refactor(media): replace hand-rolled SigV4 with maintained minio-go SDK; add /admin/media/upload endpoint

2026-09-10 07:12:35 +10:00
parent df4a19933c
commit 5acddaa605
5 changed files with 166 additions and 157 deletions
--- a/app/go.mod
+++ b/app/go.mod
@@ -7,3 +7,13 @@ require (
 	github.com/goccy/go-yaml v1.19.2
 	github.com/yuin/goldmark v1.8.6
 )
+
+require (
+	github.com/go-ini/ini v1.67.0 // indirect
+	github.com/minio/minio-go v6.0.14+incompatible // indirect
+	github.com/mitchellh/go-homedir v1.1.0 // indirect
+	golang.org/x/crypto v0.48.0 // indirect
+	golang.org/x/net v0.51.0 // indirect
+	golang.org/x/sys v0.41.0 // indirect
+	golang.org/x/text v0.34.0 // indirect
+)
--- a/app/go.sum
+++ b/app/go.sum
@@ -1,6 +1,20 @@
 github.com/a-h/templ v0.3.1020 h1:ypAT/L5ySWEnZ6Zft/5yfoWXYYkhFNvEFOeeqecg4tw=
 github.com/a-h/templ v0.3.1020/go.mod h1:A2DlK61v+K+NRoGnhmYbNYVmtYHcFO5/AisMvBdDxTM=
+github.com/go-ini/ini v1.67.0 h1:z6ZrTEZqSWOTyH2FlglNbNgARyHG8oLW9gMELqKr06A=
+github.com/go-ini/ini v1.67.0/go.mod h1:ByCAeIL28uOIIG0E3PJtZPDL8WnHpFKFOtgjp+3Ies8=
 github.com/goccy/go-yaml v1.19.2 h1:PmFC1S6h8ljIz6gMRBopkjP1TVT7xuwrButHID66PoM=
 github.com/goccy/go-yaml v1.19.2/go.mod h1:XBurs7gK8ATbW4ZPGKgcbrY1Br56PdM69F7LkFRi1kA=
+github.com/minio/minio-go v6.0.14+incompatible h1:fnV+GD28LeqdN6vT2XdGKW8Qe/IfjJDswNVuni6km9o=
+github.com/minio/minio-go v6.0.14+incompatible/go.mod h1:7guKYtitv8dktvNUGrhzmNlA5wrAABTQXCoesZdFQO8=
+github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
+github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/yuin/goldmark v1.8.6 h1:d0VcaP1sx9GkFVkoW+KtggpGi2KZ965i14b0+bDQST4=
 github.com/yuin/goldmark v1.8.6/go.mod h1:ip/1k0VRfGynBgxOz0yCqHrbZXhcjxyuS66Brc7iBKg=
+golang.org/x/crypto v0.48.0 h1:/VRzVqiRSggnhY7gNRxPauEQ5Drw9haKdM0jqfcCFts=
+golang.org/x/crypto v0.48.0/go.mod h1:r0kV5h3qnFPlQnBSrULhlsRfryS2pmewsg+XfMgkVos=
+golang.org/x/net v0.51.0 h1:94R/GTO7mt3/4wIKpcR5gkGmRLOuE/2hNGeWq/GBIFo=
+golang.org/x/net v0.51.0/go.mod h1:aamm+2QF5ogm02fjy5Bb7CQ0WMt1/WVM7FtyaTLlA9Y=
+golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
+golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/text v0.34.0 h1:oL/Qq0Kdaqxa1KbNeMKwQq0reLCCaFtqu2eNuSeNHbk=
+golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
--- a/app/src/main.go
+++ b/app/src/main.go
@@ -37,25 +37,16 @@ func main() {
 	log.Printf("loaded %d articles across %d subjects", len(c.Articles), len(c.Subjects))

 	s := NewSite(c)
-	// media proxy config (Garage S3)
-	s.Media = &S3MediaClient{
-		Endpoint: os.Getenv("KONTRA_S3_ENDPOINT"),
-		Bucket:   os.Getenv("KONTRA_S3_BUCKET"),
-		Key:      os.Getenv("KONTRA_S3_KEY"),
-		Secret:   os.Getenv("KONTRA_S3_SECRET"),
-		Client:   http.Client{},
-	}
-	if s.Media.Endpoint == "" {
-		s.Media.Endpoint = "http://127.0.0.1:3900"
-	}
-	if s.Media.Bucket == "" {
-		s.Media.Bucket = "kontra-day"
-	}
+	// media (Garage S3 via minio-go SDK)
+	s.Media = NewMediaClient()

 	// Routes — register specific paths BEFORE the catch-all.
 	http.HandleFunc("/media/{path...}", func(w http.ResponseWriter, r *http.Request) {
 		s.media(w, r, r.PathValue("path"))
 	})
+	http.HandleFunc("/admin/media/upload", func(w http.ResponseWriter, r *http.Request) {
+		s.mediaUpload(w, r)
+	})
 	http.HandleFunc("/subjects/{slug}", func(w http.ResponseWriter, r *http.Request) {
 		s.subject(w, r, r.PathValue("slug"))
 	})
--- a/app/src/media.go
+++ b/app/src/media.go
@@ -1,157 +1,106 @@
-// Kontra — Garage S3 media serving via AWS Signature Version 4.
-// The app signs a GET for the scoped key and streams the object bytes back,
-// so /media/{name} works through the same container (no public Garage).
+// Kontra — Garage S3 media serving + upload via the maintained minio-go SDK.
+// (No hand-rolled signing: minio-go handles AWS SigV4 + path-style against Garage.)

 package main

 import (
-	"crypto/hmac"
-	"crypto/sha256"
+	"bytes"
 	"fmt"
 	"io"
+	"log"
 	"net/http"
+	"os"
 	"strings"
-	"time"
+
+	"github.com/minio/minio-go"
 )

-// hexLower encodes b as lowercase hex.
-func hexLower(b []byte) string {
-	const hexc = "0123456789abcdef"
-	var out strings.Builder
-	for _, x := range b {
-		out.Write([]byte{
-			byte(hexc[x >> 4]),
-			byte(hexc[x & 0xF]),
-		})
-	}
-	return out.String()
-}
-
-// sha256Hex returns hex(sha256(data)).
-func sha256Hex(data []byte) string {
-	sum := sha256.Sum256(data)
-	var s []byte
-	for _, ch := range sum {
-		s = append(s, ch)
-	}
-	return hexLower(s)
-}
-
-// hmacSha256 returns the raw 32-byte HMAC-SHA256(key, data).
-func hmacSha256(key, data []byte) []byte {
-	h := hmac.New(sha256.New, key)
-	h.Write(data)
-	return h.Sum(nil)
-}
-
-// hmacSha256Hex returns hex(HMAC-SHA256(key, data)).
-func hmacSha256Hex(key, data []byte) string {
-	return hexLower(hmacSha256(key, data))
-}
-
-// SignedGet is the prepared request.
-type SignedGet struct {
-	URL     string
-	Auth    string
-	Date    string
-	Host    string
-}
-
-// signGet builds a SigV4 GET for path-style access: <endpoint>/<bucket>/<name>.
-func signGet(endpoint, bucket, key, secret, name string, now time.Time) SignedGet {
-	const region = "garage"   // s3_region
-	const service = "s3"
-
-	utc := now.UTC()
-	date := utc.Format("2006") + utc.Format("01") + utc.Format("02")
-	tstamp := utc.Format("15") + utc.Format("04") + utc.Format("05")
-	amzDate := date + "T" + tstamp + "Z"
-
-	host := endpoint
-	if strings.HasPrefix(host, "http://") {
-		host = strings.TrimPrefix(host, "http://")
-	} else if strings.HasPrefix(host, "https://") {
-		host = strings.TrimPrefix(host, "https://")
-	}
-
-	canonicalPath := "/" + bucket + "/" + name
-	canonicalQuery := ""
-	payloadHash := "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855" // sha256("")
-	canonicalHeaders := "host:" + host + "\n" +
-		"x-amz-checksum-mode:ENABLED\n" +
-		"x-amz-content-sha256:" + payloadHash + "\n" +
-		"x-amz-date:" + amzDate + "\n"
-	signedHeaders := "host;x-amz-checksum-mode;x-amz-content-sha256;x-amz-date"
-
-	canonicalRequest := strings.Join([]string{
-		"GET",
-		canonicalPath,
-		canonicalQuery,
-		canonicalHeaders,
-		signedHeaders,
-		payloadHash,
-	}, "\n")
-
-	scope := date + "/" + region + "/" + service + "/aws4_request"
-	stringToSign := strings.Join([]string{
-		"AWS4-HMAC-SHA256",
-		amzDate,
-		scope,
-		sha256Hex([]byte(canonicalRequest)),
-	}, "\n")
-
-	kDate := hmacSha256([]byte("AWS4" + secret), []byte(date))
-	kRegion := hmacSha256(kDate, []byte(region))
-	kService := hmacSha256(kRegion, []byte(service))
-	kSigning := hmacSha256(kService, []byte("aws4_request"))
-	signature := hmacSha256Hex(kSigning, []byte(stringToSign))
-
-	auth := "AWS4-HMAC-SHA256 Credential=" + key + "/" + scope +
-		", SignedHeaders=" + signedHeaders + ", Signature=" + signature
-
-	return SignedGet{URL: endpoint + canonicalPath, Auth: auth, Date: amzDate, Host: host}
-}
-
-// S3MediaClient fetches objects from Garage with SigV4.
-type S3MediaClient struct {
+// MediaClient wraps minio-go for the kontra-day bucket.
+type MediaClient struct {
 	Endpoint string
 	Bucket   string
 	Key      string
 	Secret   string
-	Client   http.Client
+	Reader   *minio.Client // nil until New() succeeds
+	Err      error
 }

-// Get streams object `name` to w; returns upstream status (0 on transport error).
-func (c *S3MediaClient) Get(name string, w http.ResponseWriter) int {
-	sg := signGet(c.Endpoint, c.Bucket, c.Key, c.Secret, name, time.Now())
-	req, err := http.NewRequest("GET", sg.URL, nil)
+// NewMediaClient builds the client (call once at startup).
+func NewMediaClient() *MediaClient {
+	mc := &MediaClient{
+		Endpoint: os.Getenv("KONTRA_S3_ENDPOINT"),
+		Bucket:   os.Getenv("KONTRA_S3_BUCKET"),
+		Key:      os.Getenv("KONTRA_S3_KEY"),
+		Secret:   os.Getenv("KONTRA_S3_SECRET"),
+	}
+	if mc.Endpoint == "" {
+		mc.Endpoint = "http://127.0.0.1:3900"
+	}
+	if mc.Bucket == "" {
+		mc.Bucket = "kontra-day"
+	}
+	if mc.Key != "" && mc.Secret != "" {
+		secure := strings.HasPrefix(mc.Endpoint, "https://")
+		addr := mc.Endpoint
+		if strings.HasPrefix(addr, "http://") {
+			addr = strings.TrimPrefix(addr, "http://")
+		} else if strings.HasPrefix(addr, "https://") {
+			addr = strings.TrimPrefix(addr, "https://")
+		}
+		cl, err := minio.New(addr, mc.Key, mc.Secret, secure)
 		if err != nil {
-		return 0
+			mc.Err = err
+		} else {
+			mc.Reader = cl
 		}
-	req.Header.Set("Authorization", sg.Auth)
-	req.Header.Set("x-amz-date", sg.Date)
-	req.Header.Set("x-amz-content-sha256", "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855")
-	req.Header.Set("x-amz-checksum-mode", "ENABLED")
-	req.Header.Set("Host", sg.Host)
-
-	resp, rerr := c.Client.Do(req)
-	if rerr != nil {
-		return 0
+	} else {
+		mc.Err = fmt.Errorf("KONTRA_S3_KEY/SECRET not set")
 	}
-	defer resp.Body.Close()
-	status := resp.StatusCode
-	if status == 200 {
-		if ct := resp.Header.Get("Content-Type"); ct != "" {
-			w.Header().Set("Content-Type", ct)
-		}
-		// read the whole object then write once (small media; keeps Content-Length exact)
-		all, berr := io.ReadAll(resp.Body)
-		if berr == nil {
-			w.Header().Set("Content-Length", fmt.Sprintf("%d", len(all)))
-			_, _ = w.Write(all)
-		}
-	}
-	return status
+	return mc
 }

-var _ = fmt.Sprintf("") // silence unused-import lint
+// Get streams the object named `name` to the response. Returns true on success.
+func (c *MediaClient) Get(name string, w http.ResponseWriter) bool {
+	if c.Reader == nil {
+		log.Printf("media: client not configured: %v", c.Err)
+		http.Error(w, "media not configured", http.StatusServiceUnavailable)
+		return false
+	}
+	obj, err := c.Reader.GetObject(c.Bucket, name, minio.GetObjectOptions{})
+	if err != nil {
+		// treat missing object as 404
+		log.Printf("media get %s: %v", name, err)
+		http.Error(w, "media not found", http.StatusNotFound)
+		return false
+	}
+	defer obj.Close()
+	info, ierr := obj.Stat()
+	if ierr == nil && info.ContentType != "" {
+		w.Header().Set("Content-Type", info.ContentType)
+	}
+	data, derr := io.ReadAll(obj)
+	if derr != nil {
+		http.Error(w, "media read error", http.StatusBadGateway)
+		return false
+	}
+	w.Header().Set("Content-Length", fmt.Sprintf("%d", len(data)))
+	_, _ = w.Write(data)
+	return true
+}
+
+// Put stores bytes as an object in the bucket. Returns ok.
+func (c *MediaClient) Put(name string, contentType string, data []byte) (bool, error) {
+	if c.Reader == nil {
+		return false, c.Err
+	}
+	rdr := bytes.NewBuffer(data)
+	opts := minio.PutObjectOptions{}
+	if contentType != "" {
+		opts.ContentType = contentType
+	}
+	_, perr := c.Reader.PutObject(c.Bucket, name, rdr, int64(len(data)), opts)
+	if perr != nil {
+		return false, perr
+	}
+	return true, nil
+}
--- a/app/src/server.go
+++ b/app/src/server.go
@@ -3,8 +3,9 @@
 package main

 import (
+	"io"
 	"net/http"
-	"os"
+	"strings"

 	"github.com/a-h/templ"
 )
@@ -12,20 +13,64 @@ import (
 // Site routes requests to content renderers.
 type Site struct {
 	Content *Content
-	Media   *S3MediaClient
+	Media   *MediaClient
 }

-// media serves /media/{name} by proxying the Garage bucket (S3 SigV4).
+// media serves /media/{name} from the Garage bucket (via minio-go SDK).
 func (s *Site) media(w http.ResponseWriter, r *http.Request, name string) {
-	if s.Media == nil || s.Media.Key == "" {
+	if s.Media == nil {
 		http.Error(w, "media not configured", http.StatusServiceUnavailable)
 		return
 	}
-	status := s.Media.Get(name, w)
-	if status != 200 && status != 0 {
-		http.Error(w, "media not found", http.StatusNotFound)
+	s.Media.Get(name, w)
+}
+
+// mediaUpload handles POST /admin/media/upload (multipart) for the CMS editor.
+func (s *Site) mediaUpload(w http.ResponseWriter, r *http.Request) {
+	file, fh, ferr := r.FormFile("file")
+	if ferr != nil || file == nil || fh == nil {
+		http.Error(w, "no file part", http.StatusBadRequest)
+		return
 	}
-	_ = os.Getenv("")
+	defer file.Close()
+	name := r.FormValue("name")
+	if name == "" {
+		name = fh.Filename
+	}
+	name = sanitizeMediaName(name)
+	if name == "" {
+		http.Error(w, "bad file name", http.StatusBadRequest)
+		return
+	}
+	data, derr := io.ReadAll(file)
+	if derr != nil {
+		http.Error(w, "read error", http.StatusBadRequest)
+		return
+	}
+	ctype := fh.Header.Get("Content-Type")
+	ok, perr := s.Media.Put("media/" + name, ctype, data)
+	if !ok || perr != nil {
+		http.Error(w, "upload failed", http.StatusInternalServerError)
+		return
+	}
+	http.Redirect(w, r, "/media/" + name, http.StatusSeeOther)
+}
+
+// sanitizeMediaName keeps the base name, strips any path/unsafe chars.
+func sanitizeMediaName(name string) string {
+	// keep only the final path element
+	base := name
+	if i := strings.LastIndexByte(base, '/'); i >= 0 {
+		base = base[i+1:]
+	}
+	var b strings.Builder
+	for i := 0; i < len(base); i++ {
+		ch := base[i]
+		if (ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9') || ch == '.' || ch == '-' || ch == '_' {
+			b.Write([]byte{ch})
+		}
+	}
+	return b.String()
 }

 // home renders the front page.