Finish up the initial packserver implementation

.gitignore

@@ -1 +1,2 @@
 /cmd/htpacker/htpacker
+/cmd/packserver/packserver

cmd/packserver/go.mod

@@ -0,0 +1,10 @@
+module github.com/lwithers/htpack/cmd/packserver
+
+go 1.12
+
+require (
+	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/lwithers/htpack v0.0.0-20190412081623-ea77f42dc393
+	github.com/spf13/cobra v0.0.3
+	github.com/spf13/pflag v1.0.3 // indirect
+)

cmd/packserver/go.sum

@@ -0,0 +1,15 @@
+github.com/gogo/protobuf v1.2.1 h1:/s5zKNz0uPFCZ5hddgPdo2TK2TVrUNMn0OOX8/aZMTE=
+github.com/gogo/protobuf v1.2.1/go.mod h1:hp+jE20tsWTFYpLwKvXlhS1hjn+gTNwPg2I6zVXpSg4=
+github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
+github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
+github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
+github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
+github.com/lwithers/htpack v0.0.0-20190412081623-ea77f42dc393 h1:h++VdZ2eeJC9hf+W+LTVsYdYclJZcz6H5DYAMtGfzBA=
+github.com/lwithers/htpack v0.0.0-20190412081623-ea77f42dc393/go.mod h1:+9noAoJ9IIiHkwn2Z2Po5upZOKItKKFgYr/cMESGYrc=
+github.com/spf13/cobra v0.0.3 h1:ZlrZ4XsMRm04Fr5pSFxBgfND2EBVa1nLpiy1stUsX/8=
+github.com/spf13/cobra v0.0.3/go.mod h1:1l0Ry5zgKvJasoi3XT1TypsSe7PqH0Sj9dhYf7v3XqQ=
+github.com/spf13/pflag v1.0.3 h1:zPAT6CGy6wXeQ7NtTnaTerfKOsV6V6F8agHXFiazDkg=
+github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
+golang.org/x/sys v0.0.0-20180924175946-90868a75fefd h1:ELJRxcWg6//yYBDjuf/SnMg1+X0jj5+BP5xXF31wl4w=
+golang.org/x/sys v0.0.0-20180924175946-90868a75fefd/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/tools v0.0.0-20180221164845-07fd8470d635/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

cmd/packserver/main.go

@@ -0,0 +1,219 @@
+/*
+Packserver is a standalone HTTP server that serves up one or more pack files.
+*/
+package main
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/lwithers/htpack"
+	"github.com/spf13/cobra"
+)
+
+var rootCmd = &cobra.Command{
+	Use:   "packserver",
+	Short: "packserver is an HTTP server which serves .htpack files",
+	Long: `packserver can efficiently serve a pre-packed file tree over HTTP(S).
+The files must first have been prepared using the ‘htpacker’ tool.
+
+In order to use HTTPS, specify the --key (or -k) flag. This should name a
+PEM-encoded key file. This file may also contain the certificate; if not, then
+pass the --cert (or -c) flag in addition.
+
+Pack files may be specified as "/prefix=file", or just as "file" (which implies
+"/=file"). Any /prefix present in the request URL will be stripped off before
+searching the .htpack for the named file. Only one .htpack file can be served
+at a particular prefix, and serving matches the longest (most specific)
+prefixes first.`,
+	RunE: run,
+}
+
+func main() {
+	rootCmd.Flags().StringP("bind", "b", ":8080",
+		"Address to listen on / bind to")
+	rootCmd.Flags().StringP("key", "k", "",
+		"Path to PEM-encoded HTTPS key")
+	rootCmd.Flags().StringP("cert", "c", "",
+		"Path to PEM-encoded HTTPS cert")
+	rootCmd.Flags().StringSliceP("header", "H", nil,
+		"Extra headers; use flag once for each, in form -H header=value")
+	rootCmd.Flags().String("header-file", "",
+		"Path to text file containing one line for each header=value to add")
+	rootCmd.Flags().Duration("expiry", 0,
+		"Tell client how long it can cache data for; 0 means no caching")
+
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func run(c *cobra.Command, args []string) error {
+	bindAddr, err := c.Flags().GetString("bind")
+	if err != nil {
+		return err
+	}
+
+	// parse TLS arguments
+	keyFile, err := c.Flags().GetString("key")
+	if err != nil {
+		return err
+	}
+	certFile, err := c.Flags().GetString("cert")
+	if err != nil {
+		return err
+	}
+	switch {
+	case keyFile == "" && certFile == "":
+		// nothing to do
+	case keyFile == "":
+		return errors.New("cannot specify --cert without --key")
+	case certFile == "":
+		certFile = keyFile
+	}
+
+	// parse extra headers
+	extraHeaders := make(http.Header)
+	hdrs, err := c.Flags().GetStringSlice("header")
+	if err != nil {
+		return err
+	}
+	for _, hdr := range hdrs {
+		pos := strings.IndexRune(hdr, '=')
+		if pos == -1 {
+			return fmt.Errorf("header %q must be in form "+
+				"name=value", hdr)
+		}
+		extraHeaders.Add(hdr[:pos], hdr[pos+1:])
+	}
+
+	hdrfile, err := c.Flags().GetString("header-file")
+	if err != nil {
+		return err
+	}
+	if err := loadHeaderFile(hdrfile, extraHeaders); err != nil {
+		fmt.Fprintln(os.Stderr, "--header-file:", err)
+		os.Exit(1)
+	}
+
+	// parse expiry time
+	//  NB: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
+	expiry, err := c.Flags().GetDuration("expiry")
+	if err != nil {
+		return err
+	}
+	if expiry <= 0 {
+		extraHeaders.Set("Cache-Control", "no-store")
+	} else {
+		extraHeaders.Set("Cache-Control",
+			fmt.Sprintf("public, max-age=%d", expiry/1e9))
+	}
+
+	// verify .htpack specifications
+	if len(args) == 0 {
+		return errors.New("must specify one or more .htpack files")
+	}
+
+	packPaths := make(map[string]string)
+	for _, arg := range args {
+		prefix, packfile := "/", arg
+		if pos := strings.IndexRune(arg, '='); pos != -1 {
+			prefix, packfile = arg[:pos], arg[pos+1:]
+		}
+
+		prefix = filepath.Clean(prefix)
+		if prefix[0] != '/' {
+			return fmt.Errorf("%s: prefix must start with '/'", arg)
+		}
+
+		if other, used := packPaths[prefix]; used {
+			return fmt.Errorf("%s: prefix %q already used by %s",
+				arg, prefix, other)
+		}
+		packPaths[prefix] = packfile
+	}
+
+	// load packfiles, registering handlers as we go
+	for prefix, packfile := range packPaths {
+		var handler http.Handler
+		handler, err = htpack.New(packfile)
+		if err != nil {
+			return err
+		}
+
+		handler = &addHeaders{
+			extraHeaders: extraHeaders,
+			handler:      handler,
+		}
+
+		if prefix != "/" {
+			http.Handle(prefix+"/",
+				http.StripPrefix(prefix, handler))
+		} else {
+			http.Handle("/", handler)
+		}
+	}
+
+	// main server loop
+	if keyFile == "" {
+		err = http.ListenAndServe(bindAddr, nil)
+	} else {
+		err = http.ListenAndServeTLS(bindAddr, certFile, keyFile, nil)
+	}
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+	return nil
+}
+
+func loadHeaderFile(hdrfile string, extraHeaders http.Header) error {
+	if hdrfile == "" {
+		return nil
+	}
+
+	f, err := os.Open(hdrfile)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	var lineNum int
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		lineNum++
+		if line == "" {
+			continue
+		}
+
+		pos := strings.IndexRune(line, '=')
+		if pos == -1 {
+			return fmt.Errorf("%s: line %d: not in form "+
+				"header=value", hdrfile, lineNum)
+		}
+		extraHeaders.Add(line[:pos], line[pos+1:])
+	}
+	if err := scanner.Err(); err != nil {
+		return fmt.Errorf("%s: %v", hdrfile, err)
+	}
+	return nil
+}
+
+type addHeaders struct {
+	extraHeaders http.Header
+	handler      http.Handler
+}
+
+func (ah *addHeaders) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	for name, values := range ah.extraHeaders {
+		w.Header()[name] = append(w.Header()[name], values...)
+	}
+	ah.handler.ServeHTTP(w, r)
+}