Linux bluetooth RFCOMM example in C(C 상 리눅스 블루투스 예제)

1. 목적

ㄱ. 리눅스 상에서 블루투스를 통한 통신을 하기 위하여 rfcomm 방식의 통신의 예를 통해 통신하여 본다.

2. 본론

ㄱ. 먼저 블루투스 통신은 크게 2가지로 나뉜다. 

a. TCP 같은 기능을 하는 RFCOMM : TCP는 65535개의 포트를 지원하지만 RFCOMM은 30개의 포트를 지원함

b. UDP와 같은 기능을 하는 L2CAP

ㄴ. 아래의 소스코드는 RFCOMM 예제이이다. RFCOMM 프로토콜은 더욱 믿을 수 있는 연결을 지원한다(TCP와 유사함)

ㄷ. 다음의 명령어를 통해 서버측 디바이스의 블루투스 address를 알아 볼 수 있다.

$ hcitool dev

Devices:
hci0 00:1F:81:03:11:22

ㄹ. RFCOMM server.c 소스

view plaincopy to clipboardprint?

1. /*  
2. compilation step  
3.  
4. # gcc -o server server.c -lbluetooth -lpthread  
5.  
6. */   
7. #include <stdio.h>   
8. #include <stdlib.h>   
9. #include <string.h>   
10. #include <unistd.h>   
11. #include <signal.h>   
12. #include <pthread.h>   
13. #include <sys/socket.h>   
14. #include <bluetooth/bluetooth.h>   
15. #include <bluetooth/rfcomm.h>   
16.   
17. int s,client ;   
18. void ctrl_c_handler(int signal);   
19. void close_sockets();   
20. void *readMsg();   
21. void *sendMsg();   
22.   
23. int main(int argc,char **argv){   
24. (void) signal(SIGINT,ctrl_c_handler);   
25.   
26. pthread_t readT, writeT;   
27. char *message1 = "Read thread\n";   
28. char *message2 = "Write thread\n";   
29. int iret1, iret2;   
30.   
31. struct sockaddr_rc loc_addr={ 0 },client_addr={ 0 };   
32. char buf[18] = { 0 };   
33.   
34. unsigned int opt = sizeof(client_addr) ;   
35.   
36.   
37. //allocate socket   
38. s = socket(AF_BLUETOOTH,SOCK_STREAM,BTPROTO_RFCOMM) ;   
39.   
40.   
41. //bind socket to port 1 of the first available   
42. loc_addr.rc_family = AF_BLUETOOTH ;   
43. str2ba("00:1F:81:00:00:01",&loc_addr.rc_bdaddr) ;//hci0; server device address is given   
44. loc_addr.rc_channel = 1 ; //port (maximum should be 30 for RFCOMM)   
45.   
46. bind(s,(struct sockaddr *)&loc_addr,sizeof(loc_addr));   
47. printf("Binding success\n");   
48.   
49. //put socket into listen mode   
50. listen(s,1) ;   
51. printf("socket in listen mode\n");   
52. //accept one connection   
53.   
54. client = accept(s,(struct sockaddr *)&client_addr,&opt);   
55. ba2str(&client_addr.rc_bdaddr,buf);   
56. fprintf(stdout,"Connection accepted from %s\n",buf);   
57.   
58. /* Create independent threads each of which will execute function */   
59.   
60. iret1 = pthread_create(&readT,NULL,readMsg,(void*) message1);   
61. iret2 = pthread_create(&writeT,NULL,sendMsg,(void*) message2);   
62.   
63. pthread_join(readT,NULL);   
64. pthread_join(writeT,NULL);   
65.   
66. close_sockets() ;   
67. return 0 ;   
68. }   
69.   
70. void *sendMsg(){   
71. char msg[25] ;   
72. int status ;   
73.   
74. do{   
75. memset(msg,0,sizeof(msg));   
76. fgets(msg,24,stdin);   
77. if(strncmp("EXIT",msg,4)==0 || strncmp("exit",msg,4)==0)break;   
78. status = send(client,msg,strlen(msg),0);   
79. fprintf(stdout,"Status = %d\n",status);   
80. }while(status > 0);   
81. }   
82.   
83. void *readMsg(){   
84. int bytes_read;   
85. char buf[1024] = { 0 };   
86. do{   
87. memset(buf,0,sizeof(buf));   
88. //read data from the client   
89. bytes_read = recv(client,buf,sizeof(buf),0) ;   
90. fprintf(stdout,"Bytes read = %d\n",bytes_read);   
91. if(bytes_read <= 0)break;   
92. fprintf(stdout,"<<>> %s",buf);   
93. }while(1);   
94. }   
95.   
96. void close_sockets(){   
97. //close connection   
98. close(client);   
99. close(s) ;   
100. printf("sockets closed\n");   
101. }   
102.   
103. void ctrl_c_handler(int signal) {   
104. printf("Catched signal: %d ... !!\n", signal);   
105. close_sockets();   
106. exit(0);   
107. //(void) signal(SIGINT, SIG_DFL);   
108. }   

/* compilation step # gcc -o server server.c -lbluetooth -lpthread */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <signal.h> #include <pthread.h> #include <sys/socket.h> #include <bluetooth/bluetooth.h> #include <bluetooth/rfcomm.h> int s,client ; void ctrl_c_handler(int signal); void close_sockets(); void *readMsg(); void *sendMsg(); int main(int argc,char **argv){ (void) signal(SIGINT,ctrl_c_handler); pthread_t readT, writeT; char *message1 = "Read thread\n"; char *message2 = "Write thread\n"; int iret1, iret2; struct sockaddr_rc loc_addr={ 0 },client_addr={ 0 }; char buf[18] = { 0 }; unsigned int opt = sizeof(client_addr) ; //allocate socket s = socket(AF_BLUETOOTH,SOCK_STREAM,BTPROTO_RFCOMM) ; //bind socket to port 1 of the first available loc_addr.rc_family = AF_BLUETOOTH ; str2ba("00:1F:81:00:00:01",&loc_addr.rc_bdaddr) ;//hci0; server device address is given loc_addr.rc_channel = 1 ; //port (maximum should be 30 for RFCOMM) bind(s,(struct sockaddr *)&loc_addr,sizeof(loc_addr)); printf("Binding success\n"); //put socket into listen mode listen(s,1) ; printf("socket in listen mode\n"); //accept one connection client = accept(s,(struct sockaddr *)&client_addr,&opt); ba2str(&client_addr.rc_bdaddr,buf); fprintf(stdout,"Connection accepted from %s\n",buf); /* Create independent threads each of which will execute function */ iret1 = pthread_create(&readT,NULL,readMsg,(void*) message1); iret2 = pthread_create(&writeT,NULL,sendMsg,(void*) message2); pthread_join(readT,NULL); pthread_join(writeT,NULL); close_sockets() ; return 0 ; } void *sendMsg(){ char msg[25] ; int status ; do{ memset(msg,0,sizeof(msg)); fgets(msg,24,stdin); if(strncmp("EXIT",msg,4)==0 || strncmp("exit",msg,4)==0)break; status = send(client,msg,strlen(msg),0); fprintf(stdout,"Status = %d\n",status); }while(status > 0); } void *readMsg(){ int bytes_read; char buf[1024] = { 0 }; do{ memset(buf,0,sizeof(buf)); //read data from the client bytes_read = recv(client,buf,sizeof(buf),0) ; fprintf(stdout,"Bytes read = %d\n",bytes_read); if(bytes_read <= 0)break; fprintf(stdout,"<<>> %s",buf); }while(1); } void close_sockets(){ //close connection close(client); close(s) ; printf("sockets closed\n"); } void ctrl_c_handler(int signal) { printf("Catched signal: %d ... !!\n", signal); close_sockets(); exit(0); //(void) signal(SIGINT, SIG_DFL); }

ㅁ. RFCOMM client.c 소스

view plaincopy to clipboardprint?

1. /*  
2. compilation step  
3.  
4. # gcc -o client client.c -lbluetooth -lpthread  
5.  
6. */   
7.   
8. #include <stdio.h>   
9. #include <stdlib.h>   
10. #include <signal.h>   
11. #include <pthread.h>   
12. #include <unistd.h>   
13. #include <sys/socket.h>   
14. #include <bluetooth/bluetooth.h>   
15. #include <bluetooth/rfcomm.h>   
16.   
17. int s ;   
18. void ctrl_c_handler(int signal);   
19. void close_sockets();   
20. void *readMsg();   
21. void *sendMsg();   
22.   
23. int main(int argc,char **argv){   
24. (void) signal(SIGINT,ctrl_c_handler);   
25.   
26. pthread_t readT, writeT;   
27. char *message1 = "Read thread\n";   
28. char *message2 = "Write thread\n";   
29. int iret1, iret2;   
30.   
31. struct sockaddr_rc addr= { 0 };   
32. int status ;   
33. char dest[18] = "00:1F:81:00:00:01";   
34. char msg[25];   
35.   
36. //allocate a socket   
37. s = socket(AF_BLUETOOTH,SOCK_STREAM,BTPROTO_RFCOMM);   
38. addr.rc_family = AF_BLUETOOTH ;   
39. addr.rc_channel = 1 ;   
40. str2ba(dest,&addr.rc_bdaddr);   
41.   
42. //connect to server   
43. printf("going 2 connect\n");   
44. status = connect(s,(struct sockaddr *)&addr,sizeof(addr)) ;   
45.   
46. //send a message   
47. if(0 == status){   
48. printf("connect success\n");   
49.   
50. /* Create independent threads each of which will execute function */   
51.   
52. iret1 = pthread_create(&readT,NULL,readMsg,(void*) message1);   
53. iret2 = pthread_create(&writeT,NULL,sendMsg,(void*) message2);   
54.   
55. pthread_join(readT,NULL);   
56. pthread_join(writeT,NULL);   
57.   
58. }   
59.   
60.   
61. close_sockets();   
62. return 0;   
63. }   
64.   
65. void *sendMsg(){   
66. char msg[25] ;   
67. int status ;   
68.   
69. do{   
70. memset(msg,0,sizeof(msg));   
71. fgets(msg,24,stdin);   
72. if(strncmp("EXIT",msg,4)==0 || strncmp("exit",msg,4)==0)break;   
73. status = send(s,msg,strlen(msg),0);   
74. fprintf(stdout,"Status = %d\n",status);   
75. }while(status > 0);   
76. }   
77.   
78. void *readMsg(){   
79. int bytes_read;   
80. char buf[1024] = { 0 };   
81. do{   
82. memset(buf,0,sizeof(buf));   
83. //read data from the client   
84. bytes_read = recv(s,buf,sizeof(buf),0) ;   
85. fprintf(stdout,"Bytes read = %d\n",bytes_read);   
86. if(bytes_read <= 0)break;   
87. fprintf(stdout,"<<>> %s",buf);   
88. }while(1);   
89. }   
90.   
91. void close_sockets(){   
92. close(s);   
93. fprintf(stdout,"Close sockets\n");   
94. }   
95.   
96. void ctrl_c_handler(int signal){   
97. fprintf(stdout,"Interrupt caught[NO: %d ]\n",signal);   
98. close_sockets();   
99. exit(0);   
100. }   

/* compilation step # gcc -o client client.c -lbluetooth -lpthread */ #include <stdio.h> #include <stdlib.h> #include <signal.h> #include <pthread.h> #include <unistd.h> #include <sys/socket.h> #include <bluetooth/bluetooth.h> #include <bluetooth/rfcomm.h> int s ; void ctrl_c_handler(int signal); void close_sockets(); void *readMsg(); void *sendMsg(); int main(int argc,char **argv){ (void) signal(SIGINT,ctrl_c_handler); pthread_t readT, writeT; char *message1 = "Read thread\n"; char *message2 = "Write thread\n"; int iret1, iret2; struct sockaddr_rc addr= { 0 }; int status ; char dest[18] = "00:1F:81:00:00:01"; char msg[25]; //allocate a socket s = socket(AF_BLUETOOTH,SOCK_STREAM,BTPROTO_RFCOMM); addr.rc_family = AF_BLUETOOTH ; addr.rc_channel = 1 ; str2ba(dest,&addr.rc_bdaddr); //connect to server printf("going 2 connect\n"); status = connect(s,(struct sockaddr *)&addr,sizeof(addr)) ; //send a message if(0 == status){ printf("connect success\n"); /* Create independent threads each of which will execute function */ iret1 = pthread_create(&readT,NULL,readMsg,(void*) message1); iret2 = pthread_create(&writeT,NULL,sendMsg,(void*) message2); pthread_join(readT,NULL); pthread_join(writeT,NULL); } close_sockets(); return 0; } void *sendMsg(){ char msg[25] ; int status ; do{ memset(msg,0,sizeof(msg)); fgets(msg,24,stdin); if(strncmp("EXIT",msg,4)==0 || strncmp("exit",msg,4)==0)break; status = send(s,msg,strlen(msg),0); fprintf(stdout,"Status = %d\n",status); }while(status > 0); } void *readMsg(){ int bytes_read; char buf[1024] = { 0 }; do{ memset(buf,0,sizeof(buf)); //read data from the client bytes_read = recv(s,buf,sizeof(buf),0) ; fprintf(stdout,"Bytes read = %d\n",bytes_read); if(bytes_read <= 0)break; fprintf(stdout,"<<>> %s",buf); }while(1); } void close_sockets(){ close(s); fprintf(stdout,"Close sockets\n"); } void ctrl_c_handler(int signal){ fprintf(stdout,"Interrupt caught[NO: %d ]\n",signal); close_sockets(); exit(0); }

3. 결론

ㄱ. 블루투스의 RFCOMM  프로토콜 통신의 예를 통해 학습하여 보았다.