From 2e0ba7bb5b13af2c9d4bde40ae11d83f727fd9fe Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Fri, 10 Jan 2014 15:02:39 +0100
Subject: [PATCH] anetResolveIP() added to anet.c.

The new function is used when we want to normalize an IP address without
performing a DNS lookup if the string to resolve is not a valid IP.

This is useful every time only IPs are valid inputs or when we want to
skip DNS resolution that is slow during runtime operations if we are
required to block.
---
 src/anet.c | 19 ++++++++++++++++++-
 src/anet.h |  4 ++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/anet.c b/src/anet.c
index ef52d955..fc585c8d 100644
--- a/src/anet.c
+++ b/src/anet.c
@@ -163,12 +163,21 @@ int anetTcpKeepAlive(char *err, int fd)
     return ANET_OK;
 }
 
-int anetResolve(char *err, char *host, char *ipbuf, size_t ipbuf_len)
+/* anetGenericResolve() is called by anetResolve() and anetResolveIP() to
+ * do the actual work. It resolves the hostname "host" and set the string
+ * representation of the IP address into the buffer pointed by "ipbuf".
+ *
+ * If flags is set to ANET_IP_ONLY the function only resolves hostnames
+ * that are actually already IPv4 or IPv6 addresses. This turns the function
+ * into a validating / normalizing function. */
+int anetGenericResolve(char *err, char *host, char *ipbuf, size_t ipbuf_len,
+                       int flags)
 {
     struct addrinfo hints, *info;
     int rv;
 
     memset(&hints,0,sizeof(hints));
+    if (flags & ANET_IP_ONLY) hints.ai_flags = AI_NUMERICHOST;
     hints.ai_family = AF_UNSPEC;
     hints.ai_socktype = SOCK_STREAM;  /* specify socktype to avoid dups */
 
@@ -188,6 +197,14 @@ int anetResolve(char *err, char *host, char *ipbuf, size_t ipbuf_len)
     return ANET_OK;
 }
 
+int anetResolve(char *err, char *host, char *ipbuf, size_t ipbuf_len) {
+    return anetGenericResolve(err,host,ipbuf,ipbuf_len,ANET_NONE);
+}
+
+int anetResolveIP(char *err, char *host, char *ipbuf, size_t ipbuf_len) {
+    return anetGenericResolve(err,host,ipbuf,ipbuf_len,ANET_IP_ONLY);
+}
+
 static int anetSetReuseAddr(char *err, int fd) {
     int yes = 1;
     /* Make sure connection-intensive things like the redis benckmark
diff --git a/src/anet.h b/src/anet.h
index b23411cb..f0ab63ab 100644
--- a/src/anet.h
+++ b/src/anet.h
@@ -35,6 +35,10 @@
 #define ANET_ERR -1
 #define ANET_ERR_LEN 256
 
+/* Flags used with certain functions. */
+#define ANET_NONE 0
+#define ANET_IP_ONLY (1<<0)
+
 #if defined(__sun)
 #define AF_LOCAL AF_UNIX
 #endif