Clean up DECnet address handling.

In gen_scode() make any id invalid DECnet address.  In gen_ncode() make
{N} invalid DECnet address.  In __pcap_atodn() replace sscanf() with an
FSM to parse the entire input string and to require a valid nominal
DECnet address syntax.  Remove __pcap_nametodnaddr(), which worked on
Ultrix only.  Add various comments to explain the context better.  In
pcap-filter(3PCAP) clarify the nominal DECnet address syntax and remove
mentions of the host name translation.

Before:

filtertest: decnet name support not included, 'abc' cannot be translated
1 -- no error
100.2000 -- no error
1.2.3 -- no error
1.2.3.4 -- no error

After:

filtertest: invalid DECnet address 'abc'
filtertest: invalid DECnet address '1'
filtertest: invalid DECnet address '100.2000'
filtertest: invalid DECnet address '1.2.3'
filtertest: invalid DECnet address '1.2.3.4'

1 files changed, 75 insertions, 34 deletions

diff --git a/nametoaddr.c b/nametoaddr.c
index 7a04a61d..a746cb6d 100644
--- a/nametoaddr.c
+++ b/nametoaddr.c
@@ -26,11 +26,6 @@
 #include <config.h>
 #endif
 
-#ifdef DECNETLIB
-#include <sys/types.h>
-#include <netdnet/dnetdb.h>
-#endif
-
 #ifdef _WIN32
   #include <winsock2.h>
   #include <ws2tcpip.h>
@@ -685,6 +680,13 @@ __pcap_atoin(const char *s, bpf_u_int32 *addr)
 	/* NOTREACHED */
 }
 
+/*
+ * If 's' is not a string that is a well-formed DECnet address (aa.nnnn),
+ * return zero.  Otherwise parse the address into the low 16 bits of 'addr'
+ * and return a non-zero.  The binary DECnet address consists of a 6-bit area
+ * number and a 10-bit node number; neither area 0 nor node 0 are valid for
+ * normal addressing purposes, but either can appear on the wire.
+ */
 int
 __pcap_atodn(const char *s, bpf_u_int32 *addr)
 {
@@ -692,14 +694,76 @@ __pcap_atodn(const char *s, bpf_u_int32 *addr)
 #define AREAMASK 0176000
 #define NODEMASK 01777
 
-	u_int node, area;
-
-	if (sscanf(s, "%d.%d", &area, &node) != 2)
-		return(0);
+	/* Initialize to squelch a compiler warning only. */
+	u_int node = 0, area = 0;
+	/*
+	 *               +--+             +--+
+	 *               |  |             |  |
+	 *               v  |             v  |
+	 * --> START --> AREA --> DOT --> NODE -->
+	 *       |          |     |        |
+	 *       |          v     v        |
+	 *       +--------> INVALID <------+
+	 */
+	enum {
+		START,
+		AREA,
+		DOT,
+		NODE,
+		INVALID
+	} fsm_state = START;
 
-	*addr = (area << AREASHIFT) & AREAMASK;
-	*addr |= (node & NODEMASK);
+	while (*s) {
+		switch (fsm_state) {
+		case START:
+			if (PCAP_ISDIGIT(*s)) {
+				area = *s - '0';
+				fsm_state = AREA;
+				break;
+			}
+			fsm_state = INVALID;
+			break;
+		case AREA:
+			if (*s == '.') {
+				fsm_state = DOT;
+				break;
+			}
+			if (PCAP_ISDIGIT(*s)) {
+				area = area * 10 + *s - '0';
+				if (area <= AREAMASK >> AREASHIFT)
+					break;
+			}
+			fsm_state = INVALID;
+			break;
+		case DOT:
+			if (PCAP_ISDIGIT(*s)) {
+				node = *s - '0';
+				fsm_state = NODE;
+				break;
+			}
+			fsm_state = INVALID;
+			break;
+		case NODE:
+			if (PCAP_ISDIGIT(*s)) {
+				node = node * 10 + *s - '0';
+				if (node <= NODEMASK)
+					break;
+			}
+			fsm_state = INVALID;
+			break;
+		case INVALID:
+			return 0;
+		} /* switch */
+		s++;
+	} /* while */
+	/*
+	 * This condition is false if the string comes from the lexer, but
+	 * let's not depend on that.
+	 */
+	if (fsm_state != NODE)
+		return 0;
 
+	*addr = area << AREASHIFT | node;
 	return(32);
 }
 
@@ -800,26 +864,3 @@ pcap_ether_hostton(const char *name)
 	return (ap);
 }
 #endif
-
-/*
- * XXX - not guaranteed to be thread-safe!
- */
-int
-#ifdef	DECNETLIB
-__pcap_nametodnaddr(const char *name, u_short *res)
-{
-	struct nodeent *getnodebyname();
-	struct nodeent *nep;
-
-	nep = getnodebyname(name);
-	if (nep == ((struct nodeent *)0))
-		return(0);
-
-	memcpy((char *)res, (char *)nep->n_addr, sizeof(unsigned short));
-	return(1);
-#else
-__pcap_nametodnaddr(const char *name _U_, u_short *res _U_)
-{
-	return(0);
-#endif
-}