fileserver requested by Grez at http://dou.ua/forums/topic/16012/?ref=email&utm_source=transactional&utm_medium=email&utm_campaign=reply-comment#841957

dou-fileserver.go

// Example static file server. Serves static files from the given directory.
package main

import (
        "flag"
        "fmt"
        "log"
        "strconv"
        "strings"

        "github.com/valyala/fasthttp"
)

var (
        addr               = flag.String("addr", ":8080", "TCP address to listen to")
        compress           = flag.Bool("compress", false, "Enables transparent response compression if set to true")
        dir                = flag.String("dir", "/usr/share/nginx/html", "Directory to serve static files from")
        generateIndexPages = flag.Bool("generateIndexPages", true, "Whether to generate directory index pages")
)

func main() {
        flag.Parse()

        fs := &fasthttp.FS{
                Root:               *dir,
                IndexNames:         []string{"index.html"},
                GenerateIndexPages: *generateIndexPages,
                Compress:           *compress,
        }
        h := fs.NewRequestHandler()
        h = DOURequestHandler(h)

        if err := fasthttp.ListenAndServe(*addr, h); err != nil {
                log.Fatalf("error in ListenAndServe: %s", err)
        }
}

func DOURequestHandler(fsHandler fasthttp.RequestHandler) fasthttp.RequestHandler {
        return func(ctx *fasthttp.RequestCtx) {
                path := string(ctx.Path())
                if strings.HasPrefix(path, "/plus/") {
                        b := path[len("/plus/"):]
                        sum := 0
                        for _, s := range strings.Split(b, "/") {
                                n, err := strconv.Atoi(s)
                                if err != nil {
                                        fmt.Fprintf(ctx, "cannot parse number %q in the path %q: %s", s, path, err)
                                        ctx.SetStatusCode(fasthttp.StatusBadRequest)
                                        return
                                }
                                sum += n
                        }
                        fmt.Fprintf(ctx, "%d", sum)
                } else {
                        fsHandler(ctx)
                }
        }
}