From bb05cf2928604ad9a7c43ab07a978d6e86479333 Mon Sep 17 00:00:00 2001
From: David Florness <david@florness.com>
Date: Sat, 23 Jan 2021 18:19:50 -0500
Subject: [PATCH] Use .well-know/matrix/client to discover homeserver URL

https://matrix.org/docs/spec/client_server/r0.6.1#get-well-known-matrix-client
---
 matrix/auth.go | 70 +++++++++++++++++++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 24 deletions(-)

diff --git a/matrix/auth.go b/matrix/auth.go
index 731dba8..d17fb8a 100644
--- a/matrix/auth.go
+++ b/matrix/auth.go
@@ -6,8 +6,10 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"syscall"
 
 	"github.com/kyoh86/xdg"
+	"golang.org/x/crypto/ssh/terminal"
 	"maunium.net/go/mautrix"
 	"maunium.net/go/mautrix/id"
 )
@@ -56,48 +58,68 @@ func stripNewline(s string) string {
 }
 
 func inquireForAuthInfo() (authInfo *AuthInfo, err error) {
-	var (
-		password string
-		reader   = bufio.NewReader(os.Stdin)
-	)
+	reader := bufio.NewReader(os.Stdin)
 
+	fmt.Println(`============================== DISCLAIMER ==============================
+tallyard won't make any attempts to read your personal Matrix messages.
+It uses a Matrix filter that restricts messages it reads to only those
+with a type beginning with "xyz.tallyard.".  If you're skeptical, I
+encourage you to read the source code.
+========================================================================
+`)
+
+try:
 	authInfo = &AuthInfo{}
 
-	for authInfo.Homeserver == "" || authInfo.Homeserver == "\n" {
-		fmt.Print("enter homeserver: ")
-		authInfo.Homeserver, err = reader.ReadString('\n')
-		if err != nil {
-			return nil, fmt.Errorf("error reading homeserver: %s", err)
-		}
+	fmt.Print("Enter full Matrix username (@localpart:domain): ")
+	username, err := reader.ReadString('\n')
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error reading username: %s\n", err)
+		goto try
+	}
+	username = stripNewline(username)
+	localPart, serverName, err := id.UserID(username).Parse()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error parsing username: %s\n", err)
+		goto try
 	}
-	authInfo.Homeserver = stripNewline(authInfo.Homeserver)
+	authInfo.Username = localPart
 
-	for authInfo.Username == "" || authInfo.Username == "\n" {
-		fmt.Print("enter username: ")
-		authInfo.Username, err = reader.ReadString('\n')
+	wellKnownResp, err := mautrix.DiscoverClientAPI(serverName)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error discovering homeserver: %s\n", err)
+		goto try
+	}
+	if wellKnownResp == nil {
+		fmt.Println("You should contact your homeserver sysadmin to setup /.well-known/matrix/client")
+		fmt.Print("Enter homeserver: ")
+		homeserver, err := reader.ReadString('\n')
 		if err != nil {
-			return nil, fmt.Errorf("error reading username: %s", err)
+			fmt.Printf("Error reading homeserver: %s\n", err)
+			goto try
 		}
+		authInfo.Homeserver = stripNewline(homeserver)
+	} else {
+		authInfo.Homeserver = wellKnownResp.Homeserver.BaseURL
 	}
-	authInfo.Username = stripNewline(authInfo.Username)
 
-	for password == "" || password == "\n" {
-		fmt.Print("enter password: ")
-		password, err = reader.ReadString('\n')
-		if err != nil {
-			return nil, fmt.Errorf("error reading password: %s", err)
-		}
+	fmt.Print("Enter password: ")
+	rawPassword, err := terminal.ReadPassword(syscall.Stdin)
+	if err != nil {
+		fmt.Printf("Error reading password: %s\n", err)
+		goto try
 	}
-	password = stripNewline(password)
 
 	client, err := mautrix.NewClient(authInfo.Homeserver, "", "")
 	if err != nil {
 		return nil, fmt.Errorf("error creating mautrix client: %s", err)
 	}
+	// entering a password doesn't insert a newline
+	fmt.Printf("\nAttempting login...\n")
 	respLogin, err := client.Login(&mautrix.ReqLogin{
 		Type:             "m.login.password",
 		Identifier:       mautrix.UserIdentifier{Type: mautrix.IdentifierTypeUser, User: authInfo.Username},
-		Password:         password,
+		Password:         string(rawPassword),
 		StoreCredentials: true,
 	})
 	if err != nil {
-- 
2.38.4