Add command action to execute arbitrary logic

Signed-off-by: Knut Ahlers <knut@ahlers.me>

action_script.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"os"
+	"os/exec"
+
+	"github.com/go-irc/irc"
+	"github.com/pkg/errors"
+)
+
+func init() {
+	registerAction(func(c *irc.Client, m *irc.Message, ruleDef *rule, r *ruleAction) error {
+		if len(r.Command) == 0 {
+			return nil
+		}
+
+		ctx, cancel := context.WithTimeout(context.Background(), cfg.CommandTimeout)
+		defer cancel()
+
+		var (
+			stdin  = new(bytes.Buffer)
+			stdout = new(bytes.Buffer)
+		)
+
+		if err := json.NewEncoder(stdin).Encode(map[string]interface{}{
+			"badges":   ircHandler{}.ParseBadgeLevels(m),
+			"channel":  m.Params[0],
+			"message":  m.Trailing(),
+			"tags":     m.Tags,
+			"username": m.User,
+		}); err != nil {
+			return errors.Wrap(err, "encoding script input")
+		}
+
+		cmd := exec.CommandContext(ctx, r.Command[0], r.Command[1:]...)
+		cmd.Env = os.Environ()
+		cmd.Stderr = os.Stderr
+		cmd.Stdin = stdin
+		cmd.Stdout = stdout
+
+		if err := cmd.Run(); err != nil {
+			return errors.Wrap(err, "running command")
+		}
+
+		if stdout.Len() == 0 {
+			// Script was successful but did not yield actions
+			return nil
+		}
+
+		var (
+			actions []*ruleAction
+			decoder = json.NewDecoder(stdout)
+		)
+
+		decoder.DisallowUnknownFields()
+		if err := decoder.Decode(&actions); err != nil {
+			return errors.Wrap(err, "decoding actions output")
+		}
+
+		for _, action := range actions {
+			if err := triggerActions(c, m, ruleDef, action); err != nil {
+				return errors.Wrap(err, "execute returned action")
+			}
+		}
+
+		return nil
+	})
+}

config.go

@@ -177,12 +177,13 @@ func (r *rule) Matches(m *irc.Message, event *string) bool {
 }
 
 type ruleAction struct {
-	Ban           *string        `yaml:"ban"`
-	CounterStep   *int64         `yaml:"counter_step"`
-	Counter       *string        `yaml:"counter"`
-	DeleteMessage *bool          `yaml:"delete_message"`
-	Respond       *string        `yaml:"respond"`
-	Timeout       *time.Duration `yaml:"timeout"`
+	Ban           *string        `json:"ban" yaml:"ban"`
+	Command       []string       `json:"command" yaml:"command"`
+	CounterStep   *int64         `json:"counter_step" yaml:"counter_step"`
+	Counter       *string        `json:"counter" yaml:"counter"`
+	DeleteMessage *bool          `json:"delete_message" yaml:"delete_message"`
+	Respond       *string        `json:"respond" yaml:"respond"`
+	Timeout       *time.Duration `json:"timeout" yaml:"timeout"`
 }
 
 func loadConfig(filename string) error {

main.go

@@ -14,12 +14,13 @@ import (
 
 var (
 	cfg = struct {
-		Config         string `flag:"config,c" default:"./config.yaml" description:"Location of configuration file"`
-		LogLevel       string `flag:"log-level" default:"info" description:"Log level (debug, info, warn, error, fatal)"`
-		StorageFile    string `flag:"storage-file" default:"./storage.json.gz" description:"Where to store the data"`
-		TwitchClient   string `flag:"twitch-client" default:"" description:"Client ID to act as" validate:"nonzero"`
-		TwitchToken    string `flag:"twitch-token" default:"" description:"OAuth token valid for client"`
-		VersionAndExit bool   `flag:"version" default:"false" description:"Prints current version and exits"`
+		CommandTimeout time.Duration `flag:"command-timeout" default:"30s" description:"Timeout for command execution"`
+		Config         string        `flag:"config,c" default:"./config.yaml" description:"Location of configuration file"`
+		LogLevel       string        `flag:"log-level" default:"info" description:"Log level (debug, info, warn, error, fatal)"`
+		StorageFile    string        `flag:"storage-file" default:"./storage.json.gz" description:"Where to store the data"`
+		TwitchClient   string        `flag:"twitch-client" default:"" description:"Client ID to act as" validate:"nonzero"`
+		TwitchToken    string        `flag:"twitch-token" default:"" description:"OAuth token valid for client"`
+		VersionAndExit bool          `flag:"version" default:"false" description:"Prints current version and exits"`
 	}{}
 
 	config     *configFile

wiki/Home.md

@@ -19,6 +19,9 @@ rules: # See below for examples
     # Issue a ban on the user who wrote the chat-line
     - ban: "reason of ban"
 
+    # Command to execute for the chat message, must return an JSON encoded array of actions
+    - command: [/bin/bash, -c, "echo '[{\"respond\": \"Text\"}]'"]
+
     # Modify an internal counter value (does NOT send a chat line)
     - counter: "counterid" # String to identify the counter, applies templating
       counter_step: 1      # Integer, can be negative or positive, default: +1
@@ -81,6 +84,50 @@ Additionally there are some functions available in the templates:
 - `recentGame <username> [fallback]` - Returns the last played game name of the specified user (see shoutout example) or the `fallback` if the game could not be fetched. If no fallback was supplied the message will fail and not be sent.
 - `tag <tagname>` - Takes the message sent to the channel, returns the value of the tag specified
 
+## Command executions
+
+Your command will get a JSON object passed through `stdin` you can parse to gain details about the message. It is expected to yield an array of actions on `stdout` and exit with status `0`. If it does not the action will be marked failed. In case you need to output debug output you can use `stderr` which is directly piped to the bots `stderr`.
+
+This is an example input you might get on `stdin`:
+
+```json
+{
+  "badges": {
+    "glhf-pledge": 1,
+    "moderator": 1
+  },
+  "channel": "#tezrian",
+  "message": "!test",
+  "tags": {
+    "badge-info": "",
+    "badges": "moderator/1,glhf-pledge/1",
+    "client-nonce": "6801c82a341f728dbbaad87ef30eae49",
+    "color": "#A72920",
+    "display-name": "Luziferus",
+    "emotes": "",
+    "flags": "",
+    "id": "dca06466-3741-4b22-8339-4cb5b07a02cc",
+    "mod": "1",
+    "room-id": "485884564",
+    "subscriber": "0",
+    "tmi-sent-ts": "1610313040489",
+    "turbo": "0",
+    "user-id": "69699328",
+    "user-type": "mod"
+  },
+  "username": "luziferus"
+}
+```
+
+The example was dumped using this action:
+
+```yaml
+  - actions:
+    - command: [/usr/bin/bash, -c, "jq . >&2"]
+    match_channels: ['#tezrian']
+    match_message: '^!test'
+```
+
 ## Rule examples
 
 ### Game death counter with dynamic name