans
import (
"bytes"
"crypto/tls"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"net/url"
"time"
"github.com/Comcast/plax/dsl"
)
var (
DefaultBufferSize = 1024
)
func init() {
dsl.TheChanRegistry.Register(dsl.NewCtx(nil), "httpclient", NewHTTPClientChan)
}
// HTTPClient is an HTTP client Chan.
//
// This channel type implements HTTP requests. A test publishes a
// request that includes a URL. This channel performs the HTTP
// request and then forwards the response for the test to receive.
type HTTPClient struct {
opts *HTTPClientOpts
client *http.Client
c chan dsl.Msg
pollers map[string]chan bool
lastPoller string
}
func (c *HTTPClient) DocSpec() *dsl.DocSpec {
return &dsl.DocSpec{
Chan: &HTTPClient{},
Opts: &HTTPClientOpts{},
Input: &HTTPRequest{},
Output: &HTTPResponse{},
}
}
// HTTPClientOpts configures an HTTPClient.
//
// Currently this channel doesn't have any configuration.
type HTTPClientOpts struct {
}
func (c *HTTPClient) Kind() dsl.ChanKind {
return "httpclient"
}
func (c *HTTPClient) Open(ctx *dsl.Ctx) error {
c.client = &http.Client{}
return nil
}
func (c *HTTPClient) Close(ctx *dsl.Ctx) error {
c.client.CloseIdleConnections()
return nil
}
func (c *HTTPClient) Sub(ctx *dsl.Ctx, topic string) error {
return fmt.Errorf("%T doesn't support 'sub'", c)
}
// HTTPRequest represents a complete HTTP request, which is typically
// provided as a message payload in JSON.
type HTTPRequest struct {
// We can't just use https://golang.org/pkg/net/http/#Header because
// its URL field is actually a URL and not a string. (Other reasons,
// too.)
// Method is the usual HTTP request method (e.g., GET, POST).
Method string `json:"method"`
// URL is the target for the request.
URL string `json:"url"`
// Headers is map of HTTP header names to values.
Headers map[string][]string `json:"headers"`
// Body is the request body.
Body interface{} `json:"body,omitempty"`
// RequestBodySerialization specifies what serialization
// (if any) to perform on the request's body.
//
// Possible values are 'string' and 'json' (default).
RequestBodySerialization dsl.Serialization `json:"requestBodySerialization,omitempty" yaml:"requestbodyserialization,omitempty"`
// ResponseBodyDeserialization specifies what deserialization
// (if any) to perform on the response's body.
//
// Possible values are 'string' and 'json' (default).
ResponseBodyDeserialization dsl.Serialization `json:"responseBodyDeserialization,omitempty" yaml:"responsebodydeserialization,omitempty"`
// Form can contain form values, and you can specify these
// values instead of providing an explicit Body.
Form url.Values `json:"form,omitempty"`
// HTTPRequestCtl is optional data for managing polling
// requests.
HTTPRequestCtl `json:"ctl,omitempty" yaml:"ctl"`
// Insecure if true will skip server credentials verification.
Insecure bool `json:"insecure,omitempty"`
// body will be the serialized Body.
body []byte
req *http.Request
}
// HTTPRequestCtl directs management of polling requests (if any).
type HTTPRequestCtl struct {
// Id is used to refer to this request when it has a polling
// interval.
Id string `json:"id,omitempty"`
// PollInterval, when not zero, will cause this channel to
// repeated the HTTP request at this interval.
//
// The timer starts after the last request has completed.
// (Previously the timer fired requests at this interval
// regardless of the latency of the previous HTTP request(s).)
//
// Value should be a string that time.ParseDuration can parse.
PollInterval string `json:"pollInterval"`
pollInterval time.Duration
// Terminate, when not zero, should be the Id of a previous polling
// request, and that polling request will be terminated.
//
// No other properties in this struct should be provided.
Terminate string `json:"terminate,omitempty"`
}
// extractHTTPRequest attempts to make an http.Request from the
// (payload of the) given message.
//
// The message payload should be a JSON-serialized http.Request.
func extractHTTPRequest(ctx *dsl.Ctx, m dsl.Msg) (*HTTPRequest, error) {
// m.Body is a JSON serialization of an HTTPRequest.
// Parse the HTTPRequest.
var (
js = m.Payload
req = &HTTPRequest{
RequestBodySerialization: dsl.DefaultSerialization,
ResponseBodyDeserialization: dsl.DefaultSerialization,
}
)
if err := json.Unmarshal([]byte(js), &req); err != nil {
return nil, err
}
// Parse the URL.
u, err := url.Parse(req.URL)
if err != nil {
return nil, err
}
if req.Body != nil {
s, err := req.RequestBodySerialization.Serialize(req.Body)
if err != nil {
return nil, err
}
req.body = []byte(s)
}
// Construct the actual http.Request.
real := &http.Request{
URL: u,
Method: req.Method,
Header: req.Headers,
}
if req.Form != nil {
if req.Body != nil {
return nil, fmt.Errorf("can't specify both Body and Form")
}
// real.Header.Add("Content-Type", "application/x-www-form-urlencoded")
req.body = []byte(req.Form.Encode())
}
if req.Body != nil {
real.Body = ioutil.NopCloser(bytes.NewReader(req.body))
real.ContentLength = int64(len(req.body))
}
req.req = real
return req, nil
}
func (c *HTTPClient) terminate(ctx *dsl.Ctx, id string) error {
ctx.Logf("%T terminating poller %s", c, id)
if id == "last" {
if c.lastPoller == "" {
return fmt.Errorf("no last polling request")
}
id = c.lastPoller
}
ctl, have := c.pollers[id]
if !have {
return fmt.Errorf("unknown poller id '%s'", id)
}
close(ctl)
delete(c.pollers, id)
c.lastPoller = ""
return nil
}
func (c *HTTPClient) poll(ctx *dsl.Ctx, ctl chan bool, req *HTTPRequest) error {
go func() {
d := req.pollInterval
if d <= 0 {
ctx.Logf("Warning HTTP request PollInterval %v", d)
d = time.Second
}
timer := time.NewTimer(d)
LOOP:
for {
select {
case <-ctx.Done():
case <-timer.C:
ctx.Logf("%T making polling request", c)
if err := c.do(ctx, req); err != nil {
r := dsl.Msg{
Payload: dsl.JSON(map[string]interface{}{
"error": err.Error(),
}),
}
go c.To(ctx, r)
}
// Start a new timer after the HTTP
// request completes (but perhaps
// before the response is forwarded to
// the consumers).
timer = time.NewTimer(d)
case <-ctl:
break LOOP
}
}
}()
return nil
}
// HTTPResponse represents the HTTP response received from the HTTP
// server.
//
type HTTPResponse struct {
// StatusCode is the HTTP status code returned by the HTTP server.
StatusCode int `json:"statuscode" yaml:"statuscode"`
// Body is the either the raw body or parsed body returned by
// the HTTP server.
//
// The requests's ResponseBodyDeserialization determines if
// and how deserialization occurs.
Body interface{} `json:"body"`
// Error describes a channel processing error (if any) that
// occured during the request or response.
Error string `json:"error,omitempty"`
// Headers contains the response headers from the HTTP server.
Headers map[string][]string `json:"headers"`
}
func (c *HTTPClient) do(ctx *dsl.Ctx, req *HTTPRequest) error {
ctx.Logf("%T making request", c)
if req.Insecure {
c.client.Transport = &http.Transport{
TLSClientConfig: &tls.Config{
InsecureSkipVerify: true,
},
}
} else {
c.client.Transport = nil
}
resp, err := c.client.Do(req.req)
if err != nil {
return err
}
ctx.Logf("%T received message", c)
ctx.Logdf("%T received %#v", c, resp)
bs, err := ioutil.ReadAll(resp.Body)
if err != nil {
return err
}
ctx.Logdf("%T received body %s", c, bs)
r := &HTTPResponse{
StatusCode: resp.StatusCode,
Headers: resp.Header,
}
body, err := req.ResponseBodyDeserialization.Deserialize(string(bs))
if err != nil {
r.Error = err.Error()
} else {
r.Body = body
}
js, err := json.Marshal(&r)
if err != nil {
m := map[string]interface{}{
"error": err.Error(),
}
js, _ = json.Marshal(&m)
}
msg := dsl.Msg{
Payload: string(js),
}
return c.To(ctx, msg)
}
func (c *HTTPClient) Pub(ctx *dsl.Ctx, m dsl.Msg) error {
ctx.Logf("%T Pub", c)
req, err := extractHTTPRequest(ctx, m)
if err != nil {
return err
}
if req.Terminate != "" {
return c.terminate(ctx, req.Terminate)
}
if req.PollInterval != "" {
d, err := time.ParseDuration(req.PollInterval)
if err != nil {
return err
}
req.pollInterval = d
if req.Id == "" {
req.Id = "NA"
}
ctl := make(chan bool)
c.pollers[req.Id] = ctl
c.lastPoller = req.Id
if err := c.poll(ctx, ctl, req); err != nil {
return err
}
// Start polling but go ahead an do this first one
// below.
}
go func() {
if err := c.do(ctx, req); err != nil {
// ToDo: Probably publish this message.
ctx.Warnf("httpclient request error: %v", err)
}
}()
return nil
}
func (c *HTTPClient) Recv(ctx *dsl.Ctx) chan dsl.Msg {
return c.c
}
func (c *HTTPClient) Kill(ctx *dsl.Ctx) error {
return fmt.Errorf("%T doesn't support 'Kill'", c)
}
func (c *HTTPClient) To(ctx *dsl.Ctx, m dsl.Msg) error {
ctx.Logf("%T To", c)
ctx.Logdf(" %T payload: %s", c, m.Payload)
m.ReceivedAt = time.Now().UTC()
select {
case <-ctx.Done():
case c.c <- m:
ctx.Logf("%T queued message", c)
ctx.Logf("%T queued %s", c, dsl.JSON(m))
default:
panic(fmt.Errorf("Warning: %T channel full", c))
}
return nil
}
func NewHTTPClientChan(ctx *dsl.Ctx, opts interface{}) (dsl.Chan, error) {
o := HTTPClientOpts{}
js, err := json.Marshal(opts)
if err != nil {
return nil, err
}
if err = json.Unmarshal(js, &o); err != nil {
return nil, fmt.Errorf("NewHTTPClientChan: %w", err)
}
return &HTTPClient{
opts: &o,
c: make(chan dsl.Msg, DefaultBufferSize),
pollers: make(map[string]chan bool),
}, nil
}