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package main
import (
"encoding/json"
"github.com/lox/httpcache"
"github.com/pkg/errors"
"net"
"net/http"
"net/url"
"strings"
"time"
)
type CautiousHTTPClient interface {
Get(string) (*http.Response, error)
GetJSON(string, interface{}) error
GetJSONExpires(string, interface{}) (time.Duration, error)
}
type cautiousHttpClient struct {
allowHttp bool
client *http.Client
}
// allowHttp is UNSAFE and technically validates the spec but it does make it
// easier to work in dev so leaving it in for now
func NewCautiousHTTPClient(allowHttp bool) (CautiousHTTPClient, error) {
CautiousTransport := &http.Transport{
Proxy: http.ProxyFromEnvironment,
DialContext: (&net.Dialer{
Timeout: 1 * time.Second,
KeepAlive: 30 * time.Second,
DualStack: true,
}).DialContext,
MaxIdleConns: 100,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 1 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
ResponseHeaderTimeout: 10 * time.Second,
MaxResponseHeaderBytes: 500000, // .5 MB
}
return &cautiousHttpClient{
allowHttp: allowHttp,
client: &http.Client{
Transport: CautiousTransport,
Timeout: 30 * time.Second,
},
}, nil
}
func (c *cautiousHttpClient) Get(gurl string) (*http.Response, error) {
u, err := url.Parse(gurl)
if err != nil {
return nil, errors.WithStack(err)
}
if u.Scheme != "https" && !c.allowHttp {
return nil, errors.Errorf("URL for GET must be secure")
}
r, err := c.client.Get(u.String())
if err != nil {
return nil, errors.WithStack(err)
}
r.Body = http.MaxBytesReader(nil, r.Body, 1000000)
return r, nil
}
func (c *cautiousHttpClient) GetJSON(url string, rv interface{}) error {
r, err := c.Get(url)
if err != nil {
return errors.WithStack(err)
}
defer r.Body.Close()
d := json.NewDecoder(r.Body)
err = d.Decode(rv)
if err != nil {
return errors.WithStack(err)
}
return nil
}
func (c *cautiousHttpClient) GetJSONExpires(url string, rv interface{}) (time.Duration, error) {
r, err := c.Get(url)
if err != nil {
return time.Duration(0), errors.WithStack(err)
}
defer r.Body.Close()
res := httpcache.NewResource(r.StatusCode, nil, r.Header)
d := json.NewDecoder(r.Body)
err = d.Decode(rv)
if err != nil {
return time.Duration(0), errors.WithStack(err)
}
return refreshAfter(res), nil
}
type JSONURL struct {
*url.URL
}
func (u *JSONURL) AsURL() *url.URL {
return u.URL
}
func (u *JSONURL) UnmarshalJSON(data []byte) error {
d := strings.Trim(string(data), "\"")
pu, err := url.Parse(d)
if err != nil {
return errors.WithStack(err)
}
u.URL = pu
return nil
}
func refreshAfter(res *httpcache.Resource) time.Duration {
maxAge, err := res.MaxAge(false)
if err != nil {
return time.Duration(0)
}
age, err := res.Age()
if err != nil {
return time.Duration(0)
}
if hFresh := res.HeuristicFreshness(); hFresh > maxAge {
maxAge = hFresh
}
return maxAge - age
}
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