document conditional redirects

.gitignore

@@ -1,3 +1,2 @@
 redis
-sus
 .env

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.16
+FROM golang:1.18
 
 WORKDIR /go/src/app
 COPY . .

docker-compose.yml

@@ -6,10 +6,7 @@ services:
     ports: [ "8430:80" ]
     environment:
       - SECRET=${SECRET}
-      - MAX_AGE_MS=${MAX_AGE_MS}
-    restart: unless-stopped
   redis:
-    hostname: sus-redis
     image: redis:7
     volumes: [ "./redis:/data" ]
-    restart: unless-stopped
+    ports: [ "6379:6379" ]

main.go

@@ -25,6 +25,7 @@ import (
 	"net/http"
 	"os"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/go-redis/redis/v8"
@@ -33,19 +34,17 @@ import (
 )
 
 var client = redis.NewClient(&redis.Options{
-	Addr:     "sus-redis:6379",
+	Addr:     "redis:6379",
 	Password: "",
 	DB:       0,
 })
 
 var SECRET string
 var INDEX_GET_REDIRECT = "http://alv.cx"
-var MAX_AGE_MS int64 = 500
 
 func main() {
 	r := mux.NewRouter()
 	r.HandleFunc("/{shortlink}", shortlinkHandler)
-	r.HandleFunc("/{shortlink}/", shortlinkHandler)
 	r.HandleFunc("/", indexHandler)
 
 	listenAddress := "0.0.0.0:80"
@@ -62,14 +61,6 @@ func main() {
 		INDEX_GET_REDIRECT = p
 	}
 
-	if p, ok := os.LookupEnv("MAX_AGE_MS"); ok {
-		if v, err := strconv.ParseInt(p, 10, 64); err != nil {
-			fmt.Printf("Unable to parse environment variable MAX_AGE_MS: %v\n", p)
-		} else {
-			MAX_AGE_MS = v
-		}
-	}
-
 	log.Fatal(http.ListenAndServe(listenAddress, r))
 }
 
@@ -84,30 +75,27 @@ func indexHandler(w http.ResponseWriter, r *http.Request) {
 
 	command := r.PostForm.Get("Command")
 	shortlink := r.PostForm.Get("Shortlink")
-	value := r.PostForm.Get("Value")
-	req_timestamp := r.PostForm.Get("Timestamp")
-	req_timestamp_int, err := strconv.ParseInt(req_timestamp, 10, 64)
-	if err != nil {
-		w.WriteHeader(http.StatusBadRequest)
-		w.Write([]byte("Bad request"))
-		return
-	}
+	redirect := r.PostForm.Get("Redirect")
+	alt_redirect := r.PostForm.Get("AltRedirect")
+	alt_condition := r.PostForm.Get("AltCondition")
+	fmt.Printf("command: %v, shortlink: %v, redirect: %v, alt_redirect: %v, alt_condition: %v\n",
+		command,
+		shortlink,
+		redirect,
+		alt_redirect,
+		alt_condition,
+	)
 
-	cur_timestamp := time.Now().UnixNano()
-	if req_timestamp_int+MAX_AGE_MS*1000*1000 < cur_timestamp {
-		w.WriteHeader(http.StatusBadRequest)
-		w.Write([]byte("Bad request"))
-		return
-	}
+	formstring := command + ":" + shortlink + ":" + redirect + ":" + alt_condition + ":" + alt_redirect
 
-	fmt.Printf("req_timestamp: %v, command: %v, shortlink: %v, value: %v\n", req_timestamp, command, shortlink, value)
+	fmt.Println("formstring: " + formstring)
 
 	signature := r.Header.Get("Signature")
 	calculatedSignature := fmt.Sprintf(
 		"SUS-SIGNATURE-%v",
 		getSha256HMACSignature(
 			[]byte(SECRET),
-			req_timestamp+":"+command+":"+shortlink+":"+value,
+			command+":"+shortlink+":"+redirect+":"+alt_condition+":"+alt_redirect,
 		),
 	)
 
@@ -125,7 +113,21 @@ func indexHandler(w http.ResponseWriter, r *http.Request) {
 		ctx := context.Background()
 		_, err := client.Get(ctx, shortlink).Result()
 		if err == redis.Nil {
-			err = client.Set(ctx, shortlink, value, 0).Err()
+			err = client.Set(ctx, shortlink+":redirect", shortlink, 0).Err()
+			if err != nil {
+				fmt.Println(err)
+				w.WriteHeader(500)
+				w.Write([]byte("500 Internal Server Error"))
+				return
+			}
+			err = client.Set(ctx, shortlink+":altcondition", alt_condition, 0).Err()
+			if err != nil {
+				fmt.Println(err)
+				w.WriteHeader(500)
+				w.Write([]byte("500 Internal Server Error"))
+				return
+			}
+			err = client.Set(ctx, shortlink+":altredirect", alt_redirect, 0).Err()
 
 			if err != nil {
 				fmt.Println(err)
@@ -153,13 +155,16 @@ func indexHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if command == "delete" {
-		if value != "confirm" {
-			w.WriteHeader(400)
-			w.Write([]byte("400 Bad Request"))
-		}
-
 		ctx := context.Background()
-		if err := client.Del(ctx, shortlink).Err(); err != nil {
+		if err := client.Del(ctx, shortlink+":redirect").Err(); err != nil {
+			w.WriteHeader(500)
+			w.Write([]byte("500 Internal Server Error"))
+		}
+		if err := client.Del(ctx, shortlink+":altredirect").Err(); err != nil {
+			w.WriteHeader(500)
+			w.Write([]byte("500 Internal Server Error"))
+		}
+		if err := client.Del(ctx, shortlink+":altcondition").Err(); err != nil {
 			w.WriteHeader(500)
 			w.Write([]byte("500 Internal Server Error"))
 		}
@@ -177,13 +182,13 @@ func indexHandler(w http.ResponseWriter, r *http.Request) {
 
 		resp := ""
 		for _, key := range keys {
-			value, err = client.Get(ctx, key).Result()
+			shortlink, err = client.Get(ctx, key).Result()
 			if err == redis.Nil {
 				w.WriteHeader(500)
 				w.Write([]byte("500 Internal Server Error"))
 				return
 			}
-			resp += key + ":" + value + "\n"
+			resp += key + ":" + shortlink + "\n"
 		}
 
 		w.WriteHeader(200)
@@ -196,7 +201,9 @@ func shortlinkHandler(w http.ResponseWriter, r *http.Request) {
 	fmt.Println("shortlinkHandler called")
 	shortlink := string(mux.Vars(r)["shortlink"])
 	ctx := context.Background()
-	redirect, err := client.Get(ctx, shortlink).Result()
+	client.Incr(ctx, shortlink + ":hits")
+
+	redirect, err := client.Get(ctx, shortlink+":redirect").Result()
 	fmt.Printf("shortlink: %v, redirect: %v\n", shortlink, redirect)
 	if err == redis.Nil {
 		w.WriteHeader(404)
@@ -204,13 +211,67 @@ func shortlinkHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	} else if err != nil {
 		fmt.Println(err)
+		fmt.Println(0)
 		w.WriteHeader(500)
 		w.Write([]byte("500 Internal Server Error"))
 		return
 	}
 
+	altcondition, err := client.Get(ctx, shortlink+":altcondition").Result()
+	if err == redis.Nil {
 		http.Redirect(w, r, redirect, 302)
 		return
+	} else if err != nil {
+		fmt.Println(err)
+		fmt.Println(1)
+		w.WriteHeader(500)
+		w.Write([]byte("500 Internal Server Error"))
+		return
+	}
+
+	altredirect, err := client.Get(ctx, shortlink+":altredirect").Result()
+	if err == redis.Nil {
+		http.Redirect(w, r, redirect, 302)
+		return
+	} else if err != nil {
+		fmt.Println(err)
+		fmt.Println(2)
+		w.WriteHeader(500)
+		w.Write([]byte("500 Internal Server Error"))
+		return
+	}
+
+	altcondition_split := strings.Split(altcondition, ",")
+	ac_varname := altcondition_split[0]
+	ac_operator := altcondition_split[1]
+	ac_required_value, _ := strconv.Atoi(altcondition_split[2])
+
+	var ac_varval int
+
+	if ac_varname != "timestamp" {
+		ac_varvalstr, err := client.Get(ctx, shortlink+":"+ac_varname).Result()
+		if err == redis.Nil {
+			ac_varval = 0
+		} else if err != nil {
+			fmt.Println(err)
+			fmt.Println(3)
+			w.WriteHeader(500)
+			w.Write([]byte("500 Internal Server Error"))
+			return
+		} else {
+			ac_varval, _ = strconv.Atoi(ac_varvalstr)
+		}
+	} else {
+		ac_varval = int(time.Now().Unix())
+	}
+
+	if (ac_operator == "eq" && ac_varval == ac_required_value) ||
+		(ac_operator == "gt" && ac_varval > ac_required_value) ||
+		(ac_operator == "lt" && ac_varval < ac_required_value) {
+		http.Redirect(w, r, altredirect, 307)
+	} else {
+		http.Redirect(w, r, redirect, 307)
+	}
 }
 
 func getSha256HMACSignature(secret []byte, data string) string {

readme.md

@@ -7,11 +7,21 @@ sus URL shortener
 
 - creating a new shortlink at https://pls.cx/shortlink
 
-        susmng [-s pls.cx] create -l shortlink -v https://example.com
+        susmng [-s pls.cx] create -l shortlink -r https://example.com
+
+- creating a new shortlink at https://pls.cx/shortlink which redirects to https://example.com/a the first n times, https://example.com/b any other times
+
+        susmng [-s pls.cx] create -l shortlink -r https://example.com/a \
+                -c hits,gt,<n> -a https://example.com/b
+
+- creating a new shortlink at https://pls.cx/shortlink which redirects to https://example.com/before before unix timestamp n (seconds), https://example.com/after after that
+
+        susmng [-s pls.cx] create -l shortlink -r https://example.com/before \
+                -c timestamp,gt,<n> -a https://example.com/after
 
 - deleting the shortlink https://pls.cx/shortlink
 
-        susmng [-s pls.cx] delete -l shortlink -v confirm
+        susmng [-s pls.cx] delete -l shortlink
 
 - listing all shortlinks on the server pls.cx
 
@@ -33,14 +43,12 @@ flag is not provided.
 
         docker-compose up -d --build
 
-### server environment variables
+#### server environment variables
 
-| Variable             | Default         | Description                                                                            |
-|----------------------|-----------------|----------------------------------------------------------------------------------------|
-| `SECRET`             | N/A             | the secret used for signature verification                                             |
-| `LISTEN_ADDRESS`     | `0.0.0.0:80`    | the address the server is listening on                                                 |
-| `INDEX_GET_REDIRECT` | `http://alv.cx` | the URL the user should be redirected to if they try to access `/` on the server       |
-| `MAX_AGE_MS`         | 500             | how old a request can be (in milliseconds) before the server will refuse to process it |
+- `SECRET`---the secret used for signature verification
+- `LISTEN_ADDRESS`---the address the server is listening on (default is `0.0.0.0:80`)
+- `INDEX_GET_REDIRECT`---the URL the user should be redirected to if they try to access `/` on the
+   server (default is `http://alv.cx`)
 
 ### setting up susmng
 

susmng.py

@@ -8,7 +8,6 @@ import pathlib
 import os
 import json
 import sys
-import time
 
 
 def get_args():
@@ -19,8 +18,10 @@ def get_args():
     parser.add_argument('command')
     parser.add_argument('-s', '--server', default="")
     parser.add_argument('-l', '--shortlink', default="")
-    parser.add_argument('-v', '--value', default="")
-    parser.add_argument('-c', '--config', type=pathlib.Path, default=pathlib.Path(os.path.expanduser('~/.config/susmng/config.json')))
+    parser.add_argument('-r', '--redirect', default="")
+    parser.add_argument('-a', '--alt-redirect', default="")
+    parser.add_argument('-c', '--alt-condition', default="")
+    parser.add_argument('--config', type=pathlib.Path, default=pathlib.Path(os.path.expanduser('~/.config/susmng/config.json')))
     parser.add_argument('-H', '--http', action='store_true')
     return parser.parse_args()
 
@@ -49,37 +50,25 @@ def main(args):
 
     secret = config['secrets'][server]
 
-    if args.command == "delete" and args.value != "confirm":
-        print("--value not set to 'confirm'... delete operation may fail")
-
-    # accoring to python documentation (https://docs.python.org/3/library/time.html#time.time)
-    # this function does not explicitly have to use unix time, and implementation is dependent
-    # platform.
-    # most platforms (windows, unix) will probably give unix time though.
-    #
-    # the server side (main.go file) does explicitly use unix time (time.Now().UnixNano()) to get
-    # this number, but hopefully there should be no issues on most platforms.
-    timestamp = str(time.time_ns())
+    formstring = args.command+":"+args.shortlink+":"+args.redirect+":"+args.alt_condition+":"+args.alt_redirect
+    print(f"{formstring=}")
 
+    r = requests.post(f"{'http' if args.http else 'https'}://{server}",
             data = {
                 'Command': args.command,
                 'Shortlink': args.shortlink,
-        'Value': args.value,
-        'Timestamp': timestamp,
-        }
-
+                'Redirect': args.redirect,
+                'AltCondition': args.alt_condition,
+                'AltRedirect': args.alt_redirect,
+                },
             headers = {
                 'Signature': 'SUS-SIGNATURE-' + hmac.new(
                     secret.encode("UTF-8"),
-            (timestamp + ":" + args.command + ":" + args.shortlink + ":" + args.value).encode("UTF-8"),
+                    formstring.encode("UTF-8"),
                     hashlib.sha256
                     ).hexdigest()
                 }
-
-    print(f"{data=}")
-    print(f"{headers=}")
-
-    r = requests.post(f"{'http' if args.http else 'https'}://{server}", data=data, headers=headers)
+            )
     print(r, file=sys.stderr)
     print(r.content.decode().strip())
     return 0