client: Make Get and Do accept a Context

This removes the need for Request.Context.

client.go

@@ -5,8 +5,8 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"errors"
-	"fmt"
 	"net"
+	"net/url"
 	"time"
 )
 
@@ -28,6 +28,10 @@ type Client struct {
 	//
 	// A Timeout of zero means no timeout.
 	Timeout time.Duration
+
+	// DialContext specifies the dial function for creating TCP connections.
+	// If DialContext is nil, the client dials using package net.
+	DialContext func(ctx context.Context, network, addr string) (net.Conn, error)
 }
 
 // Get sends a Gemini request for the given URL.
@@ -39,12 +43,12 @@ type Client struct {
 // which the user is expected to close.
 //
 // For more control over requests, use NewRequest and Client.Do.
-func (c *Client) Get(url string) (*Response, error) {
+func (c *Client) Get(ctx context.Context, url string) (*Response, error) {
 	req, err := NewRequest(url)
 	if err != nil {
 		return nil, err
 	}
-	return c.Do(req)
+	return c.Do(ctx, req)
 }
 
 // Do sends a Gemini request and returns a Gemini response, following
@@ -57,48 +61,56 @@ func (c *Client) Get(url string) (*Response, error) {
 // which the user is expected to close.
 //
 // Generally Get will be used instead of Do.
-func (c *Client) Do(req *Request) (*Response, error) {
-	// Punycode request URL host
-	hostname, port, err := net.SplitHostPort(req.URL.Host)
-	if err != nil {
-		// Likely no port
-		hostname = req.URL.Host
-		port = "1965"
+func (c *Client) Do(ctx context.Context, req *Request) (*Response, error) {
+	if ctx == nil {
+		panic("nil context")
 	}
-	punycode, err := punycodeHostname(hostname)
+
+	// Punycode request URL host
+	host, port := splitHostPort(req.URL.Host)
+	punycode, err := punycodeHostname(host)
 	if err != nil {
 		return nil, err
 	}
-	if hostname != punycode {
-		hostname = punycode
+	if host != punycode {
+		host = punycode
 
 		// Make a copy of the request
-		_req := *req
-		req = &_req
-		_url := *req.URL
-		req.URL = &_url
+		r2 := new(Request)
+		*r2 = *req
+		r2.URL = new(url.URL)
+		*r2.URL = *req.URL
+		req = r2
 
 		// Set the host
-		req.URL.Host = net.JoinHostPort(hostname, port)
+		req.URL.Host = net.JoinHostPort(host, port)
 	}
 
 	// Use request host if provided
 	if req.Host != "" {
-		hostname, port, err = net.SplitHostPort(req.Host)
-		if err != nil {
-			// Likely no port
-			hostname = req.Host
-			port = "1965"
-		}
-		// Punycode hostname
-		hostname, err = punycodeHostname(hostname)
+		host, port = splitHostPort(req.Host)
+		host, err = punycodeHostname(host)
 		if err != nil {
 			return nil, err
 		}
 	}
 
+	addr := net.JoinHostPort(host, port)
+
 	// Connect to the host
-	config := &tls.Config{
+	start := time.Now()
+	conn, err := c.dialContext(ctx, "tcp", addr)
+	if err != nil {
+		return nil, err
+	}
+
+	// Set the connection deadline
+	if c.Timeout != 0 {
+		conn.SetDeadline(start.Add(c.Timeout))
+	}
+
+	// Setup TLS
+	conn = tls.Client(conn, &tls.Config{
 		InsecureSkipVerify: true,
 		MinVersion:         tls.VersionTLS12,
 		GetClientCertificate: func(_ *tls.CertificateRequestInfo) (*tls.Certificate, error) {
@@ -108,83 +120,84 @@ func (c *Client) Do(req *Request) (*Response, error) {
 			return &tls.Certificate{}, nil
 		},
 		VerifyConnection: func(cs tls.ConnectionState) error {
-			return c.verifyConnection(hostname, punycode, cs)
+			return c.verifyConnection(cs, host)
 		},
-		ServerName: hostname,
+		ServerName: host,
+	})
+
+	res := make(chan result, 1)
+	go func() {
+		res <- c.do(conn, req)
+	}()
+
+	select {
+	case <-ctx.Done():
+		conn.Close()
+		return nil, ctx.Err()
+	case r := <-res:
+		return r.resp, r.err
 	}
-
-	ctx := req.Context
-	if ctx == nil {
-		ctx = context.Background()
-	}
-
-	start := time.Now()
-	dialer := net.Dialer{
-		Timeout: c.Timeout,
-	}
-
-	address := net.JoinHostPort(hostname, port)
-	netConn, err := dialer.DialContext(ctx, "tcp", address)
-	if err != nil {
-		return nil, err
-	}
-
-	conn := tls.Client(netConn, config)
-
-	// Set connection deadline
-	if c.Timeout != 0 {
-		err := conn.SetDeadline(start.Add(c.Timeout))
-		if err != nil {
-			return nil, fmt.Errorf("failed to set connection deadline: %w", err)
-		}
-	}
-
-	resp, err := c.do(conn, req)
-	if err != nil {
-		// If we fail to perform the request/response we have
-		// to take responsibility for closing the connection.
-		_ = conn.Close()
-
-		return nil, err
-	}
-
-	// Store connection state
-	state := conn.ConnectionState()
-	resp.TLS = &state
-
-	return resp, nil
 }
 
-func (c *Client) do(conn *tls.Conn, req *Request) (*Response, error) {
+type result struct {
+	resp *Response
+	err  error
+}
+
+func (c *Client) do(conn net.Conn, req *Request) result {
 	// Write the request
-	err := req.Write(conn)
-	if err != nil {
-		return nil, fmt.Errorf("failed to write request: %w", err)
+	if err := req.Write(conn); err != nil {
+		return result{nil, err}
 	}
 
 	// Read the response
 	resp, err := ReadResponse(conn)
 	if err != nil {
-		return nil, err
+		return result{nil, err}
 	}
 
-	return resp, nil
+	// Store TLS connection state
+	if tlsConn, ok := conn.(*tls.Conn); ok {
+		state := tlsConn.ConnectionState()
+		resp.TLS = &state
+	}
+
+	return result{resp, nil}
 }
 
-func (c *Client) verifyConnection(hostname, punycode string, cs tls.ConnectionState) error {
+func (c *Client) dialContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	if c.DialContext != nil {
+		return c.DialContext(ctx, network, addr)
+	}
+	return (&net.Dialer{
+		Timeout: c.Timeout,
+	}).DialContext(ctx, network, addr)
+}
+
+func (c *Client) verifyConnection(cs tls.ConnectionState, hostname string) error {
 	cert := cs.PeerCertificates[0]
-	// Verify punycoded hostname
-	if err := verifyHostname(cert, punycode); err != nil {
+	// Verify hostname
+	if err := verifyHostname(cert, hostname); err != nil {
 		return err
 	}
 	// Check expiration date
 	if !time.Now().Before(cert.NotAfter) {
 		return errors.New("gemini: certificate expired")
 	}
-
 	// See if the client trusts the certificate
 	if c.TrustCertificate != nil {
 		return c.TrustCertificate(hostname, cert)
 	}
 	return nil
 }
+
+func splitHostPort(hostport string) (host, port string) {
+	var err error
+	host, port, err = net.SplitHostPort(hostport)
+	if err != nil {
+		// Likely no port
+		host = hostport
+		port = "1965"
+	}
+	return
+}

request.go

@@ -2,7 +2,6 @@ package gemini
 
 import (
 	"bufio"
-	"context"
 	"crypto/tls"
 	"io"
 	"net/url"
@@ -48,14 +47,6 @@ type Request struct {
 	// otherwise it leaves the field nil.
 	// This field is ignored by the Gemini client.
 	TLS *tls.ConnectionState
-
-	// Context specifies the context to use for outgoing requests.
-	// The context controls the entire lifetime of a request and its
-	// response: obtaining a connection, sending the request, and
-	// reading the response header and body.
-	// If Context is nil, the background context will be used.
-	// This field is ignored by the Gemini server.
-	Context context.Context
 }
 
 // NewRequest returns a new request.

timeout.go

@@ -28,13 +28,8 @@ type timeoutHandler struct {
 }
 
 func (t *timeoutHandler) ServeGemini(w ResponseWriter, r *Request) {
-	ctx := r.Context
-	if ctx == nil {
-		ctx = context.Background()
-	}
-	var cancelCtx func()
-	ctx, cancelCtx = context.WithTimeout(ctx, t.dt)
-	defer cancelCtx()
+	ctx, cancel := context.WithTimeout(context.TODO(), t.dt)
+	defer cancel()
 
 	done := make(chan struct{})
 	tw := &timeoutWriter{}