This is the new inet_addr/inet_aton with proper error checking. This

should close all outstanding PRs on incorrect inet_aton behavior, and
since it has a decent parsing routine, doesn't allow some hysterically
working behavior.

PR:		13628
Submitted by:	Adrian Chadd <adrian@FreeBSD.org>

1 files changed, 69 insertions, 65 deletions

diff --git a/lib/libc/net/inet_addr.c b/lib/libc/net/inet_addr.c
index 3fac1ca..8998624 100644
--- a/lib/libc/net/inet_addr.c
+++ b/lib/libc/net/inet_addr.c
@@ -59,15 +59,19 @@ static char rcsid[] = "$FreeBSD$";
 #endif /* LIBC_SCCS and not lint */
 
 #include <sys/param.h>
+
 #include <netinet/in.h>
 #include <arpa/inet.h>
+
 #include <ctype.h>
+#include <errno.h>
+#include <string.h>
 
 /*
- * Ascii internet address interpretation routine.
+ * ASCII internet address interpretation routine.
  * The value returned is in network order.
  */
-u_long
+u_long		/* XXX should be struct in_addr :( */
 inet_addr(cp)
 	register const char *cp;
 {
@@ -79,7 +83,7 @@ inet_addr(cp)
 }
 
 /* 
- * Check whether "cp" is a valid ascii representation
+ * Check whether "cp" is a valid ASCII representation
  * of an Internet address and convert to a binary address.
  * Returns 1 if the address is valid, 0 if not.
  * This replaces inet_addr, the return value from which
@@ -90,91 +94,91 @@ inet_aton(cp, addr)
 	register const char *cp;
 	struct in_addr *addr;
 {
-	register u_long val;
-	register int base, n;
-	register char c;
-	u_int parts[4];
-	register u_int *pp = parts;
-
-	c = *cp;
-	for (;;) {
-		/*
-		 * Collect number up to ``.''.
-		 * Values are specified as for C:
-		 * 0x=hex, 0=octal, isdigit=decimal.
+	u_long parts[4];
+	u_long val;
+	char *c;
+	char *endptr;
+	int base, gotend, n;
+
+	c = (char *)cp;
+	n = 0;
+	/*
+	 * Run through the string, grabbing numbers until
+	 * the end of the string, or some error
+	 */
+	gotend = 0;
+	while (!gotend) {
+		errno = 0;
+		val = strtoul(c, &endptr, 0);
+
+		if (val == ERANGE)	/* Fail completely if it overflowed. */
+			return (0);
+		
+		/* 
+		 * If the whole string is invalid, endptr will equal
+		 * c.. this way we can make sure someone hasn't
+		 * gone '.12' or something which would get past
+		 * the next check.
 		 */
-		if (!isdigit(c))
+		if (endptr == c)
 			return (0);
-		val = 0; base = 10;
-		if (c == '0') {
-			c = *++cp;
-			if (c == 'x' || c == 'X')
-				base = 16, c = *++cp;
-			else
-				base = 8;
-		}
-		for (;;) {
-			if (isascii(c) && isdigit(c)) {
-				val = (val * base) + (c - '0');
-				c = *++cp;
-			} else if (base == 16 && isascii(c) && isxdigit(c)) {
-				val = (val << 4) |
-					(c + 10 - (islower(c) ? 'a' : 'A'));
-				c = *++cp;
-			} else
-				break;
-		}
-		if (c == '.') {
-			/*
-			 * Internet format:
-			 *	a.b.c.d
-			 *	a.b.c	(with c treated as 16 bits)
-			 *	a.b	(with b treated as 24 bits)
-			 */
-			if (pp >= parts + 3)
+		parts[n] = val;
+		c = endptr;
+
+		/* Check the next character past the previous number's end */
+		switch (*c) {
+		case '.' :
+			/* Make sure we only do 3 dots .. */
+			if (n == 3)	/* Whoops. Quit. */
 				return (0);
-			*pp++ = val;
-			c = *++cp;
-		} else
+			n++;
+			c++;
 			break;
+
+		case '\0' :
+			gotend = 1;
+			break;
+
+		default:
+			/* Invalid character, so fail */
+			return (0);
+		}
+
 	}
-	/*
-	 * Check for trailing characters.
-	 */
-	if (c != '\0' && (!isascii(c) || !isspace(c)))
-		return (0);
+
 	/*
 	 * Concoct the address according to
 	 * the number of parts specified.
 	 */
-	n = pp - parts + 1;
-	switch (n) {
 
-	case 0:
-		return (0);		/* initial nondigit */
-
-	case 1:				/* a -- 32 bits */
+	switch (n) {
+	case 0:				/* a -- 32 bits */
+		/*
+		 * Nothing is necessary here.  Overflow checking was
+		 * already done in strtoul().
+		 */
 		break;
-
-	case 2:				/* a.b -- 8.24 bits */
-		if (val > 0xffffff)
+	case 1:				/* a.b -- 8.24 bits */
+		if (val > 0xffffff || parts[0] > 0xff)
 			return (0);
 		val |= parts[0] << 24;
 		break;
 
-	case 3:				/* a.b.c -- 8.8.16 bits */
-		if (val > 0xffff)
+	case 2:				/* a.b.c -- 8.8.16 bits */
+		if (val > 0xffff || parts[0] > 0xff || parts[1] > 0xff)
 			return (0);
 		val |= (parts[0] << 24) | (parts[1] << 16);
 		break;
 
-	case 4:				/* a.b.c.d -- 8.8.8.8 bits */
-		if (val > 0xff)
+	case 3:				/* a.b.c.d -- 8.8.8.8 bits */
+		if (val > 0xff || parts[0] > 0xff || parts[1] > 0xff ||
+		    parts[2] > 0xff)
 			return (0);
 		val |= (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8);
 		break;
 	}
-	if (addr)
+
+	if (addr != NULL)
 		addr->s_addr = htonl(val);
 	return (1);
 }