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server.go
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server.go
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package kipp
import (
"context"
"crypto/rand"
"encoding/base64"
"errors"
"fmt"
"io"
"log"
"mime"
"mime/multipart"
"net/http"
"net/url"
"os"
"path"
"path/filepath"
"strconv"
"strings"
"time"
"github.com/gabriel-vasile/mimetype"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/uhthomas/kipp/database"
"github.com/uhthomas/kipp/filesystem"
"github.com/zeebo/blake3"
)
// Server acts as the HTTP server and configuration.
type Server struct {
Database database.Database
FileSystem filesystem.FileSystem
Lifetime time.Duration
Limit int64
PublicPath string
metricHandler http.Handler
}
func New(ctx context.Context, opts ...Option) (*Server, error) {
r := prometheus.NewRegistry()
if err := r.Register(prometheus.NewGoCollector()); err != nil {
return nil, fmt.Errorf("register go collector: %w", err)
}
s := &Server{
metricHandler: promhttp.InstrumentMetricHandler(
r, promhttp.HandlerFor(r, promhttp.HandlerOpts{}),
),
}
for _, opt := range opts {
if err := opt(ctx, s); err != nil {
return nil, err
}
}
return s, nil
}
// ServeHTTP will serve HTTP requests. It first tries to determine if the
// request is for uploading, it then tries to serve static files and then will
// try to serve public files.
func (s Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
switch r.Method {
case http.MethodGet, http.MethodHead:
case http.MethodPost:
if r.URL.Path == "/" {
s.UploadHandler(w, r)
return
}
fallthrough
default:
allow := "GET, HEAD, OPTIONS"
if r.URL.Path == "/" {
allow = "GET, HEAD, OPTIONS, POST"
}
if r.Method == http.MethodOptions {
w.Header().Set("Access-Control-Allow-Methods", allow)
} else {
w.Header().Set("Allow", allow)
http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
}
return
}
switch r.URL.Path {
case "/healthz":
s.Health(w, r)
return
case "/varz":
s.metricHandler.ServeHTTP(w, r)
return
}
http.FileServer(fileSystemFunc(func(name string) (_ http.File, err error) {
if f, err := http.Dir(s.PublicPath).Open(name); !os.IsNotExist(err) {
d, err := f.Stat()
if err != nil {
return nil, err
}
if !d.IsDir() {
w.Header().Set("Cache-Control", "max-age=31536000")
// nginx style weak Etag
w.Header().Set("Etag", fmt.Sprintf(
`W/"%x-%x"`,
d.ModTime().Unix(), d.Size(),
))
}
return f, nil
}
dir, name := path.Split(name)
if dir != "/" {
return nil, os.ErrNotExist
}
// trim anything after the first "."
if i := strings.Index(name, "."); i > -1 {
name = name[:i]
}
e, err := s.Database.Lookup(r.Context(), name)
if err != nil {
if errors.Is(err, database.ErrNoResults) {
return nil, os.ErrNotExist
}
return nil, err
}
cache := "max-age=31536000" // ~ 1 year
if e.Lifetime != nil {
now := time.Now()
if e.Lifetime.Before(now) {
return nil, os.ErrNotExist
}
cache = fmt.Sprintf(
"public, must-revalidate, max-age=%d",
int(e.Lifetime.Sub(now).Seconds()),
)
}
f, err := s.FileSystem.Open(r.Context(), e.Slug)
if err != nil {
return nil, err
}
defer func() {
if err != nil {
f.Close()
}
}()
ctype, err := detectContentType(e.Name, f)
if err != nil {
return nil, fmt.Errorf("detect content type: %w", err)
}
// catches text/html and text/html; charset=utf-8
const prefix = "text/html"
if strings.HasPrefix(ctype, prefix) {
ctype = "text/plain" + ctype[len(prefix):]
}
w.Header().Set("Cache-Control", cache)
w.Header().Set("Content-Disposition", fmt.Sprintf(
"filename=%q; filename*=UTF-8''%[1]s",
url.PathEscape(e.Name),
))
w.Header().Set("Content-Type", ctype)
w.Header().Set("Etag", strconv.Quote(e.Sum))
if e.Lifetime != nil {
w.Header().Set("Expires", e.Lifetime.Format(http.TimeFormat))
}
w.Header().Set("X-Content-Type-Options", "nosniff")
return &file{Reader: f, entry: e}, nil
})).ServeHTTP(w, r)
}
func (s Server) Health(w http.ResponseWriter, r *http.Request) {
ctx, cancel := context.WithTimeout(r.Context(), time.Second)
defer cancel()
if err := s.Database.Ping(ctx); err != nil {
log.Printf("ping: %v", err)
http.Error(w, err.Error(), http.StatusInternalServerError)
}
}
// UploadHandler write the contents of the "file" part to a filesystem.Reader,
// persists the entry to the database and writes the location of the file
// to the response.
func (s Server) UploadHandler(w http.ResponseWriter, r *http.Request) {
// Due to the overhead of multipart bodies, the actual limit for files
// is smaller than it should be. It's not really feasible to calculate
// the overhead so this is *good enough* for the time being.
//
// TODO(thomas): is there a better way to limit the size for the
// part, rather than the whole body?
if r.ContentLength > s.Limit {
http.Error(w, http.StatusText(http.StatusRequestEntityTooLarge), http.StatusRequestEntityTooLarge)
return
}
r.Body = http.MaxBytesReader(w, r.Body, s.Limit)
mr, err := r.MultipartReader()
if err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
}
var p *multipart.Part
for {
if p, err = mr.NextPart(); err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
}
if p.FormName() == "file" {
break
}
}
defer p.Close()
name := p.FileName()
if len(name) > 255 {
http.Error(w, "invalid name", http.StatusBadRequest)
return
}
var b [9]byte
if _, err := io.ReadFull(rand.Reader, b[:]); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
slug := base64.RawURLEncoding.EncodeToString(b[:])
if err := s.FileSystem.Create(r.Context(), slug, filesystem.PipeReader(func(w io.Writer) error {
h := blake3.New()
n, err := io.Copy(io.MultiWriter(w, h), p)
if err != nil {
return fmt.Errorf("copy: %w", err)
}
now := time.Now()
var l *time.Time
if s.Lifetime > 0 {
t := now.Add(s.Lifetime)
l = &t
}
if err := s.Database.Create(r.Context(), database.Entry{
Slug: slug,
Name: name,
Sum: base64.RawURLEncoding.EncodeToString(h.Sum(nil)),
Size: n,
Timestamp: now,
Lifetime: l,
}); err != nil {
return fmt.Errorf("create entry: %w", err)
}
return nil
})); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
ext := filepath.Ext(name)
var sb strings.Builder
sb.Grow(len(slug) + len(ext) + 2)
sb.WriteRune('/')
sb.WriteString(slug)
sb.WriteString(ext)
http.Redirect(w, r, sb.String(), http.StatusSeeOther)
sb.WriteRune('\n')
io.WriteString(w, sb.String())
}
// detectContentType sniffs up-to the first 3072 bytes of the stream,
// falling back to extension if the content type could not be detected.
func detectContentType(name string, r io.ReadSeeker) (string, error) {
var b [3072]byte
n, _ := io.ReadFull(r, b[:])
if _, err := r.Seek(0, io.SeekStart); err != nil {
return "", errors.New("seeker can't seek")
}
m := mimetype.Detect(b[:n])
if m.Is("application/octet-stream") {
if ctype := mime.TypeByExtension(filepath.Ext(name)); ctype != "" {
return ctype, nil
}
}
return m.String(), nil
}