Consolidating validate and extract sip URI into one util function (#1864)

Author: genseric-ghiro

.changeset/sip-name-addr-parser.md

@@ -0,0 +1,6 @@
+---
+"github.com/livekit/protocol": patch
+"@livekit/protocol": patch
+---
+
+Add `ParseSIPNameAddr`, which validates a name-addr value and returns its user part, replacing `sip.URIUser`

livekit/sip_validation.go

@@ -283,7 +283,10 @@ func findAngleBrackets(value string) (int, int, error) {
 	start := -1
 	end := -1
 
-	for i, r := range value {
+	// A leading quoted display name may contain angle brackets of its own.
+	offset := len(value) - len(skipQuotedDisplayName(value))
+	for i, r := range value[offset:] {
+		i += offset
 		switch r {
 		case '<':
 			if start != -1 {
@@ -313,27 +316,52 @@ func findAngleBrackets(value string) (int, int, error) {
 
 // validateNameAddrHeader validates headers that use name-addr format per RFC 3261 Section 20.10
 func validateNameAddrHeader(value string) error {
+	_, err := ParseSIPNameAddr(value)
+	return err
+}
+
+// ParseSIPNameAddr validates a value in name-addr or addr-spec format, as found
+// in From, To and Refer-To headers, and returns the user part of its URI. The
+// user is empty when the URI has none.
+func ParseSIPNameAddr(value string) (string, error) {
 	// RFC 3261 Section 20.10 - name-addr format
 	// name-addr = [display-name] <addr-spec>
 	// addr-spec = SIP-URI / SIPS-URI / absoluteURI
 
 	uri := value
 	start, end, err := findAngleBrackets(value)
 	if err != nil {
-		return err
+		return "", err
 	}
 	if start >= 0 || end >= 0 {
 		uri = value[start+1 : end]
 		if err := validateDisplayName(strings.TrimSpace(value[:start])); err != nil {
-			return err
+			return "", err
 		}
 	} else {
 		// This is a bare URI, and should comply with addr-spec, no special characters
 		if strings.ContainsAny(value, ",? ") {
-			return errors.New("bare URI with special characters")
+			return "", errors.New("bare URI with special characters")
 		}
 	}
-	return validateURI(uri)
+	return uriUser(uri)
+}
+
+// skipQuotedDisplayName returns the part of a name-addr after a leading quoted
+// display name. An unterminated quote returns the value unchanged.
+func skipQuotedDisplayName(s string) string {
+	if !strings.HasPrefix(s, "\"") {
+		return s
+	}
+	for i := 1; i < len(s); i++ {
+		switch s[i] {
+		case '\\':
+			i++
+		case '"':
+			return s[i+1:]
+		}
+	}
+	return s
 }
 
 // validateDisplayName validates a display name in name-addr format
@@ -360,20 +388,31 @@ func validateDisplayName(displayName string) error {
 	return nil
 }
 
-// validateURI validates URIs that can appear in name-addr format
-func validateURI(uri string) error {
+// uriUser validates a URI that can appear in name-addr format and returns its
+// user part: up to the "@" for sip and sips, the whole number for tel, without
+// parameters or headers.
+func uriUser(uri string) (string, error) {
 	// Just do the basics, full validation should be done by sip service
-	scheme := strings.SplitN(uri, ":", 2)[0]
-	if scheme != "sip" && scheme != "sips" && scheme != "tel" {
+	scheme, rest, _ := strings.Cut(uri, ":")
+	var user string
+	switch strings.ToLower(scheme) {
+	case "sip", "sips":
+		if u, _, found := strings.Cut(rest, "@"); found {
+			user = u
+		}
+	case "tel":
 		// Technically, it either needs to be sip/s: or scheme://...
 		// Thus, tel: uri should not be supported here... but we allow it because of de-facto usage.
-		return errors.New("uri: scheme not one of sip, sips, or tel")
+		user = rest
+	default:
+		return "", errors.New("uri: scheme not one of sip, sips, or tel")
 	}
 
 	// Just no spaces, proper validation should be done in sip service
 	if strings.Contains(uri, " ") {
-		return errors.New("uri: contains spaces")
+		return "", errors.New("uri: contains spaces")
 	}
 
-	return nil
+	user, _, _ = strings.Cut(user, ";")
+	return user, nil
 }

livekit/sip_validation_test.go

@@ -165,7 +165,13 @@ var ValidNameAddrHeaders = []string{
 	`Alice Johnson <sip:u3@example.com>`,
 	`"Alice \"Ace\" Johnson's device\\" <sip:user@host>`, // quoted + escapes
 	`"Alice & Bob" <sip:user@host>`,                      // special char in quoted display
+	`"Smith <Jr>" <sip:user@host>`,                       // angle brackets in quoted display
 	`Alice <sip:user@host;transport=tcp?X-Custom=val>;tag=abc`,
+
+	// scheme is case-insensitive (RFC 3261 §19.1.4)
+	`SIP:user@host`,
+	`<SIPS:user@host>`,
+	`Alice <Tel:+15551234567>`,
 }
 
 // InvalidNameAddrHeaders contains invalid Name-addr format headers
@@ -304,3 +310,44 @@ func TestForbiddenSipHeaderNames(t *testing.T) {
 		})
 	}
 }
+
+func TestParseSIPNameAddr(t *testing.T) {
+	cases := []struct {
+		value string
+		user  string
+		ok    bool
+	}{
+		{`sip:911@example.com`, "911", true},
+		{`sips:911@example.com`, "911", true},
+		{`tel:911`, "911", true},
+		{`tel:+1-555-123-4567`, "+1-555-123-4567", true},
+		{`<sip:911@example.com>`, "911", true},
+		{`<sip:911@example.com;transport=tcp>`, "911", true},
+		{`<sip:911@example.com?X-Custom=val>`, "911", true},
+		{`<sip:911;phone-context=example.com@example.com>`, "911", true},
+		{`<tel:911;phone-context=example.com>`, "911", true},
+		{`<sip:911@example.com>;tag=abc`, "911", true},
+		{`Alice <sip:911@example.com>`, "911", true},
+		{`"Alice Johnson" <sip:911@example.com>`, "911", true},
+		{`"Smith <Jr>" <sip:911@example.com>`, "911", true},
+		{`SIP:911@example.com`, "911", true},
+		{`sip:example.com`, "", true},
+		{`<sip:u7@example.com`, "", false},
+		{`Alice sip:u13@example.com`, "", false},
+		{`"Alice <sip:911@example.com>`, "", false},
+		{`http://example.com`, "", false},
+		{`911`, "", false},
+		{``, "", false},
+	}
+	for _, c := range cases {
+		t.Run(c.value, func(t *testing.T) {
+			user, err := ParseSIPNameAddr(c.value)
+			if c.ok != (err == nil) {
+				t.Fatalf("ParseSIPNameAddr(%q) error = %v, want ok=%v", c.value, err, c.ok)
+			}
+			if user != c.user {
+				t.Errorf("ParseSIPNameAddr(%q) user = %q, want %q", c.value, user, c.user)
+			}
+		})
+	}
+}

sip/phonenumber.go

@@ -1,8 +1,6 @@
 package sip
 
 import (
-	"strings"
-
 	"github.com/livekit/protocol/livekit"
 	"github.com/nyaruka/phonenumbers"
 )
@@ -72,55 +70,3 @@ func IsEmergencyNumber(number string) bool {
 	}
 	return false
 }
-
-// URIUser returns the user part of a sip, sips or tel URI, with the display
-// name, angle brackets, host and parameters removed. A URI with no user part
-// and anything that is not a URI returns an empty string.
-func URIUser(uri string) string {
-	uri = skipQuotedDisplayName(uri)
-	if i := strings.Index(uri, "<"); i >= 0 {
-		uri = uri[i+1:]
-		if j := strings.Index(uri, ">"); j >= 0 {
-			uri = uri[:j]
-		}
-	}
-	colon := strings.Index(uri, ":")
-	if colon < 0 {
-		return ""
-	}
-	scheme, rest := strings.ToLower(uri[:colon]), uri[colon+1:]
-	var user string
-	switch scheme {
-	case "sip", "sips":
-		at := strings.Index(rest, "@")
-		if at < 0 {
-			return ""
-		}
-		user = rest[:at]
-	case "tel":
-		user = rest
-	default:
-		return ""
-	}
-	if i := strings.IndexAny(user, ";?"); i >= 0 {
-		user = user[:i]
-	}
-	return user
-}
-
-// skipQuotedDisplayName returns the part of a name-addr after a leading quoted
-// display name, so that a "<" inside the quotes is not taken as the URI start.
-func skipQuotedDisplayName(s string) string {
-	if !strings.HasPrefix(s, "\"") {
-		return s
-	}
-	for i := 1; i < len(s); i++ {
-		switch s[i] {
-		case '\\':
-			i++
-		case '"':
-			return s[i+1:]
-		}
-	}
-	return s
-}