inet/resolv: add ns_initparse, ns_parserr, ns_skiprr and ns_msg_getflag

There are build 'ifdef L_ns_parse'.

Signed-off-by: Daniel Mack <zonque@gmail.com>

1 files changed, 195 insertions, 0 deletions

diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index 6bfe52c79..011cd5e56 100644
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -3886,6 +3886,201 @@ void ns_put32(unsigned long src, unsigned char *dst)
 }
 #endif /* L_ns_netint */
 
+#ifdef L_ns_parse
+/* These need to be in the same order as the nres.h:ns_flag enum. */
+const struct _ns_flagdata _ns_flagdata[16] = {
+	{ 0x8000, 15 },         /*%< qr. */
+	{ 0x7800, 11 },         /*%< opcode. */
+	{ 0x0400, 10 },         /*%< aa. */
+	{ 0x0200, 9 },          /*%< tc. */
+	{ 0x0100, 8 },          /*%< rd. */
+	{ 0x0080, 7 },          /*%< ra. */
+	{ 0x0040, 6 },          /*%< z. */
+	{ 0x0020, 5 },          /*%< ad. */
+	{ 0x0010, 4 },          /*%< cd. */
+	{ 0x000f, 0 },          /*%< rcode. */
+	{ 0x0000, 0 },          /*%< expansion (1/6). */
+	{ 0x0000, 0 },          /*%< expansion (2/6). */
+	{ 0x0000, 0 },          /*%< expansion (3/6). */
+	{ 0x0000, 0 },          /*%< expansion (4/6). */
+	{ 0x0000, 0 },          /*%< expansion (5/6). */
+	{ 0x0000, 0 },          /*%< expansion (6/6). */
+};
+
+static void setsection(ns_msg *msg, ns_sect sect)
+{
+	msg->_sect = sect;
+	if (sect == ns_s_max) {
+		msg->_rrnum = -1;
+		msg->_ptr = NULL;
+	} else {
+		msg->_rrnum = 0;
+		msg->_ptr = msg->_sections[(int)sect];
+	}
+}
+
+int ns_skiprr(const unsigned char *ptr,
+			  const unsigned char *eom,
+			  ns_sect section, int count)
+{
+	const u_char *optr = ptr;
+
+	for (; count > 0; count--) {
+		int b, rdlength;
+
+		b = dn_skipname(ptr, eom);
+		if (b < 0) {
+			errno = EMSGSIZE;
+			return -1;
+		}
+
+		ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
+		if (section != ns_s_qd) {
+			if (ptr + NS_INT32SZ + NS_INT16SZ > eom) {
+				errno = EMSGSIZE;
+				return -1;
+			}
+
+			ptr += NS_INT32SZ/*TTL*/;
+			NS_GET16(rdlength, ptr);
+			ptr += rdlength/*RData*/;
+		}
+	}
+
+	if (ptr > eom) {
+		errno = EMSGSIZE;
+		return -1;
+	}
+
+	return ptr - optr;
+}
+
+int
+ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle)
+{
+	const u_char *eom = msg + msglen;
+	int i;
+
+	handle->_msg = msg;
+	handle->_eom = eom;
+	if (msg + NS_INT16SZ > eom) {
+		errno = EMSGSIZE;
+		return -1;
+	}
+
+	NS_GET16(handle->_id, msg);
+	if (msg + NS_INT16SZ > eom) {
+		errno = EMSGSIZE;
+		return -1;
+	}
+
+	NS_GET16(handle->_flags, msg);
+	for (i = 0; i < ns_s_max; i++) {
+		if (msg + NS_INT16SZ > eom) {
+			errno = EMSGSIZE;
+			return -1;
+		}
+
+		NS_GET16(handle->_counts[i], msg);
+	}
+	for (i = 0; i < ns_s_max; i++)
+		if (handle->_counts[i] == 0)
+			handle->_sections[i] = NULL;
+		else {
+			int b = ns_skiprr(msg, eom, (ns_sect)i,
+					  handle->_counts[i]);
+
+			if (b < 0)
+				return -1;
+			handle->_sections[i] = msg;
+			msg += b;
+		}
+
+	if (msg != eom) {
+		errno = EMSGSIZE;
+		return -1;
+	}
+
+	setsection(handle, ns_s_max);
+	return 0;
+}
+
+int
+ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr)
+{
+	int b;
+	int tmp;
+
+	/* Make section right. */
+	tmp = section;
+	if (tmp < 0 || section >= ns_s_max) {
+		errno = ENODEV;
+		return -1;
+	}
+
+	if (section != handle->_sect)
+		setsection(handle, section);
+
+	/* Make rrnum right. */
+	if (rrnum == -1)
+		rrnum = handle->_rrnum;
+	if (rrnum < 0 || rrnum >= handle->_counts[(int)section]) {
+		errno = ENODEV;
+		return -1;
+	}
+	if (rrnum < handle->_rrnum)
+		setsection(handle, section);
+	if (rrnum > handle->_rrnum) {
+		b = ns_skiprr(handle->_ptr, handle->_eom, section,
+			      rrnum - handle->_rrnum);
+
+		if (b < 0)
+			return (-1);
+		handle->_ptr += b;
+		handle->_rrnum = rrnum;
+	}
+
+	/* Do the parse. */
+	b = dn_expand(handle->_msg, handle->_eom,
+		      handle->_ptr, rr->name, NS_MAXDNAME);
+	if (b < 0)
+		return (-1);
+	handle->_ptr += b;
+	if (handle->_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom) {
+		errno = EMSGSIZE;
+		return -1;
+	}
+	NS_GET16(rr->type, handle->_ptr);
+	NS_GET16(rr->rr_class, handle->_ptr);
+	if (section == ns_s_qd) {
+		rr->ttl = 0;
+		rr->rdlength = 0;
+		rr->rdata = NULL;
+	} else {
+		if (handle->_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom) {
+			errno = EMSGSIZE;
+			return -1;
+		}
+		NS_GET32(rr->ttl, handle->_ptr);
+		NS_GET16(rr->rdlength, handle->_ptr);
+		if (handle->_ptr + rr->rdlength > handle->_eom) {
+			errno = EMSGSIZE;
+			return -1;
+		}
+		rr->rdata = handle->_ptr;
+		handle->_ptr += rr->rdlength;
+	}
+	if (++handle->_rrnum > handle->_counts[(int)section])
+		setsection(handle, (ns_sect)((int)section + 1));
+
+	return 0;
+}
+
+int ns_msg_getflag(ns_msg handle, int flag) {
+	return ((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift;
+}
+#endif /* L_ns_parse */
+
 /* Unimplemented: */
 /* res_mkquery */
 /* res_send */