From c5120a914a51220de18345fcb19e8cf725bfb407 Mon Sep 17 00:00:00 2001
From: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Date: Mon, 5 Sep 2011 19:08:27 +0200
Subject: [PATCH] Implement first draft of DNS-SD support in git-daemon

---
 Makefile | 11 +++++++++++
 daemon.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/Makefile b/Makefile
index 840057cba7..7608290fc3 100644
--- a/Makefile
+++ b/Makefile
@@ -164,6 +164,8 @@ all::
 # Notably on Solaris hstrerror resides in libresolv and on Solaris 7
 # inet_ntop and inet_pton additionally reside there.
 #
+# Define NO_DNSSD if you lack DNS-SD support.
+#
 # Define NO_MMAP if you want to avoid mmap.
 #
 # Define NO_SYS_POLL_H if you don't have sys/poll.h.
@@ -405,6 +407,8 @@ XGETTEXT = xgettext
 MSGFMT = msgfmt
 PTHREAD_LIBS = -lpthread
 PTHREAD_CFLAGS =
+DNSSD_LIBS = -ldns_sd
+DNSSD_CFLAGS =
 GCOV = gcov
 
 export TCL_PATH TCLTK_PATH
@@ -1450,6 +1454,13 @@ else
 	LIB_OBJS += thread-utils.o
 endif
 
+ifdef NO_DNSSD
+	BASIC_CFLAGS += -DNO_DNSSD
+else
+	BASIC_CFLAGS += $(DNSSD_CFLAGS)
+	EXTLIBS += $(DNSSD_LIBS)
+endif
+
 ifdef HAVE_PATHS_H
 	BASIC_CFLAGS += -DHAVE_PATHS_H
 endif
diff --git a/daemon.c b/daemon.c
index 1eb6631723..260cf43e04 100644
--- a/daemon.c
+++ b/daemon.c
@@ -5,6 +5,14 @@
 #include "strbuf.h"
 #include "string-list.h"
 
+#ifndef NO_DNSSD
+#include <dns_sd.h>
+static DNSServiceRef sdRef;
+#endif
+
+static void dnssd_register(struct string_list *listen_addr, int listen_port);
+static void dnssd_unregister(void);
+
 #ifndef HOST_NAME_MAX
 #define HOST_NAME_MAX 256
 #endif
@@ -103,6 +111,7 @@ static void loginfo(const char *err, ...)
 static void NORETURN daemon_die(const char *err, va_list params)
 {
 	logreport(LOG_ERR, err, params);
+	dnssd_unregister();
 	exit(1);
 }
 
@@ -1094,6 +1103,55 @@ static struct credentials *prepare_credentials(const char *user_name,
 }
 #endif
 
+#ifndef NO_DNSSD
+static void register_dnssd_addr(const char *listen_addr, int listen_port)
+{
+	/* We can use if_nametoindex() to turn an interface name
+	   into an index, but how do we turn a listen_addr into
+	   an interface name? */
+	unsigned if_idx = 0;
+	DNSServiceErrorType err = DNSServiceRegister(&sdRef,
+			0, /* Default flags */
+			if_idx,
+			"git daemon", /* TODO customize */
+			"_git._tcp",
+			NULL, /* domain */
+			NULL, /* host */
+			listen_port,
+			0, NULL, /* TODO customize TXT */
+			NULL, NULL);
+	if (err != kDNSServiceErr_NoError)
+		logerror("failed to register service on DNS-SD (%d)\n", err);
+	else
+		loginfo("registered git service for port %d on DNS-SD\n",
+			listen_port);
+}
+
+static void dnssd_register(struct string_list *listen_addr, int listen_port)
+{
+	if (!listen_addr->nr)
+		register_dnssd_addr("", listen_port);
+	else {
+		int i;
+		for (i = 0; i < listen_addr->nr; ++i) {
+			register_dnssd_addr(listen_addr->items[i].string,
+					    listen_port);
+		}
+	}
+}
+
+static void dnssd_unregister(void)
+{
+	DNSServiceRefDeallocate(sdRef);
+	sdRef = NULL;
+}
+#else
+static void dnssd_register(struct string_list *listen_addr, int listen_port)
+{};
+static void dnssd_unregister(void)
+{};
+#endif
+
 static void store_pid(const char *path)
 {
 	FILE *f = fopen(path, "w");
@@ -1115,6 +1173,8 @@ static int serve(struct string_list *listen_addr, int listen_port,
 
 	drop_privileges(cred);
 
+	dnssd_register(listen_addr, listen_port);
+
 	loginfo("Ready to rumble");
 
 	return service_loop(&socklist);
-- 
2.32.0.93.g670b81a890