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|
package gemini
import (
"bytes"
"context"
"crypto/tls"
"errors"
"io"
"net"
neturl "net/url"
"strconv"
"strings"
"tildegit.org/tjp/sliderule/internal/types"
)
// Client is used for sending gemini requests and parsing gemini responses.
//
// It carries no state and is usable and reusable simultaneously by multiple goroutines.
// The only reason you might create more than one Client is to support separate TLS-cert
// driven identities.
//
// The zero value is a usable Client with no client TLS certificate and which will not
// follow redirects.
type Client struct {
MaxRedirects int
tlsConf *tls.Config
}
// NewClient creates a gemini Client with the given TLS configuration and default MaxRedirects.
func NewClient(tlsConf *tls.Config) Client {
if tlsConf != nil && !tlsConf.InsecureSkipVerify {
tlsConf = tlsConf.Clone()
tlsConf.InsecureSkipVerify = true
}
return Client{tlsConf: tlsConf, 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 ExceededMaxRedirects = errors.New("gemini.Client: exceeded MaxRedirects")
// RoundTrip sends a single gemini request to the correct server and returns its response.
//
// It also populates the TLSState and RemoteAddr fields on the request - the only field
// it needs populated beforehand is the URL.
//
// This method will not automatically follow redirects or cache permanent failures or
// redirects.
func (client Client) RoundTrip(ctx context.Context, request *types.Request) (*types.Response, error) {
if request.Scheme != "gemini" && request.Scheme != "titan" && request.Scheme != "" {
return nil, errors.New("non-gemini protocols not supported")
}
host := request.Host
if _, port, _ := net.SplitHostPort(host); port == "" {
host = net.JoinHostPort(host, "1965")
}
tlsConf := client.tlsConf
if tlsConf == nil {
tlsConf = &tls.Config{InsecureSkipVerify: true}
}
conn, err := (&tls.Dialer{Config: tlsConf}).DialContext(ctx, "tcp", host)
if err != nil {
return nil, err
}
defer conn.Close()
request.RemoteAddr = conn.RemoteAddr()
st := conn.(*tls.Conn).ConnectionState()
request.TLSState = &st
destURL := *request.URL
var body []byte
if request.Scheme == "titan" {
var err error
if bodyrdr, ok := request.Meta.(io.Reader); ok {
body, err = io.ReadAll(bodyrdr)
if err != nil {
return nil, err
}
if err := close(request.Meta); err != nil {
return nil, err
}
path, params := pathparams(destURL.Path)
params["size"] = strconv.Itoa(len(body))
destURL.Path = assemblepath(path, params)
} else {
body = []byte{}
}
}
if _, err := conn.Write([]byte(destURL.String() + "\r\n")); err != nil {
return nil, err
}
if _, err := conn.Write(body); err != nil {
return nil, err
}
response, err := ParseResponse(conn)
if err != nil {
return nil, err
}
// read and store the request body in full or we may miss doing so before
// closing the connection
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 gemini 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, ExceededMaxRedirects
}
func (c Client) IsRedirect(response *types.Response) bool {
return ResponseCategoryForStatus(response.Status) == ResponseCategoryRedirect
}
func pathparams(basepath string) (string, map[string]string) {
params := map[string]string{}
path, paramstr, found := strings.Cut(basepath, ";")
if !found {
return path, params
}
for _, pairstr := range strings.Split(paramstr, ";") {
key, val, found := strings.Cut(pairstr, "=")
if found {
params[key] = val
}
}
return path, params
}
func assemblepath(basepath string, params map[string]string) string {
path := strings.Builder{}
_, _ = path.WriteString(basepath)
for key, val := range params {
_ = path.WriteByte(';')
_, _ = path.WriteString(key)
_ = path.WriteByte('=')
_, _ = path.WriteString(val)
}
return path.String()
}
func close(closer any) error {
if cl, ok := closer.(io.Closer); ok {
return cl.Close()
}
return nil
}
|
