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handler.go
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handler.go
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package http
import (
"errors"
"fmt"
"io"
"net/http"
"net/url"
"runtime/debug"
"strconv"
"strings"
"sync"
context "context"
"github.com/ipfs/go-ipfs/repo/config"
cors "gx/ipfs/QmQzTLDsi3a37CJyMDBXnjiHKQpth3AGS1yqwU57FfLwfG/cors"
cmds "github.com/ipfs/go-ipfs/commands"
logging "gx/ipfs/QmSpJByNKFX1sCsHBEp3R73FL4NF6FnQTEGyNAXHm2GS52/go-log"
)
var log = logging.Logger("commands/http")
// the internal handler for the API
type internalHandler struct {
ctx cmds.Context
root *cmds.Command
cfg *ServerConfig
}
// The Handler struct is funny because we want to wrap our internal handler
// with CORS while keeping our fields.
type Handler struct {
internalHandler
corsHandler http.Handler
}
var (
ErrNotFound = errors.New("404 page not found")
errApiVersionMismatch = errors.New("api version mismatch")
)
const (
StreamErrHeader = "X-Stream-Error"
streamHeader = "X-Stream-Output"
channelHeader = "X-Chunked-Output"
extraContentLengthHeader = "X-Content-Length"
uaHeader = "User-Agent"
contentTypeHeader = "Content-Type"
contentDispHeader = "Content-Disposition"
transferEncodingHeader = "Transfer-Encoding"
applicationJson = "application/json"
applicationOctetStream = "application/octet-stream"
plainText = "text/plain"
originHeader = "origin"
)
var AllowedExposedHeadersArr = []string{streamHeader, channelHeader, extraContentLengthHeader}
var AllowedExposedHeaders = strings.Join(AllowedExposedHeadersArr, ", ")
const (
ACAOrigin = "Access-Control-Allow-Origin"
ACAMethods = "Access-Control-Allow-Methods"
ACACredentials = "Access-Control-Allow-Credentials"
)
var mimeTypes = map[string]string{
cmds.Protobuf: "application/protobuf",
cmds.JSON: "application/json",
cmds.XML: "application/xml",
cmds.Text: "text/plain",
}
type ServerConfig struct {
// Headers is an optional map of headers that is written out.
Headers map[string][]string
// cORSOpts is a set of options for CORS headers.
cORSOpts *cors.Options
// cORSOptsRWMutex is a RWMutex for read/write CORSOpts
cORSOptsRWMutex sync.RWMutex
}
func skipAPIHeader(h string) bool {
switch h {
case "Access-Control-Allow-Origin":
return true
case "Access-Control-Allow-Methods":
return true
case "Access-Control-Allow-Credentials":
return true
default:
return false
}
}
func NewHandler(ctx cmds.Context, root *cmds.Command, cfg *ServerConfig) http.Handler {
if cfg == nil {
panic("must provide a valid ServerConfig")
}
// setup request logger
ctx.ReqLog = new(cmds.ReqLog)
// Wrap the internal handler with CORS handling-middleware.
// Create a handler for the API.
internal := internalHandler{
ctx: ctx,
root: root,
cfg: cfg,
}
c := cors.New(*cfg.cORSOpts)
return &Handler{internal, c.Handler(internal)}
}
func (i Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// Call the CORS handler which wraps the internal handler.
i.corsHandler.ServeHTTP(w, r)
}
func (i internalHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
log.Debug("incoming API request: ", r.URL)
defer func() {
if r := recover(); r != nil {
log.Error("a panic has occurred in the commands handler!")
log.Error(r)
debug.PrintStack()
}
}()
// get the node's context to pass into the commands.
node, err := i.ctx.GetNode()
if err != nil {
s := fmt.Sprintf("cmds/http: couldn't GetNode(): %s", err)
http.Error(w, s, http.StatusInternalServerError)
return
}
ctx, cancel := context.WithCancel(node.Context())
defer cancel()
if cn, ok := w.(http.CloseNotifier); ok {
clientGone := cn.CloseNotify()
go func() {
select {
case <-clientGone:
case <-ctx.Done():
}
cancel()
}()
}
if !allowOrigin(r, i.cfg) || !allowReferer(r, i.cfg) {
w.WriteHeader(http.StatusForbidden)
w.Write([]byte("403 - Forbidden"))
log.Warningf("API blocked request to %s. (possible CSRF)", r.URL)
return
}
req, err := Parse(r, i.root)
if err != nil {
if err == ErrNotFound {
w.WriteHeader(http.StatusNotFound)
} else {
w.WriteHeader(http.StatusBadRequest)
}
w.Write([]byte(err.Error()))
return
}
rlog := i.ctx.ReqLog.Add(req)
defer rlog.Finish()
//ps: take note of the name clash - commands.Context != context.Context
req.SetInvocContext(i.ctx)
err = req.SetRootContext(ctx)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
// call the command
res := i.root.Call(req)
// set user's headers first.
for k, v := range i.cfg.Headers {
if !skipAPIHeader(k) {
w.Header()[k] = v
}
}
// now handle responding to the client properly
sendResponse(w, r, res, req)
}
func guessMimeType(res cmds.Response) (string, error) {
// Try to guess mimeType from the encoding option
enc, found, err := res.Request().Option(cmds.EncShort).String()
if err != nil {
return "", err
}
if !found {
return "", errors.New("no encoding option set")
}
if m, ok := mimeTypes[enc]; ok {
return m, nil
}
return mimeTypes[cmds.JSON], nil
}
func sendResponse(w http.ResponseWriter, r *http.Request, res cmds.Response, req cmds.Request) {
h := w.Header()
// Expose our agent to allow identification
h.Set("Server", "go-ipfs/"+config.CurrentVersionNumber)
mime, err := guessMimeType(res)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
status := http.StatusOK
// if response contains an error, write an HTTP error status code
if e := res.Error(); e != nil {
if e.Code == cmds.ErrClient {
status = http.StatusBadRequest
} else {
status = http.StatusInternalServerError
}
// NOTE: The error will actually be written out by the reader below
}
out, err := res.Reader()
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
// Set up our potential trailer
h.Set("Trailer", StreamErrHeader)
if res.Length() > 0 {
h.Set("X-Content-Length", strconv.FormatUint(res.Length(), 10))
}
if _, ok := res.Output().(io.Reader); ok {
// set streams output type to text to avoid issues with browsers rendering
// html pages on priveleged api ports
mime = "text/plain"
h.Set(streamHeader, "1")
}
// if output is a channel and user requested streaming channels,
// use chunk copier for the output
_, isChan := res.Output().(chan interface{})
if !isChan {
_, isChan = res.Output().(<-chan interface{})
}
if isChan {
h.Set(channelHeader, "1")
}
// catch-all, set to text as default
if mime == "" {
mime = "text/plain"
}
h.Set(contentTypeHeader, mime)
// set 'allowed' headers
h.Set("Access-Control-Allow-Headers", AllowedExposedHeaders)
// expose those headers
h.Set("Access-Control-Expose-Headers", AllowedExposedHeaders)
if r.Method == "HEAD" { // after all the headers.
return
}
w.WriteHeader(status)
err = flushCopy(w, out)
if err != nil {
log.Error("err: ", err)
w.Header().Set(StreamErrHeader, sanitizedErrStr(err))
}
}
func flushCopy(w io.Writer, r io.Reader) error {
buf := make([]byte, 4096)
f, ok := w.(http.Flusher)
if !ok {
_, err := io.Copy(w, r)
return err
}
for {
n, err := r.Read(buf)
switch err {
case io.EOF:
if n <= 0 {
return nil
}
// if data was returned alongside the EOF, pretend we didnt
// get an EOF. The next read call should also EOF.
case nil:
// continue
default:
return err
}
nw, err := w.Write(buf[:n])
if err != nil {
return err
}
if nw != n {
return fmt.Errorf("http write failed to write full amount: %d != %d", nw, n)
}
f.Flush()
}
return nil
}
func sanitizedErrStr(err error) string {
s := err.Error()
s = strings.Split(s, "\n")[0]
s = strings.Split(s, "\r")[0]
return s
}
func NewServerConfig() *ServerConfig {
cfg := new(ServerConfig)
cfg.cORSOpts = new(cors.Options)
return cfg
}
func (cfg ServerConfig) AllowedOrigins() []string {
cfg.cORSOptsRWMutex.RLock()
defer cfg.cORSOptsRWMutex.RUnlock()
return cfg.cORSOpts.AllowedOrigins
}
func (cfg *ServerConfig) SetAllowedOrigins(origins ...string) {
cfg.cORSOptsRWMutex.Lock()
defer cfg.cORSOptsRWMutex.Unlock()
o := make([]string, len(origins))
copy(o, origins)
cfg.cORSOpts.AllowedOrigins = o
}
func (cfg *ServerConfig) AppendAllowedOrigins(origins ...string) {
cfg.cORSOptsRWMutex.Lock()
defer cfg.cORSOptsRWMutex.Unlock()
cfg.cORSOpts.AllowedOrigins = append(cfg.cORSOpts.AllowedOrigins, origins...)
}
func (cfg ServerConfig) AllowedMethods() []string {
cfg.cORSOptsRWMutex.RLock()
defer cfg.cORSOptsRWMutex.RUnlock()
return []string(cfg.cORSOpts.AllowedMethods)
}
func (cfg *ServerConfig) SetAllowedMethods(methods ...string) {
cfg.cORSOptsRWMutex.Lock()
defer cfg.cORSOptsRWMutex.Unlock()
if cfg.cORSOpts == nil {
cfg.cORSOpts = new(cors.Options)
}
cfg.cORSOpts.AllowedMethods = methods
}
func (cfg *ServerConfig) SetAllowCredentials(flag bool) {
cfg.cORSOptsRWMutex.Lock()
defer cfg.cORSOptsRWMutex.Unlock()
cfg.cORSOpts.AllowCredentials = flag
}
// allowOrigin just stops the request if the origin is not allowed.
// the CORS middleware apparently does not do this for us...
func allowOrigin(r *http.Request, cfg *ServerConfig) bool {
origin := r.Header.Get("Origin")
// curl, or ipfs shell, typing it in manually, or clicking link
// NOT in a browser. this opens up a hole. we should close it,
// but right now it would break things. TODO
if origin == "" {
return true
}
origins := cfg.AllowedOrigins()
for _, o := range origins {
if o == "*" { // ok! you asked for it!
return true
}
if o == origin { // allowed explicitly
return true
}
}
return false
}
// allowReferer this is here to prevent some CSRF attacks that
// the API would be vulnerable to. We check that the Referer
// is allowed by CORS Origin (origins and referrers here will
// work similarly in the normla uses of the API).
// See discussion at https://github.com/ipfs/go-ipfs/issues/1532
func allowReferer(r *http.Request, cfg *ServerConfig) bool {
referer := r.Referer()
// curl, or ipfs shell, typing it in manually, or clicking link
// NOT in a browser. this opens up a hole. we should close it,
// but right now it would break things. TODO
if referer == "" {
return true
}
u, err := url.Parse(referer)
if err != nil {
// bad referer. but there _is_ something, so bail.
log.Debug("failed to parse referer: ", referer)
// debug because referer comes straight from the client. dont want to
// let people DOS by putting a huge referer that gets stored in log files.
return false
}
origin := u.Scheme + "://" + u.Host
// check CORS ACAOs and pretend Referer works like an origin.
// this is valid for many (most?) sane uses of the API in
// other applications, and will have the desired effect.
origins := cfg.AllowedOrigins()
for _, o := range origins {
if o == "*" { // ok! you asked for it!
return true
}
// referer is allowed explicitly
if o == origin {
return true
}
}
return false
}
// apiVersionMatches checks whether the api client is running the
// same version of go-ipfs. for now, only the exact same version of
// client + server work. In the future, we should use semver for
// proper API versioning! \o/
func apiVersionMatches(r *http.Request) error {
clientVersion := r.UserAgent()
// skips check if client is not go-ipfs
if clientVersion == "" || !strings.Contains(clientVersion, "/go-ipfs/") {
return nil
}
daemonVersion := config.ApiVersion
if daemonVersion != clientVersion {
return fmt.Errorf("%s (%s != %s)", errApiVersionMismatch, daemonVersion, clientVersion)
}
return nil
}