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Always allow requests with IP-address as host in checkHost() #1007

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merged 3 commits into from
Jul 27, 2017
Merged

Always allow requests with IP-address as host in checkHost() #1007

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d3fc704
Always allow requests with IP-address as host in checkHost()
usefulthink Jul 24, 2017
077337b
use 'ip'-module to handle ip-address validation.
usefulthink Jul 27, 2017
79219db
Merge branch 'master' into check-hosts-allow-ips
shellscape Jul 27, 2017
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3 changes: 3 additions & 0 deletions lib/Server.js
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Original file line number Diff line number Diff line change
Expand Up @@ -444,6 +444,9 @@ Server.prototype.checkHost = function(headers) {
// always allow localhost host, for convience
if(hostname === "127.0.0.1" || hostname === "localhost") return true;

// always allow requests with explicit IP-address
if(/^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.|$)){4}$/.test(hostname)) return true;
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Should we add a few more testcases, for both the valid and invalid IP cases?

Also, I wonder if a simplified regex that just checked that each octet was numeric would be simpler to read/faster/still as secure? RFC3696 section 2 says that top level domain names aren't allowed to be all-numeric, so eg 999.999.999.999 still won't be treated as a domain, so can't be used for DNS rebinding.

For example:

// Requests to explicit IP-addresses can't be exploited by DNS rebinding.
// For simplicity the regex matches numeric ranges that aren't valid IPs, but
// this is still secure since top level domain names can never be all-numeric:
// https://tools.ietf.org/html/rfc3696#section-2
if(/^([0-9]{1,3}(\.|$)){4}$/.test(hostname)) return true;

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I like the simplicity and probably would want to do that. We don't validate other aspects of IP adress as well (reserved, multicast, etc) and I can't think of a way to have an invalid or unrouteable IP-address in the browser anyway.

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I'd like to see https://www.npmjs.com/package/ip and ip.isV4Format used here, rather than a regex.

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I thought about that as well, but didn't want to introduce any new dependencies for something that could be put in a simple (ok, thats arguable) regex. Is there any policy regarding adding dependencies?

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If the dependencies were being packaged for a production environment, I'd agree with you. Since this is strictly a development tool, tried and true dependencies to perform utility functions are acceptable. You'll see that pattern throughout the commit history. (for example; loglevel over a custom implementation).


// allow if hostname is in allowedHosts
if(this.allowedHosts && this.allowedHosts.length) {
for(let hostIdx = 0; hostIdx < this.allowedHosts.length; hostIdx++) {
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11 changes: 11 additions & 0 deletions test/Validation.test.js
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Expand Up @@ -111,6 +111,17 @@ describe("Validation", function() {
}
});

it("should allow access for every requests using an IP", function() {
const options = {};
const headers = {
host: "192.168.1.123"
};
const server = new Server(compiler, options);
if(!server.checkHost(headers)) {
throw new Error("Validation didn't fail");
}
});

it("should not allow hostnames that don't match options.public", function() {
const options = {
public: "test.host:80",
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