src/core/channel/http_server_filter.c

/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "src/core/channel/http_server_filter.h"

#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>

typedef struct call_data
{
  gpr_uint8 got_initial_metadata;
  gpr_uint8 seen_path;
  gpr_uint8 seen_post;
  gpr_uint8 sent_status;
  gpr_uint8 seen_scheme;
  gpr_uint8 seen_te_trailers;
  gpr_uint8 seen_authority;
  grpc_linked_mdelem status;
  grpc_linked_mdelem content_type;

  grpc_stream_op_buffer *recv_ops;
  /** Closure to call when finished with the hs_on_recv hook */
  grpc_closure *on_done_recv;
  /** Receive closures are chained: we inject this closure as the on_done_recv
      up-call on transport_op, and remember to call our on_done_recv member
      after handling it. */
  grpc_closure hs_on_recv;
} call_data;

typedef struct channel_data
{
  grpc_mdelem *te_trailers;
  grpc_mdelem *method_post;
  grpc_mdelem *http_scheme;
  grpc_mdelem *https_scheme;
  /* TODO(klempner): Remove this once we stop using it */
  grpc_mdelem *grpc_scheme;
  grpc_mdelem *content_type;
  grpc_mdelem *status_ok;
  grpc_mdelem *status_not_found;
  grpc_mdstr *path_key;
  grpc_mdstr *authority_key;
  grpc_mdstr *host_key;

  grpc_mdctx *mdctx;
} channel_data;

typedef struct
{
  grpc_call_element *elem;
  grpc_closure_list *closure_list;
} server_filter_args;

static grpc_mdelem *
server_filter (void *user_data, grpc_mdelem * md)
{
  server_filter_args *a = user_data;
  grpc_call_element *elem = a->elem;
  channel_data *channeld = elem->channel_data;
  call_data *calld = elem->call_data;

  /* Check if it is one of the headers we care about. */
  if (md == channeld->te_trailers || md == channeld->method_post || md == channeld->http_scheme || md == channeld->https_scheme || md == channeld->grpc_scheme || md == channeld->content_type)
    {
      /* swallow it */
      if (md == channeld->method_post)
	{
	  calld->seen_post = 1;
	}
      else if (md->key == channeld->http_scheme->key)
	{
	  calld->seen_scheme = 1;
	}
      else if (md == channeld->te_trailers)
	{
	  calld->seen_te_trailers = 1;
	}
      /* TODO(klempner): Track that we've seen all the headers we should
         require */
      return NULL;
    }
  else if (md->key == channeld->content_type->key)
    {
      if (strncmp (grpc_mdstr_as_c_string (md->value), "application/grpc+", 17) == 0)
	{
	  /* Although the C implementation doesn't (currently) generate them,
	     any custom +-suffix is explicitly valid. */
	  /* TODO(klempner): We should consider preallocating common values such
	     as +proto or +json, or at least stashing them if we see them. */
	  /* TODO(klempner): Should we be surfacing this to application code? */
	}
      else
	{
	  /* TODO(klempner): We're currently allowing this, but we shouldn't
	     see it without a proxy so log for now. */
	  gpr_log (GPR_INFO, "Unexpected content-type %s", channeld->content_type->key);
	}
      return NULL;
    }
  else if (md->key == channeld->te_trailers->key || md->key == channeld->method_post->key || md->key == channeld->http_scheme->key)
    {
      gpr_log (GPR_ERROR, "Invalid %s: header: '%s'", grpc_mdstr_as_c_string (md->key), grpc_mdstr_as_c_string (md->value));
      /* swallow it and error everything out. */
      /* TODO(klempner): We ought to generate more descriptive error messages
         on the wire here. */
      grpc_call_element_send_cancel (elem, a->closure_list);
      return NULL;
    }
  else if (md->key == channeld->path_key)
    {
      if (calld->seen_path)
	{
	  gpr_log (GPR_ERROR, "Received :path twice");
	  return NULL;
	}
      calld->seen_path = 1;
      return md;
    }
  else if (md->key == channeld->authority_key)
    {
      calld->seen_authority = 1;
      return md;
    }
  else if (md->key == channeld->host_key)
    {
      /* translate host to :authority since :authority may be
         omitted */
      grpc_mdelem *authority = grpc_mdelem_from_metadata_strings (channeld->mdctx, GRPC_MDSTR_REF (channeld->authority_key),
								  GRPC_MDSTR_REF (md->value));
      GRPC_MDELEM_UNREF (md);
      calld->seen_authority = 1;
      return authority;
    }
  else
    {
      return md;
    }
}

static void
hs_on_recv (grpc_exec_ctx * exec_ctx, void *user_data, int success)
{
  grpc_call_element *elem = user_data;
  call_data *calld = elem->call_data;
  if (success)
    {
      size_t i;
      size_t nops = calld->recv_ops->nops;
      grpc_stream_op *ops = calld->recv_ops->ops;
      for (i = 0; i < nops; i++)
	{
	  grpc_stream_op *op = &ops[i];
	  server_filter_args a;
	  if (op->type != GRPC_OP_METADATA)
	    continue;
	  calld->got_initial_metadata = 1;
	  a.elem = elem;
	  a.closure_list = closure_list;
	  grpc_metadata_batch_filter (&op->data.metadata, server_filter, &a);
	  /* Have we seen the required http2 transport headers?
	     (:method, :scheme, content-type, with :path and :authority covered
	     at the channel level right now) */
	  if (calld->seen_post && calld->seen_scheme && calld->seen_te_trailers && calld->seen_path && calld->seen_authority)
	    {
	      /* do nothing */
	    }
	  else
	    {
	      if (!calld->seen_path)
		{
		  gpr_log (GPR_ERROR, "Missing :path header");
		}
	      if (!calld->seen_authority)
		{
		  gpr_log (GPR_ERROR, "Missing :authority header");
		}
	      if (!calld->seen_post)
		{
		  gpr_log (GPR_ERROR, "Missing :method header");
		}
	      if (!calld->seen_scheme)
		{
		  gpr_log (GPR_ERROR, "Missing :scheme header");
		}
	      if (!calld->seen_te_trailers)
		{
		  gpr_log (GPR_ERROR, "Missing te trailers header");
		}
	      /* Error this call out */
	      success = 0;
	      grpc_call_element_send_cancel (exec_ctx, elem);
	    }
	}
    }
  calld->on_done_recv->cb (exec_ctx, calld->on_done_recv->cb_arg, success);
}

static void
hs_mutate_op (grpc_call_element * elem, grpc_transport_stream_op * op)
{
  /* grab pointers to our data from the call element */
  call_data *calld = elem->call_data;
  channel_data *channeld = elem->channel_data;
  size_t i;

  if (op->send_ops && !calld->sent_status)
    {
      size_t nops = op->send_ops->nops;
      grpc_stream_op *ops = op->send_ops->ops;
      for (i = 0; i < nops; i++)
	{
	  grpc_stream_op *op = &ops[i];
	  if (op->type != GRPC_OP_METADATA)
	    continue;
	  calld->sent_status = 1;
	  grpc_metadata_batch_add_head (&op->data.metadata, &calld->status, GRPC_MDELEM_REF (channeld->status_ok));
	  grpc_metadata_batch_add_tail (&op->data.metadata, &calld->content_type, GRPC_MDELEM_REF (channeld->content_type));
	  break;
	}
    }

  if (op->recv_ops && !calld->got_initial_metadata)
    {
      /* substitute our callback for the higher callback */
      calld->recv_ops = op->recv_ops;
      calld->on_done_recv = op->on_done_recv;
      op->on_done_recv = &calld->hs_on_recv;
    }
}

static void
hs_start_transport_op (grpc_exec_ctx * exec_ctx, grpc_call_element * elem, grpc_transport_stream_op * op)
{
  GRPC_CALL_LOG_OP (GPR_INFO, elem, op);
  hs_mutate_op (elem, op);
  grpc_call_next_op (exec_ctx, elem, op);
}

/* Constructor for call_data */
static void
init_call_elem (grpc_exec_ctx * exec_ctx, grpc_call_element * elem, const void *server_transport_data, grpc_transport_stream_op * initial_op)
{
  /* grab pointers to our data from the call element */
  call_data *calld = elem->call_data;
  /* initialize members */
  memset (calld, 0, sizeof (*calld));
  grpc_closure_init (&calld->hs_on_recv, hs_on_recv, elem);
  if (initial_op)
    hs_mutate_op (elem, initial_op);
}

/* Destructor for call_data */
static void
destroy_call_elem (grpc_exec_ctx * exec_ctx, grpc_call_element * elem)
{
}

/* Constructor for channel_data */
static void
init_channel_elem (grpc_exec_ctx * exec_ctx, grpc_channel_element * elem, grpc_channel * master, const grpc_channel_args * args, grpc_mdctx * mdctx, int is_first, int is_last)
{
  /* grab pointers to our data from the channel element */
  channel_data *channeld = elem->channel_data;

  /* The first and the last filters tend to be implemented differently to
     handle the case that there's no 'next' filter to call on the up or down
     path */
  GPR_ASSERT (!is_first);
  GPR_ASSERT (!is_last);

  /* initialize members */
  channeld->te_trailers = grpc_mdelem_from_strings (mdctx, "te", "trailers");
  channeld->status_ok = grpc_mdelem_from_strings (mdctx, ":status", "200");
  channeld->status_not_found = grpc_mdelem_from_strings (mdctx, ":status", "404");
  channeld->method_post = grpc_mdelem_from_strings (mdctx, ":method", "POST");
  channeld->http_scheme = grpc_mdelem_from_strings (mdctx, ":scheme", "http");
  channeld->https_scheme = grpc_mdelem_from_strings (mdctx, ":scheme", "https");
  channeld->grpc_scheme = grpc_mdelem_from_strings (mdctx, ":scheme", "grpc");
  channeld->path_key = grpc_mdstr_from_string (mdctx, ":path", 0);
  channeld->authority_key = grpc_mdstr_from_string (mdctx, ":authority", 0);
  channeld->host_key = grpc_mdstr_from_string (mdctx, "host", 0);
  channeld->content_type = grpc_mdelem_from_strings (mdctx, "content-type", "application/grpc");

  channeld->mdctx = mdctx;
}

/* Destructor for channel data */
static void
destroy_channel_elem (grpc_exec_ctx * exec_ctx, grpc_channel_element * elem)
{
  /* grab pointers to our data from the channel element */
  channel_data *channeld = elem->channel_data;

  GRPC_MDELEM_UNREF (channeld->te_trailers);
  GRPC_MDELEM_UNREF (channeld->status_ok);
  GRPC_MDELEM_UNREF (channeld->status_not_found);
  GRPC_MDELEM_UNREF (channeld->method_post);
  GRPC_MDELEM_UNREF (channeld->http_scheme);
  GRPC_MDELEM_UNREF (channeld->https_scheme);
  GRPC_MDELEM_UNREF (channeld->grpc_scheme);
  GRPC_MDELEM_UNREF (channeld->content_type);
  GRPC_MDSTR_UNREF (channeld->path_key);
  GRPC_MDSTR_UNREF (channeld->authority_key);
  GRPC_MDSTR_UNREF (channeld->host_key);
}

const grpc_channel_filter grpc_http_server_filter = {
  hs_start_transport_op, grpc_channel_next_op, sizeof (call_data),
  init_call_elem, destroy_call_elem, sizeof (channel_data),
  init_channel_elem, destroy_channel_elem, grpc_call_next_get_peer,
  "http-server"
};