Server socket BIO (BIO_s_accept)

BIO_s_accept can be used as an server socket object, and has it’s own data struct BIO_ACCEPT, which is stored in BIO.ptr. in the struct, a status value BIO_ACCEPT.state is introduced to record the current state of socket, The statues are:

#define ACPT_S_BEFORE               1

#define ACPT_S_GET_ACCEPT_SOCKET   2

#define ACPT_S_OK               3

The status indicate what to do next step. Use the internal function conn_state() take the next action. Until call the blocking accept() or an error happens.

The BIO_s_connect’s bio_accept_st uses a bio list to restores the accepted socket, and add the remote socket at the end of the list.

If the remote client is closed, the BIO_read() will wake and return 0; if the close is not graceful, will return -1;

 

Notes that all the socket functions run in blocking mode.

All the functions are implemented in file Bss_acpt.c.

 

Use steps:

    Create a socket bio and input port number.

    You may use just one line:

BIO *abio = BIO_new_accept("2000");

Then accept:

    If (BIO_do_accept(abio) <= 0) …

Notes the function only initial the BIO, if wanna accept connection you need to call it twice. The first time push state from ACPT_S_BEFORE  to ACPT_S_GET_ACCEPT_SOCKET, the second time do the actual accept BIO_accept().

 

Get remote IP

So strange, BIO_s_accept doesn’t support get the remove IP. Only can get the port number… while the BIO popped don’t have a BIO.ptr, and can only be used to send and recv data.

/* BIO_s_accept_socket() */

#define BIO_set_accept_port(b,name) BIO_ctrl(b,BIO_C_SET_ACCEPT,0,(char *)name)

#define BIO_get_accept_port(b)  BIO_ptr_ctrl(b,BIO_C_GET_ACCEPT,0)

/* #define BIO_set_nbio(b,n)    BIO_ctrl(b,BIO_C_SET_NBIO,(n),NULL) */

#define BIO_set_nbio_accept(b,n) BIO_ctrl(b,BIO_C_SET_ACCEPT,1,(n)?"a":NULL)

#define BIO_set_accept_bios(b,bio) BIO_ctrl(b,BIO_C_SET_ACCEPT,2,(char *)bio)

Our solution: to get remote IP:

       char* pch = NULL;

       pch = ((BIO_ACCEPT*)(abio->ptr))->addr;

and you have to copy definition of BIO_ACCEPT ahead of code, and BIO_ACCEPT.addr only restore the recent connected client IP.

 

And also you may get the remote IP by the classical way:

       SOCKET sClient = (SOCKET)BIO_get_fd(cbio, NULL);

       SOCKADDR sName;

       int iAddLen = sizeof(sName);

       getpeername(sClient, &sName, &iAddLen);

 

OK, said so much, now give the sample echo server code:

 

DWORD WINAPI listenThread(LPVOID lpParameter) {     BIO *abio, *cbio;     HANDLE hThread;     unsigned long ulthID = 0;       if (NULL == (abio = BIO_new_accept("2000")))        return 0;       if(BIO_do_accept(abio) <= 0) {        printf("Error setting up accept/n");        return 0;     }     printf("Server started/n");       while(TRUE) {          if(BIO_do_accept(abio) <= 0) {            printf("Error setting up accept/n");            return 0;        }          // try to get client IP        char* pch = NULL;        pch = ((BIO_ACCEPT*)(abio->ptr))->addr;        //pch = BIO_get_accept_port(abio);        printf("client IP:%s/n", pch);          cbio = BIO_pop(abio);        //SOCKET sClient = (SOCKET)BIO_get_fd(cbio, NULL);        //SOCKADDR sName;        //int iAddLen = sizeof(sName);        //getpeername(sClient, &sName, &iAddLen);        //pch = inet_ntoa(*(in_addr*)(sName.sa_data +2));        //printf("client IP:%s/n", pch);          hThread = CreateThread(NULL, 0, rwThread, cbio, NULL, &ulthID);        if (hThread == NULL) {            printf("CreateThread failed./n" );            return 0;        }        printf("client thread %x created/n", ulthID);     } }   DWORD WINAPI listenThreadBss(LPVOID lpParameter) {     BIO *bClient=NULL,*bAccept=NULL;     int sock,ret;     char *addr=NULL;     HANDLE hThread;     unsigned long ulthID = 0;         if (INVALID_SOCKET == (sock = BIO_get_accept_socket("2000", BIO_BIND_NORMAL)))        return 0;     printf("Server started/n");         while(TRUE) {          // the same as accept, blocking mode, with the address containing remote client address.        // but if addr == NULL, memory would be allocated.        // the ret is the SOCKET object.        if (INVALID_SOCKET == (ret = BIO_accept(sock,&addr)))            return 0;        printf("client IP:%s/n", addr);          bClient = BIO_new(BIO_s_socket());        if (NULL == bClient)            return 0;        // set the SOCKET object "ret" into bio.num. then the bClient can be used to read and write from remote client.        BIO_set_fd(bClient,ret,BIO_NOCLOSE);          hThread = CreateThread(NULL, 0, rwThread, bClient, NULL, &ulthID);        if (hThread == NULL) {            printf("CreateThread failed./n" );        }        printf("client thread %x created/n", ulthID);     }   }   DWORD WINAPI rwThread(LPVOID lpParameter) {     BIO *cbio = (BIO *)lpParameter;     int        sock,ret,len;     char          *addr=NULL;     char          in[80];     unsigned long ulthID = GetCurrentThreadId();       while(1)     {        memset(in,0,80);        len=BIO_read(cbio,in,80);        if(in[0]=='q' || -1 == len)            break;        printf("thread %x from the client: %s/n",ulthID, in);          // echo the message        len = BIO_write(cbio, in, len);        if (0 == len)            break;     }     BIO_free(cbio);     return 0; }     int _tmain(int argc, _TCHAR* argv[]) {     HANDLE hThread;       hThread = CreateThread(NULL, 0, listenThread, NULL, NULL, NULL);     //hThread = CreateThread(NULL, 0, listenThreadBss, NULL, NULL, NULL);     if (hThread == NULL) {        printf("CreateThread failed./n" );     }       WaitForSingleObject(hThread, INFINITE);       return 0; }