Implement draft/message-redaction (#2065)

* Makefile: Add dependencies between targets

* Implement draft/message-redaction for channels

Permission to use REDACT mirrors permission for 'HistServ DELETE'

* Error when the given targetmsg does not exist

* gofmt

* Add CanDelete enum type

* gofmt

* Add support for PMs

* Fix documentation of allow-individual-delete.

* Remove 'TODO: add configurable fallback'

slingamn says it's probably not desirable, and I'm on the fence.
Out of laziness, let's omit it for now, as it's not a regression
compared to '/msg HistServ DELETE'.

* Revert "Makefile: Add dependencies between targets"

This reverts commit 2182b1da69.

---------

Co-authored-by: Val Lorentz <progval+git+ergo@progval.net>

default.yaml

@@ -982,7 +982,8 @@ history:
 
     # options to control how messages are stored and deleted:
     retention:
-        # allow users to delete their own messages from history?
+        # allow users to delete their own messages from history,
+        # and channel operators to delete messages in their channel?
         allow-individual-delete: false
 
         # if persistent history is enabled, create additional index tables,

gencapdefs.py

@@ -87,6 +87,12 @@ CAPDEFS = [
         url="https://gist.github.com/DanielOaks/8126122f74b26012a3de37db80e4e0c6",
         standard="proposed IRCv3",
     ),
+    CapDef(
+        identifier="MessageRedaction",
+        name="draft/message-redaction",
+        url="https://github.com/progval/ircv3-specifications/blob/redaction/extensions/message-redaction.md",
+        standard="proposed IRCv3",
+    ),
     CapDef(
         identifier="MessageTags",
         name="message-tags",

irc/caps/defs.go

@@ -7,9 +7,9 @@ package caps
 
 const (
 	// number of recognized capabilities:
-	numCapabs = 32
+	numCapabs = 33
 	// length of the uint32 array that represents the bitset:
-	bitsetLen = 1
+	bitsetLen = 2
 )
 
 const (
@@ -57,6 +57,10 @@ const (
 	// https://gist.github.com/DanielOaks/8126122f74b26012a3de37db80e4e0c6
 	Languages Capability = iota
 
+	// MessageRedaction is the proposed IRCv3 capability named "draft/message-redaction":
+	// https://github.com/progval/ircv3-specifications/blob/redaction/extensions/message-redaction.md
+	MessageRedaction Capability = iota
+
 	// Multiline is the proposed IRCv3 capability named "draft/multiline":
 	// https://github.com/ircv3/ircv3-specifications/pull/398
 	Multiline Capability = iota
@@ -156,6 +160,7 @@ var (
 		"draft/chathistory",
 		"draft/event-playback",
 		"draft/languages",
+		"draft/message-redaction",
 		"draft/multiline",
 		"draft/persistence",
 		"draft/pre-away",

irc/commands.go

@@ -301,6 +301,10 @@ func init() {
 			usablePreReg: true,
 			minParams:    0,
 		},
+		"REDACT": {
+			handler:   redactHandler,
+			minParams: 2,
+		},
 		"REHASH": {
 			handler:   rehashHandler,
 			minParams: 0,

irc/handlers.go

@@ -2663,6 +2663,97 @@ fail:
 	return false
 }
 
+// REDACT <target> <targetmsgid> [:<reason>]
+func redactHandler(server *Server, client *Client, msg ircmsg.Message, rb *ResponseBuffer) bool {
+	target := msg.Params[0]
+	targetmsgid := msg.Params[1]
+	//clientOnlyTags := msg.ClientOnlyTags()
+	var reason string
+	if len(msg.Params) > 2 {
+		reason = msg.Params[2]
+	}
+	var members []*Client // members of a channel, or both parties of a PM
+	var canDelete CanDelete
+
+	msgid := utils.GenerateSecretToken()
+	time := time.Now().UTC().Round(0)
+	details := client.Details()
+	isBot := client.HasMode(modes.Bot)
+
+	if target[0] == '#' {
+		channel := server.channels.Get(target)
+		if channel == nil {
+			rb.Add(nil, server.name, ERR_NOSUCHCHANNEL, client.Nick(), utils.SafeErrorParam(target), client.t("No such channel"))
+			return false
+		}
+		members = channel.Members()
+		canDelete = deletionPolicy(server, client, target)
+	} else {
+		targetClient := server.clients.Get(target)
+		if targetClient == nil {
+			rb.Add(nil, server.name, ERR_NOSUCHNICK, client.Nick(), target, "No such nick")
+			return false
+		}
+		members = []*Client{client, targetClient}
+		canDelete = canDeleteSelf
+	}
+
+	if canDelete == canDeleteNone {
+		rb.Add(nil, server.name, "FAIL", "REDACT", "REDACT_FORBIDDEN", utils.SafeErrorParam(target), utils.SafeErrorParam(targetmsgid), client.t("You are not authorized to delete messages"))
+		return false
+	}
+	accountName := "*"
+	if canDelete == canDeleteSelf {
+		accountName = client.AccountName()
+		if accountName == "*" {
+			rb.Add(nil, server.name, "FAIL", "REDACT", "REDACT_FORBIDDEN", utils.SafeErrorParam(target), utils.SafeErrorParam(targetmsgid), client.t("You are not authorized to delete because you are logged out"))
+			return false
+		}
+	}
+
+	err := server.DeleteMessage(target, targetmsgid, accountName)
+	if err == errNoop {
+		rb.Add(nil, server.name, "FAIL", "REDACT", "UNKNOWN_MSGID", utils.SafeErrorParam(target), utils.SafeErrorParam(targetmsgid), client.t("This message does not exist or is too old"))
+		return false
+	} else if err != nil {
+		isOper := client.HasRoleCapabs("history")
+		if isOper {
+			rb.Add(nil, server.name, "FAIL", "REDACT", "REDACT_FORBIDDEN", utils.SafeErrorParam(target), utils.SafeErrorParam(targetmsgid), fmt.Sprintf(client.t("Error deleting message: %v"), err))
+		} else {
+			rb.Add(nil, server.name, "FAIL", "REDACT", "REDACT_FORBIDDEN", utils.SafeErrorParam(target), utils.SafeErrorParam(targetmsgid), client.t("Could not delete message"))
+		}
+		return false
+	}
+
+	if target[0] != '#' {
+		// If this is a PM, we just removed the message from the buffer of the other party;
+		// now we have to remove it from the buffer of the client who sent the REDACT command
+		err := server.DeleteMessage(client.Nick(), targetmsgid, accountName)
+
+		if err != nil {
+			client.server.logger.Error("internal", fmt.Sprintf("Private message %s is not deletable by %s from their own buffer's even though we just deleted it from %s's. This is a bug, please report it in details.", targetmsgid, client.Nick(), target), client.Nick())
+			isOper := client.HasRoleCapabs("history")
+			if isOper {
+				rb.Add(nil, server.name, "FAIL", "REDACT", "REDACT_FORBIDDEN", utils.SafeErrorParam(target), utils.SafeErrorParam(targetmsgid), fmt.Sprintf(client.t("Error deleting message: %v"), err))
+			} else {
+				rb.Add(nil, server.name, "FAIL", "REDACT", "REDACT_FORBIDDEN", utils.SafeErrorParam(target), utils.SafeErrorParam(targetmsgid), client.t("Error deleting message"))
+			}
+		}
+	}
+
+	for _, member := range members {
+		for _, session := range member.Sessions() {
+			if session.capabilities.Has(caps.MessageRedaction) {
+				session.sendFromClientInternal(false, time, msgid, details.nickMask, details.accountName, isBot, nil, "REDACT", target, targetmsgid, reason)
+			} else {
+				// If we wanted to send a fallback to clients which do not support
+				// draft/message-redaction, we would do it from here.
+			}
+		}
+	}
+	return false
+}
+
 func reportPersistenceStatus(client *Client, rb *ResponseBuffer, broadcast bool) {
 	settings := client.AccountSettings()
 	serverSetting := client.server.Config().Accounts.Multiclient.AlwaysOn

irc/help.go

@@ -435,6 +435,12 @@ Replies to a PING. Used to check link connectivity.`,
 		text: `PRIVMSG <target>{,<target>} <text to be sent>
 
 Sends the text to the given targets as a PRIVMSG.`,
+	},
+	"redact": {
+		text: `REDACT <target> <targetmsgid> [<reason>]
+
+Removes the message of the target msgid from the chat history of a channel
+or target user.`,
 	},
 	"relaymsg": {
 		text: `RELAYMSG <channel> <spoofed nick> :<message>

irc/histserv.go

@@ -15,6 +15,14 @@ import (
 	"github.com/ergochat/ergo/irc/utils"
 )
 
+type CanDelete uint
+
+const (
+	canDeleteAny  CanDelete = iota // User is allowed to delete any message (for a given channel/PM)
+	canDeleteSelf                  // User is allowed to delete their own messages (ditto)
+	canDeleteNone                  // User is not allowed to delete any message (ditto)
+)
+
 const (
 	histservHelp = `HistServ provides commands related to history.`
 )
@@ -92,33 +100,53 @@ func histservForgetHandler(service *ircService, server *Server, client *Client,
 	service.Notice(rb, fmt.Sprintf(client.t("Enqueued account %s for message deletion"), accountName))
 }
 
-func histservDeleteHandler(service *ircService, server *Server, client *Client, command string, params []string, rb *ResponseBuffer) {
-	target, msgid := params[0], params[1] // Fix #1881 2 params are required
-
-	// operators can delete; if individual delete is allowed, a chanop or
-	// the message author can delete
-	accountName := "*"
-	isChanop := false
+// Returns:
+//
+// 1. `canDeleteAny` if the client allowed to delete other users' messages from the target, ie.:
+//   - the client is a channel operator, or
+//   - the client is an operator with "history" capability
+//
+// 2. `canDeleteSelf` if the client is allowed to delete their own messages from the target
+// 3. `canDeleteNone` otherwise
+func deletionPolicy(server *Server, client *Client, target string) CanDelete {
 	isOper := client.HasRoleCapabs("history")
-	if !isOper {
+	if isOper {
+		return canDeleteAny
+	} else {
 		if server.Config().History.Retention.AllowIndividualDelete {
 			channel := server.channels.Get(target)
 			if channel != nil && channel.ClientIsAtLeast(client, modes.Operator) {
-				isChanop = true
+				return canDeleteAny
 			} else {
-				accountName = client.AccountName()
+				return canDeleteSelf
+			}
+		} else {
+			return canDeleteNone
 		}
 	}
-	}
-	if !isOper && !isChanop && accountName == "*" {
+}
+
+func histservDeleteHandler(service *ircService, server *Server, client *Client, command string, params []string, rb *ResponseBuffer) {
+	target, msgid := params[0], params[1] // Fix #1881 2 params are required
+
+	canDelete := deletionPolicy(server, client, target)
+	accountName := "*"
+	if canDelete == canDeleteNone {
 		service.Notice(rb, client.t("Insufficient privileges"))
 		return
+	} else if canDelete == canDeleteSelf {
+		accountName = client.AccountName()
+		if accountName == "*" {
+			service.Notice(rb, client.t("Insufficient privileges"))
+			return
+		}
 	}
 
 	err := server.DeleteMessage(target, msgid, accountName)
 	if err == nil {
 		service.Notice(rb, client.t("Successfully deleted message"))
 	} else {
+		isOper := client.HasRoleCapabs("history")
 		if isOper {
 			service.Notice(rb, fmt.Sprintf(client.t("Error deleting message: %v"), err))
 		} else {

traditional.yaml

@@ -954,7 +954,8 @@ history:
 
     # options to control how messages are stored and deleted:
     retention:
-        # allow users to delete their own messages from history?
+        # allow users to delete their own messages from history,
+        # and channel operators to delete messages in their channel?
         allow-individual-delete: false
 
         # if persistent history is enabled, create additional index tables,