trick/trick_source/sim_services/JSONVariableServer/JSONVariableServerThread.cpp

#include <iostream>
#include <sstream>
#include <stdlib.h>
#include <string.h>

#include "trick/JSONVariableServerThread.hh"
#include "trick/MemoryManager.hh"
#include "trick/memorymanager_c_intf.h"
#include "trick/exec_proto.h"
#include "trick/PythonPrint.hh"
#include "trick/tc_proto.h"
#include "trick/TrickConstant.hh"

Trick::JSONVariableServerThread::JSONVariableServerThread(TCDevice * listen_dev) :
 Trick::ThreadBase("JSONVarServer") {

    connection.disable_handshaking = TC_COMM_TRUE ;
    connection.blockio_type = TC_COMM_BLOCKIO ;

    tc_accept(listen_dev, &connection);

    // Save the hostname and port of the listen server
    hostname = listen_dev->hostname ;
    port = listen_dev->port ;

    incoming_msg = new char[MAX_CMD_LEN] ;
}

/*
@details
-# delete the space for incominig_msg.
-# These classes are always allocated... free the memory on the way out.
*/
Trick::JSONVariableServerThread::~JSONVariableServerThread() {
    delete [] incoming_msg ;
    delete this ;
}

/*
@details
-# Loop until the connection is broken or timed_out
 -# Call select to wait up to 15 seconds for a message.
 -# If a message is found, read it into the incoming_msg buffer
 -# Call parse_request on the incoming_msg buffer
-# Disconnect the socket connection
*/
void * Trick::JSONVariableServerThread::thread_body() {

    int nbytes = -1 ;
    socklen_t sock_size = sizeof(connection.remoteServAddr) ;
    fd_set rfds;
    struct timeval timeout_time = { 15, 0 };
    bool timed_out = false ;

    while (! timed_out and nbytes != 0 ) {
        FD_ZERO(&rfds);
        FD_SET(connection.socket, &rfds);
        timeout_time.tv_sec = 15 ;
        select(connection.socket + 1, &rfds, NULL, NULL, &timeout_time);

        if ( FD_ISSET(connection.socket, &rfds)) {
            nbytes = recvfrom( connection.socket, incoming_msg, MAX_CMD_LEN, 0 ,
                     (struct sockaddr *)&connection.remoteServAddr, &sock_size ) ;
            //std::cout << "nbytes = " << nbytes << std::endl ;
            if (nbytes != 0 ) {
                //std::cout << incoming_msg << std::endl ;
                parse_request() ;
            }
        } else {
            timed_out = true ;
        }
    }
    tc_disconnect(&connection) ;
    //std::cout << "closed variable server connection" << std::endl ;

    return NULL ;
}

/*
@details
-# scan the incoming message for the command and requested path
-# start the return message with a "{"
-# if both a command and request is present
 -# if the command is "GET"
  -# if the path is "/" call get_top_page
  -# else if the path starts with "/vars" call get_vars
  -# else if the path starts with "/commands" call get_commands
  -# else create an error message reply
 -# else if the command is "POST" do something at some point.
 -# else create an error message reply
-# else create an error message reply
-# close the return message with a "}"
-# create the http header for the reply message
-# call tc_write to send the reply message
*/
void Trick::JSONVariableServerThread::parse_request() {
    // Need to protect against buffer overflow
    char command[32] ;
    char path[512] ;
    std::stringstream ss ;
    std::stringstream body ;
    int ret ;

    ret = sscanf(incoming_msg, "%s %s", command , path) ;

    body << "{" << std::endl ;
    if ( ret == 2 ) {
        //std::cout << "command = " << command << std::endl ;
        //std::cout << "path = " << path << std::endl ;

        if ( ! strcmp(command, "GET") ) {
            if ( ! strcmp(path, "/") ) {
                // send the top page
                ret = get_top_page(body) ;
            } else if ( ! strncmp(path, "/vars", 5)) {
                // get list of variables or value
                ret = get_vars(body, &path[5]) ;
            } else if ( ! strncmp(path, "/commands", 9)) {
                // get list of commands
                ret = get_commands(body, &path[9]) ;
            } else {
                ret = 404 ;
                body << "    \"name\" : \"" << path << "\" ," << std::endl ;
                body << "    \"message\" : \"Not Found\"" << std::endl ;
            }
        } else if ( ! strcmp( command, "POST") ) {
            //TODO: Allow setting variable values with POST.
            ret = 405 ;
            body << "    \"verb\" : \"" << command << "\" ," << std::endl ;
            body << "    \"message\" : \"Method not allowed\"" << std::endl ;
        } else {
            ret = 405 ;
            body << "    \"verb\" : \"" << command << "\" ," << std::endl ;
            body << "    \"message\" : \"Method not allowed\"" << std::endl ;
        }

    } else {
        ret = 400 ;
        body << "    \"message\" : \"Bad Request\"" << std::endl ;
    }
    body << "}" << std::endl ;

    ss << "HTTP/1.1 " << ret ;
    switch (ret) {
        case 200:
            ss << " OK" ;
            break ;
        case 400:
            ss << " Bad Request" ;
            break ;
        case 404:
            ss << " Not Found" ;
            break ;
        case 405:
            ss << " Method Not Allowed" ;
            break ;
        default:
            ss << " Unknown" ;
            break ;
    }
    ss << std::endl ;
    ss << "Content-Type: application/json" << std::endl ;
    ss << "Content-Length: " << body.str().size() << std::endl << std::endl ;
    ss << body.str() ;
    //std::cout << ss.str() ;
    tc_write(&connection, (char *)ss.str().c_str() , ss.str().size()) ;
}

/*
@details
-# create top page contents and return success
*/
int Trick::JSONVariableServerThread::get_top_page( std::stringstream & body ) {
    body << "   \"commands\": \"http://" << hostname << ":" << port << "/commands\"," << std::endl ;
    body << "   \"vars\": \"http://" << hostname << ":" << port << "/vars\"" << std::endl ;
    return 200 ;
}

/*
@details
-# if the path is empty after /commands create commands top level page.
-# else if the path is exec_get_sim_time return create a message with the sim time.
-# else create an error message.
*/
int Trick::JSONVariableServerThread::get_commands( std::stringstream & body , char * path ) {
    int ret = 200 ;
    if ( path[strlen(path) - 1] == '/') {
        path[strlen(path) - 1] = '\0' ;
    }
    if ( path[0] == '\0' ) {
        body << "   \"exec_get_sim_time\": \"exec_get_sim_time()\"" << std::endl ;
    } else if ( ! strcmp( path , "/exec_get_sim_time" ) ) {
        body << "   \"sim_time\": \"" << exec_get_sim_time() << "\"" << std::endl ;
    } else {
        body << "    \"message\" : \"Not Found\"" << std::endl ;
        ret = 404 ;
    }
    return ret ;
}

/*
@details
-# if the path is empty after /vars
 -# loop through all allocations in the memory manager
 -# if the allocation has a name create an item in the reply message for that allocation.
-# else
 -# convert "/" characters to "." in the path and strip trailing "/" characters.
 -# add converted variable name to the reply message.
 -# call ref_attributes to find the variable.
  -# if the variable exists
   -# if the variable type is a structure.
    -# loop through the attributes and add each of the struct/class variables as links in the reply message.
   -# else add the variables value and units to the reply message.
   -# add the description text to the reply message
   -# add the type information to the reply message
   -# add the type io specification to the reply message
   -# if the variable has dimensions add the dimension information to the reply message.
 -# else add an error message to the reply message
*/
int Trick::JSONVariableServerThread::get_vars( std::stringstream & body , char * path ) {

    int ret = 200 ;

    //std::cout << "get_vars " << path << std::endl ;
    if ( path[0] == '\0' ) {
        Trick::ALLOC_INFO_MAP_ITER aim_it ;
        bool first_item = true ;
        for ( aim_it = trick_MM->alloc_info_map_begin() ; aim_it != trick_MM->alloc_info_map_end() ; aim_it++ ) {
            ALLOC_INFO * alloc_info = (*aim_it).second ;
            if ( alloc_info->name != NULL and alloc_info->user_type_name != NULL ) {
                if ( first_item == true ) {
                    first_item = false ;
                } else {
                    body << " ," << std::endl ;
                }
                body << "    \"" << alloc_info->name << "\" : \"" << alloc_info->user_type_name << "\"" ;
            }
        }
        body << std::endl ;
    } else {

        //TODO: More path character translations for characters like "[]"

        if ( path[strlen(path) - 1] == '/') {
            path[strlen(path) - 1] = '\0' ;
        }
        for ( unsigned int ii = 1 ; ii < strlen(path) ; ii++ ) {
            if ( path[ii] == '/') {
                path[ii] = '.' ;
            }
        }

        body << "    \"name\" : \"" << &path[1] << "\" ," << std::endl ;
        //std::cout << "getting var " << path << std::endl ;
        // skip leading "/"
        REF2 * ref = ref_attributes( &path[1] ) ;
        if ( ref != NULL and ref->attr != NULL ) {
            ret = 200 ;
            //std::cout << "num_index " << ref->num_index << std::endl ;
            if ( ref->attr->type == TRICK_STRUCTURED ) {
                ATTRIBUTES * attr = (ATTRIBUTES *)ref->attr->attr ;
                body << "    \"links\" : [" << std::endl ;
                for ( int ii = 0 ; attr[ii].name[0] != '\0' ; ii++ ) {
                    if ( ii != 0 ) {
                        body << " ," << std::endl ;
                    }
                    body << "                \"" << attr[ii].name << "\"" ;
                }
                body << std::endl << "              ] ," << std::endl ;
            } else {
                body << "    \"value\" : " ;
                Trick::PythonPrint::write_rvalue(body, ref->address, ref->attr, ref->num_index, 0, false, true) ;
                body << " ," << std::endl ;
                if ( ref->attr->units != NULL ) {
                    body << "    \"units\" : \"" << ref->attr->units << "\" ," << std::endl ;
                }
            }
            if ( ref->attr->des != NULL ) {
                body << "    \"description\" : \"" << ref->attr->des << "\" ," << std::endl ;
            }
            body << "    \"type_name\" : " ;
            if ( ref->attr->type_name != NULL ) {
                body << "\"" << ref->attr->type_name << "\" ," << std::endl ;
            } else {
                body << "\"(null)\" ," << std::endl ;
            }
            body << "    \"type\" : " << ref->attr->type << " ," << std::endl ;
            body << "    \"io\" : " << ref->attr->io ;
            if ( (ref->attr->num_index - ref->num_index) > 0 ) {
                body << " ," << std::endl ;
                body << "    \"num_index\" : " << ref->attr->num_index - ref->num_index << " ," << std::endl ;
                body << "    \"index\" : [" << std::endl ;
                for ( int ii = ref->num_index , jj = 0 ; ii < ref->attr->num_index ; ii++ , jj++ ) {
                    if ( jj != 0 ) {
                        body << " ," << std::endl ;
                    }
                    body << "                {" << std::endl ;
                    body << "                    \"size\" : " << ref->attr->index[ii].size << " ," << std::endl ;
                    body << "                    \"start\" : " << ref->attr->index[ii].start << std::endl ;
                    body << "                }" ;
                }
                body << std::endl << "              ]" << std::endl ;
            } else {
                body << std::endl ;
            }
            free(ref) ;
        } else {
            body << "    \"message\" : \"Not Found\"" << std::endl ;
            ret = 404 ;
        }
    }
    return ret ;
}