Add experimental support for HTTP/3 (#8)

* Wait for service in integration tests instead of watching for a string

* Add http3 experimental support

README.md

@@ -7,18 +7,19 @@
 [![License Apache 2.0](https://img.shields.io/badge/license-Apache%202.0-blue.svg)](./LICENSE)
 
 - [What is my IP address](#what-is-my-ip-address)
-  - [Features](#features)
-  - [Endpoints](#endpoints)
-  - [Build](#build)
-  - [Usage](#usage)
-  - [Examples](#examples)
-    - [Run a default TCP server](#run-a-default-tcp-server)
-    - [Run a TLS (HTTP/2) server only](#run-a-tls-http2-server-only)
-    - [Run a default TCP server with a custom template and trust a pair of custom headers set by an upstream proxy](#run-a-default-tcp-server-with-a-custom-template-and-trust-a-pair-of-custom-headers-set-by-an-upstream-proxy)
-  - [Download](#download)
-  - [Docker](#docker)
-    - [Run a container locally using test databases](#run-a-container-locally-using-test-databases)
-    - [From Docker Hub](#from-docker-hub)
+    - [Features](#features)
+    - [Endpoints](#endpoints)
+    - [Build](#build)
+    - [Usage](#usage)
+    - [Examples](#examples)
+        - [Run a default TCP server](#run-a-default-tcp-server)
+        - [Run a TLS (HTTP/2) server only](#run-a-tls-http2-server-only)
+        - [Run an HTTP/3 server](#run-an-http3-server)
+        - [Run a default TCP server with a custom template and trust a pair of custom headers set by an upstream proxy](#run-a-default-tcp-server-with-a-custom-template-and-trust-a-pair-of-custom-headers-set-by-an-upstream-proxy)
+    - [Download](#download)
+    - [Docker](#docker)
+        - [Run a container locally using test databases](#run-a-container-locally-using-test-databases)
+        - [From Docker Hub](#from-docker-hub)
 
 Just another "what is my IP address" service, including geolocation and headers information, written in go with high performance in mind, it uses [gin](https://github.com/gin-gonic/gin) which uses [httprouter](https://github.com/julienschmidt/httprouter) a lightweight high performance HTTP multiplexer.
 
@@ -37,6 +38,7 @@ curl -6 ifconfig.es
 ## Features
 
 - TLS and HTTP/2.
+- Experimental support to HTTP/3. HTTP/3 requires a TLS server running (`-tls-bind`), as HTTP/3 starts as a TLS connection that then gets upgraded to UDP. The UDP port is the same as the one used for the TLS server.
 - Can run behind a proxy by trusting a custom header (usually `X-Real-IP`) to figure out the source IP address. It also supports a custom header to resolve the client port, if the proxy can only add a header for the IP (for example a fixed header from CDNs) the client port is shown as unknown.
 - IPv4 and IPv6.
 - Geolocation info including ASN. This feature is possible thanks to [maxmind](https://dev.maxmind.com/geoip/geolite2-free-geolocation-data?lang=en) GeoLite2 databases. In order to use these databases, a license key is needed. Please visit Maxmind site for further instructions and get a free license.
@@ -67,7 +69,7 @@ curl -6 ifconfig.es
 
 ## Build
 
-Golang >= 1.17 is required. Previous versions may work.
+Golang >= 1.19 is required.
 
 `make build`
 
@@ -77,6 +79,8 @@ Golang >= 1.17 is required. Previous versions may work.
 Usage of whatismyip:
   -bind string
         Listening address (see https://pkg.go.dev/net?#Listen) (default ":8080")
+  -enable-http3
+        Enable HTTP/3 protocol. HTTP/3 requires --tls-bind set, as HTTP/3 starts as a TLS connection that then gets upgraded to UDP. The UDP port is the same as the one used for the TLS server.
   -enable-secure-headers
         Add sane security-related headers to every response
   -geoip2-asn string
@@ -114,6 +118,13 @@ Usage of whatismyip:
              -bind "" -tls-bind :8081 -tls-crt ./test/server.pem -tls-key ./test/server.key
 ```
 
+### Run an HTTP/3 server
+
+```bash
+./whatismyip -geoip2-city ./test/GeoIP2-City-Test.mmdb -geoip2-asn ./test/GeoLite2-ASN-Test.mmdb \
+             -bind "" -tls-bind :8081 -tls-crt ./test/server.pem -tls-key ./test/server.key -enable-http3
+```
+
 ### Run a default TCP server with a custom template and trust a pair of custom headers set by an upstream proxy
 
 ```bash
@@ -127,7 +138,7 @@ Download latest version from https://github.com/dcarrillo/whatismyip/releases
 
 ## Docker
 
-An ultra-light (~10MB) image is available at [docker hub](https://hub.docker.com/r/dcarrillo/whatismyip).
+An ultra-light (~12MB) image is available at [docker hub](https://hub.docker.com/r/dcarrillo/whatismyip).
 
 ### Run a container locally using test databases