[PATCH 2/5] daemon: make host resolution a separate function

[Jonathan Nieder <jrnieder@gmail.com>]

Date: Mon, 6 Jun 2011 04:38:45 -0500

The locate_host() function looks up the IP address and canonical
hostname of the host named by its argument.  If it succeeds,
*ip_address and *canon_hostname are freed and replaced by the hosts'
IP address and canonical hostname, respectively, as strings.  If it
fails, *ip_address and *canon_hostname are left alone.

The git daemon uses this functionality to support the %IP and %CH
placeholders for its --interpolated-path feature.  Splitting it out as
a separate function would make it easier to tweak, for example to
unify the ipv6 and ipv4 code paths or to share code with other parts
of git that make DNS queries.

Signed-off-by; Jonathan Nieder <jrnieder@gmail.com>
---
From http://thread.gmane.org/gmane.comp.version-control.git/175106/focus=175108

The commit message was tweaked, but the patch is the same as before.

 daemon.c |  112 +++++++++++++++++++++++++++++++++++---------------------------
 1 file changed, 63 insertions(+), 49 deletions(-)

diff --git a/daemon.c b/daemon.c
index 15ce918a..2a9dfea0 100644
--- a/daemon.c
+++ b/daemon.c
@@ -441,6 +441,65 @@ static void parse_host_and_port(char *hostport, char **host,
 	}
 }
 
+#ifndef NO_IPV6
+
+static void locate_host(const char *hostname, char **ip_address,
+						char **canon_hostname)
+{
+	struct addrinfo hints;
+	struct addrinfo *ai;
+	int gai;
+	static char addrbuf[HOST_NAME_MAX + 1];
+	struct sockaddr_in *sin_addr;
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_flags = AI_CANONNAME;
+
+	gai = getaddrinfo(hostname, NULL, &hints, &ai);
+	if (gai)
+		return;
+
+	sin_addr = (void *)ai->ai_addr;
+	inet_ntop(AF_INET, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
+	free(*ip_address);
+	*ip_address = xstrdup(addrbuf);
+
+	free(*canon_hostname);
+	*canon_hostname = xstrdup(ai->ai_canonname ?
+				  ai->ai_canonname : *ip_address);
+
+	freeaddrinfo(ai);
+}
+
+#else
+
+static void locate_host(const char *hostname, char **ip_address,
+						char **canon_hostname)
+{
+	struct hostent *hent;
+	struct sockaddr_in sa;
+	char **ap;
+	static char addrbuf[HOST_NAME_MAX + 1];
+
+	hent = gethostbyname(hostname);
+
+	ap = hent->h_addr_list;
+	memset(&sa, 0, sizeof sa);
+	sa.sin_family = hent->h_addrtype;
+	sa.sin_port = htons(0);
+	memcpy(&sa.sin_addr, *ap, hent->h_length);
+
+	inet_ntop(hent->h_addrtype, &sa.sin_addr,
+		  addrbuf, sizeof(addrbuf));
+
+	free(*canon_hostname);
+	*canon_hostname = xstrdup(hent->h_name);
+	free(*ip_address);
+	*ip_address = xstrdup(addrbuf);
+}
+
+#endif
+
 /*
  * Read the host as supplied by the client connection.
  */
@@ -476,56 +535,11 @@ static void parse_host_arg(char *extra_args, int buflen)
 	}
 
 	/*
-	 * Locate canonical hostname and its IP address.
+	 * Locate canonical hostname and its IP address,
+	 * if possible.
 	 */
-	if (hostname) {
-#ifndef NO_IPV6
-		struct addrinfo hints;
-		struct addrinfo *ai;
-		int gai;
-		static char addrbuf[HOST_NAME_MAX + 1];
-
-		memset(&hints, 0, sizeof(hints));
-		hints.ai_flags = AI_CANONNAME;
-
-		gai = getaddrinfo(hostname, NULL, &hints, &ai);
-		if (!gai) {
-			struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
-
-			inet_ntop(AF_INET, &sin_addr->sin_addr,
-				  addrbuf, sizeof(addrbuf));
-			free(ip_address);
-			ip_address = xstrdup(addrbuf);
-
-			free(canon_hostname);
-			canon_hostname = xstrdup(ai->ai_canonname ?
-						 ai->ai_canonname : ip_address);
-
-			freeaddrinfo(ai);
-		}
-#else
-		struct hostent *hent;
-		struct sockaddr_in sa;
-		char **ap;
-		static char addrbuf[HOST_NAME_MAX + 1];
-
-		hent = gethostbyname(hostname);
-
-		ap = hent->h_addr_list;
-		memset(&sa, 0, sizeof sa);
-		sa.sin_family = hent->h_addrtype;
-		sa.sin_port = htons(0);
-		memcpy(&sa.sin_addr, *ap, hent->h_length);
-
-		inet_ntop(hent->h_addrtype, &sa.sin_addr,
-			  addrbuf, sizeof(addrbuf));
-
-		free(canon_hostname);
-		canon_hostname = xstrdup(hent->h_name);
-		free(ip_address);
-		ip_address = xstrdup(addrbuf);
-#endif
-	}
+	if (hostname)
+		locate_host(hostname, &ip_address, &canon_hostname);
 }
 
 
-- 
1.7.9.2