status-im/status-go

package protocol

import (
    "context"
    "fmt"
    "io/ioutil"
    "net/http"
    neturl "net/url"
    "time"

    "go.uber.org/zap"

    "github.com/status-im/status-go/protocol/common"
)

const (
    DefaultRequestTimeout = 15000 * time.Millisecond

    headerAcceptJSON = "application/json; charset=utf-8"
    headerAcceptText = "text/html; charset=utf-8"

    // Without a particular user agent, many providers treat status-go as a
    // gluttony bot, and either respond more frequently with a 429 (Too Many
    // Requests), or simply refuse to return valid data. Note that using a known
    // browser UA doesn't work well with some providers, such as Spotify,
    // apparently they still flag status-go as a bad actor.
    headerUserAgent = "status-go/v0.151.15"

    // Currently set to English, but we could make this setting dynamic according
    // to the user's language of choice.
    headerAcceptLanguage = "en-US,en;q=0.5"
)

type Headers map[string]string

type Unfurler interface {
    Unfurl() (*common.LinkPreview, error)
}

func newDefaultLinkPreview(url *neturl.URL) *common.LinkPreview {
    return &common.LinkPreview{
        URL:      url.String(),
        Hostname: url.Hostname(),
    }
}

func fetchBody(logger *zap.Logger, httpClient *http.Client, url string, headers Headers) ([]byte, error) {
    ctx, cancel := context.WithTimeout(context.Background(), DefaultRequestTimeout)
    defer cancel()

    req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
    if err != nil {
        return nil, fmt.Errorf("failed to perform HTTP request: %w", err)
    }

    for k, v := range headers {
        req.Header.Set(k, v)
    }

    res, err := httpClient.Do(req)
    if err != nil {
        return nil, err
    }
    defer func() {
        if err := res.Body.Close(); err != nil {
            logger.Error("failed to close response body", zap.Error(err))
        }
    }()

    if res.StatusCode >= http.StatusBadRequest {
        return nil, fmt.Errorf("http request failed, statusCode='%d'", res.StatusCode)
    }

    bodyBytes, err := ioutil.ReadAll(res.Body)
    if err != nil {
        return nil, fmt.Errorf("failed to read body bytes: %w", err)
    }

    return bodyBytes, nil
}