commit 5140f1f399d22736db31c83c5d5330e87fad5472
Author: Alexander "PapaTutuWawa <papatutuwawa@polynom.me>
Date:   Wed Sep 15 15:25:23 2021 +0200

    Initial commit

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..648e8f1
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,8 @@
+module papatutuwawa/miniproxy
+
+go 1.16
+
+require (
+	github.com/BurntSushi/toml v0.4.1 // indirect
+	github.com/gorilla/mux v1.8.0 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..7937496
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,4 @@
+github.com/BurntSushi/toml v0.4.1 h1:GaI7EiDXDRfa8VshkTj7Fym7ha+y8/XxIgD2okUIjLw=
+github.com/BurntSushi/toml v0.4.1/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ=
+github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
+github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..5f4a383
--- /dev/null
+++ b/main.go
@@ -0,0 +1,102 @@
+package main
+
+import (
+	"net/http"
+	"net/url"
+	"log"
+	"os"
+	"strconv"
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"io"
+	"github.com/gorilla/mux"
+	"github.com/BurntSushi/toml"
+)
+
+type tomlConfig struct {
+	Port   int `toml:"port"`
+	Secret string `toml:"secret"`
+}
+
+func proxyRequest(w http.ResponseWriter, r *http.Request, secret []byte) {
+	vars := mux.Vars(r)
+	requestUrl, err := url.QueryUnescape(vars["url"])
+	if err != nil {
+		log.Printf("Failed to url decode url: %s", err)
+		return
+	}
+	macRaw, err := url.QueryUnescape(vars["hmac"])
+	if err != nil {
+		log.Printf("Failed to url decode HMAC: %s", err)
+		return
+	}
+
+	mac := hmac.New(sha256.New, secret)
+	mac.Write([]byte(requestUrl))
+	
+	expectedMac := mac.Sum(nil)
+	receivedMac, err := base64.StdEncoding.DecodeString(macRaw)
+	if err != nil {
+		log.Printf("Failed to decode HMAC: %s", err)
+		return
+	}
+
+	if !hmac.Equal(expectedMac, receivedMac) {
+		log.Printf("invalid-hmac:%s", r.RemoteAddr)
+		log.Printf("URL: '%s'", requestUrl)
+		http.Error(w, "Invalid HMAC", http.StatusUnauthorized)
+		return
+	}
+
+	client := &http.Client{}
+	resp, err := client.Get(requestUrl)
+	defer resp.Body.Close()
+
+	if err != nil {
+		log.Fatalf("Failed to perform GET: %s", err)
+	}
+
+	w.WriteHeader(resp.StatusCode)
+	io.Copy(w, resp.Body)
+}
+
+func makeProxyRequestHandler(secret []byte) http.HandlerFunc {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		proxyRequest(w, r, secret)
+	}
+
+	return http.HandlerFunc(fn)
+}
+
+func exists(path string) bool {
+	// Returns true if path exists. false otherwise
+	_, err := os.Stat(path)
+	return !os.IsNotExist(err)
+}
+
+func main() {
+	config := tomlConfig {
+		Port: 8080,
+	}
+
+	switch {
+	case exists("./config.toml"):
+		_, err := toml.DecodeFile("./config.toml", &config)
+		if err != nil {
+			log.Fatalf("Failed to read ./config.toml: %s", err)
+		}
+	case exists("/etc/miniproxy/config.toml"):
+		_, err := toml.DecodeFile("/etc/miniproxy/config.toml", &config)
+		if err != nil {
+			log.Fatalf("Failed to read /etc/miniproxy/config.toml: %s", err)
+		}
+	}
+
+	log.Printf("Running on :%d\n", config.Port)
+	
+	r := mux.NewRouter()
+	r.UseEncodedPath()
+	r.HandleFunc("/proxy/{hmac}/{url:.+}", makeProxyRequestHandler([]byte(config.Secret)))
+	log.Fatal(http.ListenAndServe(":" + strconv.Itoa(config.Port), r))
+}