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Add support for invokedynamic string concatenation. #95

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RobertWesner wants to merge 1 commit into from
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Add support for invokedynamic string concatenation. #95

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48 changes: 36 additions & 12 deletions Agent/src/main/java/net/lenni0451/authhook/UrlRedirector.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.InvokeDynamicInsnNode;
import org.objectweb.asm.tree.LdcInsnNode;
import org.objectweb.asm.tree.MethodNode;

Expand Down Expand Up @@ -59,21 +60,33 @@ public byte[] transform(final ClassLoader loader, final String className, final
boolean modified = false;
for (MethodNode method : node.methods) {
for (AbstractInsnNode insn : method.instructions) {
String str = null;
if (insn instanceof LdcInsnNode && ((LdcInsnNode) insn).cst instanceof String) {
final LdcInsnNode ldc = (LdcInsnNode) insn;
String str = (String) ldc.cst;
for (String url : URLS) {
if (str.startsWith(url)) {
str = str.substring(url.length());
str = this.targetAddress + "/" + this.secretKey + "/" + Base64.getUrlEncoder().encodeToString(url.getBytes(StandardCharsets.UTF_8)) + str;
ldc.cst = str;

modified = true;
System.out.println("Redirected '" + url + "' in class '" + node.name + "' method '" + method.name + "'");
break;
}
str = (String) ((LdcInsnNode) insn).cst;
} else if (insn instanceof InvokeDynamicInsnNode) {
final InvokeDynamicInsnNode indy = (InvokeDynamicInsnNode) insn;

if (indy.bsm.getOwner().equals("java/lang/invoke/StringConcatFactory")
&& indy.bsm.getName().equals("makeConcatWithConstants")
&& indy.bsmArgs.length > 0
&& indy.bsmArgs[0] instanceof String) {
str = (String) indy.bsmArgs[0];
}
}

if (str == null) continue;

final String redirected = this.redirectUrl(str);
if (redirected == null) continue;

if (insn instanceof LdcInsnNode) {
((LdcInsnNode) insn).cst = redirected;
} else {
((InvokeDynamicInsnNode) insn).bsmArgs[0] = redirected;
}

modified = true;
System.out.println("Redirected URL in class '" + node.name + "' method '" + method.name + "'");
}
}
return modified ? this.write(node) : null;
Expand All @@ -95,4 +108,15 @@ private byte[] write(final ClassNode node) {
return writer.toByteArray();
}

private String redirectUrl(final String str) {
for (String url : URLS) {
if (str.startsWith(url)) {
return this.targetAddress + "/" + this.secretKey + "/"
+ Base64.getUrlEncoder().encodeToString(url.getBytes(StandardCharsets.UTF_8))
+ str.substring(url.length());
}
}
return null;
}

}