hCaptcha Support (#12594)

* Initial work on hCaptcha

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Use module

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Format

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* At least return and debug log a captcha error

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Pass context to hCaptcha

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add context to recaptcha

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* fix lint

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Finish hcaptcha

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Update example config

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Apply error fix for recaptcha

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Change recaptcha ChallengeTS to string

Signed-off-by: jolheiser <john.olheiser@gmail.com>

Co-authored-by: Andrew Thornton <art27@cantab.net>

vendor/go.jolheiser.com/hcaptcha/hcaptcha.go

@@ -0,0 +1,105 @@
+package hcaptcha
+
+import (
+	"context"
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+const verifyURL = "https://hcaptcha.com/siteverify"
+
+// Client is an hCaptcha client
+type Client struct {
+	ctx  context.Context
+	http *http.Client
+
+	secret string
+}
+
+// PostOptions are optional post form values
+type PostOptions struct {
+	RemoteIP string
+	Sitekey  string
+}
+
+// ClientOption is a func to modify a new Client
+type ClientOption func(*Client)
+
+// WithHTTP sets the http.Client of a Client
+func WithHTTP(httpClient *http.Client) func(*Client) {
+	return func(hClient *Client) {
+		hClient.http = httpClient
+	}
+}
+
+// WithContext sets the context.Context of a Client
+func WithContext(ctx context.Context) func(*Client) {
+	return func(hClient *Client) {
+		hClient.ctx = ctx
+	}
+}
+
+// New returns a new hCaptcha Client
+func New(secret string, options ...ClientOption) (*Client, error) {
+	if strings.TrimSpace(secret) == "" {
+		return nil, ErrMissingInputSecret
+	}
+
+	client := &Client{
+		ctx:    context.Background(),
+		http:   http.DefaultClient,
+		secret: secret,
+	}
+
+	for _, opt := range options {
+		opt(client)
+	}
+
+	return client, nil
+}
+
+// Verify checks the response against the hCaptcha API
+func (c *Client) Verify(token string, opts PostOptions) (*Response, error) {
+	if strings.TrimSpace(token) == "" {
+		return nil, ErrMissingInputResponse
+	}
+
+	post := url.Values{
+		"secret":   []string{c.secret},
+		"response": []string{token},
+	}
+	if strings.TrimSpace(opts.RemoteIP) != "" {
+		post.Add("remoteip", opts.RemoteIP)
+	}
+	if strings.TrimSpace(opts.Sitekey) != "" {
+		post.Add("sitekey", opts.Sitekey)
+	}
+
+	// Basically a copy of http.PostForm, but with a context
+	req, err := http.NewRequestWithContext(c.ctx, http.MethodPost, verifyURL, strings.NewReader(post.Encode()))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	var response *Response
+	if err := json.Unmarshal(body, &response); err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}