jetsamctl way.

LetMeBlock.plist

@@ -1 +1 @@
-{ Filter = { Executables = ( "mDNSResponder" ); }; }
+{ Filter = { Executables = ( "mDNSResponder", "mDNSResponderHelper" ); }; }

Makefile

@@ -1,4 +1,4 @@
-PACKAGE_VERSION = 0.0.4.4
+PACKAGE_VERSION = 0.0.5
 
 TARGET = iphone:latest:9.0
 

README.md

@@ -1,8 +1,8 @@
 # LetMeBlock
 Makes mDNSResponder care about `/etc/hosts` on iOS 12, and load **all** entries on iOS 9+
 
-In order to load all entries on iOS 9+, the memory limits defined in `Version4 > Daemon > Override > com.apple.mDNSResponder.reloaded` of the jetsam properties plist **must be increased**.
+In order to load all entries on iOS 9+, the memory limits defined in `Version4 > Daemon > Override > com.apple.mDNSResponder.reloaded` of the jetsam properties plist **must be increased**. This can be done either by manually editing the plist or using jetsamctl's API, see [here](https://github.com/conradev/jetsamctl).
 
 If in any cases the tweak does not seem to work, you either
 * Reinstall LetMeBlock from Cydia
-* Run the command `killall -9 mDNSResponder` as root
+* Run the command `killall -9 mDNSResponder; killall -9 mDNSResponderHelper` as root

Tweak.xm

@@ -1,23 +1,31 @@
 #import <substrate.h>
 
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/sysctl.h>
+#include <sys/kern_memorystatus.h>
+
 #define DEFAULT_HOSTS_PATH "/etc/hosts"
 #define NEW_HOSTS_PATH "/etc/hosts.lmb"
 
 unsigned int *_mDNS_StatusCallback_allocated = NULL;
 
+// Allow /etc/hosts to be read on iOS 12
 %hookf(bool, "_os_variant_has_internal_diagnostics", const char *subsystem) {
 	if (subsystem && strcmp(subsystem, "com.apple.mDNSResponder") == 0)
 		return 1;
 	return %orig;
 }
 
+// Reset the memory counter every time it is increased
 %hookf(void, "_mDNS_StatusCallback", void *arg1, int arg2) {
 	if (_mDNS_StatusCallback_allocated)
 		*_mDNS_StatusCallback_allocated = 0;
 	%orig;
 }
 
-// The new UHB will place all the blocked addresses to NEW_HOSTS_PATH so we won't mess up with the original file
+// Open UHB's hosts instead of /etc/hosts
+// This new UHB will place all the blocked addresses to NEW_HOSTS_PATH so we won't mess up with the original file
 // If in any cases NEW_HOSTS_PATH got corrupted, we fallback to the original one (DEFAULT_HOSTS_PATH)
 %hookf(int, "_open", const char *path, int oflag, ...) {
 	int result = 0;
@@ -54,5 +62,35 @@ hook:
 %ctor {
 	_mDNS_StatusCallback_allocated = (unsigned int *)MSFindSymbol(NULL, "_mDNS_StatusCallback.allocated");
 	HBLogDebug(@"Found _mDNS_StatusCallback_allocated: %d", _mDNS_StatusCallback_allocated != NULL);
-	%init;
+	if (_mDNS_StatusCallback_allocated) {
+		// mDNSResponder (_mDNSResponder)
+		%init;
+	} else {
+		// mDNSResponderHelper (root)
+		pid_t pid = 0;
+		int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_ALL, 0};
+        size_t size;
+        if (sysctl(mib, 4, NULL, &size, NULL, 0) == -1)
+            HBLogError(@"LetMeBlock-jetsamctl: error: %s", strerror(errno));
+        else {
+			struct kinfo_proc *processes = (struct kinfo_proc *)malloc(size);
+			if (processes == NULL)
+				HBLogError(@"LetMeBlock-jetsamctl: error: %s", strerror(errno));
+			else if (sysctl(mib, 4, processes, &size, NULL, 0) == -1)
+				HBLogError(@"LetMeBlock-jetsamctl: error: %s", strerror(errno));
+			else {
+				for (unsigned long i = 0; i < size / sizeof(struct kinfo_proc); i++) {
+					if (strcmp(processes[i].kp_proc.p_comm, "mDNSResponder") == 0) {
+						pid = processes[i].kp_proc.p_pid;
+						break;
+					}
+				}
+				free(processes);
+				if (pid == 0)
+					HBLogError(@"LetMeBlock-jetsamctl: error: %s", strerror(ESRCH));
+				else if (memorystatus_control(MEMORYSTATUS_CMD_SET_JETSAM_TASK_LIMIT, pid, 384, NULL, 0) == -1)
+					HBLogError(@"LetMeBlock-jetsamctl: error: %s", strerror(errno));
+			}
+		}
+	}
 }

control

@@ -1,6 +1,6 @@
 Package: com.ps.letmeblock
 Name: LetMeBlock
-Depends: mobilesubstrate, firmware (>= 9.0), com.bingner.plutil
+Depends: mobilesubstrate, firmware (>= 9.0)
 Version: 0.0.1
 Architecture: iphoneos-arm
 Description: Make mDNSResponder care more about /etc/hosts

layout/DEBIAN/extrainst_

@@ -12,4 +12,5 @@ if [[ $1 == install ]];then
     finish reboot
 elif [[ $1 == upgrade ]];then
 	killall -9 mDNSResponder || true
+	killall -9 mDNSResponderHelper || true
 fi

layout/DEBIAN/postrm

@@ -1,19 +1,5 @@
 #!/bin/sh
 
-model=$(uname -i)
-model=${model/AP/}
-
-jetsam_orig_plist="/System/Library/LaunchDaemons/com.apple.jetsamproperties.${model}.plist.bak"
-jetsam_plist="/System/Library/LaunchDaemons/com.apple.jetsamproperties.${model}.plist"
-
-if [[ ! -f "${jetsam_orig_plist}" ]];then
-    echo "Error: Couldn't find the original jetsam properties plist (${jetsam_orig_plist})"
-    exit 1
-fi
-
-mv "${jetsam_orig_plist}" "${jetsam_plist}"
-echo "Restored the backup file"
-
 function finish() {
 	f="${1}"
 	[[ -z "${f}" || -z "${CYDIA}" ]] && return
@@ -27,4 +13,5 @@ if [[ "$1" == "remove" || "$1" == "abort-install" ]];then
 		finish reboot
 	fi
 	killall -9 mDNSResponder || true
+	killall -9 mDNSResponderHelper || true
 fi