[c++,bson,linux]网络编程之使用 BSON 来收发消息

在前几篇的博客中简单的介绍了一下 BSON 的使用方法，那么在这片文章中将介绍一下网络编程中，
如何使用 BSON 来在服务器和客户端收发消息结构。
本篇文章中的示例代码是基于前一篇文章中"[c++, linux]网络编程之 poll 的使用方法" 所编写的服务器端和客户端代码实现的。

代码结构
message_sender/
                 |-------------/utils/
                                     |------ message.h
                 |-------------/client/
                                      |----- client.cpp
                                      |----- build.sh
                                      |----- Makefile.am
                                      |----- configure.in
                 |------------/server/                   
                                      |----- server.cpp
                                      |----- build.sh
                                      |----- Makefile.am
                                      |----- configure.in             
示例代码
utils/message.h

#ifndef MESSAGE_H
#define MESSAGE_H

typedef struct  msg_header
{
  int len ;

  msg_header() : len (0)
  {}

} header_t;

typedef struct msg
{
  header_t header ;
  char data[0] ;

} message_t;


#endif // message.h

Client
1. build.sh

#!/bin/sh

autoscan
aclocal
autoconf
autoheader   #after autoheader , create a Makefile.am then continue execute follow command
automake --add-missing
./configure CXXFLAGS= CFLAGS=
make

2.configure.in

# -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.

AC_INIT(message_sender_client)
AC_CONFIG_SRCDIR([client.cpp])
AC_CONFIG_HEADERS([config.h])

AM_INIT_AUTOMAKE(message_sender_client, 1.0)


# Checks for programs.
AC_PROG_CXX
AC_PROG_CC

#add by Aimer , cause method use realloc
AC_FUNC_REALLOC

# Checks for header files.
AC_CHECK_HEADERS([arpa/inet.h netinet/in.h strings.h sys/socket.h unistd.h])

# Checks for typedefs, structures, and compiler characteristics.
AC_TYPE_SSIZE_T

# Checks for library functions.
AC_CHECK_FUNCS([bzero socket])

AC_OUTPUT(Makefile)

3.Makefile.am

AUTOMAKE_OPTIONS=foreign
bin_PROGRAMS=message_sender_client

#define short names for bson path and boost path
BSON_PATH=/unixC/Bson/bson/src
BOOST_PATH=/unixC/Boost/boost_1_58_0

message_sender_client_SOURCES=\
client.cpp \
$(BSON_PATH)/bsonobj.cpp $(BSON_PATH)/util/json.cpp \
$(BSON_PATH)/oid.cpp $(BSON_PATH)/lib/base64.cpp \
$(BSON_PATH)/lib/md5.cpp $(BSON_PATH)/lib/nonce.cpp


message_sender_client_CXXFLAGS=\
-I$(BOOST_PATH) -I$(BSON_PATH) \
-D_FILE_OFFSET_BITS=64 -ggdb -Wall -O0

message_sender_client_LDADD=\
-lpthread -lm -lboost_system -lboost_thread \
-lboost_thread -lboost_program_options -lrt

message_sender_client_LDFLAGS=\
-fPIC -rdynamic -L$(BOOST_PATH)/stage/lib -pthread

4.client.cpp

#include <cstdio> // perror
#include <cstring> // string
#include <strings.h> // memset
#include <iostream>
#include <sys/types.h> // AF_INET, SOCK_STREAM
#include <sys/socket.h> // socket , connect
#include <arpa/inet.h> // inet_aton
#include <netinet/in.h>
#include <unistd.h>

#include <bson.h> // BSONObj , BSONObjBuilder

#include "../utils/message.h" // struct message_t

#define SERVER_PORT  1027
#define SERVER_IP "10.0.2.15"
#define MAXLINE      1024*2

using namespace std ;
using namespace bson ;

// add method buildMessage  here
/**
method :
 int buildMessage ( char **ppBuffer[out], int *pBufferSize[out], BSONObj *obj[in] )
 return :
        0 if success building a message
        -1 if failed building a message
*/

int buildMessage ( char **ppBuffer , int *pBufferSize , BSONObj *obj )
{
   message_t *pMessage = NULL ;
   int size = sizeof(message_t) ;

   if ( obj != NULL )
       size += obj->objsize() ;

   if ( size > *pBufferSize )
   {
    *ppBuffer = (char*)realloc(*ppBuffer , size*sizeof(char)) ;
         *pBufferSize = size ;

         if ( *ppBuffer == NULL )
     {
        perror ("failed to realloc space for ppBuffer") ;
        return -1 ;
         }
   }

  pMessage = (message_t*)(*ppBuffer) ;
  pMessage->header.len = size ;

  if ( obj != NULL )
  {
    memcpy (&pMessage->data[0] , obj->objdata() , obj->objsize() ) ;
  }

  return 0 ;
}


int main ( int argc , char **argv )
{
   char buf [MAXLINE] ;
   ssize_t n ; // message content length
   struct sockaddr_in server_addr ;
   int connfd ;
   int ret ;
   string msg ;

   connfd = socket (AF_INET , SOCK_STREAM , 0 ) ;
   bzero (&server_addr , sizeof(struct sockaddr_in)) ;

   server_addr.sin_family = AF_INET ;
   server_addr.sin_port = htons (SERVER_PORT) ;
   inet_aton (SERVER_IP , &server_addr.sin_addr ) ;

   ret = connect ( connfd , (struct sockaddr*)&server_addr , sizeof(struct sockaddr_in) ) ;


 if ( ret < 0 )
  {
    perror ("failed connect") ;
    return -1;
  }

  cout << "input message "<< endl ;
  cin >> msg ;

  BSONObjBuilder builder ;

  builder.append ("message data", msg.c_str ()) ;

  BSONObj obj = builder.obj() ;

  char *pBuffer = NULL ;
  int pBufferSize = 0 ;

  cout << obj.toString() << endl ;

  cout << "-------- /test build message/ ------------"<<endl ;

  buildMessage (&pBuffer , &pBufferSize , &obj) ;

// pBuffer content can not be seen on console
// cout << " here is the pBuffer content \n "<< pBuffer << endl ;
  cout <<"message size " << pBufferSize << endl ;
  cout << "message data size " << obj.objsize() << endl ;
  cout << "message header size " << pBufferSize - obj.objsize() << endl ;

  write (connfd , pBuffer , pBufferSize ) ;


 return 0 ;
}

---

---

Server
1.build.sh

#!/bin/sh

autoscan
aclocal
autoconf
autoheader
automake --add-missing
./configure CXXFLAGS= CFLAGS=
make

2.configure.in

#                 -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.


AC_INIT(message_sender_server)

AC_USE_SYSTEM_EXTENSIONS    # we will use bson and boost

AM_INIT_AUTOMAKE(message_sender_server,1.0)

AC_CONFIG_SRCDIR([server.cpp])

AC_CONFIG_HEADERS([config.h])

# Checks for programs.
AC_PROG_CXX

AC_PROG_CC

# Checks for libraries.

# Checks for header files.
AC_CHECK_HEADERS([limits.h netdb.h netinet/in.h strings.h sys/socket.h unistd.h])

# Checks for typedefs, structures, and compiler characteristics.
AC_TYPE_SSIZE_T

# Checks for library functions.
AC_CHECK_FUNCS([bzero socket])

AC_OUTPUT(Makefile)

3.Makefile.am

AUTOMAKE_OPTIONS=foreign
bin_PROGRAMS=message_sender_server

BSON_PATH=/unixC/Bson/bson/src
BOOST_PATH=/unixC/Boost/boost_1_58_0

message_sender_server_SOURCES=\
server.cpp \
$(BSON_PATH)/bsonobj.cpp $(BSON_PATH)/util/json.cpp \
$(BSON_PATH)/oid.cpp $(BSON_PATH)/lib/base64.cpp \
$(BSON_PATH)/lib/md5.cpp $(BSON_PATH)/lib/nonce.cpp

message_sender_server_CXXFLAGS=\
-I$(BOOST_PATH) -I$(BSON_PATH) -D_FILE_OFFSET_BITS=64 \
-ggdb -Wall -O0

message_sender_server_LDADD=\
-lpthread -lm -lboost_system -lboost_thread \
-lboost_thread -lboost_program_options -lrt

message_sender_server_LDFLAGS=\
-fPIC -rdynamic -L$(BOOST_PATH)/stage/lib -pthread

4.server.cpp

#include <cstdio>
#include <limits.h>
#include <sys/types.h>     // socket , bind , accept
#include <sys/socket.h>     // socket , bind , socklen_t , accept
#include <poll.h>     // poll, struct pollfd
#include <netdb.h>     // socklen_t
#include <netinet/in.h>     // struct sockaddr_in , sockaddr
#include <errno.h>         // errno
#include <unistd.h> // read, write
#include <strings.h>        // bzero
#include <iostream> // cout , endl , cin

#include <bson.h> // BSONObj
#include "../utils/message.h" // struct message_t

#define MAXLINE     1024*2
#define OPEN_MAX     1024
#define SERVER_PORT     1027
#define INFTIM        1024

using namespace std ;
using namespace bson ;

//add method parseMessage
/**
method :
    this method is used to extract message's data
    from char *pBuffer , into BSONObj this object
    int parseMessage( char *pBuffer [in], BSONObj &msgData [out])
    return:
    0 : success extracting  message data into BSONObj
        -1: failed extracting   message data into BSONObj

   [in] : means this parameter is pass-in-value parameter
   [out] : means this parameter is value-result which can
       also be recognized as the return value of the method
*/

int parseMessage ( char *pBuffer, BSONObj &msgData )
{
  if ( pBuffer == NULL )
  {
    perror ("message is invalid ") ;
    return -1 ;
  }

  message_t *pMessage = (message_t*)(pBuffer) ;

  if ( pMessage->header.len < sizeof(message_t) )
  {
    perror ("message content is invalid ") ;
    return -1 ;
  }

 // cout << pMessage->header.len << endl ;
// cout << &pMessage->data[0] << endl ;

// BSONObjBuilder builder ;
// builder.append ("", &(pMessage->data[0])) ;

  msgData = BSONObj(&pMessage->data[0]) ;


  return 0 ;
}


int main ( int argc , char ** argv )
{
    int i , maxi , listenfd , connfd , sockfd ;
    int nready ;
    ssize_t n ;
    char buf[MAXLINE] ;
    socklen_t client_len ;
    struct pollfd client[OPEN_MAX] ;
    struct sockaddr_in client_addr , server_addr ;

    listenfd = socket ( AF_INET , SOCK_STREAM , 0 ) ;
    bzero ( &server_addr , sizeof(struct sockaddr_in)) ;

    server_addr.sin_family = AF_INET ;
    server_addr.sin_addr.s_addr = htonl (INADDR_ANY) ;
    server_addr.sin_port = htons ( SERVER_PORT ) ;

    bind (listenfd , (struct sockaddr*)&server_addr ,
            sizeof(struct sockaddr_in) ) ;

    listen ( listenfd , 10 ) ;

    client[0].fd = listenfd ;
    client[0].events = POLLRDNORM ; // poll read normal

    for ( i = 1 ; i < OPEN_MAX ; i++ )
    {
      client[i].fd = -1;
    }

    maxi = 0 ;

    for ( ; ; )
    {
        nready = poll (client , maxi+1 , INFTIM) ;

     if ( client[0].revents & POLLRDNORM )
     {
         // this means new client connection request come
           client_len = sizeof( struct sockaddr_in ) ;
           connfd = accept ( listenfd , (struct sockaddr*)&client_addr ,
            &client_len ) ;

         // updates maxi, and check if i out of limition of OPEN_MAX
         for ( i = 1 ; i < OPEN_MAX ; i++ )
         {
            if ( client[i].fd < 0 )
            {
               client[i].fd = connfd ;
               break ;
            }
         } // for

         if ( i == OPEN_MAX )
         {
            perror ("too many client requests ") ;
            return -1 ;
         }

          client[i].events = POLLRDNORM ;

                  if ( i > maxi )
             maxi = i ;

         if ( --nready <= 0 )
            continue ;
     } // if

        for ( i = 1 ; i <= maxi ; i++ )
        {
         if ( ( sockfd = client[i].fd ) < 0 )
            continue ; // continue the sub for cycle

         if ( client[i].revents & (POLLRDNORM | POLLERR) )
         {
                    if ( ( n = read(sockfd , buf , MAXLINE)) < 0 )
                 {
                // read n < 0 , it must some error happen
                  // if client reset connection , release client[i].fd
                // else return error code
                    if ( errno == ECONNRESET )
             {
                    // this means client reset connection
                    close (sockfd) ;
                    client[i].fd = -1 ;
                }
                else
                {
                    perror ("error when server read from client") ;
                    return -1 ;
                }

                 }
                 else if ( n == 0 )
                 {
                // this means client close connection
                close (sockfd) ;
                client[i].fd = -1 ;
                 }
                 else
                 {

                //cout << "n = " << n << endl ;

                BSONObj msgData ;

                parseMessage (buf , msgData) ;
                cout << msgData.toString() << endl ;

                // n > 0 , server read something from client
     // cout << "receive message len " << msgData.objsize() <<endl ;
            }

         } // if POLLRDNORM | POLLERROR

        }// for

    } // main cycle

    return 0 ;
}

end