seaweedfs/weed/s3api/s3api_object_handlers_postpolicy.go

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package s3api
import (
"bytes"
"encoding/base64"
"errors"
"fmt"
"io"
"mime/multipart"
"net/http"
"net/url"
"strings"
"github.com/chrislusf/seaweedfs/weed/glog"
"github.com/chrislusf/seaweedfs/weed/s3api/policy"
"github.com/chrislusf/seaweedfs/weed/s3api/s3err"
"github.com/dustin/go-humanize"
"github.com/gorilla/mux"
)
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func (s3a *S3ApiServer) PostPolicyBucketHandler(w http.ResponseWriter, r *http.Request) {
// https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
// https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-post-example.html
bucket := mux.Vars(r)["bucket"]
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glog.V(3).Infof("PostPolicyBucketHandler %s", bucket)
reader, err := r.MultipartReader()
if err != nil {
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s3err.WriteErrorResponse(w, r, s3err.ErrMalformedPOSTRequest)
return
}
form, err := reader.ReadForm(int64(5 * humanize.MiByte))
if err != nil {
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s3err.WriteErrorResponse(w, r, s3err.ErrMalformedPOSTRequest)
return
}
defer form.RemoveAll()
fileBody, fileName, fileSize, formValues, err := extractPostPolicyFormValues(form)
if err != nil {
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s3err.WriteErrorResponse(w, r, s3err.ErrMalformedPOSTRequest)
return
}
if fileBody == nil {
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s3err.WriteErrorResponse(w, r, s3err.ErrPOSTFileRequired)
return
}
defer fileBody.Close()
formValues.Set("Bucket", bucket)
if fileName != "" && strings.Contains(formValues.Get("Key"), "${filename}") {
formValues.Set("Key", strings.Replace(formValues.Get("Key"), "${filename}", fileName, -1))
}
object := formValues.Get("Key")
successRedirect := formValues.Get("success_action_redirect")
successStatus := formValues.Get("success_action_status")
var redirectURL *url.URL
if successRedirect != "" {
redirectURL, err = url.Parse(successRedirect)
if err != nil {
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s3err.WriteErrorResponse(w, r, s3err.ErrMalformedPOSTRequest)
return
}
}
// Verify policy signature.
errCode := s3a.iam.doesPolicySignatureMatch(formValues)
if errCode != s3err.ErrNone {
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s3err.WriteErrorResponse(w, r, errCode)
return
}
policyBytes, err := base64.StdEncoding.DecodeString(formValues.Get("Policy"))
if err != nil {
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s3err.WriteErrorResponse(w, r, s3err.ErrMalformedPOSTRequest)
return
}
// Handle policy if it is set.
if len(policyBytes) > 0 {
postPolicyForm, err := policy.ParsePostPolicyForm(string(policyBytes))
if err != nil {
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s3err.WriteErrorResponse(w, r, s3err.ErrPostPolicyConditionInvalidFormat)
return
}
// Make sure formValues adhere to policy restrictions.
if err = policy.CheckPostPolicy(formValues, postPolicyForm); err != nil {
w.Header().Set("Location", r.URL.Path)
w.WriteHeader(http.StatusTemporaryRedirect)
return
}
// Ensure that the object size is within expected range, also the file size
// should not exceed the maximum single Put size (5 GiB)
lengthRange := postPolicyForm.Conditions.ContentLengthRange
if lengthRange.Valid {
if fileSize < lengthRange.Min {
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s3err.WriteErrorResponse(w, r, s3err.ErrEntityTooSmall)
return
}
if fileSize > lengthRange.Max {
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s3err.WriteErrorResponse(w, r, s3err.ErrEntityTooLarge)
return
}
}
}
uploadUrl := fmt.Sprintf("http://%s%s/%s%s", s3a.option.Filer.ToHttpAddress(), s3a.option.BucketsPath, bucket, urlPathEscape(object))
etag, errCode := s3a.putToFiler(r, uploadUrl, fileBody)
if errCode != s3err.ErrNone {
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s3err.WriteErrorResponse(w, r, errCode)
return
}
if successRedirect != "" {
// Replace raw query params..
redirectURL.RawQuery = getRedirectPostRawQuery(bucket, object, etag)
w.Header().Set("Location", redirectURL.String())
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s3err.WriteEmptyResponse(w, r, http.StatusSeeOther)
return
}
setEtag(w, etag)
// Decide what http response to send depending on success_action_status parameter
switch successStatus {
case "201":
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resp := PostResponse{
Bucket: bucket,
Key: object,
ETag: `"` + etag + `"`,
Location: w.Header().Get("Location"),
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}
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s3err.WriteXMLResponse(w, r, http.StatusCreated, resp)
case "200":
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s3err.WriteEmptyResponse(w, r, http.StatusOK)
default:
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writeSuccessResponseEmpty(w, r)
}
}
// Extract form fields and file data from a HTTP POST Policy
func extractPostPolicyFormValues(form *multipart.Form) (filePart io.ReadCloser, fileName string, fileSize int64, formValues http.Header, err error) {
// / HTML Form values
fileName = ""
// Canonicalize the form values into http.Header.
formValues = make(http.Header)
for k, v := range form.Value {
formValues[http.CanonicalHeaderKey(k)] = v
}
// Validate form values.
if err = validateFormFieldSize(formValues); err != nil {
return nil, "", 0, nil, err
}
// this means that filename="" was not specified for file key and Go has
// an ugly way of handling this situation. Refer here
// https://golang.org/src/mime/multipart/formdata.go#L61
if len(form.File) == 0 {
var b = &bytes.Buffer{}
for _, v := range formValues["File"] {
b.WriteString(v)
}
fileSize = int64(b.Len())
filePart = io.NopCloser(b)
return filePart, fileName, fileSize, formValues, nil
}
// Iterator until we find a valid File field and break
for k, v := range form.File {
canonicalFormName := http.CanonicalHeaderKey(k)
if canonicalFormName == "File" {
if len(v) == 0 {
return nil, "", 0, nil, errors.New("Invalid arguments specified")
}
// Fetch fileHeader which has the uploaded file information
fileHeader := v[0]
// Set filename
fileName = fileHeader.Filename
// Open the uploaded part
filePart, err = fileHeader.Open()
if err != nil {
return nil, "", 0, nil, err
}
// Compute file size
fileSize, err = filePart.(io.Seeker).Seek(0, 2)
if err != nil {
return nil, "", 0, nil, err
}
// Reset Seek to the beginning
_, err = filePart.(io.Seeker).Seek(0, 0)
if err != nil {
return nil, "", 0, nil, err
}
// File found and ready for reading
break
}
}
return filePart, fileName, fileSize, formValues, nil
}
// Validate form field size for s3 specification requirement.
func validateFormFieldSize(formValues http.Header) error {
// Iterate over form values
for k := range formValues {
// Check if value's field exceeds S3 limit
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if int64(len(formValues.Get(k))) > int64(1*humanize.MiByte) {
return errors.New("Data size larger than expected")
}
}
// Success.
return nil
}
func getRedirectPostRawQuery(bucket, key, etag string) string {
redirectValues := make(url.Values)
redirectValues.Set("bucket", bucket)
redirectValues.Set("key", key)
redirectValues.Set("etag", "\""+etag+"\"")
return redirectValues.Encode()
}
// Check to see if Policy is signed correctly.
func (iam *IdentityAccessManagement) doesPolicySignatureMatch(formValues http.Header) s3err.ErrorCode {
// For SignV2 - Signature field will be valid
if _, ok := formValues["Signature"]; ok {
return iam.doesPolicySignatureV2Match(formValues)
}
return iam.doesPolicySignatureV4Match(formValues)
}