@aikidosec/firewall
Version:
Zen by Aikido is an embedded Application Firewall that autonomously protects Node.js apps against common and critical attacks, provides rate limiting, detects malicious traffic (including bots), and more.
100 lines (99 loc) • 3.16 kB
JavaScript
"use strict";
const EventEmitter = require("node:events").EventEmitter;
const inherits = require("node:util").inherits;
const getLimit = require("../../../lib/utils/getLimit");
const StreamSearch = require("../../streamsearch/sbmh");
const B_DCRLF = Buffer.from("\r\n\r\n");
const RE_CRLF = /\r\n/g;
const RE_HDR = /^([^:]+):[ \t]?([\x00-\xFF]+)?$/; // eslint-disable-line no-control-regex
function HeaderParser(cfg) {
EventEmitter.call(this);
cfg = cfg || {};
const self = this;
this.nread = 0;
this.maxed = false;
this.npairs = 0;
this.maxHeaderPairs = getLimit(cfg, "maxHeaderPairs", 2000);
this.maxHeaderSize = getLimit(cfg, "maxHeaderSize", 80 * 1024);
this.buffer = "";
this.header = {};
this.finished = false;
this.ss = new StreamSearch(B_DCRLF);
this.ss.on("info", function (isMatch, data, start, end) {
if (data && !self.maxed) {
if (self.nread + end - start >= self.maxHeaderSize) {
end = self.maxHeaderSize - self.nread + start;
self.nread = self.maxHeaderSize;
self.maxed = true;
}
else {
self.nread += end - start;
}
self.buffer += data.toString("binary", start, end);
}
if (isMatch) {
self._finish();
}
});
}
inherits(HeaderParser, EventEmitter);
HeaderParser.prototype.push = function (data) {
const r = this.ss.push(data);
if (this.finished) {
return r;
}
};
HeaderParser.prototype.reset = function () {
this.finished = false;
this.buffer = "";
this.header = {};
this.ss.reset();
};
HeaderParser.prototype._finish = function () {
if (this.buffer) {
this._parseHeader();
}
this.ss.matches = this.ss.maxMatches;
const header = this.header;
this.header = {};
this.buffer = "";
this.finished = true;
this.nread = this.npairs = 0;
this.maxed = false;
this.emit("header", header);
};
HeaderParser.prototype._parseHeader = function () {
if (this.npairs === this.maxHeaderPairs) {
return;
}
const lines = this.buffer.split(RE_CRLF);
const len = lines.length;
let m, h;
for (var i = 0; i < len; ++i) {
// eslint-disable-line no-var
if (lines[i].length === 0) {
continue;
}
if (lines[i][0] === "\t" || lines[i][0] === " ") {
// folded header content
// RFC2822 says to just remove the CRLF and not the whitespace following
// it, so we follow the RFC and include the leading whitespace ...
if (h) {
this.header[h][this.header[h].length - 1] += lines[i];
continue;
}
}
const posColon = lines[i].indexOf(":");
if (posColon === -1 || posColon === 0) {
return;
}
m = RE_HDR.exec(lines[i]);
h = m[1].toLowerCase();
this.header[h] = this.header[h] || [];
this.header[h].push(m[2] || "");
if (++this.npairs === this.maxHeaderPairs) {
break;
}
}
};
module.exports = HeaderParser;