3 files changed, 107 insertions, 5 deletions

diff --git a/gemini/client.go b/gemini/client.go
index 7c78b71..338271c 100644
--- a/gemini/client.go
+++ b/gemini/client.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"io"
 	"net"
+	neturl "net/url"
 
 	sr "tildegit.org/tjp/sliderule"
 )
@@ -18,14 +19,22 @@ import (
 //
 // The zero value is a usable Client with no client TLS certificate.
 type Client struct {
+	MaxRedirects int
+
 	tlsConf *tls.Config
 }
 
 // Create a gemini Client with the given TLS configuration.
 func NewClient(tlsConf *tls.Config) Client {
-	return Client{tlsConf: tlsConf}
+	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
@@ -77,3 +86,32 @@ func (client Client) RoundTrip(request *sr.Request) (*sr.Response, error) {
 
 	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(url string) (*sr.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(&sr.Request{URL: u})
+		if err != nil {
+			return nil, err
+		}
+		if ResponseCategoryForStatus(response.Status) != ResponseCategoryRedirect {
+			return response, nil
+		}
+
+		prev := u
+		u, err = neturl.Parse(url)
+		if err != nil {
+			return nil, err
+		}
+		u = prev.ResolveReference(u)
+	}
+
+	return nil, ExceededMaxRedirects
+}
diff --git a/gopher/client.go b/gopher/client.go
index fad9413..163d0cd 100644
--- a/gopher/client.go
+++ b/gopher/client.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"io"
 	"net"
+	neturl "net/url"
 
 	sr "tildegit.org/tjp/sliderule"
 )
@@ -53,3 +54,12 @@ func (c Client) RoundTrip(request *sr.Request) (*sr.Response, error) {
 
 	return &sr.Response{Body: bytes.NewBuffer(response)}, nil
 }
+
+// Fetch parses a URL string and fetches the gopher resource.
+func (c Client) Fetch(url string) (*sr.Response, error) {
+	u, err := neturl.Parse(url)
+	if err != nil {
+		return nil, err
+	}
+	return c.RoundTrip(&sr.Request{URL: u})
+}
diff --git a/spartan/client.go b/spartan/client.go
index 40c9dd6..a98949d 100644
--- a/spartan/client.go
+++ b/spartan/client.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"io"
 	"net"
+	neturl "net/url"
 	"strconv"
 
 	sr "tildegit.org/tjp/sliderule"
@@ -15,7 +16,19 @@ import (
 // It carries no state and is reusable simultaneously by multiple goroutines.
 //
 // The zero value is immediately usabble.
-type Client struct{}
+type Client struct{
+	MaxRedirects int
+}
+
+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 ExceededMaxRedirects = errors.New("spartan.Client: exceeded MaxRedirects")
 
 // RoundTrip sends a single spartan request and returns its response.
 func (c Client) RoundTrip(request *sr.Request) (*sr.Response, error) {
@@ -38,9 +51,15 @@ func (c Client) RoundTrip(request *sr.Request) (*sr.Response, error) {
 
 	request.RemoteAddr = conn.RemoteAddr()
 
-	rdr, ok := request.Meta.(*io.LimitedReader)
-	if !ok {
-		return nil, errors.New("request body must be an *io.LimitedReader")
+	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")
+		}
 	}
 
 	requestLine := host + " " + request.EscapedPath() + " " + strconv.Itoa(int(rdr.N)) + "\r\n"
@@ -65,3 +84,38 @@ func (c Client) RoundTrip(request *sr.Request) (*sr.Response, error) {
 
 	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(url string) (*sr.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(&sr.Request{URL: u})
+		if err != nil {
+			return nil, err
+		}
+		if response.Status != StatusRedirect {
+			return response, nil
+		}
+
+		prev := u
+		u, err = neturl.Parse(url)
+		if err != nil {
+			return nil, err
+		}
+		u = prev.ResolveReference(u)
+	}
+
+	return nil, ExceededMaxRedirects
+}
+
+type devnull struct{}
+
+func (_ devnull) Read(p []byte) (int, error) {
+	return 0, nil
+}