// Raspberry Pi LPC1114 I/O Processor Expansion Board
// SPI agent firmware XML-RPC server

// Copyright (C)2013-2018, Philip Munts, President, Munts AM Corp.
//
// 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.
//
// 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 HOLDER 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 <errno.h>
#include <grp.h>
#include <netdb.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <xmlrpc.h>
#include <xmlrpc-c/server.h>
#include <xmlrpc-c/server_abyss.h>
#include <xmlrpc-c/util.h>

#include <libsimpleio/liblinux.h>

#include "spi-agent.h"

extern void spiagent_open_ioctl(char *servername, int32_t *error);
extern void spiagent_command_ioctl(SPIAGENT_COMMAND_MSG_t *cmd, SPIAGENT_RESPONSE_MSG_t *resp, int32_t *error);

#define RESPONSEDELAY	0
#define PROGRAMNAME	"spi_agent_xmlrpc_server"
#define SERVICENAME	"spiagent-xmlrpc"

// This method function is just an XML-RPC wrapper around spiagent_command_ioctl()

static xmlrpc_value *spi_transaction(xmlrpc_env * const env,
  xmlrpc_value * const parameters, void * const serverinfo)
{
  SPIAGENT_COMMAND_MSG_t command;
  SPIAGENT_RESPONSE_MSG_t response;
  int32_t error;

  memset(&response,  0, sizeof(response));

// Extract parameters

  xmlrpc_decompose_value(env, parameters, "(iii)",
    &command.command, &command.pin, &command.data);
  if (env->fault_occurred) return NULL;

// Perform the SPI transfers

  spiagent_command_ioctl(&command, &response, &error);

  if (error)
  {
    char errormessage[256];
    memset(errormessage, 0, sizeof(errormessage));
    snprintf(errormessage, sizeof(errormessage),
    "ERROR: spiagent_command_ioctl() failed, %s", strerror(error));
    syslog(LOG_ERR, errormessage);
    XMLRPC_FAIL(env, XMLRPC_INTERNAL_ERROR, errormessage);
  }

cleanup:

  return xmlrpc_build_value(env, "(iiii)",
    response.command, response.pin, response.data, response.error);
}

int main(void)
{
  struct servent *service;
  int32_t error;
  xmlrpc_server_abyss_parms serverparms;
  xmlrpc_registry *registryP;
  xmlrpc_env env;

  openlog(PROGRAMNAME, LOG_NDELAY|LOG_PID|LOG_PERROR, LOG_DAEMON);

  syslog(LOG_INFO, "Starting LPC1114 SPI Agent Firmware XML-RPC server");

// Look up service definition

  service = getservbyname(SERVICENAME, "tcp");
  if (service == NULL)
  {
    syslog(LOG_ERR, "ERROR: getservbyname() failed, unknown service");
    exit(1);
  }

// Open the Raspberry Pi LPC1114 I/O Processor Expansion Board SPI device

  spiagent_open_ioctl(NULL, &error);

  if (error)
  {
    syslog(LOG_ERR, "ERROR: spiagent_open_ioctl(() failed, %s", strerror(error));
    exit(1);
  }

// Become a nobody

  LINUX_drop_privileges("nobody", &error);
  if (error)
  {
    syslog(LOG_ERR, "ERROR: DropPrivileges() failed, %s", strerror(error));
    exit(1);
  }

// Initialize the XML-RPC library internal data structures

  xmlrpc_env_init(&env);

// Register the XML-RPC method

  registryP = xmlrpc_registry_new(&env);
  if (env.fault_occurred)
  {
    syslog(LOG_ERR, "ERROR: xmlrpc_registry_new() failed, error=%d (%s)",
      env.fault_code, env.fault_string);
    exit(1);
  }

  xmlrpc_registry_add_method_w_doc(&env, registryP, NULL,
    "spi.agent.transaction", spi_transaction, NULL, "A:iii",
    "SPI Agent transaction wrapper");
  if (env.fault_occurred)
  {
    syslog(LOG_ERR, "ERROR: xmlrpc_add_method_w_doc() failed, error=%d (%s)",
      env.fault_code, env.fault_string);
    exit(1);
  }

// Configure the server

  serverparms.config_file_name = NULL;
  serverparms.registryP = registryP;
  serverparms.port_number = ntohs(service->s_port);

// Switch to background

  if (daemon(0, 0))
  {
    syslog(LOG_ERR, "ERROR: daemon() failed, %s", strerror(errno));
    exit(1);
  }

// Start the server

  xmlrpc_server_abyss(&env, &serverparms, XMLRPC_APSIZE(port_number));
  if (env.fault_occurred)
  {
    syslog(LOG_ERR, "ERROR: xmlrpc_server_abyss() failed, error=%d (%s)",
      env.fault_code, env.fault_string);
    exit(1);
  }

  exit(0);
}