Grab a CT logs roots in a format Trillian with accept

grab-ct-roots.go

package main

import (
        "encoding/base64"
        "encoding/json"
        "flag"
        "fmt"
        "io/ioutil"
        "net/http"
        "os"
        "encoding/pem"
)

func main() {
        logURI := flag.String("log", "", "")
        flag.Parse()
        resp, err := http.Get(fmt.Sprintf("%s/ct/v1/get-roots", *logURI))
        if err != nil {
                fmt.Fprintf(os.Stderr, "failed to get CT log roots: %s\n", err)
                return
        }
        defer resp.Body.Close()
        body, err := ioutil.ReadAll(resp.Body)
        if err != nil {
                fmt.Fprintf(os.Stderr, "failed to read CT log roots response: %s\n", err)
                return
        }
        var encodedRoots struct {
                Certificates []string `json:"certificates"`
        }
        err = json.Unmarshal(body, &encodedRoots)
        if err != nil {
                fmt.Fprintf(os.Stderr, "failed to parse CT log roots response: %s\n", err)
                return
        }
        for _, encodedRoot := range encodedRoots.Certificates {
                rawCert, err := base64.StdEncoding.DecodeString(encodedRoot)
                if err != nil {
                        continue
                }
                b := &pem.Block{Bytes: rawCert, Type: "CERTIFICATE"}
                pem.Encode(os.Stdout, b)
        }
}