Whois client code in C with Linux sockets

A whois client is a program that will simply fetch the whois information for a domain/ip address from the whois servers. The code over here works according to the algorithm discussed here.

Code

1

/*

2

* @brief

3	* Whois client program

4

*

5	* @details

6	* This program shall perform whois for a domain and get you the whois data of that domain

7

*

8	* @author Silver Moon ( m00n.silv3r@gmail.com )

9

* */

10

11	#include<stdio.h> //scanf , printf

12	#include<string.h>    //strtok

13	#include<stdlib.h>    //realloc

14	#include<sys/socket.h>    //socket

15	#include<netinet/in.h> //sockaddr_in

16	#include<arpa/inet.h> //getsockname

17	#include<netdb.h> //hostent

18	#include<unistd.h>    //close

19

20	int get_whois_data(char * , char **);

21	int hostname_to_ip(char * , char *);

22	int whois_query(char * , char * , char **);

23	char *str_replace(char *search , char *replace , char *subject );

24

25	int main(int argc , char *argv[])

26

{

27	char domain[100] , *data = NULL;

28

29	printf("Enter domain name to whois : ");

30	scanf("%s" , domain);

31

32	get_whois_data(domain , &data);

33

34	//puts(data);

35

return 0;

36

}

37

38

/*

39	* Get the whois data of a domain

40

* */

41	int get_whois_data(char *domain , char **data)

42

{

43	char ext[1024] , *pch , *response = NULL , *response_2 = NULL , *wch , *dt;

44

45	//remove "http://" and "www."

46	domain = str_replace("http://" , "" , domain);

47	domain = str_replace("www." , "" , domain);

48

49	//get the extension , com , org , edu

50	dt = strdup(domain);

51	if(dt == NULL)

52

{

53	printf("strdup failed");

54

}

55	pch = (char*)strtok(dt , ".");

56	while(pch != NULL)

57

{

58	strcpy(ext , pch);

59	pch = strtok(NULL , ".");

60

}

61

62	//This will tell the whois server for the particular TLD like com , org

63	if(whois_query("whois.iana.org" , ext , &response))

64

{

65	printf("Whois query failed");

66

}

67

68	//Now analysze the response :)

69	pch = strtok(response , "\n");

70	while(pch != NULL)

71

{

72	//Check if whois line

73	wch = strstr(pch , "whois.");

74	if(wch != NULL)

75

{

76

break;

77

}

78

79	//Next line please

80	pch = strtok(NULL , "\n");

81

}

82

83

84

85	//Now we have the TLD whois server in wch , query again

86	//This will provide minimal whois information along with the parent whois server of the specific domain :)

87	free(response);

88	//This should not be necessary , but segmentation fault without this , why ?

89	response = NULL;

90	if(wch != NULL)

91

{

92	printf("\nTLD Whois server is : %s" , wch);

93	if(whois_query(wch , domain , &response))

94

{

95	printf("Whois query failed");

96

}

97

}

98

else

99

{

100	printf("\nTLD whois server for %s not found" , ext);

101

return 1;

102

}

103

104	response_2 = strdup(response);

105

106	//Again search for a whois server in this response. :)

107	pch = strtok(response , "\n");

108	while(pch != NULL)

109

{

110	//Check if whois line

111	wch = strstr(pch , "whois.");

112	if(wch != NULL)

113

{

114

break;

115

}

116

117	//Next line please

118	pch = strtok(NULL , "\n");

119

}

120

121

122

/*

123	* If a registrar whois server is found then query it

124

* */

125

if(wch)

126

{

127	//Now we have the registrar whois server , this has the direct full information of the particular domain

128	//so lets query again

129

130	printf("\nRegistrar Whois server is : %s" , wch);

131

132	if(whois_query(wch , domain , &response))

133

{

134	printf("Whois query failed");

135

}

136

137	printf("\n%s" , response);

138

}

139

140

/*

141	* otherwise echo the output from the previous whois result

142

* */

143

else

144

{

145	printf("%s" , response_2);

146

}

147

return 0;

148

}

149

150

/*

151	* Perform a whois query to a server and record the response

152

* */

153	int whois_query(char *server , char *query , char **response)

154

{

155	char ip[32] , message[100] , buffer[1500];

156	int sock , read_size , total_size = 0;

157	struct sockaddr_in dest;

158

159	sock = socket(AF_INET , SOCK_STREAM , IPPROTO_TCP);

160

161	//Prepare connection structures :)

162	memset( &dest , 0 , sizeof(dest) );

163	dest.sin_family = AF_INET;

164

165	printf("\nResolving %s..." , server);

166	if(hostname_to_ip(server , ip))

167

{

168	printf("Failed");

169

return 1;

170

}

171	printf("%s" , ip);

172	dest.sin_addr.s_addr = inet_addr( ip );

173	dest.sin_port = htons( 43 );

174

175	//Now connect to remote server

176	if(connect( sock , (const struct sockaddr*) &dest , sizeof(dest) ) < 0)

177

{

178	perror("connect failed");

179

}

180

181	//Now send some data or message

182	printf("\nQuerying for ... %s ..." , query);

183	sprintf(message , "%s\r\n" , query);

184	if( send(sock , message , strlen(message) , 0) < 0)

185

{

186	perror("send failed");

187

}

188

189	//Now receive the response

190	while( (read_size = recv(sock , buffer , sizeof(buffer) , 0) ) )

191

{

192	*response = realloc(*response , read_size + total_size);

193	if(*response == NULL)

194

{

195	printf("realloc failed");

196

}

197	memcpy(*response + total_size , buffer , read_size);

198	total_size += read_size;

199

}

200	printf("Done");

201	fflush(stdout);

202

203	*response = realloc(*response , total_size + 1);

204	*(*response + total_size) = '\0';

205

206	close(sock);

207

return 0;

208

}

209

210

/*

211

* @brief

212	* Get the ip address of a given hostname

213

*

214

* */

215	int hostname_to_ip(char * hostname , char* ip)

216

{

217	struct hostent *he;

218	struct in_addr **addr_list;

219

int i;

220

221	if ( (he = gethostbyname( hostname ) ) == NULL)

222

{

223	// get the host info

224	herror("gethostbyname");

225

return 1;

226

}

227

228	addr_list = (struct in_addr **) he->h_addr_list;

229

230	for(i = 0; addr_list[i] != NULL; i++)

231

{

232	//Return the first one;

233	strcpy(ip , inet_ntoa(*addr_list[i]) );

234

return 0;

235

}

236

237

return 0;

238

}

239

240

/*

241	* Search and replace a string with another string , in a string

242

* */

243	char *str_replace(char *search , char *replace , char *subject)

244

{

245	char  *p = NULL , *old = NULL , *new_subject = NULL ;

246	int c = 0 , search_size;

247

248	search_size = strlen(search);

249

250	//Count how many occurences

251	for(p = strstr(subject , search) ; p != NULL ; p = strstr(p + search_size , search))

252

{

253

c++;

254

}

255

256	//Final size

257	c = ( strlen(replace) - search_size )*c + strlen(subject);

258

259	//New subject with new size

260	new_subject = malloc( c );

261

262	//Set it to blank

263	strcpy(new_subject , "");

264

265	//The start position

266	old = subject;

267

268	for(p = strstr(subject , search) ; p != NULL ; p = strstr(p + search_size , search))

269

{

270	//move ahead and copy some text from original subject , from a certain position

271	strncpy(new_subject + strlen(new_subject) , old , p - old);

272

273	//move ahead and copy the replacement text

274	strcpy(new_subject + strlen(new_subject) , replace);

275

276	//The new start position after this search match

277	old = p + search_size;

278

}

279

280	//Copy the part after the last search match

281	strcpy(new_subject + strlen(new_subject) , old);

282

283	return new_subject;

284

}

hostname_to_ip – This is a simple function to get an IP of a domain.
str_replace – This is a generic string processing function that is used to search for a string in another big string and replace it with another string.

Output

view source

print?

1	Enter domain name to whois : www.wikipedia.org

2

3	Resolving whois.iana.org...192.0.47.59

4	Querying for ... org ...Done

5	TLD Whois server is : whois.pir.org

6	Resolving whois.pir.org...149.17.192.7

7	Querying for ... wikipedia.org ...DoneAccess to .ORG WHOIS information is provided to assist persons in

8	determining the contents of a domain name registration record in the

9	Public Interest Registry registry database. The data in this record is provided by

10	Public Interest Registry for informational purposes only, and Public Interest Registry does not

11	guarantee its accuracy.  This service is intended only for query-based

12	access. You agree that you will use this data only for lawful purposes

13	and that, under no circumstances will you use this data to: (a) allow,

14	enable, or otherwise support the transmission by e-mail, telephone, or

15	facsimile of mass unsolicited, commercial advertising or solicitations

16	to entities other than the data recipient's own existing customers; or

17	(b) enable high volume, automated, electronic processes that send

18	queries or data to the systems of Registry Operator, a Registrar, or

19	Afilias except as reasonably necessary to register domain names or

20	modify existing registrations. All rights reserved. Public Interest Registry reserves

21	the right to modify these terms at any time. By submitting this query,

22	you agree to abide by this policy.

23

24	Domain ID:D51687756-LROR

25	Domain Name:WIKIPEDIA.ORG

26	Created On:13-Jan-2001 00:12:14 UTC

27	Last Updated On:02-Dec-2009 20:57:17 UTC

28	Expiration Date:13-Jan-2015 00:12:14 UTC

29	Sponsoring Registrar:GoDaddy.com, Inc. (R91-LROR)

30	Status:CLIENT DELETE PROHIBITED

31	Status:CLIENT RENEW PROHIBITED

32	Status:CLIENT TRANSFER PROHIBITED

33	Status:CLIENT UPDATE PROHIBITED

34	Registrant ID:CR31094073

35	Registrant Name:DNS Admin

36	Registrant Organization:Wikimedia Foundation, Inc.

37	Registrant Street1:149 New Montgomery Street

38	Registrant Street2:Third Floor

39	Registrant Street3:

40	Registrant City:San Francisco

41	Registrant State/Province:California

42	Registrant Postal Code:94105

43	Registrant Country:US

44	Registrant Phone:+1.4158396885

45	Registrant Phone Ext.:

46	Registrant FAX:+1.4158820495

47	Registrant FAX Ext.:

48	Registrant Email:dns-admin@wikimedia.org

49	Admin ID:CR31094075

50	Admin Name:DNS Admin

51	Admin Organization:Wikimedia Foundation, Inc.

52	Admin Street1:149 New Montgomery Street

53	Admin Street2:Third Floor

54	Admin Street3:

55	Admin City:San Francisco

56	Admin State/Province:California

57	Admin Postal Code:94105

58	Admin Country:US

59	Admin Phone:+1.4158396885

60	Admin Phone Ext.:

61	Admin FAX:+1.4158820495

62	Admin FAX Ext.:

63	Admin Email:dns-admin@wikimedia.org

64	Tech ID:CR31094074

65	Tech Name:DNS Admin

66	Tech Organization:Wikimedia Foundation, Inc.

67	Tech Street1:149 New Montgomery Street

68	Tech Street2:Third Floor

69	Tech Street3:

70	Tech City:San Francisco

71	Tech State/Province:California

72	Tech Postal Code:94105

73	Tech Country:US

74	Tech Phone:+1.4158396885

75	Tech Phone Ext.:

76	Tech FAX:+1.4158820495

77	Tech FAX Ext.:

78	Tech Email:dns-admin@wikimedia.org

79	Name Server:NS0.WIKIMEDIA.ORG

80	Name Server:NS1.WIKIMEDIA.ORG

81	Name Server:NS2.WIKIMEDIA.ORG

82	Name Server:

83	Name Server:

84	Name Server:

85	Name Server:

86	Name Server:

87	Name Server:

88	Name Server:

89	Name Server:

90	Name Server:

91	Name Server:

92	DNSSEC:Unsigned

A whois client is a program that will simply fetch the whois information for a domain/ip address from the whois servers. The code over here works according to the algorithm discussed here.

Code

1

/*

2

* @brief

3	* Whois client program

4

*

5	* @details

6	* This program shall perform whois for a domain and get you the whois data of that domain

7

*

8	* @author Silver Moon ( m00n.silv3r@gmail.com )

9

* */

10

11	#include<stdio.h> //scanf , printf

12	#include<string.h>    //strtok

13	#include<stdlib.h>    //realloc

14	#include<sys/socket.h>    //socket

15	#include<netinet/in.h> //sockaddr_in

16	#include<arpa/inet.h> //getsockname

17	#include<netdb.h> //hostent

18	#include<unistd.h>    //close

19

20	int get_whois_data(char * , char **);

21	int hostname_to_ip(char * , char *);

22	int whois_query(char * , char * , char **);

23	char *str_replace(char *search , char *replace , char *subject );

24

25	int main(int argc , char *argv[])

26

{

27	char domain[100] , *data = NULL;

28

29	printf("Enter domain name to whois : ");

30	scanf("%s" , domain);

31

32	get_whois_data(domain , &data);

33

34	//puts(data);

35

return 0;

36

}

37

38

/*

39	* Get the whois data of a domain

40

* */

41	int get_whois_data(char *domain , char **data)

42

{

43	char ext[1024] , *pch , *response = NULL , *response_2 = NULL , *wch , *dt;

44

45	//remove "http://" and "www."

46	domain = str_replace("http://" , "" , domain);

47	domain = str_replace("www." , "" , domain);

48

49	//get the extension , com , org , edu

50	dt = strdup(domain);

51	if(dt == NULL)

52

{

53	printf("strdup failed");

54

}

55	pch = (char*)strtok(dt , ".");

56	while(pch != NULL)

57

{

58	strcpy(ext , pch);

59	pch = strtok(NULL , ".");

60

}

61

62	//This will tell the whois server for the particular TLD like com , org

63	if(whois_query("whois.iana.org" , ext , &response))

64

{

65	printf("Whois query failed");

66

}

67

68	//Now analysze the response :)

69	pch = strtok(response , "\n");

70	while(pch != NULL)

71

{

72	//Check if whois line

73	wch = strstr(pch , "whois.");

74	if(wch != NULL)

75

{

76

break;

77

}

78

79	//Next line please

80	pch = strtok(NULL , "\n");

81

}

82

83

84

85	//Now we have the TLD whois server in wch , query again

86	//This will provide minimal whois information along with the parent whois server of the specific domain :)

87	free(response);

88	//This should not be necessary , but segmentation fault without this , why ?

89	response = NULL;

90	if(wch != NULL)

91

{

92	printf("\nTLD Whois server is : %s" , wch);

93	if(whois_query(wch , domain , &response))

94

{

95	printf("Whois query failed");

96

}

97

}

98

else

99

{

100	printf("\nTLD whois server for %s not found" , ext);

101

return 1;

102

}

103

104	response_2 = strdup(response);

105

106	//Again search for a whois server in this response. :)

107	pch = strtok(response , "\n");

108	while(pch != NULL)

109

{

110	//Check if whois line

111	wch = strstr(pch , "whois.");

112	if(wch != NULL)

113

{

114

break;

115

}

116

117	//Next line please

118	pch = strtok(NULL , "\n");

119

}

120

121

122

/*

123	* If a registrar whois server is found then query it

124

* */

125

if(wch)

126

{

127	//Now we have the registrar whois server , this has the direct full information of the particular domain

128	//so lets query again

129

130	printf("\nRegistrar Whois server is : %s" , wch);

131

132	if(whois_query(wch , domain , &response))

133

{

134	printf("Whois query failed");

135

}

136

137	printf("\n%s" , response);

138

}

139

140

/*

141	* otherwise echo the output from the previous whois result

142

* */

143

else

144

{

145	printf("%s" , response_2);

146

}

147

return 0;

148

}

149

150

/*

151	* Perform a whois query to a server and record the response

152

* */

153	int whois_query(char *server , char *query , char **response)

154

{

155	char ip[32] , message[100] , buffer[1500];

156	int sock , read_size , total_size = 0;

157	struct sockaddr_in dest;

158

159	sock = socket(AF_INET , SOCK_STREAM , IPPROTO_TCP);

160

161	//Prepare connection structures :)

162	memset( &dest , 0 , sizeof(dest) );

163	dest.sin_family = AF_INET;

164

165	printf("\nResolving %s..." , server);

166	if(hostname_to_ip(server , ip))

167

{

168	printf("Failed");

169

return 1;

170

}

171	printf("%s" , ip);

172	dest.sin_addr.s_addr = inet_addr( ip );

173	dest.sin_port = htons( 43 );

174

175	//Now connect to remote server

176	if(connect( sock , (const struct sockaddr*) &dest , sizeof(dest) ) < 0)

177

{

178	perror("connect failed");

179

}

180

181	//Now send some data or message

182	printf("\nQuerying for ... %s ..." , query);

183	sprintf(message , "%s\r\n" , query);

184	if( send(sock , message , strlen(message) , 0) < 0)

185

{

186	perror("send failed");

187

}

188

189	//Now receive the response

190	while( (read_size = recv(sock , buffer , sizeof(buffer) , 0) ) )

191

{

192	*response = realloc(*response , read_size + total_size);

193	if(*response == NULL)

194

{

195	printf("realloc failed");

196

}

197	memcpy(*response + total_size , buffer , read_size);

198	total_size += read_size;

199

}

200	printf("Done");

201	fflush(stdout);

202

203	*response = realloc(*response , total_size + 1);

204	*(*response + total_size) = '\0';

205

206	close(sock);

207

return 0;

208

}

209

210

/*

211

* @brief

212	* Get the ip address of a given hostname

213

*

214

* */

215	int hostname_to_ip(char * hostname , char* ip)

216

{

217	struct hostent *he;

218	struct in_addr **addr_list;

219

int i;

220

221	if ( (he = gethostbyname( hostname ) ) == NULL)

222

{

223	// get the host info

224	herror("gethostbyname");

225

return 1;

226

}

227

228	addr_list = (struct in_addr **) he->h_addr_list;

229

230	for(i = 0; addr_list[i] != NULL; i++)

231

{

232	//Return the first one;

233	strcpy(ip , inet_ntoa(*addr_list[i]) );

234

return 0;

235

}

236

237

return 0;

238

}

239

240

/*

241	* Search and replace a string with another string , in a string

242

* */

243	char *str_replace(char *search , char *replace , char *subject)

244

{

245	char  *p = NULL , *old = NULL , *new_subject = NULL ;

246	int c = 0 , search_size;

247

248	search_size = strlen(search);

249

250	//Count how many occurences

251	for(p = strstr(subject , search) ; p != NULL ; p = strstr(p + search_size , search))

252

{

253

c++;

254

}

255

256	//Final size

257	c = ( strlen(replace) - search_size )*c + strlen(subject);

258

259	//New subject with new size

260	new_subject = malloc( c );

261

262	//Set it to blank

263	strcpy(new_subject , "");

264

265	//The start position

266	old = subject;

267

268	for(p = strstr(subject , search) ; p != NULL ; p = strstr(p + search_size , search))

269

{

270	//move ahead and copy some text from original subject , from a certain position

271	strncpy(new_subject + strlen(new_subject) , old , p - old);

272

273	//move ahead and copy the replacement text

274	strcpy(new_subject + strlen(new_subject) , replace);

275

276	//The new start position after this search match

277	old = p + search_size;

278

}

279

280	//Copy the part after the last search match

281	strcpy(new_subject + strlen(new_subject) , old);

282

283	return new_subject;

284

}

hostname_to_ip – This is a simple function to get an IP of a domain.
str_replace – This is a generic string processing function that is used to search for a string in another big string and replace it with another string.

Output

view source

print?

1	Enter domain name to whois : www.wikipedia.org

2

3	Resolving whois.iana.org...192.0.47.59

4	Querying for ... org ...Done

5	TLD Whois server is : whois.pir.org

6	Resolving whois.pir.org...149.17.192.7

7	Querying for ... wikipedia.org ...DoneAccess to .ORG WHOIS information is provided to assist persons in

8	determining the contents of a domain name registration record in the

9	Public Interest Registry registry database. The data in this record is provided by

10	Public Interest Registry for informational purposes only, and Public Interest Registry does not

11	guarantee its accuracy.  This service is intended only for query-based

12	access. You agree that you will use this data only for lawful purposes

13	and that, under no circumstances will you use this data to: (a) allow,

14	enable, or otherwise support the transmission by e-mail, telephone, or

15	facsimile of mass unsolicited, commercial advertising or solicitations

16	to entities other than the data recipient's own existing customers; or

17	(b) enable high volume, automated, electronic processes that send

18	queries or data to the systems of Registry Operator, a Registrar, or

19	Afilias except as reasonably necessary to register domain names or

20	modify existing registrations. All rights reserved. Public Interest Registry reserves

21	the right to modify these terms at any time. By submitting this query,

22	you agree to abide by this policy.

23

24	Domain ID:D51687756-LROR

25	Domain Name:WIKIPEDIA.ORG

26	Created On:13-Jan-2001 00:12:14 UTC

27	Last Updated On:02-Dec-2009 20:57:17 UTC

28	Expiration Date:13-Jan-2015 00:12:14 UTC

29	Sponsoring Registrar:GoDaddy.com, Inc. (R91-LROR)

30	Status:CLIENT DELETE PROHIBITED

31	Status:CLIENT RENEW PROHIBITED

32	Status:CLIENT TRANSFER PROHIBITED

33	Status:CLIENT UPDATE PROHIBITED

34	Registrant ID:CR31094073

35	Registrant Name:DNS Admin

36	Registrant Organization:Wikimedia Foundation, Inc.

37	Registrant Street1:149 New Montgomery Street

38	Registrant Street2:Third Floor

39	Registrant Street3:

40	Registrant City:San Francisco

41	Registrant State/Province:California

42	Registrant Postal Code:94105

43	Registrant Country:US

44	Registrant Phone:+1.4158396885

45	Registrant Phone Ext.:

46	Registrant FAX:+1.4158820495

47	Registrant FAX Ext.:

48	Registrant Email:dns-admin@wikimedia.org

49	Admin ID:CR31094075

50	Admin Name:DNS Admin

51	Admin Organization:Wikimedia Foundation, Inc.

52	Admin Street1:149 New Montgomery Street

53	Admin Street2:Third Floor

54	Admin Street3:

55	Admin City:San Francisco

56	Admin State/Province:California

57	Admin Postal Code:94105

58	Admin Country:US

59	Admin Phone:+1.4158396885

60	Admin Phone Ext.:

61	Admin FAX:+1.4158820495

62	Admin FAX Ext.:

63	Admin Email:dns-admin@wikimedia.org

64	Tech ID:CR31094074

65	Tech Name:DNS Admin

66	Tech Organization:Wikimedia Foundation, Inc.

67	Tech Street1:149 New Montgomery Street

68	Tech Street2:Third Floor

69	Tech Street3:

70	Tech City:San Francisco

71	Tech State/Province:California

72	Tech Postal Code:94105

73	Tech Country:US

74	Tech Phone:+1.4158396885

75	Tech Phone Ext.:

76	Tech FAX:+1.4158820495

77	Tech FAX Ext.:

78	Tech Email:dns-admin@wikimedia.org

79	Name Server:NS0.WIKIMEDIA.ORG

80	Name Server:NS1.WIKIMEDIA.ORG

81	Name Server:NS2.WIKIMEDIA.ORG

82	Name Server:

83	Name Server:

84	Name Server:

85	Name Server:

86	Name Server:

87	Name Server:

88	Name Server:

89	Name Server:

90	Name Server:

91	Name Server:

92	DNSSEC:Unsigned