gecko/netwerk/protocol/about/nsAboutProtocolHandler.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "base/basictypes.h"

#include "nsAboutProtocolHandler.h"
#include "nsIURI.h"
#include "nsIAboutModule.h"
#include "nsString.h"
#include "nsNetCID.h"
#include "nsAboutProtocolUtils.h"
#include "nsError.h"
#include "nsNetUtil.h"
#include "nsIObjectInputStream.h"
#include "nsIObjectOutputStream.h"
#include "nsAutoPtr.h"
#include "nsIWritablePropertyBag2.h"

static NS_DEFINE_CID(kSimpleURICID,     NS_SIMPLEURI_CID);
static NS_DEFINE_CID(kNestedAboutURICID, NS_NESTEDABOUTURI_CID);

static bool IsSafeForUntrustedContent(nsIAboutModule *aModule, nsIURI *aURI) {
  uint32_t flags;
  nsresult rv = aModule->GetURIFlags(aURI, &flags);
  NS_ENSURE_SUCCESS(rv, false);

  return (flags & nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT) != 0;
}
////////////////////////////////////////////////////////////////////////////////

NS_IMPL_ISUPPORTS(nsAboutProtocolHandler, nsIProtocolHandler)

////////////////////////////////////////////////////////////////////////////////
// nsIProtocolHandler methods:

NS_IMETHODIMP
nsAboutProtocolHandler::GetScheme(nsACString &result)
{
    result.AssignLiteral("about");
    return NS_OK;
}

NS_IMETHODIMP
nsAboutProtocolHandler::GetDefaultPort(int32_t *result)
{
    *result = -1;        // no port for about: URLs
    return NS_OK;
}

NS_IMETHODIMP
nsAboutProtocolHandler::GetProtocolFlags(uint32_t *result)
{
    *result = URI_NORELATIVE | URI_NOAUTH | URI_DANGEROUS_TO_LOAD;
    return NS_OK;
}

NS_IMETHODIMP
nsAboutProtocolHandler::NewURI(const nsACString &aSpec,
                               const char *aCharset, // ignore charset info
                               nsIURI *aBaseURI,
                               nsIURI **result)
{
    *result = nullptr;
    nsresult rv;

    // Use a simple URI to parse out some stuff first
    nsCOMPtr<nsIURI> url = do_CreateInstance(kSimpleURICID, &rv);
    if (NS_FAILED(rv)) return rv;

    rv = url->SetSpec(aSpec);
    if (NS_FAILED(rv)) {
        return rv;
    }

    // Unfortunately, people create random about: URIs that don't correspond to
    // about: modules...  Since those URIs will never open a channel, might as
    // well consider them unsafe for better perf, and just in case.
    bool isSafe = false;
    
    nsCOMPtr<nsIAboutModule> aboutMod;
    rv = NS_GetAboutModule(url, getter_AddRefs(aboutMod));
    if (NS_SUCCEEDED(rv)) {
        isSafe = IsSafeForUntrustedContent(aboutMod, url);
    }

    if (isSafe) {
        // We need to indicate that this baby is safe.  Use an inner URI that
        // no one but the security manager will see.  Make sure to preserve our
        // path, in case someone decides to hardcode checks for particular
        // about: URIs somewhere.
        nsAutoCString spec;
        rv = url->GetPath(spec);
        NS_ENSURE_SUCCESS(rv, rv);
        
        spec.Insert("moz-safe-about:", 0);

        nsCOMPtr<nsIURI> inner;
        rv = NS_NewURI(getter_AddRefs(inner), spec);
        NS_ENSURE_SUCCESS(rv, rv);

        nsSimpleNestedURI* outer = new nsNestedAboutURI(inner, aBaseURI);
        NS_ENSURE_TRUE(outer, NS_ERROR_OUT_OF_MEMORY);

        // Take a ref to it in the COMPtr we plan to return
        url = outer;

        rv = outer->SetSpec(aSpec);
        NS_ENSURE_SUCCESS(rv, rv);
    }

    // We don't want to allow mutation, since it would allow safe and
    // unsafe URIs to change into each other...
    NS_TryToSetImmutable(url);
    url.swap(*result);
    return NS_OK;
}

NS_IMETHODIMP
nsAboutProtocolHandler::NewChannel(nsIURI* uri, nsIChannel* *result)
{
    NS_ENSURE_ARG_POINTER(uri);

    // about:what you ask?
    nsCOMPtr<nsIAboutModule> aboutMod;
    nsresult rv = NS_GetAboutModule(uri, getter_AddRefs(aboutMod));

    nsAutoCString path;
    nsresult rv2 = NS_GetAboutModuleName(uri, path);
    if (NS_SUCCEEDED(rv2) && path.EqualsLiteral("srcdoc")) {
        // about:srcdoc is meant to be unresolvable, yet is included in the 
        // about lookup tables so that it can pass security checks when used in
        // a srcdoc iframe.  To ensure that it stays unresolvable, we pretend
        // that it doesn't exist.
      rv = NS_ERROR_FACTORY_NOT_REGISTERED;
    }

    if (NS_SUCCEEDED(rv)) {
        // The standard return case:
        rv = aboutMod->NewChannel(uri, result);
        if (NS_SUCCEEDED(rv)) {
            // If this URI is safe for untrusted content, enforce that its
            // principal be based on the channel's originalURI by setting the
            // owner to null.
            // Note: this relies on aboutMod's newChannel implementation
            // having set the proper originalURI, which probably isn't ideal.
            if (IsSafeForUntrustedContent(aboutMod, uri)) {
                (*result)->SetOwner(nullptr);
            }

            nsRefPtr<nsNestedAboutURI> aboutURI;
            nsresult rv2 = uri->QueryInterface(kNestedAboutURICID,
                                               getter_AddRefs(aboutURI));
            if (NS_SUCCEEDED(rv2) && aboutURI->GetBaseURI()) {
                nsCOMPtr<nsIWritablePropertyBag2> writableBag =
                    do_QueryInterface(*result);
                if (writableBag) {
                    writableBag->
                        SetPropertyAsInterface(NS_LITERAL_STRING("baseURI"),
                                               aboutURI->GetBaseURI());
                }
            }
        }
        return rv;
    }

    // mumble...

    if (rv == NS_ERROR_FACTORY_NOT_REGISTERED) {
        // This looks like an about: we don't know about.  Convert
        // this to an invalid URI error.
        rv = NS_ERROR_MALFORMED_URI;
    }

    return rv;
}

NS_IMETHODIMP 
nsAboutProtocolHandler::AllowPort(int32_t port, const char *scheme, bool *_retval)
{
    // don't override anything.  
    *_retval = false;
    return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////
// Safe about protocol handler impl

NS_IMPL_ISUPPORTS(nsSafeAboutProtocolHandler, nsIProtocolHandler)

// nsIProtocolHandler methods:

NS_IMETHODIMP
nsSafeAboutProtocolHandler::GetScheme(nsACString &result)
{
    result.AssignLiteral("moz-safe-about");
    return NS_OK;
}

NS_IMETHODIMP
nsSafeAboutProtocolHandler::GetDefaultPort(int32_t *result)
{
    *result = -1;        // no port for moz-safe-about: URLs
    return NS_OK;
}

NS_IMETHODIMP
nsSafeAboutProtocolHandler::GetProtocolFlags(uint32_t *result)
{
    *result = URI_NORELATIVE | URI_NOAUTH | URI_LOADABLE_BY_ANYONE | URI_SAFE_TO_LOAD_IN_SECURE_CONTEXT;
    return NS_OK;
}

NS_IMETHODIMP
nsSafeAboutProtocolHandler::NewURI(const nsACString &aSpec,
                                   const char *aCharset, // ignore charset info
                                   nsIURI *aBaseURI,
                                   nsIURI **result)
{
    nsresult rv;

    nsCOMPtr<nsIURI> url = do_CreateInstance(kSimpleURICID, &rv);
    if (NS_FAILED(rv)) return rv;

    rv = url->SetSpec(aSpec);
    if (NS_FAILED(rv)) {
        return rv;
    }

    NS_TryToSetImmutable(url);
    
    *result = nullptr;
    url.swap(*result);
    return rv;
}

NS_IMETHODIMP
nsSafeAboutProtocolHandler::NewChannel(nsIURI* uri, nsIChannel* *result)
{
    *result = nullptr;
    return NS_ERROR_NOT_AVAILABLE;
}

NS_IMETHODIMP 
nsSafeAboutProtocolHandler::AllowPort(int32_t port, const char *scheme, bool *_retval)
{
    // don't override anything.  
    *_retval = false;
    return NS_OK;
}

////////////////////////////////////////////////////////////
// nsNestedAboutURI implementation
NS_INTERFACE_MAP_BEGIN(nsNestedAboutURI)
  if (aIID.Equals(kNestedAboutURICID))
      foundInterface = static_cast<nsIURI*>(this);
  else
NS_INTERFACE_MAP_END_INHERITING(nsSimpleNestedURI)

// nsISerializable
NS_IMETHODIMP
nsNestedAboutURI::Read(nsIObjectInputStream* aStream)
{
    nsresult rv = nsSimpleNestedURI::Read(aStream);
    if (NS_FAILED(rv)) return rv;

    bool haveBase;
    rv = aStream->ReadBoolean(&haveBase);
    if (NS_FAILED(rv)) return rv;

    if (haveBase) {
        nsCOMPtr<nsISupports> supports;
        rv = aStream->ReadObject(true, getter_AddRefs(supports));
        if (NS_FAILED(rv)) return rv;

        mBaseURI = do_QueryInterface(supports, &rv);
        if (NS_FAILED(rv)) return rv;
    }

    return NS_OK;
}

NS_IMETHODIMP
nsNestedAboutURI::Write(nsIObjectOutputStream* aStream)
{
    nsresult rv = nsSimpleNestedURI::Write(aStream);
    if (NS_FAILED(rv)) return rv;

    rv = aStream->WriteBoolean(mBaseURI != nullptr);
    if (NS_FAILED(rv)) return rv;

    if (mBaseURI) {
        // A previous iteration of this code wrote out mBaseURI as nsISupports
        // and then read it in as nsIURI, which is non-kosher when mBaseURI
        // implements more than just a single line of interfaces and the
        // canonical nsISupports* isn't the one a static_cast<> of mBaseURI
        // would produce.  For backwards compatibility with existing
        // serializations we continue to write mBaseURI as nsISupports but
        // switch to reading it as nsISupports, with a post-read QI to get to
        // nsIURI.
        rv = aStream->WriteCompoundObject(mBaseURI, NS_GET_IID(nsISupports),
                                          true);
        if (NS_FAILED(rv)) return rv;
    }

    return NS_OK;
}

// nsSimpleURI
/* virtual */ nsSimpleURI*
nsNestedAboutURI::StartClone(nsSimpleURI::RefHandlingEnum aRefHandlingMode)
{
    // Sadly, we can't make use of nsSimpleNestedURI::StartClone here.
    // However, this function is expected to exactly match that function,
    // aside from the "new ns***URI()" call.
    NS_ENSURE_TRUE(mInnerURI, nullptr);

    nsCOMPtr<nsIURI> innerClone;
    nsresult rv = aRefHandlingMode == eHonorRef ?
        mInnerURI->Clone(getter_AddRefs(innerClone)) :
        mInnerURI->CloneIgnoringRef(getter_AddRefs(innerClone));

    if (NS_FAILED(rv)) {
        return nullptr;
    }

    nsNestedAboutURI* url = new nsNestedAboutURI(innerClone, mBaseURI);
    url->SetMutable(false);

    return url;
}

// nsIClassInfo
NS_IMETHODIMP
nsNestedAboutURI::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
{
    *aClassIDNoAlloc = kNestedAboutURICID;
    return NS_OK;
}