Add missing files

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@1559 65c4cc65-6c06-0410-ace0-fbb531ad65f3

dns.c

+/*
+ * DNS Support for Asterisk
+ *
+ * Written by Thorsten Lockert <tholo@trollphone.org>
+ *
+ * Funding provided by Troll Phone Networks AS
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/nameser.h>
+#include <resolv.h>
+#include <unistd.h>
+
+#include <asterisk/logger.h>
+#include <asterisk/channel.h>
+#include <asterisk/dns.h>
+
+#define MAX_SIZE 4096
+
+typedef struct {
+	unsigned	id :16;		/* query identification number */
+#if BYTE_ORDER == BIG_ENDIAN
+			/* fields in third byte */
+	unsigned	qr: 1;		/* response flag */
+	unsigned	opcode: 4;	/* purpose of message */
+	unsigned	aa: 1;		/* authoritive answer */
+	unsigned	tc: 1;		/* truncated message */
+	unsigned	rd: 1;		/* recursion desired */
+			/* fields in fourth byte */
+	unsigned	ra: 1;		/* recursion available */
+	unsigned	unused :1;	/* unused bits (MBZ as of 4.9.3a3) */
+	unsigned	ad: 1;		/* authentic data from named */
+	unsigned	cd: 1;		/* checking disabled by resolver */
+	unsigned	rcode :4;	/* response code */
+#endif
+#if BYTE_ORDER == LITTLE_ENDIAN || BYTE_ORDER == PDP_ENDIAN
+			/* fields in third byte */
+	unsigned	rd :1;		/* recursion desired */
+	unsigned	tc :1;		/* truncated message */
+	unsigned	aa :1;		/* authoritive answer */
+	unsigned	opcode :4;	/* purpose of message */
+	unsigned	qr :1;		/* response flag */
+			/* fields in fourth byte */
+	unsigned	rcode :4;	/* response code */
+	unsigned	cd: 1;		/* checking disabled by resolver */
+	unsigned	ad: 1;		/* authentic data from named */
+	unsigned	unused :1;	/* unused bits (MBZ as of 4.9.3a3) */
+	unsigned	ra :1;		/* recursion available */
+#endif
+			/* remaining bytes */
+	unsigned	qdcount :16;	/* number of question entries */
+	unsigned	ancount :16;	/* number of answer entries */
+	unsigned	nscount :16;	/* number of authority entries */
+	unsigned	arcount :16;	/* number of resource entries */
+} dns_HEADER;
+
+struct dn_answer {
+	unsigned short rtype;
+	unsigned short class;
+	unsigned int ttl;
+	unsigned short size;
+} __attribute__ ((__packed__));
+
+static int skip_name(u_char *s, int len)
+{
+	int x = 0;
+
+	while (x < len) {
+		if (*s == '\0') {
+			s++;
+			x++;
+			break;
+		}
+		if ((*s & 0xc0) == 0xc0) {
+			s += 2;
+			x += 2;
+			break;
+		}
+		x += *s + 1;
+		s += *s + 1;
+	}
+	if (x >= len)
+		return -1;
+	return x;
+}
+
+static int dns_parse_answer(void *context,
+							int class, int type, u_char *answer, int len,
+							int (*callback)(void *context, u_char *answer, int len, u_char *fullanswer))
+{
+	u_char *fullanswer = answer;
+	struct dn_answer *ans;
+	dns_HEADER *h;
+	int res;
+	int x;
+
+    h = (dns_HEADER *)answer;
+	answer += sizeof(dns_HEADER);
+	len -= sizeof(dns_HEADER);
+
+	for (x = 0; x < ntohs(h->qdcount); x++) {
+		if ((res = skip_name(answer, len)) < 0) {
+			ast_log(LOG_WARNING, "Couldn't skip over name\n");
+			return -1;
+		}
+		answer += res + 4;	/* Skip name and QCODE / QCLASS */
+		len -= res + 4;
+		if (len < 0) {
+			ast_log(LOG_WARNING, "Strange query size\n");
+			return -1;
+		}
+	}
+
+	for (x = 0; x < ntohs(h->ancount); x++) {
+		if ((res = skip_name(answer, len)) < 0) {
+			ast_log(LOG_WARNING, "Failed skipping name\n");
+			return -1;
+		}
+		answer += res;
+		len -= res;
+		ans = (struct dn_answer *)answer;
+		answer += sizeof(struct dn_answer);
+		len -= sizeof(struct dn_answer);
+		if (len < 0) {
+			ast_log(LOG_WARNING, "Strange result size\n");
+			return -1;
+		}
+		if (len < 0) {
+			ast_log(LOG_WARNING, "Length exceeds frame\n");
+			return -1;
+		}
+
+		if (ntohs(ans->class) == class && ntohs(ans->rtype) == type) {
+			if (callback) {
+				if ((res = callback(context, answer, ntohs(ans->size), fullanswer)) < 0)
+					ast_log(LOG_WARNING, "Failed to parse result\n");
+				if (res > 0)
+					return 1;
+			}
+		}
+		answer += ntohs(ans->size);
+		len -= ntohs(ans->size);
+	}
+	return 0;
+}
+
+int ast_search_dns(void *context,
+				   const char *dname, int class, int type,
+				   int (*callback)(void *context, u_char *answer, int len, u_char *fullanswer))
+{
+#ifdef __Linux__
+	struct __res_state dnsstate;
+#endif
+	char answer[MAX_SIZE];
+	int res, ret = -1;
+
+#ifdef __Linux__
+	res_ninit(&dnsstate);
+	res = res_nsearch(&dnsstate, dname, class, type, answer, sizeof(answer));
+#else
+	res_init();
+	res = res_search(dname, class, type, answer, sizeof(answer));
+#endif
+	if (res > 0) {
+		if ((res = dns_parse_answer(context, class, type, answer, res, callback)) < 0) {
+			ast_log(LOG_WARNING, "Parse error\n");
+			ret = -1;
+		}
+		else if (ret == 0) {
+			ast_log(LOG_DEBUG, "No matches found\n");
+			ret = 0;
+		}
+		else
+			ret = 1;
+	}
+#ifdef __Linux__
+	res_nclose(&srvstate);
+#else
+	res_close();
+#endif
+	return ret;
+}

include/asterisk/dns.h

+/*
+ * DNS support
+ * 
+ * Written by Thorsten Lockert <tholo@trollphone.org>
+ *
+ * Funding provided by Troll Phone Networks AS
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License
+ */
+
+#ifndef _ASTERISK_DNS_H
+#define _ASTERISK_DNS_H
+
+struct ast_channel;
+
+extern int ast_search_dns(void *context, const char *dname, int class, int type,
+			  int (*callback)(void *context, u_char *answer, int len, u_char *fullanswer));
+
+#endif /* _ASTERISK_DNS_H */