Add debug handler for fetching a remote actor

Will be used later to add to internal db

web/shared/client.go

@@ -0,0 +1,79 @@
+package webshared
+
+import (
+	"crypto/sha256"
+	"net/http"
+	"time"
+
+	"git.mstar.dev/mstar/goutils/maputils"
+
+	"git.mstar.dev/mstar/linstrom/config"
+)
+
+// No init needed, zero value is good
+
+var RequestClient http.Client
+
+const xRandomHeader = "X-Auth-Random"
+
+// Sign a given outbound request for authorized fetch.
+// At the end, the Signature header will have the signature needed,
+// nothing else is modified.
+// If the request is POST, the postBody must contain the raw body of
+// the request and the Digest header will also be added
+func SignRequest(r *http.Request, keyId string, privateKeyBytes, postBody []byte) error {
+	method := r.Method
+	headers := r.Header
+	var nowString string
+	if dateString := headers.Get("Date"); dateString != "" {
+		nowString = dateString
+	} else {
+		nowString = time.Now().Format("Mon, 02 Jan 2006 15:04:05 MST")
+		headers.Set("Date", nowString)
+	}
+	var host string
+	if hostString := headers.Get("Host"); hostString != "" {
+		host = hostString
+	} else {
+		host = config.GlobalConfig.General.GetFullDomain()
+		headers.Set("Date", host)
+	}
+	applyBodyHash(headers, postBody)
+	mappedHeaders := maputils.MapSameKeys(headers, func(k string, v []string) string {
+		if len(v) > 0 {
+			return v[0]
+		} else {
+			return ""
+		}
+	})
+	var signedString string
+	if config.GlobalConfig.Experimental.UseEd25519Keys {
+		tmp, err := CreateSignatureED(method, r.URL.RawPath, mappedHeaders, privateKeyBytes)
+		if err != nil {
+			return err
+		}
+		signedString = tmp
+	} else {
+		tmp, err := CreateSignatureRSA(method, r.URL.RawPath, mappedHeaders, privateKeyBytes)
+		if err != nil {
+			return err
+		}
+		signedString = tmp
+	}
+	signature := CreateSignatureHeaderContent(
+		keyId,
+		signedString,
+		maputils.KeysFromMap(mappedHeaders)...,
+	)
+	headers.Set("Signature", signature)
+	return nil
+}
+
+func applyBodyHash(headers http.Header, body []byte) error {
+	if body == nil {
+		return nil
+	}
+	hash := sha256.Sum256(body)
+	headers.Set("Digest", string(hash[:]))
+	return nil
+}