我正在尝试开发一个需要访问当前加载页面的 SSL 证书信息的 Firefox 扩展/附加组件。获得此信息后，我计划根据 SSL 信息修改页面内容。不过，在我到达那里之前，我首先需要获取 SSL 信息。
此处概述的方法使用单独的 XMLHTTPRequest 来获取安全证书。如果我可以避免它，我宁愿不这样做，因为它会带来安全问题。
例如，恶意站点/中间人可以在页面的第一个请求（浏览器将验证）上提供一个证书，然后为我的扩展程序将发出的 XMLHTTPRequest 提供另一个证书。这将导致扩展程序根据不一致的信息修改站点内容。因此，我想获取浏览器本身在验证站点时使用的 SSL 证书信息。
考虑到这一点，我将上述方法与更改 Firefox 扩展中的 HTTP 响应中概述的方法相结合，通过添加“http-on-examine-response”事件的观察者来拦截所有 HTTP 响应。我认为使用这种方法，我可以简单地获取从站点下载的证书信息。
这是我的代码的主要内容，其中大部分来自上述链接（其余的是 Firefox 扩展样板）：
function dumpSecurityInfo(channel) {
const Cc = Components.classes
const Ci = Components.interfaces;
// Do we have a valid channel argument?
if (! channel instanceof Ci.nsIChannel) {
dump("No channel available\n");
return;
}
var secInfo = channel.securityInfo;
// Print general connection security state
if (secInfo instanceof Ci.nsITransportSecurityInfo) {
dump("name: " + channel.name + "\n");
secInfo.QueryInterface(Ci.nsITransportSecurityInfo);
dump("\tSecurity state: ");
// Check security state flags
if ((secInfo.securityState & Ci.nsIWebProgressListener.STATE_IS_SECURE) == Ci.nsIWebProgressListener.STATE_IS_SECURE)
dump("secure\n");
else if ((secInfo.securityState & Ci.nsIWebProgressListener.STATE_IS_INSECURE) == Ci.nsIWebProgressListener.STATE_IS_INSECURE)
dump("insecure\n");
else if ((secInfo.securityState & Ci.nsIWebProgressListener.STATE_IS_BROKEN) == Ci.nsIWebProgressListener.STATE_IS_BROKEN)
dump("unknown\n");
dump("\tSecurity description: " + secInfo.shortSecurityDescription + "\n");
dump("\tSecurity error message: " + secInfo.errorMessage + "\n");
}
// Print SSL certificate details
if (secInfo instanceof Ci.nsISSLStatusProvider) {
var cert = secInfo.QueryInterface(Ci.nsISSLStatusProvider).
SSLStatus.QueryInterface(Ci.nsISSLStatus).serverCert;
dump("\nCertificate Status:\n");
var verificationResult = cert.verifyForUsage(Ci.nsIX509Cert.CERT_USAGE_SSLServer);
dump("\tVerification: ");
switch (verificationResult) {
case Ci.nsIX509Cert.VERIFIED_OK:
dump("OK");
break;
case Ci.nsIX509Cert.NOT_VERIFIED_UNKNOWN:
dump("not verfied/unknown");
break;
case Ci.nsIX509Cert.CERT_REVOKED:
dump("revoked");
break;
case Ci.nsIX509Cert.CERT_EXPIRED:
dump("expired");
break;
case Ci.nsIX509Cert.CERT_NOT_TRUSTED:
dump("not trusted");
break;
case Ci.nsIX509Cert.ISSUER_NOT_TRUSTED:
dump("issuer not trusted");
break;
case Ci.nsIX509Cert.ISSUER_UNKNOWN:
dump("issuer unknown");
break;
case Ci.nsIX509Cert.INVALID_CA:
dump("invalid CA");
break;
default:
dump("unexpected failure");
break;
}
dump("\n");
dump("\tCommon name (CN) = " + cert.commonName + "\n");
dump("\tOrganisation = " + cert.organization + "\n");
dump("\tIssuer = " + cert.issuerOrganization + "\n");
dump("\tSHA1 fingerprint = " + cert.sha1Fingerprint + "\n");
var validity = cert.validity.QueryInterface(Ci.nsIX509CertValidity);
dump("\tValid from " + validity.notBeforeGMT + "\n");
dump("\tValid until " + validity.notAfterGMT + "\n");
}
}
function TracingListener() {
}
TracingListener.prototype =
{
originalListener: null,
onDataAvailable: function(request, context, inputStream, offset, count) {
try
{
dumpSecurityInfo(request)
this.originalListener.onDataAvailable(request, context, inputStream, offset, count);
} catch (err) {
dump(err);
if (err instanceof Ci.nsIException)
{
request.cancel(e.result);
}
}
},
onStartRequest: function(request, context) {
try
{
dumpSecurityInfo(request)
this.originalListener.onStartRequest(request, context);
} catch (err) {
dump(err);
if (err instanceof Ci.nsIException)
{
request.cancel(e.result);
}
}
},
onStopRequest: function(request, context, statusCode) {
this.originalListener.onStopRequest(request, context, statusCode);
},
QueryInterface: function (aIID) {
const Ci = Components.interfaces;
if ( iid.equals(Ci.nsIObserver) ||
iid.equals(Ci.nsISupportsWeakReference) ||
iid.equals(Ci.nsISupports))
{
return this;
}
throw Components.results.NS_NOINTERFACE;
}
}
var httpRequestObserver =
{
observe: function(aSubject, aTopic, aData)
{
const Ci = Components.interfaces;
if (aTopic == "http-on-examine-response")
{
var newListener = new TracingListener();
aSubject.QueryInterface(Ci.nsITraceableChannel);
newListener.originalListener = aSubject.setNewListener(newListener);
}
},
QueryInterface : function (aIID)
{
const Ci = Components.interfaces;
if (aIID.equals(Ci.nsIObserver) ||
aIID.equals(Ci.nsISupports))
{
return this;
}
throw Components.results.NS_NOINTERFACE;
}
};
var test =
{
run: function() {
const Ci = Components.interfaces;
dump("run");
var observerService = Components.classes["@mozilla.org/observer-service;1"]
.getService(Ci.nsIObserverService);
observerService.addObserver(httpRequestObserver,
"http-on-examine-response", false);
}
};
window.addEventListener("load", function () { test.run(); }, false);
我发现这个实现是不一致的。当我在 Firefox 中加载 gmail.com 时，有时会获得证书信息，有时却不会。我怀疑这是一个缓存问题，因为刷新页面通常会导致证书信息被下载/打印。
对于我的预期应用程序，这种行为是不可接受的。这是一个研究项目，因此，如果必须，我愿意修改 Firefox 源代码，但我更喜欢使用扩展/附加 API 来执行此操作。
是否有更好、更一致的方式来获取 SSL 证书信息？