ntp: simplifications; libbb: simpler resolution of numeric hostnames

function                                             old     new   delta
str2sockaddr                                         405     567    +162
ntp_init                                             310     317      +7
scale_interval                                        58      59      +1
error_interval                                        22      23      +1
ntpd_main                                           3257    3214     -43
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/1 up/down: 171/-43)           Total: 128 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 36 insertions, 5 deletions

diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index f018ca9d9..81a2b048f 100644
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -161,6 +161,7 @@ static len_and_sockaddr* str2sockaddr(
 IF_FEATURE_IPV6(sa_family_t af,)
                 int ai_flags)
 {
+IF_NOT_FEATURE_IPV6(sa_family_t af = AF_INET;)
         int rc;
         len_and_sockaddr *r;
         struct addrinfo *result = NULL;
@@ -221,12 +222,40 @@ IF_FEATURE_IPV6(sa_family_t af,)
  skip: ;
         }
 
+        /* Next two if blocks allow to skip getaddrinfo()
+         * in case host is a numeric IP(v6) address,
+         * getaddrinfo() initializes DNS resolution machinery,
+         * scans network config and such - tens of syscalls.
+         */
+        /* If we were not asked specifically for IPv6,
+         * check whether this is a numeric IPv4 */
+        IF_FEATURE_IPV6(if(af != AF_INET6)) {
+                struct in_addr in4;
+                if (inet_aton(host, &in4) != 0) {
+                        r = xzalloc(LSA_LEN_SIZE + sizeof(struct sockaddr_in));
+                        r->len = sizeof(struct sockaddr_in);
+                        r->u.sa.sa_family = AF_INET;
+                        r->u.sin.sin_addr = in4;
+                        goto set_port;
+                }
+        }
+#if ENABLE_FEATURE_IPV6
+        /* If we were not asked specifically for IPv4,
+         * check whether this is a numeric IPv6 */
+        if (af != AF_INET) {
+                struct in6_addr in6;
+                if (inet_pton(AF_INET6, host, &in6) > 0) {
+                        r = xzalloc(LSA_LEN_SIZE + sizeof(struct sockaddr_in6));
+                        r->len = sizeof(struct sockaddr_in6);
+                        r->u.sa.sa_family = AF_INET6;
+                        r->u.sin6.sin6_addr = in6;
+                        goto set_port;
+                }
+        }
+#endif
+
         memset(&hint, 0 , sizeof(hint));
-#if !ENABLE_FEATURE_IPV6
-        hint.ai_family = AF_INET; /* do not try to find IPv6 */
-#else
         hint.ai_family = af;
-#endif
         /* Needed. Or else we will get each address thrice (or more)
          * for each possible socket type (tcp,udp,raw...): */
         hint.ai_socktype = SOCK_STREAM;
@@ -250,9 +279,11 @@ IF_FEATURE_IPV6(sa_family_t af,)
                 }
         }
 #endif
-        r = xmalloc(offsetof(len_and_sockaddr, u.sa) + used_res->ai_addrlen);
+        r = xmalloc(LSA_LEN_SIZE + used_res->ai_addrlen);
         r->len = used_res->ai_addrlen;
         memcpy(&r->u.sa, used_res->ai_addr, used_res->ai_addrlen);
+
+ IF_FEATURE_IPV6(set_port:)
         set_nport(r, htons(port));
  ret:
         freeaddrinfo(result);