From d49a29a4015026a012a03a2ebb3f8f845decb2d4 Mon Sep 17 00:00:00 2001
From: Mike Crute <mike@crute.us>
Date: Sat, 19 Aug 2023 19:10:51 -0700
Subject: WIP upgrade

---
 TODO.txt                 |  4 ++++
 cmd/client/autoupdate.go | 28 ++++++++++++++++++++++++++++
 cmd/client/client.go     |  8 ++++++--
 3 files changed, 38 insertions(+), 2 deletions(-)
 create mode 100644 cmd/client/autoupdate.go

diff --git a/TODO.txt b/TODO.txt
index f0dba8d..e8b167f 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -1,3 +1,7 @@
 [ ] Add metrics
 [ ] Log sessions to DB table
 [ ] Email on new session (maybe?)
+[ ] Automatically upgrade client
+[ ] Server driven session max TTL
+[ ] Rate limit tokens
+[ ] Rate limit CA
diff --git a/cmd/client/autoupdate.go b/cmd/client/autoupdate.go
new file mode 100644
index 0000000..feb272e
--- /dev/null
+++ b/cmd/client/autoupdate.go
@@ -0,0 +1,28 @@
+package client
+
+import (
+	"context"
+	"log"
+	"os"
+)
+
+// TODO:
+// Check the Server header from the host and if the second part does not match
+// - Use HEAD, ignore 404
+// Download the latest client for this os/arch (remap GOARCH=amd64 to x86_64)
+// Re-execute the client in the same process so the latest client is used
+// Log some output to let the user know this happened
+// Verify SHA256 based on server ETag
+func upgradeAndRestartClient(ctx context.Context, version, host string) error {
+	// Download, chmod, verify, unlink original, rename old to new, exec new
+	exec, err := os.Executable()
+	if err != nil {
+		return err
+	}
+
+	// Refuse if any path segment starts with go-build.*
+
+	log.Printf("Executable is %s", exec)
+
+	return nil
+}
diff --git a/cmd/client/client.go b/cmd/client/client.go
index b72003d..afc7a1d 100644
--- a/cmd/client/client.go
+++ b/cmd/client/client.go
@@ -37,7 +37,7 @@ func NewClientCommand(appVersion string) *cobra.Command {
 		Run: func(c *cobra.Command, args []string) {
 			cfg := app.Config{}
 			cli.MustGetConfig(c, &cfg)
-			clientMain(cfg, args[0], args[1], args[2])
+			clientMain(cfg, appVersion, args[0], args[1], args[2])
 		},
 	}
 	cli.AddFlags(clientCmd, &app.Config{}, app.DefaultConfig, "client")
@@ -202,12 +202,16 @@ func fetchOauthToken(ctx context.Context, clientId, proxyHost string) (string, e
 	return tokenResponse.AccessToken, nil
 }
 
-func clientMain(cfg app.Config, host, port, username string) {
+func clientMain(cfg app.Config, appVersion, host, port, username string) {
 	log.SetOutput(os.Stderr)
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
+	if err := upgradeAndRestartClient(ctx, appVersion, cfg.ClientHost); err != nil {
+		log.Fatalf("Error attempting to upgrade client: %s", err)
+	}
+
 	agentConn, err := connectToAgent()
 	if err != nil {
 		log.Fatalf("Error connecting to agent, is it started?")
-- 
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