- fix ip route rejecting dotted quads as prefix

- adjust error message for wrong prefix not to mention address
  Previously e.g. ip route add 127.0.0.0/255.0.0.0 dev dummy0
  was rejected, saying
ip: an inet address is expected rather than "127.0.0.0/255.0.0.0"
 
function                                             old     new   delta
get_prefix_1                                         201     309    +108
get_prefix                                            55      73     +18
get_addr                                              55      73     +18
get_addr32                                            48      58     +10
get_addr_1                                           249     204     -45
.rodata                                           114569  114524     -45
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/2 up/down: 154/-90)            Total: 64 bytes

2 files changed, 35 insertions, 31 deletions

diff --git a/networking/libiproute/utils.c b/networking/libiproute/utils.c
index 706710e1f..cd101f176 100644
--- a/networking/libiproute/utils.c
+++ b/networking/libiproute/utils.c
@@ -115,10 +115,6 @@ int get_s8(int8_t * val, char *arg, int base)
 
 int get_addr_1(inet_prefix * addr, char *name, int family)
 {
-        char *cp;
-        unsigned char *ap = (unsigned char *) addr->data;
-        int i;
-
         memset(addr, 0, sizeof(*addr));
 
         if (strcmp(name, bb_str_default) == 0 ||
@@ -143,24 +139,17 @@ int get_addr_1(inet_prefix * addr, char *name, int family)
         addr->family = AF_INET;
         if (family != AF_UNSPEC && family != AF_INET)
                 return -1;
+        if (inet_pton(AF_INET, name, addr->data) <= 0)
+                return -1;
         addr->bytelen = 4;
         addr->bitlen = -1;
-        for (cp = name, i = 0; *cp; cp++) {
-                if (*cp <= '9' && *cp >= '0') {
-                        ap[i] = 10 * ap[i] + (*cp - '0');
-                        continue;
-                }
-                if (*cp == '.' && ++i <= 3)
-                        continue;
-                return -1;
-        }
         return 0;
 }
 
 int get_prefix_1(inet_prefix * dst, char *arg, int family)
 {
         int err;
-        int plen;
+        unsigned plen;
         char *slash;
 
         memset(dst, 0, sizeof(*dst));
@@ -177,23 +166,36 @@ int get_prefix_1(inet_prefix * dst, char *arg, int family)
                 *slash = '\0';
         err = get_addr_1(dst, arg, family);
         if (err == 0) {
-                switch (dst->family) {
-                case AF_INET6:
-                        dst->bitlen = 128;
-                        break;
-                default:
-                case AF_INET:
-                        dst->bitlen = 32;
-                }
+                dst->bitlen = (dst->family == AF_INET6) ? 128 : 32;
                 if (slash) {
-                        if (get_integer(&plen, slash + 1, 0) || plen > dst->bitlen) {
+                        inet_prefix netmask_pfx;
+
+                        netmask_pfx.family = AF_UNSPEC;
+                        if ((get_unsigned(&plen, slash + 1, 0) || plen > dst->bitlen)
+                                && (get_addr_1(&netmask_pfx, slash + 1, family)))
                                 err = -1;
-                                goto done;
+                        else if (netmask_pfx.family == AF_INET) {
+                                /* fill in prefix length of dotted quad */
+                                uint32_t mask = ntohl(netmask_pfx.data[0]);
+                                uint32_t host = ~mask;
+
+                                /* a valid netmask must be 2^n - 1 */
+                                if (!(host & (host + 1))) {
+                                        for (plen = 0; mask; mask <<= 1)
+                                                ++plen;
+                                        if (plen >= 0 && plen <= dst->bitlen) {
+                                                        dst->bitlen = plen;
+                                                        /* dst->flags |= PREFIXLEN_SPECIFIED; */
+                                        } else
+                                                err = -1;
+                                } else
+                                        err = -1;
+                        } else {
+                                /* plain prefix */
+                                dst->bitlen = plen;
                         }
-                        dst->bitlen = plen;
                 }
         }
- done:
         if (slash)
                 *slash = '/';
         return err;
@@ -202,10 +204,10 @@ int get_prefix_1(inet_prefix * dst, char *arg, int family)
 int get_addr(inet_prefix * dst, char *arg, int family)
 {
         if (family == AF_PACKET) {
-                bb_error_msg_and_die("\"%s\" may be inet address, but it is not allowed in this context", arg);
+                bb_error_msg_and_die("\"%s\" may be inet %s, but it is not allowed in this context", arg, "address");
         }
         if (get_addr_1(dst, arg, family)) {
-                bb_error_msg_and_die("an inet address is expected rather than \"%s\"", arg);
+                bb_error_msg_and_die("an %s %s is expected rather than \"%s\"", "inet", "address", arg);
         }
         return 0;
 }
@@ -213,10 +215,10 @@ int get_addr(inet_prefix * dst, char *arg, int family)
 int get_prefix(inet_prefix * dst, char *arg, int family)
 {
         if (family == AF_PACKET) {
-                bb_error_msg_and_die("\"%s\" may be inet address, but it is not allowed in this context", arg);
+                bb_error_msg_and_die("\"%s\" may be inet %s, but it is not allowed in this context", arg, "prefix");
         }
         if (get_prefix_1(dst, arg, family)) {
-                bb_error_msg_and_die("an inet address is expected rather than \"%s\"", arg);
+                bb_error_msg_and_die("an %s %s is expected rather than \"%s\"", "inet", "prefix", arg);
         }
         return 0;
 }
@@ -226,7 +228,7 @@ uint32_t get_addr32(char *name)
         inet_prefix addr;
 
         if (get_addr_1(&addr, name, AF_INET)) {
-                bb_error_msg_and_die("an IP address is expected rather than \"%s\"", name);
+                bb_error_msg_and_die("an %s %s is expected rather than \"%s\"", "IP", "address", name);
         }
         return addr.data[0];
 }
diff --git a/networking/libiproute/utils.h b/networking/libiproute/utils.h
index 607083af8..1af39ffe1 100644
--- a/networking/libiproute/utils.h
+++ b/networking/libiproute/utils.h
@@ -39,6 +39,8 @@ typedef struct {
         uint32_t data[4];
 } inet_prefix;
 
+#define PREFIXLEN_SPECIFIED 1
+
 #define DN_MAXADDL 20
 #ifndef AF_DECnet
 #define AF_DECnet 12