redact: Initial commit

files/redact.c

@@ -0,0 +1,268 @@
+/*
+** Copyright (C) 2023 Valentin Lorentz
+** License: GPLv3 https://www.gnu.org/licenses/gpl-3.0.html
+*/
+
+/*** <<<MODULE MANAGER START>>>
+module
+{
+		documentation "Implements the draft IRCv3 message-redaction specification https://github.com/ircv3/ircv3-specifications/pull/524"
+		troubleshooting "In case of problems, contact val on irc.unrealircd.org.";
+		min-unrealircd-version "6.*";
+		post-install-text {
+				"The module is installed. Now all you need to do is add a loadmodule line:";
+				"loadmodule \"third/redact\";";
+  				"And /REHASH the IRCd.";
+				"The module may be additionaly configured to change the defaults.";
+				"See documentation for help.";
+				"Please note that the implemented feature is still \"Work In Progress\".";
+		}
+}
+*** <<<MODULE MANAGER END>>>
+*/
+
+#include "unrealircd.h"
+
+
+ModuleHeader MOD_HEADER = {
+	"third/redact",
+	"6.0",
+	"draft/message-redaction cap",
+	"val",
+	"unrealircd-6"
+};
+
+/* Forward declarations */
+CMD_FUNC(cmd_redact);
+
+/* Global variables */
+long CAP_MESSAGE_REDACTION = 0L;
+bool sender_can_redact = 0;
+char *chan_access_pattern = "";
+
+
+int redact_config_run(ConfigFile *cf, ConfigEntry *ce, int type) {
+	int errors = 0;
+	ConfigEntry *cep, *cep2;
+
+	if (type != CONFIG_SET)
+		return 0;
+
+	if (!ce || !ce->name || strcmp(ce->name, "redacters"))
+		return 0;
+
+	bool owners_can_redact = 0;
+	bool admins_can_redact = 0;
+	bool ops_can_redact = 0;
+	bool halfops_can_redact = 0;
+
+	for (cep = ce->items; cep; cep = cep->next)
+	{
+		if (!cep->name)
+		{
+			config_error("%s:%i: blank set::redacters item",
+				cep->file->filename, cep->line_number);
+			errors++;
+			continue;
+		}
+		else if (!strcmp(cep->name, "owner"))
+			owners_can_redact = 1;
+		else if (!strcmp(cep->name, "admin"))
+			admins_can_redact = 1;
+		else if (!strcmp(cep->name, "op"))
+			ops_can_redact = 1;
+		else if (!strcmp(cep->name, "halfop"))
+			halfops_can_redact = 1;
+		else if (!strcmp(cep->name, "sender"))
+			sender_can_redact = 1;
+		else {
+			/* Should have been caught in redact_config_test */
+			continue;
+		}
+	}
+
+	if (halfops_can_redact)
+		chan_access_pattern = "hoaq";
+	else if (ops_can_redact)
+		chan_access_pattern = "oaq";
+	else if (admins_can_redact)
+		chan_access_pattern = "aq";
+	else if (owners_can_redact)
+		chan_access_pattern = "q";
+	else
+		chan_access_pattern = "";
+
+	return 1;
+}
+
+int redact_config_test(ConfigFile *cf, ConfigEntry *ce, int type, int *errs) {
+	int errors = 0;
+	ConfigEntry *cep, *cep2;
+
+	if (type != CONFIG_SET)
+		return 0;
+
+	if (!ce || !ce->name || strcmp(ce->name, "redacters"))
+		return 0;
+
+	for (cep = ce->items; cep; cep = cep->next)
+	{
+		if (!cep->name)
+		{
+			config_error("%s:%i: blank set::redacters item",
+				cep->file->filename, cep->line_number);
+			errors++;
+			continue;
+		}
+		else if (!strcmp(cep->name, "owner") && !strcmp(cep->name, "admin") && !strcmp(cep->name, "op") && !strcmp(cep->name, "halfop") && !strcmp(cep->name, "sender")) {
+			config_error("%s:%i: invalid set::redacters item: %s",
+				cep->file->filename, cep->line_number, cep->name);
+			errors++;
+			continue;
+		}
+	}
+
+	*errs = errors;
+	return errors ? -1 : 1;
+}
+
+MOD_INIT()
+{
+	ClientCapabilityInfo c;
+
+	/* Will be set when reading the config */
+	chan_access_pattern = "";
+	sender_can_redact = 0;
+
+	CommandAdd(modinfo->handle, "REDACT", cmd_redact, MAXPARA, CMD_USER|CMD_SERVER);
+	HookAdd(modinfo->handle, HOOKTYPE_CONFIGRUN, 0, redact_config_run);
+
+	memset(&c, 0, sizeof(c));
+	c.name = "draft/message-redaction";
+	ClientCapabilityAdd(modinfo->handle, &c, &CAP_MESSAGE_REDACTION);
+	return MOD_SUCCESS;
+}
+
+MOD_LOAD()
+{
+	HookAdd(modinfo->handle, HOOKTYPE_CONFIGRUN, 0, redact_config_run);
+	return MOD_SUCCESS;
+}
+
+MOD_TEST()
+{
+	HookAdd(modinfo->handle, HOOKTYPE_CONFIGTEST, 0, redact_config_test);
+	return MOD_SUCCESS;
+}
+
+MOD_UNLOAD()
+{
+	return MOD_SUCCESS;
+}
+
+CMD_FUNC(cmd_redact)
+{
+	HistoryFilter *filter = NULL;
+	HistoryResult *r = NULL;
+	Channel *channel;
+	char *account;
+	char *error;
+	int deleted, rejected_deletes;
+
+	if ((parc < 2) || BadPtr(parv[1]))
+	{
+		sendnumeric(client, ERR_NEEDMOREPARAMS, "REDACT");
+		return;
+	}
+
+	channel = find_channel(parv[1]);
+	if (!channel)
+	{
+		sendto_one(client, NULL, ":%s FAIL REDACT INVALID_TARGET %s :Chat history is not enabled in PM",
+			me.name, parv[1]);
+		return;
+	}
+
+	int is_oper = ValidatePermissionsForPath("chat:redact",client,NULL,NULL,NULL);
+	bool check_sender = 0;
+
+	if (MyUser(client) && !is_oper && (BadPtr(chan_access_pattern) || !check_channel_access(client, channel, chan_access_pattern)))
+	{
+		if (sender_can_redact)
+			/* Provisionally allow the command, until we retrieved the message
+			 * they are trying to delete (because we need to check they are its
+			 * sender */
+			check_sender = 1;
+		else {
+			error = "sender can't redact, and neither oper nor chanop";
+			goto unauthorized;
+		}
+	}
+
+
+	filter = safe_alloc(sizeof(HistoryFilter));
+	filter->cmd = HFC_AROUND;
+	filter->msgid_a = strdup(parv[2]);
+	filter->limit = 1;
+
+	if (check_sender) {
+		if (IsLoggedIn(client))
+			filter->account = strdup(client->user->account);
+		else {
+			error = "neither oper/chanop nor logged in";
+			goto unauthorized;
+		}
+	}
+
+	deleted = history_delete(channel->name, filter, &rejected_deletes);
+
+	if (deleted > 1) {
+		sendto_one(client, NULL, ":%s FAIL REDACT UNKNOWN_ERROR %s :history_delete found more than one result",
+			me.name, parv[1]);
+		goto end;
+	}
+	else if (rejected_deletes > 1) {
+		sendto_one(client, NULL, ":%s FAIL REDACT UNKNOWN_ERROR %s :history_delete rejected more than one result",
+			me.name, parv[1]);
+		goto end;
+	}
+	else if (deleted && rejected_deletes) {
+		sendto_one(client, NULL, ":%s FAIL REDACT UNKNOWN_ERROR %s %s :history_delete both deleted and rejected",
+			me.name, parv[1], parv[2]);
+		goto end;
+	}
+	else if (rejected_deletes) {
+		error = "not sender";
+		goto unauthorized;
+	}
+	else if (!deleted) {
+		sendto_one(client, NULL, ":%s FAIL REDACT UNKNOWN_MSGID %s %s :This message does not exist or is too old",
+			me.name, parv[1], parv[2]);
+		goto end;
+	}
+
+	if (parc >= 3) {
+		/* Has a reason */
+		sendto_channel(channel, client, /* skip */ NULL, /* member_modes */ NULL,
+				   CAP_MESSAGE_REDACTION, SEND_ALL, /* mtags */ NULL,
+				   ":%s REDACT %s %s :%s",
+				   client->name, parv[1], parv[2], parv[3]);
+	}
+	else {
+		sendto_channel(channel, client, /* skip */ NULL, /* member_modes */ NULL,
+				   CAP_MESSAGE_REDACTION, SEND_ALL, /* mtags */ NULL,
+				   ":%s REDACT %s %s",
+				   client->name, parv[1], parv[2]);
+	}
+
+	goto end;
+
+unauthorized:
+	sendto_one(client, NULL, ":%s FAIL REDACT REDACT_FORBIDDEN %s %s :Your are not authorized to redact messages in %s: %s",
+		me.name, parv[1], parv[2], parv[1], error);
+end:
+	if (filter)
+		free_history_filter(filter);
+	if (r)
+		free_history_result(r);
+}