move auth utils into dedicated folder

auth/server.go

@@ -0,0 +1,159 @@
+package auth
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/hex"
+	"fmt"
+	"net/url"
+	"strings"
+
+	"github.com/aler9/gortsplib/base"
+	"github.com/aler9/gortsplib/headers"
+)
+
+// Server is an object that helps a server to validate the credentials of
+// a client.
+type Server struct {
+	user    string
+	pass    string
+	methods []headers.AuthMethod
+	realm   string
+	nonce   string
+}
+
+// NewServer allocates an Server.
+// If methods is nil, the Basic and Digest methods are used.
+func NewServer(user string, pass string, methods []headers.AuthMethod) *Server {
+	if methods == nil {
+		methods = []headers.AuthMethod{headers.AuthBasic, headers.AuthDigest}
+	}
+
+	nonceByts := make([]byte, 16)
+	rand.Read(nonceByts)
+	nonce := hex.EncodeToString(nonceByts)
+
+	return &Server{
+		user:    user,
+		pass:    pass,
+		methods: methods,
+		realm:   "IPCAM",
+		nonce:   nonce,
+	}
+}
+
+// GenerateHeader generates the WWW-Authenticate header needed by a client to log in.
+func (as *Server) GenerateHeader() base.HeaderValue {
+	var ret base.HeaderValue
+	for _, m := range as.methods {
+		switch m {
+		case headers.AuthBasic:
+			ret = append(ret, (&headers.Auth{
+				Method: headers.AuthBasic,
+				Realm:  &as.realm,
+			}).Write()...)
+
+		case headers.AuthDigest:
+			ret = append(ret, (&headers.Auth{
+				Method: headers.AuthDigest,
+				Realm:  &as.realm,
+				Nonce:  &as.nonce,
+			}).Write()...)
+		}
+	}
+	return ret
+}
+
+// ValidateHeader validates the Authorization header sent by a client after receiving the
+// WWW-Authenticate header.
+func (as *Server) ValidateHeader(v base.HeaderValue, method base.Method, ur *url.URL) error {
+	if len(v) == 0 {
+		return fmt.Errorf("authorization header not provided")
+	}
+	if len(v) > 1 {
+		return fmt.Errorf("authorization header provided multiple times")
+	}
+
+	v0 := v[0]
+
+	if strings.HasPrefix(v0, "Basic ") {
+		inResponse := v0[len("Basic "):]
+
+		response := base64.StdEncoding.EncodeToString([]byte(as.user + ":" + as.pass))
+
+		if inResponse != response {
+			return fmt.Errorf("wrong response")
+		}
+
+	} else if strings.HasPrefix(v0, "Digest ") {
+		auth, err := headers.ReadAuth(base.HeaderValue{v0})
+		if err != nil {
+			return err
+		}
+
+		if auth.Realm == nil {
+			return fmt.Errorf("realm not provided")
+		}
+
+		if auth.Nonce == nil {
+			return fmt.Errorf("nonce not provided")
+		}
+
+		if auth.Username == nil {
+			return fmt.Errorf("username not provided")
+		}
+
+		if auth.URI == nil {
+			return fmt.Errorf("uri not provided")
+		}
+
+		if auth.Response == nil {
+			return fmt.Errorf("response not provided")
+		}
+
+		if *auth.Nonce != as.nonce {
+			return fmt.Errorf("wrong nonce")
+		}
+
+		if *auth.Realm != as.realm {
+			return fmt.Errorf("wrong realm")
+		}
+
+		if *auth.Username != as.user {
+			return fmt.Errorf("wrong username")
+		}
+
+		uri := ur.String()
+
+		if *auth.URI != uri {
+			// VLC strips the subpath
+			newUrl := *ur
+			newUrl.Path = func() string {
+				ret := newUrl.Path
+
+				if n := strings.Index(ret[1:], "/"); n >= 0 {
+					ret = ret[:n+2]
+				}
+
+				return ret
+			}()
+			uri = newUrl.String()
+
+			if *auth.URI != uri {
+				return fmt.Errorf("wrong url")
+			}
+		}
+
+		response := md5Hex(md5Hex(as.user+":"+as.realm+":"+as.pass) +
+			":" + as.nonce + ":" + md5Hex(string(method)+":"+uri))
+
+		if *auth.Response != response {
+			return fmt.Errorf("wrong response")
+		}
+
+	} else {
+		return fmt.Errorf("unsupported authorization header")
+	}
+
+	return nil
+}