Big Change Update

uBlock0.chromium/lib/publicsuffixlist/publicsuffixlist.js

@@ -0,0 +1,637 @@
+/*******************************************************************************
+
+    publicsuffixlist.js - an efficient javascript implementation to deal with
+    Mozilla Foundation's Public Suffix List <http://publicsuffix.org/list/>
+
+    Copyright (C) 2013-present Raymond Hill
+
+    License: pick the one which suits you:
+      GPL v3 see <https://www.gnu.org/licenses/gpl.html>
+      APL v2 see <http://www.apache.org/licenses/LICENSE-2.0>
+
+*/
+
+/*! Home: https://github.com/gorhill/publicsuffixlist.js -- GPLv3 APLv2 */
+
+'use strict';
+
+/*******************************************************************************
+
+    Reference:
+    https://publicsuffix.org/list/
+
+    Excerpt:
+
+    > Algorithm
+    > 
+    > 1. Match domain against all rules and take note of the matching ones.
+    > 2. If no rules match, the prevailing rule is "*".
+    > 3. If more than one rule matches, the prevailing rule is the one which
+         is an exception rule.
+    > 4. If there is no matching exception rule, the prevailing rule is the
+         one with the most labels.
+    > 5. If the prevailing rule is a exception rule, modify it by removing
+         the leftmost label.
+    > 6. The public suffix is the set of labels from the domain which match
+         the labels of the prevailing rule, using the matching algorithm above.
+    > 7. The registered or registrable domain is the public suffix plus one
+         additional label.
+
+*/
+
+/******************************************************************************/
+
+export default (function() {
+// >>>>>>>> start of anonymous namespace
+
+/*******************************************************************************
+
+    Tree encoding in array buffer:
+    
+     Node:
+     +  u8: length of char data
+     +  u8: flags => bit 0: is_publicsuffix, bit 1: is_exception
+     + u16: length of array of children
+     + u32: char data or offset to char data
+     + u32: offset to array of children
+     = 12 bytes
+
+    More bits in flags could be used; for example:
+    - to distinguish private suffixes
+
+*/
+
+                                    // i32 /  i8
+const HOSTNAME_SLOT         = 0;    // jshint ignore:line
+const LABEL_INDICES_SLOT    = 256;  //  -- / 256 (256/2 => 128 labels max)
+const RULES_PTR_SLOT        = 100;  // 100 / 400 (400-256=144 => 144>128)
+const SUFFIX_NOT_FOUND_SLOT = 399;  //  -- / 399 (safe, see above)
+const CHARDATA_PTR_SLOT     = 101;  // 101 / 404
+const EMPTY_STRING          = '';
+const SELFIE_MAGIC          = 3;
+
+let wasmMemory;
+let pslBuffer32;
+let pslBuffer8;
+let pslByteLength = 0;
+let hostnameArg = EMPTY_STRING;
+
+/******************************************************************************/
+
+const fireChangedEvent = function() {
+    if ( typeof window !== 'object' ) { return; }
+    if ( window instanceof Object === false ) { return; }
+    if ( window.dispatchEvent instanceof Function === false ) { return; }
+    if ( window.CustomEvent instanceof Function === false ) { return; }
+    window.dispatchEvent(new CustomEvent('publicSuffixListChanged'));
+};
+
+/******************************************************************************/
+
+const allocateBuffers = function(byteLength) {
+    pslByteLength = byteLength + 3 & ~3;
+    if (
+        pslBuffer32 !== undefined &&
+        pslBuffer32.byteLength >= pslByteLength
+    ) {
+        return;
+    }
+    if ( wasmMemory !== undefined ) {
+        const newPageCount = pslByteLength + 0xFFFF >>> 16;
+        const curPageCount = wasmMemory.buffer.byteLength >>> 16;
+        const delta = newPageCount - curPageCount;
+        if ( delta > 0 ) {
+            wasmMemory.grow(delta);
+            pslBuffer32 = new Uint32Array(wasmMemory.buffer);
+            pslBuffer8 = new Uint8Array(wasmMemory.buffer);
+        }
+    } else {
+        pslBuffer8 = new Uint8Array(pslByteLength);
+        pslBuffer32 = new Uint32Array(pslBuffer8.buffer);
+    }
+    hostnameArg = EMPTY_STRING;
+    pslBuffer8[LABEL_INDICES_SLOT] = 0;
+};
+
+/******************************************************************************/
+
+// Parse and set a UTF-8 text-based suffix list. Format is same as found at:
+// http://publicsuffix.org/list/
+//
+// `toAscii` is a converter from unicode to punycode. Required since the
+// Public Suffix List contains unicode characters.
+// Suggestion: use <https://github.com/bestiejs/punycode.js>
+
+const parse = function(text, toAscii) {
+    // Use short property names for better minifying results
+    const rootRule = {
+        l: EMPTY_STRING,    // l => label
+        f: 0,               // f => flags
+        c: undefined        // c => children
+    };
+
+    // Tree building
+    {
+        const compareLabels = function(a, b) {
+            let n = a.length;
+            let d = n - b.length;
+            if ( d !== 0 ) { return d; }
+            for ( let i = 0; i < n; i++ ) {
+                d = a.charCodeAt(i) - b.charCodeAt(i);
+                if ( d !== 0 ) { return d; }
+            }
+            return 0;
+        };
+
+        const addToTree = function(rule, exception) {
+            let node = rootRule;
+            let end = rule.length;
+            while ( end > 0 ) {
+                const beg = rule.lastIndexOf('.', end - 1);
+                const label = rule.slice(beg + 1, end);
+                end = beg;
+
+                if ( Array.isArray(node.c) === false ) {
+                    const child = { l: label, f: 0, c: undefined };
+                    node.c = [ child ];
+                    node = child;
+                    continue;
+                }
+
+                let left = 0;
+                let right = node.c.length;
+                while ( left < right ) {
+                    const i = left + right >>> 1;
+                    const d = compareLabels(label, node.c[i].l);
+                    if ( d < 0 ) {
+                        right = i;
+                        if ( right === left ) {
+                            const child = {
+                                l: label,
+                                f: 0,
+                                c: undefined
+                            };
+                            node.c.splice(left, 0, child);
+                            node = child;
+                            break;
+                        }
+                        continue;
+                    }
+                    if ( d > 0 ) {
+                        left = i + 1;
+                        if ( left === right ) {
+                            const child = {
+                                l: label,
+                                f: 0,
+                                c: undefined
+                            };
+                            node.c.splice(right, 0, child);
+                            node = child;
+                            break;
+                        }
+                        continue;
+                    }
+                    /* d === 0 */
+                    node = node.c[i];
+                    break;
+                }
+            }
+            node.f |= 0b01;
+            if ( exception ) {
+                node.f |= 0b10;
+            }
+        };
+
+        // 2. If no rules match, the prevailing rule is "*".
+        addToTree('*', false);
+
+        const mustPunycode = /[^a-z0-9.-]/;
+        const textEnd = text.length;
+        let lineBeg = 0;
+
+        while ( lineBeg < textEnd ) {
+            let lineEnd = text.indexOf('\n', lineBeg);
+            if ( lineEnd === -1 ) {
+                lineEnd = text.indexOf('\r', lineBeg);
+                if ( lineEnd === -1 ) {
+                    lineEnd = textEnd;
+                }
+            }
+            let line = text.slice(lineBeg, lineEnd).trim();
+            lineBeg = lineEnd + 1;
+
+            // Ignore comments
+            const pos = line.indexOf('//');
+            if ( pos !== -1 ) {
+                line = line.slice(0, pos);
+            }
+
+            // Ignore surrounding whitespaces
+            line = line.trim();
+            if ( line.length === 0 ) { continue; }
+
+            const exception = line.charCodeAt(0) === 0x21 /* '!' */;
+            if ( exception ) {
+                line = line.slice(1);
+            }
+
+            if ( mustPunycode.test(line) ) {
+                line = toAscii(line.toLowerCase());
+            }
+
+            addToTree(line, exception);
+        }
+    }
+
+    {
+        const labelToOffsetMap = new Map();
+        const treeData = [];
+        const charData = [];
+
+        const allocate = function(n) {
+            const ibuf = treeData.length;
+            for ( let i = 0; i < n; i++ ) {
+                treeData.push(0);
+            }
+            return ibuf;
+        };
+
+        const storeNode = function(ibuf, node) {
+            const nChars = node.l.length;
+            const nChildren = node.c !== undefined
+                ? node.c.length
+                : 0;
+            treeData[ibuf+0] = nChildren << 16 | node.f << 8 | nChars;
+            // char data
+            if ( nChars <= 4 ) {
+                let v = 0;
+                if ( nChars > 0 ) {
+                    v |= node.l.charCodeAt(0);
+                    if ( nChars > 1 ) {
+                        v |= node.l.charCodeAt(1) << 8;
+                        if ( nChars > 2 ) {
+                            v |= node.l.charCodeAt(2) << 16;
+                            if ( nChars > 3 ) {
+                                v |= node.l.charCodeAt(3) << 24;
+                            }
+                        }
+                    }
+                }
+                treeData[ibuf+1] = v;
+            } else {
+                let offset = labelToOffsetMap.get(node.l);
+                if ( offset === undefined ) {
+                    offset = charData.length;
+                    for ( let i = 0; i < nChars; i++ ) {
+                        charData.push(node.l.charCodeAt(i));
+                    }
+                    labelToOffsetMap.set(node.l, offset);
+                }
+                treeData[ibuf+1] = offset;
+            }
+            // child nodes
+            if ( Array.isArray(node.c) === false ) {
+                treeData[ibuf+2] = 0;
+                return;
+            }
+            
+            const iarray = allocate(nChildren * 3);
+            treeData[ibuf+2] = iarray;
+            for ( let i = 0; i < nChildren; i++ ) {
+                storeNode(iarray + i * 3, node.c[i]);
+            }
+        };
+
+        // First 512 bytes are reserved for internal use
+        allocate(512 >> 2);
+
+        const iRootRule = allocate(3);
+        storeNode(iRootRule, rootRule);
+        treeData[RULES_PTR_SLOT] = iRootRule;
+
+        const iCharData = treeData.length << 2;
+        treeData[CHARDATA_PTR_SLOT] = iCharData;
+
+        const byteLength = (treeData.length << 2) + (charData.length + 3 & ~3);
+        allocateBuffers(byteLength);
+        pslBuffer32.set(treeData);
+        pslBuffer8.set(charData, treeData.length << 2);
+    }
+
+    fireChangedEvent();
+};
+
+/******************************************************************************/
+
+const setHostnameArg = function(hostname) {
+    const buf = pslBuffer8;
+    if ( hostname === hostnameArg ) { return buf[LABEL_INDICES_SLOT]; }
+    if ( hostname === null || hostname.length === 0 ) {
+        hostnameArg = EMPTY_STRING;
+        return (buf[LABEL_INDICES_SLOT] = 0);
+    }
+    hostname = hostname.toLowerCase();
+    hostnameArg = hostname;
+    let n = hostname.length;
+    if ( n > 255 ) { n = 255; }
+    buf[LABEL_INDICES_SLOT] = n;
+    let i = n;
+    let j = LABEL_INDICES_SLOT + 1;
+    while ( i-- ) {
+        const c = hostname.charCodeAt(i);
+        if ( c === 0x2E /* '.' */ ) {
+            buf[j+0] = i + 1;
+            buf[j+1] = i;
+            j += 2;
+        }
+        buf[i] = c;
+    }
+    buf[j] = 0;
+    return n;
+};
+
+/******************************************************************************/
+
+// Returns an offset to the start of the public suffix.
+//
+// WASM-able, because no information outside the buffer content is required.
+
+const getPublicSuffixPosJS = function() {
+    const buf8 = pslBuffer8;
+    const buf32 = pslBuffer32;
+    const iCharData = buf32[CHARDATA_PTR_SLOT];
+
+    let iNode = pslBuffer32[RULES_PTR_SLOT];
+    let cursorPos = -1;
+    let iLabel = LABEL_INDICES_SLOT;
+
+    // Label-lookup loop
+    for (;;) {
+        // Extract label indices
+        const labelBeg = buf8[iLabel+1];
+        const labelLen = buf8[iLabel+0] - labelBeg;
+        // Match-lookup loop: binary search
+        let r = buf32[iNode+0] >>> 16;
+        if ( r === 0 ) { break; }
+        const iCandidates = buf32[iNode+2];
+        let l = 0;
+        let iFound = 0;
+        while ( l < r ) {
+            const iCandidate = l + r >>> 1;
+            const iCandidateNode = iCandidates + iCandidate + (iCandidate << 1);
+            const candidateLen = buf32[iCandidateNode+0] & 0x000000FF;
+            let d = labelLen - candidateLen;
+            if ( d === 0 ) {
+                const iCandidateChar = candidateLen <= 4
+                    ? iCandidateNode + 1 << 2
+                    : iCharData + buf32[iCandidateNode+1];
+                for ( let i = 0; i < labelLen; i++ ) {
+                    d = buf8[labelBeg+i] - buf8[iCandidateChar+i];
+                    if ( d !== 0 ) { break; }
+                }
+            }
+            if ( d < 0 ) {
+                r = iCandidate;
+            } else if ( d > 0 ) {
+                l = iCandidate + 1;
+            } else /* if ( d === 0 ) */ {
+                iFound = iCandidateNode;
+                break;
+            }
+        }
+        // 2. If no rules match, the prevailing rule is "*".
+        if ( iFound === 0 ) {
+            if ( buf32[iCandidates + 1] !== 0x2A /* '*' */ ) { break; }
+            buf8[SUFFIX_NOT_FOUND_SLOT] = 1;
+            iFound = iCandidates;
+        }
+        iNode = iFound;
+        // 5. If the prevailing rule is a exception rule, modify it by
+        //    removing the leftmost label.
+        if ( (buf32[iNode+0] & 0x00000200) !== 0 ) {
+            if ( iLabel > LABEL_INDICES_SLOT ) {
+                return iLabel - 2;
+            }
+            break;
+        }
+        if ( (buf32[iNode+0] & 0x00000100) !== 0 ) {
+            cursorPos = iLabel;
+        }
+        if ( labelBeg === 0 ) { break; }
+        iLabel += 2;
+    }
+
+    return cursorPos;
+};
+
+let getPublicSuffixPosWASM;
+let getPublicSuffixPos = getPublicSuffixPosJS;
+
+/******************************************************************************/
+
+const getPublicSuffix = function(hostname) {
+    if ( pslBuffer32 === undefined ) { return EMPTY_STRING; }
+
+    const hostnameLen = setHostnameArg(hostname);
+    const buf8 = pslBuffer8;
+    if ( hostnameLen === 0 || buf8[0] === 0x2E /* '.' */ ) {
+        return EMPTY_STRING;
+    }
+
+    const cursorPos = getPublicSuffixPos();
+    if ( cursorPos === -1 ) {
+        return EMPTY_STRING;
+    }
+
+    const beg = buf8[cursorPos + 1];
+    return beg === 0 ? hostnameArg : hostnameArg.slice(beg);
+};
+
+/******************************************************************************/
+
+const getDomain = function(hostname) {
+    if ( pslBuffer32 === undefined ) { return EMPTY_STRING; }
+
+    const hostnameLen = setHostnameArg(hostname);
+    const buf8 = pslBuffer8;
+    if ( hostnameLen === 0 || buf8[0] === 0x2E /* '.' */ ) {
+        return EMPTY_STRING;
+    }
+
+    const cursorPos = getPublicSuffixPos();
+    if ( cursorPos === -1 || buf8[cursorPos + 1] === 0 ) {
+        return EMPTY_STRING;
+    }
+
+    // 7. The registered or registrable domain is the public suffix plus one
+    //    additional label.
+    const beg = buf8[cursorPos + 3];
+    return beg === 0 ? hostnameArg : hostnameArg.slice(beg);
+};
+
+/******************************************************************************/
+
+const suffixInPSL = function(hostname) {
+    if ( pslBuffer32 === undefined ) { return false; }
+
+    const hostnameLen = setHostnameArg(hostname);
+    const buf8 = pslBuffer8;
+    if ( hostnameLen === 0 || buf8[0] === 0x2E /* '.' */ ) {
+        return false;
+    }
+
+    buf8[SUFFIX_NOT_FOUND_SLOT] = 0;
+    const cursorPos = getPublicSuffixPos();
+    return cursorPos !== -1 &&
+           buf8[cursorPos + 1] === 0 &&
+           buf8[SUFFIX_NOT_FOUND_SLOT] !== 1;
+};
+
+/******************************************************************************/
+
+const toSelfie = function(encoder) {
+    if ( pslBuffer8 === undefined ) { return ''; }
+    if ( encoder instanceof Object ) {
+        const bufferStr = encoder.encode(pslBuffer8.buffer, pslByteLength);
+        return `${SELFIE_MAGIC}\t${bufferStr}`;
+    }
+    return {
+        magic: SELFIE_MAGIC,
+        buf32: pslBuffer32.subarray(0, pslByteLength >> 2),
+    };
+};
+
+const fromSelfie = function(selfie, decoder) {
+    let byteLength = 0;
+    if (
+        typeof selfie === 'string' &&
+        selfie.length !== 0 &&
+        decoder instanceof Object
+    ) {
+        const pos = selfie.indexOf('\t');
+        if ( pos === -1 || selfie.slice(0, pos) !== `${SELFIE_MAGIC}` ) {
+            return false;
+        }
+        const bufferStr = selfie.slice(pos + 1);
+        byteLength = decoder.decodeSize(bufferStr);
+        if ( byteLength === 0 ) { return false; }
+        allocateBuffers(byteLength);
+        decoder.decode(bufferStr, pslBuffer8.buffer);
+    } else if (
+        selfie instanceof Object &&
+        selfie.magic === SELFIE_MAGIC &&
+        selfie.buf32 instanceof Uint32Array
+    ) {
+        byteLength = selfie.buf32.length << 2;
+        allocateBuffers(byteLength);
+        pslBuffer32.set(selfie.buf32);
+    } else {
+        return false;
+    }
+
+    // Important!
+    hostnameArg = EMPTY_STRING;
+    pslBuffer8[LABEL_INDICES_SLOT] = 0;
+
+    fireChangedEvent();
+
+    return true;
+};
+
+/******************************************************************************/
+
+// The WASM module is entirely optional, the JS implementation will be
+// used should the WASM module be unavailable for whatever reason.
+
+const enableWASM = (( ) => {
+    let wasmPromise;
+
+    const getWasmInstance = async function(wasmModuleFetcher, path) {
+        if ( typeof WebAssembly !== 'object' ) { return false; }
+        // The wasm code will work only if CPU is natively little-endian,
+        // as we use native uint32 array in our js code.
+        const uint32s = new Uint32Array(1);
+        const uint8s = new Uint8Array(uint32s.buffer);
+        uint32s[0] = 1;
+        if ( uint8s[0] !== 1 ) { return false; }
+
+        try {
+            const module = await wasmModuleFetcher(`${path}publicsuffixlist`);
+            if (  module instanceof WebAssembly.Module === false ) {
+                return false;
+            }
+            const pageCount = pslBuffer8 !== undefined
+                ? pslBuffer8.byteLength + 0xFFFF >>> 16
+                : 1;
+            const memory = new WebAssembly.Memory({ initial: pageCount });
+            const instance = await WebAssembly.instantiate(module, {
+                imports: { memory }
+            });
+            if (  instance instanceof WebAssembly.Instance === false ) {
+                return false;
+            }
+            const curPageCount = memory.buffer.byteLength >>> 16;
+            const newPageCount = pslBuffer8 !== undefined
+                ? pslBuffer8.byteLength + 0xFFFF >>> 16
+                : 0;
+            if ( newPageCount > curPageCount ) {
+                memory.grow(newPageCount - curPageCount);
+            }
+            if ( pslBuffer32 !== undefined ) {
+                const buf8 = new Uint8Array(memory.buffer);
+                const buf32 = new Uint32Array(memory.buffer);
+                buf32.set(pslBuffer32);
+                pslBuffer8 = buf8;
+                pslBuffer32 = buf32;
+            }
+            wasmMemory = memory;
+            getPublicSuffixPosWASM = instance.exports.getPublicSuffixPos;
+            getPublicSuffixPos = getPublicSuffixPosWASM;
+            return true;
+        } catch(reason) {
+            console.info(reason);
+        }
+        return false;
+    };
+
+    return async function(wasmModuleFetcher, path) {
+        if ( getPublicSuffixPosWASM instanceof Function ) { return true; }
+        if ( wasmPromise instanceof Promise === false ) {
+            wasmPromise = getWasmInstance(wasmModuleFetcher, path);
+        }
+        return wasmPromise;
+    };
+})();
+
+const disableWASM = function() {
+    if ( getPublicSuffixPosWASM instanceof Function ) {
+        getPublicSuffixPos = getPublicSuffixPosJS;
+        getPublicSuffixPosWASM = undefined;
+    }
+    if ( wasmMemory === undefined ) { return; }
+    if ( pslBuffer32 !== undefined ) {
+        const buf8 = new Uint8Array(pslByteLength);
+        const buf32 = new Uint32Array(buf8.buffer);
+        buf32.set(pslBuffer32);
+        pslBuffer8 = buf8;
+        pslBuffer32 = buf32;
+    }
+    wasmMemory = undefined;
+};
+
+/******************************************************************************/
+
+return ({
+    version: '2.0',
+    parse,
+    getDomain,
+    suffixInPSL,
+    getPublicSuffix,
+    toSelfie, fromSelfie,
+    disableWASM, enableWASM,
+});
+
+/******************************************************************************/
+
+// <<<<<<<< end of anonymous namespace
+})();

uBlock0.chromium/lib/publicsuffixlist/wasm/README.md

@@ -0,0 +1,29 @@
+### For code reviewers
+
+All `wasm` files in that directory where created by compiling the
+corresponding `wat` file using the command (using
+`publicsuffixlist.wat`/`publicsuffixlist.wasm` as example):
+
+    wat2wasm publicsuffixlist.wat -o publicsuffixlist.wasm
+
+Assuming:
+
+- The command is executed from within the present directory.
+
+### `wat2wasm` tool
+
+The `wat2wasm` tool can be downloaded from an official WebAssembly project:
+<https://github.com/WebAssembly/wabt/releases>.
+
+### `wat2wasm` tool online
+
+You can also use the following online `wat2wasm` tool:
+<https://webassembly.github.io/wabt/demo/wat2wasm/>.
+
+Just paste the whole content of the `wat` file to compile into the WAT pane.
+Click "Download" button to retrieve the resulting `wasm` file.
+
+### See also
+
+For the curious, the following online tool allows you to find out the machine
+code as a result from the WASM code: https://mbebenita.github.io/WasmExplorer/

uBlock0.chromium/lib/publicsuffixlist/wasm/publicsuffixlist.wat

@@ -0,0 +1,322 @@
+;;
+;; uBlock Origin - a browser extension to block requests.
+;; Copyright (C) 2019-present Raymond Hill
+;;
+;; License: pick the one which suits you:
+;;   GPL v3 see <https://www.gnu.org/licenses/gpl.html>
+;;   APL v2 see <http://www.apache.org/licenses/LICENSE-2.0>
+;;
+;; Home: https://github.com/gorhill/publicsuffixlist.js
+;; File: publicsuffixlist.wat
+;;
+;; Description: WebAssembly implementation for core lookup method in
+;;              publicsuffixlist.js
+;;
+;; How to compile:
+;;
+;;     wat2wasm publicsuffixlist.wat -o publicsuffixlist.wasm
+;;
+;; The `wat2wasm` tool can be downloaded from an official WebAssembly
+;; project:
+;; https://github.com/WebAssembly/wabt/releases
+
+
+(module
+;;
+;; module start
+;;
+
+(memory (import "imports" "memory") 1)
+
+;;
+;; Tree encoding in array buffer:
+;;
+;;  Node:
+;;  +  u8: length of char data
+;;  +  u8: flags => bit 0: is_publicsuffix, bit 1: is_exception
+;;  + u16: length of array of children
+;;  + u32: char data or offset to char data
+;;  + u32: offset to array of children
+;;  = 12 bytes
+;;
+;;                                      // i32 /  i8
+;; const HOSTNAME_SLOT         = 0;     // jshint ignore:line
+;; const LABEL_INDICES_SLOT    = 256;   //  -- / 256
+;; const RULES_PTR_SLOT        = 100;   // 100 / 400
+;; const SUFFIX_NOT_FOUND_SLOT = 399;   //  -- / 399
+;; const CHARDATA_PTR_SLOT     = 101;   // 101 / 404
+;; const EMPTY_STRING          = '';
+;; const SELFIE_MAGIC          = 2;
+;;
+
+;;
+;; Public functions
+;;
+
+;;
+;; unsigned int getPublicSuffixPos()
+;;
+;; Returns an offset to the start of the public suffix.
+;;
+(func (export "getPublicSuffixPos")
+    (result i32)                ;; result = match index, -1 = miss
+    (local $iCharData i32)      ;; offset to start of character data
+    (local $iNode i32)          ;; offset to current node
+    (local $iLabel i32)         ;; offset to label indices
+    (local $cursorPos i32)      ;; position of cursor within hostname argument
+    (local $labelBeg i32)
+    (local $labelLen i32)
+    (local $nCandidates i32)
+    (local $iCandidates i32)
+    (local $iFound i32)
+    (local $l i32)
+    (local $r i32)
+    (local $d i32)
+    (local $iCandidate i32)
+    (local $iCandidateNode i32)
+    (local $candidateLen i32)
+    (local $iCandidateChar i32)
+    (local $_1 i32)
+    (local $_2 i32)
+    (local $_3 i32)
+    ;;
+    ;; const iCharData = buf32[CHARDATA_PTR_SLOT];
+    i32.const 404
+    i32.load
+    local.set $iCharData
+    ;; let iNode = pslBuffer32[RULES_PTR_SLOT];
+    i32.const 400
+    i32.load
+    i32.const 2
+    i32.shl
+    local.set $iNode
+    ;; let iLabel = LABEL_INDICES_SLOT;
+    i32.const 256
+    local.set $iLabel
+    ;; let cursorPos = -1;
+    i32.const -1
+    local.set $cursorPos
+    ;; label-lookup loop
+    ;; for (;;) {
+    block $labelLookupDone loop $labelLookup
+        ;; // Extract label indices
+        ;; const labelBeg = buf8[iLabel+1];
+        ;; const labelLen = buf8[iLabel+0] - labelBeg;
+        local.get $iLabel
+        i32.load8_u
+        local.get $iLabel
+        i32.load8_u offset=1
+        local.tee $labelBeg
+        i32.sub
+        local.set $labelLen
+        ;; // Match-lookup loop: binary search
+        ;; let r = buf32[iNode+0] >>> 16;
+        ;; if ( r === 0 ) { break; }
+        local.get $iNode
+        i32.load16_u offset=2
+        local.tee $r
+        i32.eqz
+        br_if $labelLookupDone
+        ;; const iCandidates = buf32[iNode+2];
+        local.get $iNode
+        i32.load offset=8
+        i32.const 2
+        i32.shl
+        local.set $iCandidates
+        ;; let l = 0;
+        ;; let iFound = 0;
+        i32.const 0
+        local.tee $l
+        local.set $iFound
+        ;; while ( l < r ) {
+        block $binarySearchDone loop $binarySearch
+            local.get $l
+            local.get $r
+            i32.ge_u
+            br_if $binarySearchDone
+            ;; const iCandidate = l + r >>> 1;
+            local.get $l
+            local.get $r
+            i32.add
+            i32.const 1
+            i32.shr_u
+            local.tee $iCandidate
+            ;; const iCandidateNode = iCandidates + iCandidate + (iCandidate << 1);
+            i32.const 2
+            i32.shl
+            local.tee $_1
+            local.get $_1
+            i32.const 1
+            i32.shl
+            i32.add
+            local.get $iCandidates
+            i32.add
+            local.tee $iCandidateNode
+            ;; const candidateLen = buf32[iCandidateNode+0] & 0x000000FF;
+            i32.load8_u
+            local.set $candidateLen
+            ;; let d = labelLen - candidateLen;
+            local.get $labelLen
+            local.get $candidateLen
+            i32.sub
+            local.tee $d
+            ;; if ( d === 0 ) {
+            i32.eqz
+            if
+                ;; const iCandidateChar = candidateLen <= 4
+                local.get $candidateLen
+                i32.const 4
+                i32.le_u
+                if
+                    ;; ? iCandidateNode + 1 << 2
+                    local.get $iCandidateNode
+                    i32.const 4
+                    i32.add
+                    local.set $iCandidateChar
+                else
+                    ;; : buf32[CHARDATA_PTR_SLOT] + buf32[iCandidateNode+1];
+                    local.get $iCharData
+                    local.get $iCandidateNode
+                    i32.load offset=4
+                    i32.add
+                    local.set $iCandidateChar
+                end
+                ;; for ( let i = 0; i < labelLen; i++ ) {
+                local.get $labelBeg
+                local.tee $_1
+                local.get $labelLen
+                i32.add
+                local.set $_3
+                local.get $iCandidateChar
+                local.set $_2
+                block $findDiffDone loop $findDiff
+                    ;; d = buf8[labelBeg+i] - buf8[iCandidateChar+i];
+                    ;; if ( d !== 0 ) { break; }
+                    local.get $_1
+                    i32.load8_u
+                    local.get $_2
+                    i32.load8_u
+                    i32.sub
+                    local.tee $d
+                    br_if $findDiffDone
+                    local.get $_1
+                    i32.const 1
+                    i32.add
+                    local.tee $_1
+                    local.get $_3
+                    i32.eq
+                    br_if $findDiffDone
+                    local.get $_2
+                    i32.const 1
+                    i32.add
+                    local.set $_2
+                    br $findDiff
+                ;; }
+                end end
+            ;; }
+            end
+            ;; if ( d < 0 ) {
+            ;;     r = iCandidate;
+            local.get $d
+            i32.const 0
+            i32.lt_s
+            if
+                local.get $iCandidate
+                local.set $r
+                br $binarySearch
+            end
+            ;; } else if ( d > 0 ) {
+            ;;     l = iCandidate + 1;
+            local.get $d
+            i32.const 0
+            i32.gt_s
+            if
+                local.get $iCandidate
+                i32.const 1
+                i32.add
+                local.set $l
+                br $binarySearch
+            end
+            ;; } else /* if ( d === 0 ) */ {
+            ;;     iFound = iCandidateNode;
+            ;;     break;
+            ;; }
+            local.get $iCandidateNode
+            local.set $iFound
+        end end
+        ;; }
+        ;; // 2. If no rules match, the prevailing rule is "*".
+        ;; if ( iFound === 0 ) {
+        ;;     if ( buf32[iCandidates + 1] !== 0x2A /* '*' */ ) { break; }
+        ;;     buf8[SUFFIX_NOT_FOUND_SLOT] = 1;
+        ;;     iFound = iCandidates;
+        ;; }
+        local.get $iFound
+        i32.eqz
+        if
+            local.get $iCandidates
+            i32.load offset=4
+            i32.const 0x2A
+            i32.ne
+            br_if $labelLookupDone
+            i32.const 399
+            i32.const 1
+            i32.store8
+            local.get $iCandidates
+            local.set $iFound
+        end
+        ;; iNode = iFound;
+        local.get $iFound
+        local.tee $iNode
+        ;; // 5. If the prevailing rule is a exception rule, modify it by
+        ;; //    removing the leftmost label.
+        ;; if ( (buf32[iNode+0] & 0x00000200) !== 0 ) {
+        ;;     if ( iLabel > LABEL_INDICES_SLOT ) {
+        ;;         return iLabel - 2;
+        ;;     }
+        ;;     break;
+        ;; }
+        i32.load8_u offset=1
+        local.tee $_1
+        i32.const 0x02
+        i32.and
+        if
+            local.get $iLabel
+            i32.const 256
+            i32.gt_u
+            if
+                local.get $iLabel
+                i32.const -2
+                i32.add
+                return
+            end
+            br $labelLookupDone
+        end
+        ;; if ( (buf32[iNode+0] & 0x00000100) !== 0 ) {
+        ;;     cursorPos = labelBeg;
+        ;; }
+        local.get $_1
+        i32.const 0x01
+        i32.and
+        if
+            local.get $iLabel
+            local.set $cursorPos
+        end
+        ;; if ( labelBeg === 0 ) { break; }
+        local.get $labelBeg
+        i32.eqz
+        br_if $labelLookupDone
+        ;; iLabel += 2;
+        local.get $iLabel
+        i32.const 2
+        i32.add
+        local.set $iLabel
+        br $labelLookup
+    end end
+    local.get $cursorPos
+)
+
+;;
+;; module end
+;;
+)