From 5654318b39dae5e5a32e290849ec590cb85ee0b3 Mon Sep 17 00:00:00 2001
Message-Id: <5654318b39dae5e5a32e290849ec590cb85ee0b3.1322557154.git.n.voss@weinmann.de>
In-Reply-To: <cover.1322557154.git.n.voss@weinmann.de>
References: <cover.1322557154.git.n.voss@weinmann.de>
From: Nikolaus Voss <n.voss@weinmann.de>
Date: Mon, 28 Nov 2011 16:18:30 +0100
Subject: [PATCH 1/2] gethostbyaddr_r: add space for alias pointers
To: uclibc@uclibc.org
addr_list and alias where on the same buffer offset. This led
to corrupt addr_list which was overwritten by the resolved name.
Signed-off-by: Nikolaus Voss <n.voss@weinmann.de>
---
libc/inet/resolv.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index 021d5bf..bc596b0 100644
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -2402,6 +2402,8 @@ int gethostbyaddr_r(const void *addr, socklen_t addrlen,
*/
#define in6 ((struct in6_addr *)in)
alias = (char **)buf;
+ buf += sizeof(alias) * 2;
+ buflen -= sizeof(alias) * 2;
addr_list = (struct in_addr**)buf;
buf += sizeof(*addr_list) * 2;
buflen -= sizeof(*addr_list) * 2;
--
1.7.5.4
From 5388e302e40b12fb6682899dd4206f3e3d7a84fa Mon Sep 17 00:00:00 2001
Message-Id: <5388e302e40b12fb6682899dd4206f3e3d7a84fa.1322557154.git.n.voss@weinmann.de>
In-Reply-To: <cover.1322557154.git.n.voss@weinmann.de>
References: <cover.1322557154.git.n.voss@weinmann.de>
From: Nikolaus Voss <n.voss@weinmann.de>
Date: Mon, 28 Nov 2011 16:22:42 +0100
Subject: [PATCH 2/2] Make link-local addresses resolvable via running
avahi-daemon
To: uclibc@uclibc.org
nss-mdns is an extension to glibc to support resolution of link-local
(.local) addresses via GNU Name Service Switch (NSS) which redirects
the queries to a running avahi-daemon, which in turn does the resolution
via multicast DNS (mdns).
However, this does not work for uClibc, as it does not support NSS.
This patch integrates the nss-mdns approach into uClibc's resolver,
so getaddrinfo() and getnameinfo() calls get redirected to a running
avahi-daemon before trying to resolve via unicast DNS.
This increases the size of the library by 50 bytes on ARM.
Signed-off-by: Nikolaus Voss <n.voss@weinmann.de>
---
extra/Configs/Config.in | 19 +++
libc/inet/Makefile.in | 1 +
libc/inet/avahi.c | 183 ++++++++++++++++++++++
libc/inet/avahi.h | 33 ++++
libc/inet/resolv.c | 23 +++-
libc/sysdeps/linux/common/bits/kernel-features.h | 7 +-
6 files changed, 259 insertions(+), 7 deletions(-)
create mode 100644 libc/inet/avahi.c
create mode 100644 libc/inet/avahi.h
diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in
index e41adc4..6053a55 100644
--- a/extra/Configs/Config.in
+++ b/extra/Configs/Config.in
@@ -1268,6 +1268,25 @@ config UCLIBC_HAS_EXTRA_COMPAT_RES_STATE
Answer Y if selecting UCLIBC_HAS_COMPAT_RES_STATE is not enough.
As far as I can say, this should never be needed.
+config UCLIBC_HAS_AVAHI_RES
+ bool "Try to resolve link-local IP addresses via avahi-daemon"
+ default n
+ depends on UCLIBC_HAS_IPV4 || UCLIBC_HAS_IPV6
+ help
+ Answer Y if you want to resolve .local addresses via multicast-dns.
+ The queries are forwarded to a running avahi-daemon via a domain
+ socket interface.
+ Note that this might interfere with a .local domain on your DNS.
+ Answering N saves around 50 bytes.
+
+config UCLIBC_AVAHI_SOCKET_PATH
+ string "Path to avahi unix domain socket"
+ default "/var/run/avahi-daemon/socket"
+ depends on UCLIBC_HAS_AVAHI_RES
+ help
+ A running avahi-daemon creates a socket to listen for queries.
+ Enter the path you configured your avahi-daemon to.
+
config UCLIBC_HAS_LIBRESOLV_STUB
bool "Provide libresolv stub"
default n
diff --git a/libc/inet/Makefile.in b/libc/inet/Makefile.in
index d588220..7f436c9 100644
--- a/libc/inet/Makefile.in
+++ b/libc/inet/Makefile.in
@@ -33,6 +33,7 @@ CSRC-$(findstring y,$(UCLIBC_HAS_IPV4)$(UCLIBC_HAS_IPV6)) += \
dnslookup.c opennameservers.c closenameservers.c \
getnameinfo.c \
gethostent.c gethostent_r.c
+CSRC-$(UCLIBC_HAS_AVAHI_RES) += avahi.c
CSRC-$(findstring y,$(UCLIBC_HAS_IPV4)$(UCLIBC_HAS_IPV6)) += \
get_hosts_byaddr_r.c get_hosts_byname_r.c \
gethostbyaddr_r.c gethostbyname_r.c gethostbyname2_r.c \
diff --git a/libc/inet/avahi.c b/libc/inet/avahi.c
new file mode 100644
index 0000000..11ce055
--- /dev/null
+++ b/libc/inet/avahi.c
@@ -0,0 +1,183 @@
+/*
+ *
+ * (C) 2011 Weinmann GmbH, Hamburg, Germany
+ *
+ * Author: Nikolaus Voss <n.voss@weinmann.de>
+ *
+ * Derived from avahi.c / nss-mdns by Lennart Poettering.
+ * Copyright 2004-2007 Lennart Poettering <mzaffzqaf (at) 0pointer (dot) de>
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ *
+ */
+
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <not-cancel.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "avahi.h"
+
+#define WHITESPACE " \t"
+
+static FILE *avahi_open_socket(void)
+{
+ int fd;
+ struct sockaddr_un sa;
+ FILE *f;
+
+ fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
+
+ if (fd < 0)
+ return NULL;
+
+#ifndef __ASSUME_SOCK_CLOEXEC
+ fcntl_not_cancel(fd, F_SETFD, FD_CLOEXEC);
+#endif
+
+ memset(&sa, 0, sizeof(sa));
+ sa.sun_family = AF_UNIX;
+ strncpy(sa.sun_path, __UCLIBC_AVAHI_SOCKET_PATH__,
+ sizeof(sa.sun_path) - 1);
+ sa.sun_path[sizeof(sa.sun_path) - 1] = 0;
+
+ if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
+ goto fail;
+
+ f = fdopen(fd, "r+");
+ if (!f)
+ goto fail;
+
+ return f;
+
+fail:
+ close(fd);
+
+ return NULL;
+}
+
+static int avahi_ends_with(const char *name, const char* suffix)
+{
+ size_t ln, ls;
+
+ if (!name || !suffix)
+ return 0;
+
+ if ((ls = strlen(suffix)) > (ln = strlen(name)))
+ return 0;
+
+ return strcasecmp(name + ln - ls, suffix) == 0;
+}
+
+int __avahi_resolve_name(int af, const char* name, void* data)
+{
+ FILE *f;
+ char *p;
+ int ret = -1;
+ char ln[256];
+
+ if (af != AF_INET && af != AF_INET6)
+ return ret;
+
+ if (!avahi_ends_with(name, ".local") &&
+ !avahi_ends_with(name, ".local."))
+ return ret;
+
+ f = avahi_open_socket();
+ if (!f)
+ return ret;
+
+ fprintf(f, "RESOLVE-HOSTNAME-IPV%d %s\n", af == AF_INET ? 4 : 6, name);
+ fflush(f);
+
+ if (!fgets(ln, sizeof(ln), f))
+ goto finish;
+
+ if (ln[0] != '+') {
+ ret = 1;
+ goto finish;
+ }
+
+ p = ln + 1;
+ p += strspn(p, WHITESPACE);
+
+ /* Skip interface */
+ p += strcspn(p, WHITESPACE);
+ p += strspn(p, WHITESPACE);
+
+ /* Skip protocol */
+ p += strcspn(p, WHITESPACE);
+ p += strspn(p, WHITESPACE);
+
+ /* Skip host name */
+ p += strcspn(p, WHITESPACE);
+ p += strspn(p, WHITESPACE);
+
+ /* Cut off end of line */
+ p[strcspn(p, "\n\r\t ")] = 0;
+
+ if (inet_pton(af, p, data) <= 0)
+ goto finish;
+
+ ret = 0;
+
+finish:
+ fclose(f);
+
+ return ret;
+}
+
+int __avahi_resolve_address(int af, const void *data, char* name,
+ size_t name_len)
+{
+ FILE *f;
+ char *p;
+ int ret = -1;
+ char a[256], ln[256];
+
+ if (af != AF_INET && af != AF_INET6)
+ return ret;
+
+ f = avahi_open_socket();
+ if (!f)
+ return ret;
+
+ fprintf(f, "RESOLVE-ADDRESS %s\n", inet_ntop(af, data, a, sizeof(a)));
+
+ if (!fgets(ln, sizeof(ln), f))
+ goto finish;
+
+ if (ln[0] != '+') {
+ ret = 1;
+ goto finish;
+ }
+
+ p = ln + 1;
+ p += strspn(p, WHITESPACE);
+
+ /* Skip interface */
+ p += strcspn(p, WHITESPACE);
+ p += strspn(p, WHITESPACE);
+
+ /* Skip protocol */
+ p += strcspn(p, WHITESPACE);
+ p += strspn(p, WHITESPACE);
+
+ /* Cut off end of line */
+ p[strcspn(p, "\n\r\t ")] = 0;
+
+ strncpy(name, p, name_len - 1);
+ name[name_len - 1] = 0;
+
+ ret = 0;
+
+finish:
+ fclose(f);
+
+ return ret;
+}
diff --git a/libc/inet/avahi.h b/libc/inet/avahi.h
new file mode 100644
index 0000000..85df5f6
--- /dev/null
+++ b/libc/inet/avahi.h
@@ -0,0 +1,33 @@
+/*
+ *
+ * (C) 2011 Weinmann GmbH, Hamburg, Germany
+ *
+ * Author: Nikolaus Voss <n.voss@weinmann.de>
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ *
+ */
+
+#ifndef _UCLIBC_AVAHI_H_
+#define _UCLIBC_AVAHI_H_
+
+#ifdef __UCLIBC_HAS_AVAHI_RES__
+int __avahi_resolve_name(int af, const char* name, void* data) attribute_hidden;
+
+int __avahi_resolve_address(int af, const void *data, char* name,
+ size_t name_len) attribute_hidden;
+#else
+static inline int __avahi_resolve_name(int af, const char* name, void* data)
+ attribute_hidden
+{
+ return 1;
+}
+
+static inline int __avahi_resolve_address(int af, const void *data, char* name,
+ size_t name_len) attribute_hidden
+{
+ return 1;
+}
+#endif
+
+#endif
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index bc596b0..2527b50 100644
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -318,6 +318,7 @@ Domain name in a message can be represented as either:
#include <sys/stat.h>
#include <bits/uClibc_mutex.h>
#include "internal/parse_config.h"
+#include "avahi.h"
/* poll() is not supported in kernel <= 2.0, therefore if __NR_poll is
* not available, we assume an old Linux kernel is in use and we will
@@ -2073,10 +2074,11 @@ int gethostbyname_r(const char *name,
alias[0] = alias0;
alias[1] = NULL;
- /* maybe it is already an address? */
+ /* maybe it is resolvable via avahi or already an address? */
{
struct in_addr *in = (struct in_addr *)(buf + sizeof(addr_list[0]) * 2);
- if (inet_aton(name, in)) {
+ if (!__avahi_resolve_name(AF_INET, name, in) ||
+ inet_aton(name, in)) {
addr_list[0] = in;
addr_list[1] = NULL;
result_buf->h_name = alias0;
@@ -2263,8 +2265,9 @@ int gethostbyname2_r(const char *name,
strncpy(buf, name, buflen);
buf[buflen] = '\0';
- /* maybe it is already an address? */
- if (inet_pton(AF_INET6, name, in)) {
+ /* maybe it is resolvable via avahi or already an address? */
+ if (!__avahi_resolve_name(AF_INET6, name, in) ||
+ inet_pton(AF_INET6, name, in)) {
result_buf->h_name = buf;
result_buf->h_addrtype = AF_INET6;
result_buf->h_length = sizeof(*in);
@@ -2427,6 +2430,18 @@ int gethostbyaddr_r(const void *addr, socklen_t addrlen,
addr_list[1] = NULL;
memcpy(in, addr, addrlen);
+ /* is this a .local address? */
+ if (!__avahi_resolve_address(type, in, buf, buflen)) {
+ result_buf->h_name = buf;
+ result_buf->h_addrtype = type;
+ result_buf->h_length = addrlen;
+ result_buf->h_addr_list = (char **) addr_list;
+ result_buf->h_aliases = alias;
+ *result = result_buf;
+ *h_errnop = NETDB_SUCCESS;
+ return NETDB_SUCCESS;
+ }
+
if (0) /* nothing */;
#ifdef __UCLIBC_HAS_IPV4__
else IF_HAS_BOTH(if (type == AF_INET)) {
diff --git a/libc/sysdeps/linux/common/bits/kernel-features.h b/libc/sysdeps/linux/common/bits/kernel-features.h
index 6bf5544..a322334 100644
--- a/libc/sysdeps/linux/common/bits/kernel-features.h
+++ b/libc/sysdeps/linux/common/bits/kernel-features.h
@@ -310,11 +310,12 @@
#endif
/* Support for various CLOEXEC and NONBLOCK flags was added for x86,
- * x86-64, PPC, IA-64, and SPARC in 2.6.27. */
+ * x86-64, PPC, IA-64, ARM and SPARC in 2.6.27. */
#if __LINUX_KERNEL_VERSION >= 0x02061b \
&& (defined __i386__ || defined __x86_64__ || defined __powerpc__ \
- || defined __ia64__ || defined __sparc__ || defined __s390__)
-/* # define __ASSUME_SOCK_CLOEXEC 1 */
+ || defined __ia64__ || defined __sparc__ || defined __s390__ \
+ || defined __arm__)
+# define __ASSUME_SOCK_CLOEXEC 1
/* # define __ASSUME_IN_NONBLOCK 1 */
# define __ASSUME_PIPE2 1
/* # define __ASSUME_EVENTFD2 1 */
--
1.7.5.4