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package spartan
import (
"bytes"
"context"
"errors"
"io"
"net"
neturl "net/url"
"strconv"
"strings"
"tildegit.org/tjp/sliderule/internal/types"
)
// Client is used for sending spartan requests and receiving responses.
//
// It carries no state and is reusable simultaneously by multiple goroutines.
//
// The zero value is immediately usabble, but will not follow redirects.
type Client struct {
MaxRedirects int
}
// NewClient creates a spartan Client which will follow DefaultMaxRedirects.
func NewClient() Client {
return Client{MaxRedirects: DefaultMaxRedirects}
}
// DefaultMaxRedirects is the number of chained redirects a Client will perform for a
// single request by default. This can be changed by altering the MaxRedirects field.
const DefaultMaxRedirects int = 2
var (
ErrExceededMaxRedirects = errors.New("spartan.Client: exceeded MaxRedirects")
ErrInvalidRequest = errors.New("spartan.Client: request is invalid")
)
// RoundTrip sends a single spartan request and returns its response.
func (c Client) RoundTrip(ctx context.Context, request *types.Request) (*types.Response, error) {
if request.Scheme != "spartan" && request.Scheme != "" {
return nil, errors.New("non-spartan protocols not supported")
}
host, port, _ := net.SplitHostPort(request.Host)
if port == "" {
host = request.Host
port = "300"
}
addr := net.JoinHostPort(host, port)
conn, err := (&net.Dialer{}).DialContext(ctx, "tcp", addr)
if err != nil {
return nil, err
}
defer conn.Close()
request.RemoteAddr = conn.RemoteAddr()
var rdr *io.LimitedReader
if request.Meta == nil {
rdr = &io.LimitedReader{R: devnull{}, N: 0}
} else {
var ok bool
rdr, ok = request.Meta.(*io.LimitedReader)
if !ok {
return nil, errors.New("request body must be nil or an *io.LimitedReader")
}
}
if request.Path == "" {
request.Path = "/"
}
if !strings.HasPrefix(request.Path, "/") {
return nil, ErrInvalidRequest
}
requestLine := host + " " + request.EscapedPath() + " " + strconv.Itoa(int(rdr.N)) + "\r\n"
if _, err := conn.Write([]byte(requestLine)); err != nil {
return nil, err
}
if _, err := io.Copy(conn, rdr); err != nil {
return nil, err
}
response, err := ParseResponse(conn)
if err != nil {
return nil, err
}
bodybuf, err := io.ReadAll(response.Body)
if err != nil {
return nil, err
}
response.Body = bytes.NewBuffer(bodybuf)
response.Request = request
return response, nil
}
// Fetch parses a URL string and fetches the spartan resource.
//
// It will resolve any redirects along the way, up to client.MaxRedirects.
func (c Client) Fetch(ctx context.Context, url string) (*types.Response, error) {
u, err := neturl.Parse(url)
if err != nil {
return nil, err
}
for i := 0; i <= c.MaxRedirects; i += 1 {
response, err := c.RoundTrip(ctx, &types.Request{URL: u})
if err != nil {
return nil, err
}
if !c.IsRedirect(response) {
return response, nil
}
prev := u
u, err = neturl.Parse(response.Meta.(string))
if err != nil {
return nil, err
}
u = prev.ResolveReference(u)
}
return nil, ErrExceededMaxRedirects
}
func (c Client) IsRedirect(response *types.Response) bool {
return response.Status == StatusRedirect
}
type devnull struct{}
func (devnull) Read(p []byte) (int, error) {
return 0, nil
}
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