1 #include <u.h>
2 #include <libc.h>
3 #include <bio.h>
4 #include <ndb.h>
5 #include <ndbhf.h>
6 
7 static void nstrcpy(char*, char*, int);
8 static void mkptrname(char*, char*, int);
9 static Ndbtuple *doquery(int, char *dn, char *type);
10 
11 /*
12  *  search for a tuple that has the given 'attr=val' and also 'rattr=x'.
13  *  copy 'x' into 'buf' and return the whole tuple.
14  *
15  *  return 0 if not found.
16  */
17 Ndbtuple*
18 dnsquery(char *net, char *val, char *type)
19 {
20 	char rip[128];
21 	char *p;
22 	Ndbtuple *t;
23 	int fd;
24 
25 	/* if the address is V4 or V6 null address, give up early vwhoi*/
26 	if(strcmp(val, "::") == 0 || strcmp(val, "0.0.0.0") == 0)
27 		return nil;
28 
29 	if(net == nil)
30 		net = "/net";
31 	snprint(rip, sizeof(rip), "%s/dns", net);
32 	fd = open(rip, ORDWR);
33 	if(fd < 0){
34 		if(strcmp(net, "/net") == 0)
35 			snprint(rip, sizeof(rip), "/srv/dns");
36 		else {
37 			snprint(rip, sizeof(rip), "/srv/dns%s", net);
38 			p = strrchr(rip, '/');
39 			*p = '_';
40 		}
41 		fd = open(rip, ORDWR);
42 		if(fd < 0)
43 			return nil;
44 		if(mount(fd, -1, net, MBEFORE, "") < 0){
45 			close(fd);
46 			return nil;
47 		}
48 		/* fd is now closed */
49 		snprint(rip, sizeof(rip), "%s/dns", net);
50 		fd = open(rip, ORDWR);
51 		if(fd < 0)
52 			return nil;
53 	}
54 
55 	/* zero out the error string */
56 	werrstr("");
57 
58 	/* if this is a reverse lookup, first lookup the domain name */
59 	if(strcmp(type, "ptr") == 0){
60 		mkptrname(val, rip, sizeof rip);
61 		t = doquery(fd, rip, "ptr");
62 	} else
63 		t = doquery(fd, val, type);
64 
65 	close(fd);
66 	return t;
67 }
68 
69 /*
70  *  convert address into a reverse lookup address
71  */
72 static void
73 mkptrname(char *ip, char *rip, int rlen)
74 {
75 	char buf[128];
76 	char *p, *np;
77 	int len;
78 
79 	if(strstr(ip, "in-addr.arpa") || strstr(ip, "IN-ADDR.ARPA")){
80 		nstrcpy(rip, ip, rlen);
81 		return;
82 	}
83 
84 	nstrcpy(buf, ip, sizeof buf);
85 	for(p = buf; *p; p++)
86 		;
87 	*p = '.';
88 	np = rip;
89 	len = 0;
90 	while(p >= buf){
91 		len++;
92 		p--;
93 		if(*p == '.'){
94 			memmove(np, p+1, len);
95 			np += len;
96 			len = 0;
97 		}
98 	}
99 	memmove(np, p+1, len);
100 	np += len;
101 	strcpy(np, "in-addr.arpa");
102 }
103 
104 static void
105 nstrcpy(char *to, char *from, int len)
106 {
107 	strncpy(to, from, len);
108 	to[len-1] = 0;
109 }
110 
111 static Ndbtuple*
112 doquery(int fd, char *dn, char *type)
113 {
114 	char buf[1024];
115 	int n;
116 	Ndbtuple *t, *first, *last;
117 
118 	seek(fd, 0, 0);
119 	snprint(buf, sizeof(buf), "!%s %s", dn, type);
120 	if(write(fd, buf, strlen(buf)) < 0)
121 		return nil;
122 
123 	seek(fd, 0, 0);
124 
125 	first = last = nil;
126 
127 	for(;;){
128 		n = read(fd, buf, sizeof(buf)-2);
129 		if(n <= 0)
130 			break;
131 		if(buf[n-1] != '\n')
132 			buf[n++] = '\n';	/* ndbparsline needs a trailing new line */
133 		buf[n] = 0;
134 
135 		/* check for the error condition */
136 		if(buf[0] == '!'){
137 			werrstr("%s", buf+1);
138 			return nil;
139 		}
140 
141 		t = _ndbparseline(buf);
142 		if(t != nil){
143 			if(first)
144 				last->entry = t;
145 			else
146 				first = t;
147 			last = t;
148 
149 			while(last->entry)
150 				last = last->entry;
151 		}
152 	}
153 
154 	setmalloctag(first, getcallerpc(&fd));
155 	return first;
156 }