Initial cloud-services repo - gateway service + pkg modules

pkg/tmobtokengen/ehts.go

@@ -0,0 +1,118 @@
+package tmobtokengen
+
+import (
+	"crypto/sha256"
+	"encoding/base64"
+	"strings"
+)
+
+type EhtsKey string
+
+const (
+	Authorization EhtsKey = "Authorization"
+	URI           EhtsKey = "uri"
+	HTTPMethod    EhtsKey = "http-method"
+	ContentType   EhtsKey = "Content-Type"
+	B2BClient     EhtsKey = "B2b-client" // No idea what this is for
+	Body          EhtsKey = "body"
+)
+
+// ehtsKeyList order is important for serialization.
+var ehtsKeyList = []EhtsKey{Authorization, URI, HTTPMethod, Body, ContentType, B2BClient}
+
+func ehtsToString(ehts map[EhtsKey]string) (ks string, vs string) {
+	kb, vb := new(strings.Builder), new(strings.Builder)
+	for _, k := range ehtsKeyList {
+		v, ok := ehts[k]
+		if !ok {
+			continue
+		}
+
+		if kb.Len() > 0 {
+			kb.WriteRune(';')
+		}
+
+		kb.WriteString(string(k))
+		vb.WriteString(v)
+	}
+
+	return kb.String(), vb.String()
+}
+
+func b64EncodeEHTS(ehts []byte) []byte {
+	sum := sha256.Sum256(ehts)
+	encoded := make([]byte, base64.URLEncoding.EncodedLen(len(sum)))
+	base64.URLEncoding.Encode(encoded, sum[:])
+
+	// It appears to be that T-Mob removes the padding.
+	i := len(encoded) - 1
+	for ; i > 0; i-- {
+		if i != '=' {
+			break
+		}
+	}
+
+	return encoded[:i]
+}
+
+// EHTSMap is a map of EHTS keys and values.
+// Set[X] methods are used to set values in the map,
+// Yet if the value for the given setter is empty, it won't set anything.
+// Thus remember to set explicitly the value to empty string if there is need.
+type EHTSMap map[EhtsKey]string
+
+func (m EHTSMap) Copy() EHTSMap {
+	c := make(EHTSMap)
+	for k, v := range m {
+		c[k] = v
+	}
+
+	return c
+}
+func (m EHTSMap) SetContentType(contentType string) EHTSMap {
+	if len(contentType) > 0 {
+		m[ContentType] = contentType
+	}
+
+	return m
+}
+
+func (m EHTSMap) SetAuthorization(authorization string) EHTSMap {
+	if len(authorization) > 0 {
+		m[Authorization] = authorization
+	}
+
+	return m
+}
+
+func (m EHTSMap) SetB2BClient(b2bClient string) EHTSMap {
+	if len(b2bClient) > 0 {
+		m[B2BClient] = b2bClient
+	}
+
+	return m
+}
+
+func (m EHTSMap) SetURI(uri string) EHTSMap {
+	if len(uri) > 0 {
+		m[URI] = uri
+	}
+
+	return m
+}
+
+func (m EHTSMap) SetBody(body string) EHTSMap {
+	if len(body) > 0 {
+		m[Body] = body
+	}
+
+	return m
+}
+
+func (m EHTSMap) SetHTTPMethod(httpMethod string) EHTSMap {
+	if len(httpMethod) > 0 {
+		m[HTTPMethod] = httpMethod
+	}
+
+	return m
+}