submitter.go

package txsub

import (
	"context"
	"encoding/json"
	"net/http"
	"net/url"
	"time"

	"github.com/go-errors/errors"
)

const (
	StatusError     = "ERROR"
	StatusPending   = "PENDING"
	StatusDuplicate = "DUPLICATE"
)

// NewDefaultSubmitter returns a new, simple Submitter implementation
// that submits directly to the stellar-core at `url` using the http client
// `h`.
func NewDefaultSubmitter(h *http.Client, url string) Submitter {
	return &submitter{
		http:    h,
		coreURL: url,
	}
}

// coreSubmissionResponse is the json response from stellar-core's tx endpoint
type coreSubmissionResponse struct {
	Exception string `json:"exception"`
	Error     string `json:"error"`
	Status    string `json:"status"`
}

// submitter is the default implementation for the Submitter interface.  It
// submits directly to the configured stellar-core instance using the
// configured http client.
type submitter struct {
	http    *http.Client
	coreURL string
}

// Submit sends the provided envelope to stellar-core and parses the response into
// a SubmissionResult
func (sub *submitter) Submit(ctx context.Context, env string) (result SubmissionResult) {
	start := time.Now()
	defer func() { result.Duration = time.Since(start) }()

	// construct the request
	u, err := url.Parse(sub.coreURL)
	if err != nil {
		result.Err = errors.Wrap(err, 1)
		return
	}

	u.Path = "/tx"
	q := u.Query()
	q.Add("blob", env)
	u.RawQuery = q.Encode()

	req, err := http.NewRequest("GET", u.String(), nil)
	if err != nil {
		result.Err = errors.Wrap(err, 1)
		return
	}

	// perform the submission
	resp, err := sub.http.Do(req)
	if err != nil {
		result.Err = errors.Wrap(err, 1)
		return
	}
	defer resp.Body.Close()

	// parse response
	var cresp coreSubmissionResponse
	err = json.NewDecoder(resp.Body).Decode(&cresp)
	if err != nil {
		result.Err = errors.Wrap(err, 1)
		return
	}

	// interpet response
	if cresp.Exception != "" {
		result.Err = errors.Errorf("stellar-core exception: %s", cresp.Exception)
		return
	}

	switch cresp.Status {
	case StatusError:
		result.Err = &FailedTransactionError{cresp.Error}
	case StatusPending, StatusDuplicate:
		//noop.  A nil Err indicates success
	default:
		result.Err = errors.Errorf("Unrecognized stellar-core status response: %s", cresp.Status)
	}

	return
}