/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsDataChannel.h"
#include "nsDataHandler.h"
#include "nsNetCID.h"
#include "nsError.h"
#include "nsIOService.h"
#include "DataChannelChild.h"
#include "nsSimpleURI.h"
#include "mozilla/dom/MimeType.h"
#include "mozilla/StaticPrefs_network.h"

using namespace mozilla;

////////////////////////////////////////////////////////////////////////////////

NS_IMPL_ISUPPORTS(nsDataHandler, nsIProtocolHandler, nsISupportsWeakReference)

nsresult nsDataHandler::Create(const nsIID& aIID, void** aResult) {
  RefPtr<nsDataHandler> ph = new nsDataHandler();
  return ph->QueryInterface(aIID, aResult);
}

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

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

/* static */ nsresult nsDataHandler::CreateNewURI(const nsACString& aSpec,
                                                  const char* aCharset,
                                                  nsIURI* aBaseURI,
                                                  nsIURI** result) {
  nsCOMPtr<nsIURI> uri;
  nsAutoCString contentType;
  bool base64;
  MOZ_TRY(ParseURI(aSpec, contentType, /* contentCharset = */ nullptr, base64,
                   /* dataBuffer = */ nullptr));

  // Strip whitespace unless this is text, where whitespace is important
  // Don't strip escaped whitespace though (bug 391951)
  nsresult rv;
  if (base64 || (StaticPrefs::network_url_strip_data_url_whitespace() &&
                 strncmp(contentType.get(), "text/", 5) != 0 &&
                 contentType.Find("xml") == kNotFound)) {
    // it's ascii encoded binary, don't let any spaces in
    rv = NS_MutateURI(new mozilla::net::nsSimpleURI::Mutator())
             .Apply(&nsISimpleURIMutator::SetSpecAndFilterWhitespace, aSpec,
                    nullptr)
             .Finalize(uri);
  } else {
    rv = NS_MutateURI(new mozilla::net::nsSimpleURI::Mutator())
             .SetSpec(aSpec)
             .Finalize(uri);
  }

  if (NS_FAILED(rv)) return rv;

  uri.forget(result);
  return rv;
}

NS_IMETHODIMP
nsDataHandler::NewChannel(nsIURI* uri, nsILoadInfo* aLoadInfo,
                          nsIChannel** result) {
  NS_ENSURE_ARG_POINTER(uri);
  RefPtr<nsDataChannel> channel;
  if (XRE_IsParentProcess()) {
    channel = new nsDataChannel(uri);
  } else {
    channel = new mozilla::net::DataChannelChild(uri);
  }

  // set the loadInfo on the new channel
  nsresult rv = channel->SetLoadInfo(aLoadInfo);
  NS_ENSURE_SUCCESS(rv, rv);

  channel.forget(result);
  return NS_OK;
}

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

/**
 * Helper that performs a case insensitive match to find the offset of a given
 * pattern in a nsACString.
 * The search is performed starting from the end of the string; if the string
 * contains more than one match, the rightmost (last) match will be returned.
 */
static bool FindOffsetOf(const nsACString& aPattern, const nsACString& aSrc,
                         nsACString::size_type& aOffset) {
  nsACString::const_iterator begin, end;
  aSrc.BeginReading(begin);
  aSrc.EndReading(end);
  if (!RFindInReadable(aPattern, begin, end,
                       nsCaseInsensitiveCStringComparator)) {
    return false;
  }

  // FindInReadable updates |begin| and |end| to the match coordinates.
  aOffset = nsACString::size_type(begin.get() - aSrc.Data());
  return true;
}

nsresult nsDataHandler::ParsePathWithoutRef(
    const nsACString& aPath, nsCString& aContentType,
    nsCString* aContentCharset, bool& aIsBase64,
    nsDependentCSubstring* aDataBuffer) {
  static constexpr auto kBase64 = "base64"_ns;
  static constexpr auto kCharset = "charset"_ns;

  aIsBase64 = false;

  // First, find the start of the data
  int32_t commaIdx = aPath.FindChar(',');

  // This is a hack! When creating a URL using the DOM API we want to ignore
  // if a comma is missing. But if we're actually loading a data: URI, in which
  // case aContentCharset is not null, then we want to return an error if a
  // comma is missing.
  if (aContentCharset && commaIdx == kNotFound) {
    return NS_ERROR_MALFORMED_URI;
  }
  if (commaIdx == 0 || commaIdx == kNotFound) {
    // Nothing but data.
    aContentType.AssignLiteral("text/plain");
    if (aContentCharset) {
      aContentCharset->AssignLiteral("US-ASCII");
    }
  } else {
    auto mediaType = Substring(aPath, 0, commaIdx);

    // Determine if the data is base64 encoded.
    nsACString::size_type base64;
    if (FindOffsetOf(kBase64, mediaType, base64) && base64 > 0) {
      nsACString::size_type offset = base64 + kBase64.Length();
      // Per the RFC 2397 grammar, "base64" MUST be at the end of the
      // non-data part.
      //
      // But we also allow it in between parameters so a subsequent ";"
      // is ok as well (this deals with *broken* data URIs, see bug
      // 781693 for an example). Anything after "base64" in the non-data
      // part will be discarded in this case, however.
      if (offset == mediaType.Length() || mediaType[offset] == ';' ||
          mediaType[offset] == ' ') {
        MOZ_DIAGNOSTIC_ASSERT(base64 > 0, "Did someone remove the check?");
        // Index is on the first character of matched "base64" so we
        // move to the preceding character
        base64--;
        // Skip any preceding spaces, searching for a semicolon
        while (base64 > 0 && mediaType[base64] == ' ') {
          base64--;
        }
        if (mediaType[base64] == ';') {
          aIsBase64 = true;
          // Trim the base64 part off.
          mediaType.Rebind(aPath, 0, base64);
        }
      }
    }

    // Skip any leading spaces
    nsACString::size_type startIndex = 0;
    while (startIndex < mediaType.Length() && mediaType[startIndex] == ' ') {
      startIndex++;
    }

    nsAutoCString mediaTypeBuf;
    // If the mimetype starts with ';' we assume text/plain
    if (startIndex < mediaType.Length() && mediaType[startIndex] == ';') {
      mediaTypeBuf.AssignLiteral("text/plain");
      mediaTypeBuf.Append(mediaType);
      mediaType.Rebind(mediaTypeBuf, 0, mediaTypeBuf.Length());
    }

    // Everything else is content type.
    if (mozilla::UniquePtr<CMimeType> parsed = CMimeType::Parse(mediaType)) {
      parsed->GetFullType(aContentType);
      if (aContentCharset) {
        parsed->GetParameterValue(kCharset, *aContentCharset);
      }
    } else {
      // Mime Type parsing failed
      aContentType.AssignLiteral("text/plain");
      if (aContentCharset) {
        aContentCharset->AssignLiteral("US-ASCII");
      }
    }
  }

  if (aDataBuffer) {
    aDataBuffer->Rebind(aPath, commaIdx + 1);
  }

  return NS_OK;
}

static inline char ToLower(const char c) {
  if (c >= 'A' && c <= 'Z') {
    return char(c + ('a' - 'A'));
  }
  return c;
}

nsresult nsDataHandler::ParseURI(const nsACString& spec, nsCString& contentType,
                                 nsCString* contentCharset, bool& isBase64,
                                 nsCString* dataBuffer) {
  static constexpr auto kDataScheme = "data:"_ns;

  // move past "data:"
  const char* pos = std::search(
      spec.BeginReading(), spec.EndReading(), kDataScheme.BeginReading(),
      kDataScheme.EndReading(),
      [](const char a, const char b) { return ToLower(a) == ToLower(b); });
  if (pos == spec.EndReading()) {
    return NS_ERROR_MALFORMED_URI;
  }

  uint32_t scheme = pos - spec.BeginReading();
  scheme += kDataScheme.Length();

  // Find the start of the hash ref if present.
  int32_t hash = spec.FindChar('#', scheme);

  auto pathWithoutRef = Substring(spec, scheme, hash != kNotFound ? hash : -1);
  nsDependentCSubstring dataRange;
  nsresult rv = ParsePathWithoutRef(pathWithoutRef, contentType, contentCharset,
                                    isBase64, &dataRange);
  if (NS_SUCCEEDED(rv) && dataBuffer) {
    if (!dataBuffer->Assign(dataRange, mozilla::fallible)) {
      rv = NS_ERROR_OUT_OF_MEMORY;
    }
  }

  return rv;
}