The capability slightly varies between the old and new name, as a new
parameter was added. This adds support for both.

Fixes: #105
See: https://github.com/ircv3/ircv3-specifications/pull/435
---
 downstream.go | 40 +++++++++++++++++++++++++++++++++++++++-
 upstream.go   | 30 ++++++++++++++++++++----------
 2 files changed, 59 insertions(+), 11 deletions(-)

diff --git a/downstream.go b/downstream.go
index fee5134..540bace 100644
--- a/downstream.go
+++ b/downstream.go
@@ -137,6 +137,15 @@ var needAllDownstreamCaps = map[string]string{
 	"multi-prefix":  "",
 }
 
+// passthroughCaps is the list of downstream capabilities that are passed
+// through from the upstream server to downstream clients.
+//
+// This is only effective in single-upstream mode.
+var passthroughCaps = map[string]string{
+	"draft/account-registration": "",
+	"draft/register":             "",
+}
+
 // passthroughIsupport is the set of ISUPPORT tokens that are directly passed
 // through from the upstream server to downstream clients.
 //
@@ -894,6 +903,18 @@ func (dc *downstreamConn) updateSupportedCaps() {
 			dc.unsetSupportedCap(cap)
 		}
 	}
+
+	uc := dc.upstream()
+	for cap := range passthroughCaps {
+		if uc != nil {
+			v, ok := uc.supportedCaps[cap]
+			if ok && uc.caps[cap] {
+				dc.setSupportedCap(cap, v)
+				continue
+			}
+		}
+		dc.unsetSupportedCap(cap)
+	}
 }
 
 func (dc *downstreamConn) updateNick() {
@@ -2343,6 +2364,20 @@ func (dc *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
 				Params:  []string{"BOUNCER", "UNKNOWN_COMMAND", subcommand, "Unknown subcommand"},
 			}}
 		}
+	case "REGISTER", "VERIFY":
+		uc := dc.upstream()
+		if uc == nil {
+			return newUnknownCommandError(msg.Command)
+		}
+		uc.SendMessageLabeled(dc.id, msg)
+		if msg.Command == "REGISTER" && len(msg.Params) >= 2 {
+			username := uc.nick
+			if len(msg.Params) >= 3 && msg.Params[0] != "*" {
+				username = msg.Params[0]
+			}
+			password := msg.Params[len(msg.Params)-1]
+			dc.updateCredentials(uc, username, password)
+		}
 	default:
 		dc.logger.Printf("unhandled message: %v", msg)
 
@@ -2362,14 +2397,17 @@ func (dc *downstreamConn) handleNickServPRIVMSG(uc *upstreamConn, text string) {
 	if !ok {
 		return
 	}
+	dc.updateCredentials(uc, username, password)
+}
 
+func (dc *downstreamConn) updateCredentials(uc *upstreamConn, username, password string) {
 	// User may have e.g. EXTERNAL mechanism configured. We do not want to
 	// automatically erase the key pair or any other credentials.
 	if uc.network.SASL.Mechanism != "" && uc.network.SASL.Mechanism != "PLAIN" {
 		return
 	}
 
-	dc.logger.Printf("auto-saving NickServ credentials with username %q", username)
+	dc.logger.Printf("auto-saving credentials with username %q", username)
 	n := uc.network
 	n.SASL.Mechanism = "PLAIN"
 	n.SASL.Plain.Username = username
diff --git a/upstream.go b/upstream.go
index 104f330..46f96d1 100644
--- a/upstream.go
+++ b/upstream.go
@@ -21,16 +21,18 @@ import (
 // permanentUpstreamCaps is the static list of upstream capabilities always
 // requested when supported.
 var permanentUpstreamCaps = map[string]bool{
-	"account-tag":      true,
-	"away-notify":      true,
-	"batch":            true,
-	"extended-join":    true,
-	"invite-notify":    true,
-	"labeled-response": true,
-	"message-tags":     true,
-	"multi-prefix":     true,
-	"server-time":      true,
-	"setname":          true,
+	"account-tag":                true,
+	"away-notify":                true,
+	"batch":                      true,
+	"extended-join":              true,
+	"invite-notify":              true,
+	"labeled-response":           true,
+	"message-tags":               true,
+	"multi-prefix":               true,
+	"server-time":                true,
+	"setname":                    true,
+	"draft/account-registration": true,
+	"draft/register":             true,
 }
 
 type registrationError string
@@ -1428,6 +1430,14 @@ func (uc *upstreamConn) handleMessage(msg *irc.Message) error {
 				Params:  []string{dc.nick, upstreamChannel, trailing},
 			})
 		})
+	case "REGISTER", "VERIFY":
+		uc.forEachDownstreamByID(downstreamID, func(dc *downstreamConn) {
+			dc.SendMessage(&irc.Message{
+				Prefix:  uc.srv.prefix(),
+				Command: msg.Command,
+				Params:  msg.Params,
+			})
+		})
 	case irc.ERR_UNKNOWNCOMMAND, irc.RPL_TRYAGAIN:
 		var command, reason string
 		if err := parseMessageParams(msg, nil, &command, &reason); err != nil {
-- 
2.30.0