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|
package main
import (
"encoding/json"
"errors"
"fmt"
"net/http"
"os"
)
func fetchFacebook(domain string) ([]string, error) {
appId := os.Getenv("FB_APP_ID")
appSecret := os.Getenv("FB_APP_SECRET")
if appId == "" || appSecret == "" {
// fail silently because it's reasonable not to have
// the Facebook API creds
return []string{}, nil
}
accessToken, err := facebookAuth(appId, appSecret)
if err != nil {
return []string{}, err
}
domains, err := getFacebookCerts(accessToken, domain)
if err != nil {
return []string{}, err
}
return domains, nil
}
func getFacebookCerts(accessToken, query string) ([]string, error) {
out := make([]string, 0)
fetchURL := fmt.Sprintf(
"https://graph.facebook.com/certificates?fields=domains&access_token=%s&query=*.%s",
accessToken, query,
)
for {
wrapper := struct {
Data []struct {
Domains []string `json:"domains"`
} `json:"data"`
Paging struct {
Next string `json:"next"`
} `json:"paging"`
}{}
err := fetchJSON(fetchURL, &wrapper)
if err != nil {
return out, err
}
for _, data := range wrapper.Data {
for _, d := range data.Domains {
out = append(out, d)
}
}
fetchURL = wrapper.Paging.Next
if fetchURL == "" {
break
}
}
return out, nil
}
func facebookAuth(appId, appSecret string) (string, error) {
authUrl := fmt.Sprintf(
"https://graph.facebook.com/oauth/access_token?client_id=%s&client_secret=%s&grant_type=client_credentials",
appId, appSecret,
)
resp, err := http.Get(authUrl)
if err != nil {
return "", err
}
defer resp.Body.Close()
dec := json.NewDecoder(resp.Body)
auth := struct {
AccessToken string `json:"access_token"`
}{}
err = dec.Decode(&auth)
if err != nil {
return "", err
}
if auth.AccessToken == "" {
return "", errors.New("no access token in Facebook API response")
}
return auth.AccessToken, nil
}
|
