From 631eeb081654439ba1af0966941df0eeee3c197f Mon Sep 17 00:00:00 2001 From: Jaseem Abid Date: Mon, 1 Apr 2024 19:06:40 +0100 Subject: [PATCH] Validate ntfy.sh URL before use I had a couple of panics due to invalid URL, which could have been an error message during startup. Example: Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: 2024/04/01 17:33:49 Received valid hook from 127.0.0.1:43130 Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: 2024/04/01 17:33:49 Processing alert: {firing map[alertname:Target Down instance:devkit.local:80 job:esphome severity:high] map[description:The target is not reachable summary:Target is down] 2024-> Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: 2024/04/01 17:33:49 http: panic serving 127.0.0.1:43130: runtime error: invalid memory address or nil pointer dereference Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: goroutine 1013 [running]: Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: net/http.(*conn).serve.func1() Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: /usr/lib/go/src/net/http/server.go:1868 +0xb9 Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: panic({0x840200?, 0xd01360?}) Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: /usr/lib/go/src/runtime/panic.go:920 +0x270 Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: main.WebhookHandler({0xa1d5f0, 0xc00038e000}, 0xc0001b0000) Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: /home/j/src/alertmanager-ntfy/main.go:45 +0xbf2 Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: net/http.HandlerFunc.ServeHTTP(0x10?, {0xa1d5f0?, 0xc00038e000?}, 0xc0004020ac?) Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: /usr/lib/go/src/net/http/server.go:2136 +0x29 Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: net/http.(*ServeMux).ServeHTTP(0x411f45?, {0xa1d5f0, 0xc00038e000}, 0xc0001b0000) Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: /usr/lib/go/src/net/http/server.go:2514 +0x142 Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: net/http.serverHandler.ServeHTTP({0xa1c0c0?}, {0xa1d5f0?, 0xc00038e000?}, 0x6?) Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: /usr/lib/go/src/net/http/server.go:2938 +0x8e Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: net/http.(*conn).serve(0xc0000d21b0, {0xa1e1f0, 0xc00027a600}) Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: /usr/lib/go/src/net/http/server.go:2009 +0x5f4 Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: created by net/http.(*Server).Serve in goroutine 1 Apr 01 17:33:49 nyx.jabid.in alertmanager-ntfy[878013]: /usr/lib/go/src/net/http/server.go:3086 +0x5cb --- main.go | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/main.go b/main.go index 688b3f8..cca2f54 100644 --- a/main.go +++ b/main.go @@ -5,6 +5,7 @@ import ( "fmt" "log" "net/http" + "net/url" "os" "strings" @@ -42,7 +43,7 @@ func WebhookHandler(w http.ResponseWriter, r *http.Request) { req, err := http.NewRequest("POST", os.Getenv("NTFY_TOPIC"), strings.NewReader(alert.Annotations["description"])) if err != nil { - log.Printf("Building request to %s failed: %s", req.RemoteAddr, err) + log.Printf("Building request failed: %s", err) w.WriteHeader(http.StatusBadRequest) return } @@ -90,6 +91,11 @@ func main() { } } + _, err := url.Parse(os.Getenv("NTFY_TOPIC")) + if err != nil { + log.Fatal("Environment variable NTFY_TOPIC is not a valid URL") + } + http.HandleFunc("/", WebhookHandler) var listenAddr = fmt.Sprintf("%v:%v", os.Getenv("HTTP_ADDRESS"), os.Getenv("HTTP_PORT")) log.Printf("Listening for HTTP requests (webhooks) on %v\n", listenAddr)