The NetBIOS Datagram Program is a simple application designed to showcase the functionality of NetBIOS (Network Basic Input/Output System) in the context of datagram operations. NetBIOS is a communication protocol that allows applications on different computers to communicate over a local area network (LAN). Datagram operations involve sending and receiving data in a connectionless manner which makes it suitable for tasks such as broadcasting messages or targeted communication.
This application demonstrates the various datagram operations such as sending and receiving both directed and group datagrams as well as broadcast datagrams. The name service uses UDP Protocol on port 137. However, TCP/IP Protocol on port 137 can also be used in some cases.
Compile
cl -o Nbdgram.exe Nbdgram.c ..\Common\Nbcommon.obj Netapi32.lib User32.lib
Command Line Options
nbdgram.exe options
- -n:NAME Register my unique name NAME
- -g:NAME Register my group name NAME
- -s I will be sending datagrams
- -c:xxx Number of datagrams to send
- -r:NAME The recipients NetBIOS name
- -b Use broadcast datagrams
- -a Receive datagrams for any NetBIOS name
- -l:xxx Send datagrams on LANA number xxx only
- -d:xxx Delay (in milliseconds) between sends
You need to be familiar with the following in order to properly compile and run this program.
- The program relies on a
Nbcommonlibrary (Nbcommon.obj) for certain functions. Ensure it is available during compilation. - Understanding NetBIOS and networking concepts will enhance your comprehension of the program’s functionality.
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Also specified is the data buffer and // the number of bytes to send. // int DatagramSend(int lana, int num, char* recipient, char* buffer, int buflen) { NCB ncb; ZeroMemory(&ncb, sizeof(NCB)); ncb.ncb_command = NCBDGSEND; ncb.ncb_lana_num = lana; ncb.ncb_num = num; ncb.ncb_buffer = (PUCHAR)buffer; ncb.ncb_length = buflen; memset(ncb.ncb_callname, ' ', NCBNAMSZ); strncpy(ncb.ncb_callname, recipient, strlen(recipient)); if (Netbios(&ncb) != NRC_GOODRET) { printf("Netbios: NCBDGSEND failed: %d\n", ncb.ncb_retcode); return ncb.ncb_retcode; } return NRC_GOODRET; } // // Function: DatagramSendBC // // Description: // Send a broadcast datagram on the specified LANA number from the // given name number. Also specified is the data buffer and number // of bytes to send. // int DatagramSendBC(int lana, int num, char* buffer, int buflen) { NCB ncb; ZeroMemory(&ncb, sizeof(NCB)); ncb.ncb_command = NCBDGSENDBC; ncb.ncb_lana_num = lana; ncb.ncb_num = num; ncb.ncb_buffer = (PUCHAR)buffer; ncb.ncb_length = buflen; if (Netbios(&ncb) != NRC_GOODRET) { printf("Netbios: NCBDGSENDBC failed: %d\n", ncb.ncb_retcode); return ncb.ncb_retcode; } return NRC_GOODRET; } // // Function: DatagramRecv // // Description: // Receive a datagram on the given LANA number directed towards the // name represented by num. Data is copied into the supplied buffer. // If hEvent is not zero then the receive call is made asynchronously // with the supplied event handle. If num is 0xFF then listen for a // datagram destined for any NetBIOS name registered by the process. // int DatagramRecv(PNCB pncb, int lana, int num, char* buffer, int buflen, HANDLE hEvent) { ZeroMemory(pncb, sizeof(NCB)); if (hEvent) { pncb->ncb_command = NCBDGRECV | ASYNCH; pncb->ncb_event = hEvent; } else pncb->ncb_command = NCBDGRECV; pncb->ncb_lana_num = lana; pncb->ncb_num = num; pncb->ncb_buffer = (PUCHAR)buffer; pncb->ncb_length = buflen; if (Netbios(pncb) != NRC_GOODRET) { printf("Netbos: NCBDGRECV failed: %d\n", pncb->ncb_retcode); return pncb->ncb_retcode; } return NRC_GOODRET; } // // Function: DatagramRecvBC // // Description: // Receive a broadcast datagram on the given LANA number. // Data is copied into the supplied buffer. If hEvent is not zero // then the receive call is made asynchronously with the supplied // event handle. // int DatagramRecvBC(PNCB pncb, int lana, int num, char* buffer, int buflen, HANDLE hEvent) { ZeroMemory(pncb, sizeof(NCB)); if (hEvent) { pncb->ncb_command = NCBDGRECVBC | ASYNCH; pncb->ncb_event = hEvent; } else pncb->ncb_command = NCBDGRECVBC; pncb->ncb_lana_num = lana; pncb->ncb_num = num; pncb->ncb_buffer = (PUCHAR)buffer; pncb->ncb_length = buflen; if (Netbios(pncb) != NRC_GOODRET) { printf("Netbios: NCBDGRECVBC failed: %d\n", pncb->ncb_retcode); return pncb->ncb_retcode; } return NRC_GOODRET; } // // Function: main // // Description: // Initialize the NetBIOS interface, allocate resources, and then // send or receive datagrams according to the user's options. // int main(int argc, char** argv) { LANA_ENUM lenum; int i, j; char szMessage[MAX_DATAGRAM_SIZE], szSender[NCBNAMSZ + 1]; DWORD* dwNum = NULL, dwBytesRead, dwErr; ValidateArgs(argc, argv); // // Enumerate and reset the LANA numbers // if ((dwErr = LanaEnum(&lenum)) != NRC_GOODRET) { printf("LanaEnum failed: %d\n", dwErr); return 1; } if ((dwErr = ResetAll(&lenum, (UCHAR)MAX_SESSIONS, (UCHAR)MAX_NAMES, FALSE)) != NRC_GOODRET) { printf("ResetAll failed: %d\n", dwErr); return 1; } // // This buffer holds the name number for the NetBIOS name added // to each LANA // dwNum = (DWORD*)GlobalAlloc(GMEM_FIXED | GMEM_ZEROINIT, sizeof(DWORD) * lenum.length); if (dwNum == NULL) { printf("out of memory\n"); return 1; } // // If we're going to operate only on one LANA register the name // only on that specified LANA; otherwise register it on all. // if (bOneLana) { if (bUniqueName) AddName(dwOneLana, szLocalName, &dwNum[0]); else AddGroupName(dwOneLana, szLocalName, &dwNum[0]); } else { for (i = 0; i < lenum.length; i++) { if (bUniqueName) AddName(lenum.lana[i], szLocalName, &dwNum[i]); else AddGroupName(lenum.lana[i], szLocalName, &dwNum[i]); } } // We are sending datagrams // if (bSender) { // Broadcast sender // if (bBroadcast) { if (bOneLana) { // Broadcast the message on the one LANA only // for (j = 0; j < dwNumDatagrams; j++) { wsprintf(szMessage, "[%03d] Test broadcast datagram", j); if (DatagramSendBC(dwOneLana, dwNum[0], szMessage, strlen(szMessage)) != NRC_GOODRET) return 1; Sleep(dwDelay); } } else { // Broadcast the message on every LANA on the local // machine // for (j = 0; j < dwNumDatagrams; j++) { for (i = 0; i < lenum.length; i++) { wsprintf(szMessage, "[%03d] Test broadcast datagram", j); if (DatagramSendBC(lenum.lana[i], dwNum[i], szMessage, strlen(szMessage)) != NRC_GOODRET) return 1; } Sleep(dwDelay); } } } else { if (bOneLana) { // Send a directed message to the one LANA specified // for (j = 0; j < dwNumDatagrams; j++) { wsprintf(szMessage, "[%03d] Test directed datagram", j); if (DatagramSend(dwOneLana, dwNum[0], szRecipientName, szMessage, strlen(szMessage)) != NRC_GOODRET) return 1; Sleep(dwDelay); } } else { // Send a directed message to the each LANA on the // local machine // for (j = 0; j < dwNumDatagrams; j++) { for (i = 0; i < lenum.length; i++) { wsprintf(szMessage, "[%03d] Test directed datagram", j); printf("count: %d.%d\n", j, i); if (DatagramSend(lenum.lana[i], dwNum[i], szRecipientName, szMessage, strlen(szMessage)) != NRC_GOODRET) return 1; } Sleep(dwDelay); } } } } else // We are receiving datagrams { NCB* ncb = NULL; char** szMessageArray = NULL; HANDLE* hEvent = NULL; DWORD dwRet; // Allocate an array of NCB structure to submit to each recv // on each LANA // ncb = (NCB*)GlobalAlloc(GMEM_FIXED | GMEM_ZEROINIT, sizeof(NCB) * lenum.length); // // Allocate an array of incoming data buffers // szMessageArray = (char**)GlobalAlloc(GMEM_FIXED, sizeof(char*) * lenum.length); for (i = 0; i < lenum.length; i++) szMessageArray[i] = (char*)GlobalAlloc(GMEM_FIXED, MAX_DATAGRAM_SIZE); // // Allocate an array of event handles for // asynchronous receives // hEvent = (HANDLE*)GlobalAlloc(GMEM_FIXED | GMEM_ZEROINIT, sizeof(HANDLE) * lenum.length); for (i = 0; i < lenum.length; i++) hEvent[i] = CreateEvent(0, TRUE, FALSE, 0); if (bBroadcast) { if (bOneLana) { // Post synchronous broadcast receives on // the one LANA specified // for (j = 0; j < dwNumDatagrams; j++) { if (DatagramRecvBC(&ncb[0], dwOneLana, dwNum[0], szMessageArray[0], MAX_DATAGRAM_SIZE, NULL) != NRC_GOODRET) return 1; FormatNetbiosName(ncb[0].ncb_callname, szSender); printf("%03d [LANA %d] Message: '%s' " "received from: %s\n", j, ncb[0].ncb_lana_num, szMessageArray[0], szSender); } } else { // Post asynchronous broadcast receives on each LANA // number available. For each command that succeeded // print the message otherwise cancel the command. // for (j = 0; j < dwNumDatagrams; j++) { for (i = 0; i < lenum.length; i++) { dwBytesRead = MAX_DATAGRAM_SIZE; if (DatagramRecvBC(&ncb[i], lenum.lana[i], dwNum[i], szMessageArray[i], MAX_DATAGRAM_SIZE, hEvent[i]) != NRC_GOODRET) return 1; } dwRet = WaitForMultipleObjects(lenum.length, hEvent, FALSE, INFINITE); if (dwRet == WAIT_FAILED) { printf("WaitForMultipleObjects failed: %d\n", GetLastError()); return 1; } for (i = 0; i < lenum.length; i++) { if (ncb[i].ncb_cmd_cplt == NRC_PENDING) Cancel(&ncb[i]); else { ncb[i].ncb_buffer[ncb[i].ncb_length] = 0; FormatNetbiosName(ncb[i].ncb_callname, szSender); printf("%03d [LANA %d] Message: '%s' " "received from: %s\n", j, ncb[i].ncb_lana_num, szMessageArray[i], szSender); } ResetEvent(hEvent[i]); } } } } else { if (bOneLana) { // Make a blocking datagram receive on the specified // LANA number. // for (j = 0; j < dwNumDatagrams; j++) { if (bRecvAny) { // Receive data destined for any NetBIOS name // in this process's name table. // if (DatagramRecv(&ncb[0], dwOneLana, 0xFF, szMessageArray[0], MAX_DATAGRAM_SIZE, NULL) != NRC_GOODRET) return 1; } else { if (DatagramRecv(&ncb[0], dwOneLana, dwNum[0], szMessageArray[0], MAX_DATAGRAM_SIZE, NULL) != NRC_GOODRET) return 1; } FormatNetbiosName(ncb[0].ncb_callname, szSender); printf("%03d [LANA %d] Message: '%s' " "received from: %s\n", j, ncb[0].ncb_lana_num, szMessageArray[0], szSender); } } else { // Post asynchronous datagram receives on each LANA // available. For all those commands that succeeded, // print the data, otherwise cancel the command. // for (j = 0; j < dwNumDatagrams; j++) { for (i = 0; i < lenum.length; i++) { if (bRecvAny) { // Receive data destined for any NetBIOS // name in this process's name table. // if (DatagramRecv(&ncb[i], lenum.lana[i], 0xFF, szMessageArray[i], MAX_DATAGRAM_SIZE, hEvent[i]) != NRC_GOODRET) return 1; } else { if (DatagramRecv(&ncb[i], lenum.lana[i], dwNum[i], szMessageArray[i], MAX_DATAGRAM_SIZE, hEvent[i]) != NRC_GOODRET) return 1; } } dwRet = WaitForMultipleObjects(lenum.length, hEvent, FALSE, INFINITE); if (dwRet == WAIT_FAILED) { printf("WaitForMultipleObjects failed: %d\n", GetLastError()); return 1; } for (i = 0; i < lenum.length; i++) { if (ncb[i].ncb_cmd_cplt == NRC_PENDING) Cancel(&ncb[i]); else { ncb[i].ncb_buffer[ncb[i].ncb_length] = 0; FormatNetbiosName(ncb[i].ncb_callname, szSender); printf("%03d [LANA %d] Message: '%s' " "from: %s\n", j, ncb[i].ncb_lana_num, szMessageArray[i], szSender); } ResetEvent(hEvent[i]); } } } } // Clean up // for (i = 0; i < lenum.length; i++) { CloseHandle(hEvent[i]); GlobalFree(szMessageArray[i]); } GlobalFree(hEvent); GlobalFree(szMessageArray); } // Clean things up // if (bOneLana) DelName(dwOneLana, szLocalName); else { for (i = 0; i < lenum.length; i++) DelName(lenum.lana[i], szLocalName); } GlobalFree(dwNum); return 0; } |
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