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resolver: add c-ares support

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This patch based on the patch from @gbour (see #7). With
--enable-cares old implementation will be replaced with c-ares API.
This commit is contained in:
Dmitry Podgorny
2019-10-14 06:51:08 +03:00
parent 18b67d6eaf
commit a13847d994
5 changed files with 310 additions and 103 deletions
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3
Makefile.am
View File

@@ -8,6 +8,7 @@ PARSER_LIBS=@PARSER_LIBS@
SSL_CFLAGS = @openssl_CFLAGS@
SSL_LIBS = @openssl_LIBS@
RESOLV_CFLAGS = @RESOLV_CFLAGS@
RESOLV_LIBS = @RESOLV_LIBS@
STROPHE_FLAGS = -I$(top_srcdir) -Wall -Wextra -Wno-unused-parameter
@@ -16,7 +17,7 @@ STROPHE_LIBS = libstrophe.la
## Main build targets
lib_LTLIBRARIES = libstrophe.la
libstrophe_la_CFLAGS = $(SSL_CFLAGS) $(STROPHE_FLAGS) $(PARSER_CFLAGS)
libstrophe_la_CFLAGS = $(SSL_CFLAGS) $(STROPHE_FLAGS) $(PARSER_CFLAGS) $(RESOLV_CFLAGS)
libstrophe_la_LDFLAGS = $(SSL_LIBS) $(PARSER_LIBS) $(RESOLV_LIBS) -no-undefined
# Export only public API
libstrophe_la_LDFLAGS += -export-symbols-regex '^xmpp_'

17
configure.ac
View File

@@ -21,6 +21,8 @@ AC_ARG_WITH([libxml2],
[AS_HELP_STRING([--with-libxml2], [use libxml2 for XML parsing, expat is the default])])
AC_ARG_ENABLE([tls],
[AS_HELP_STRING([--disable-tls], [disable TLS support])])
AC_ARG_ENABLE([cares],
[AS_HELP_STRING([--enable-cares], [use c-ares for DNS resolution])])
if test "x$enable_tls" != xno; then
PKG_CHECK_MODULES([openssl], [openssl],
@@ -84,6 +86,18 @@ AC_MSG_NOTICE([libstrophe will use the $with_parser XML parser])
AC_SEARCH_LIBS([socket], [socket])
if test "x$enable_cares" = xyes; then
PKG_CHECK_MODULES([libcares], [libcares >= 1.7.0],
[
PC_REQUIRES="libcares ${PC_REQUIRES}"
RESOLV_CFLAGS=$libcares_CFLAGS
RESOLV_LIBS=$libcares_LIBS
AC_DEFINE([HAVE_CARES])
],
[AC_MSG_ERROR([libcares not found])])
# TODO: if pkg-config doesn't find, check the library manually
else
AS_CASE([$PLATFORM],
[bsd], [RESOLV_LIBS=""],
[qnx], [RESOLV_LIBS="-lsocket"],
@@ -110,6 +124,8 @@ AC_LINK_IFELSE([AC_LANG_SOURCE([
LIBS="${LIBS_TMP}"
PC_LIBS="${RESOLV_LIBS} ${PC_LIBS}"
fi
m4_ifdef([PKG_INSTALLDIR], [PKG_INSTALLDIR],
[AC_ARG_WITH([pkgconfigdir],
[AS_HELP_STRING([--with-pkgconfigdir],
@@ -126,6 +142,7 @@ AC_SUBST([PC_LIBS], [${PC_LIBS}])
AC_SUBST(PARSER_CFLAGS)
AC_SUBST(PARSER_LIBS)
AC_SUBST(RESOLV_CFLAGS)
AC_SUBST(RESOLV_LIBS)
AC_CONFIG_FILES([Makefile libstrophe.pc])
AC_OUTPUT

3
src/ctx.c
View File

@@ -47,6 +47,7 @@
#include "strophe.h"
#include "common.h"
#include "resolver.h"
#include "util.h"
/* Workaround for visual studio without va_copy support. */
@@ -63,6 +64,7 @@
void xmpp_initialize(void)
{
sock_initialize();
resolver_initialize();
tls_initialize();
}
@@ -73,6 +75,7 @@
void xmpp_shutdown(void)
{
tls_shutdown();
resolver_shutdown();
sock_shutdown();
}

387
src/resolver.c
View File

@@ -1,4 +1,4 @@
/* resolver.h
/* resolver.c
* strophe XMPP client library -- DNS resolver
*
* Copyright (C) 2015 Dmitry Podgorny <pasis.ua@gmail.com>
@@ -13,11 +13,15 @@
* DNS resolver.
*/
#ifndef _WIN32
#if !defined(_WIN32) && !defined(HAVE_CARES)
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h> /* res_query */
#endif /* _WIN32 */
#endif /* _WIN32 && HAVE_CARES */
#ifdef HAVE_CARES
#include <ares.h>
#endif /* HAVE_CARES */
#include <string.h> /* strncpy */
@@ -31,6 +35,189 @@
#define MESSAGE_T_SRV 33
#define MESSAGE_C_IN 1
/*******************************************************************************
* Forward declarations.
******************************************************************************/
#ifdef HAVE_CARES
static int resolver_ares_srv_lookup_buf(xmpp_ctx_t *ctx,
const unsigned char *buf,
size_t len,
resolver_srv_rr_t **srv_rr_list);
static int resolver_ares_srv_lookup(xmpp_ctx_t *ctx, const char *fulldomain,
resolver_srv_rr_t **srv_rr_list);
#endif /* HAVE_CARES */
#ifndef HAVE_CARES
static int resolver_raw_srv_lookup_buf(xmpp_ctx_t *ctx,
const unsigned char *buf,
size_t len,
resolver_srv_rr_t **srv_rr_list);
#endif /* !HAVE_CARES */
#ifdef _WIN32
static int resolver_win32_srv_lookup(xmpp_ctx_t *ctx, const char *fulldomain,
resolver_srv_rr_t **srv_rr_list);
static int resolver_win32_srv_query(const char *fulldomain,
unsigned char *buf, size_t len);
#endif /* _WIN32 */
/*******************************************************************************
* Implementation.
******************************************************************************/
void resolver_initialize(void)
{
#ifdef HAVE_CARES
ares_library_init(ARES_LIB_INIT_ALL);
#endif
}
void resolver_shutdown(void)
{
#ifdef HAVE_CARES
ares_library_cleanup();
#endif
}
static void resolver_srv_list_sort(resolver_srv_rr_t **srv_rr_list)
{
resolver_srv_rr_t *rr_head;
resolver_srv_rr_t *rr_current;
resolver_srv_rr_t *rr_next;
resolver_srv_rr_t *rr_prev;
int swap;
rr_head = *srv_rr_list;
if ((rr_head == NULL) || (rr_head->next == NULL)) {
/* Empty or single record list */
return;
}
do {
rr_prev = NULL;
rr_current = rr_head;
rr_next = rr_head->next;
swap = 0;
while (rr_next != NULL) {
/*
* RFC2052: A client MUST attempt to contact the target host
* with the lowest-numbered priority it can reach.
* RFC2052: When selecting a target host among the
* those that have the same priority, the chance of trying
* this one first SHOULD be proportional to its weight.
*/
if ((rr_current->priority > rr_next->priority) ||
(rr_current->priority == rr_next->priority &&
rr_current->weight < rr_next->weight))
{
/* Swap node */
swap = 1;
if (rr_prev != NULL) {
rr_prev->next = rr_next;
} else {
/* Swap head node */
rr_head = rr_next;
}
rr_current->next = rr_next->next;
rr_next->next = rr_current;
rr_prev = rr_next;
rr_next = rr_current->next;
} else {
/* Next node */
rr_prev = rr_current;
rr_current = rr_next;
rr_next = rr_next->next;
}
}
} while (swap != 0);
*srv_rr_list = rr_head;
}
int resolver_srv_lookup_buf(xmpp_ctx_t *ctx, const unsigned char *buf,
size_t len, resolver_srv_rr_t **srv_rr_list)
{
int set;
#ifdef HAVE_CARES
set = resolver_ares_srv_lookup_buf(ctx, buf, len, srv_rr_list);
#else
set = resolver_raw_srv_lookup_buf(ctx, buf, len, srv_rr_list);
#endif
resolver_srv_list_sort(srv_rr_list);
return set;
}
int resolver_srv_lookup(xmpp_ctx_t *ctx, const char *service, const char *proto,
const char *domain, resolver_srv_rr_t **srv_rr_list)
{
#define RESOLVER_BUF_MAX 65536
unsigned char *buf;
char fulldomain[2048];
int len;
int set = XMPP_DOMAIN_NOT_FOUND;
(void)buf;
(void)len;
xmpp_snprintf(fulldomain, sizeof(fulldomain),
"_%s._%s.%s", service, proto, domain);
*srv_rr_list = NULL;
#ifdef HAVE_CARES
set = resolver_ares_srv_lookup(ctx, fulldomain, srv_rr_list);
#else /* HAVE_CARES */
#ifdef _WIN32
set = resolver_win32_srv_lookup(ctx, fulldomain, srv_rr_list);
if (set == XMPP_DOMAIN_FOUND)
return set;
#endif /* _WIN32 */
buf = xmpp_alloc(ctx, RESOLVER_BUF_MAX);
if (buf == NULL)
return XMPP_DOMAIN_NOT_FOUND;
#ifdef _WIN32
len = resolver_win32_srv_query(fulldomain, buf, RESOLVER_BUF_MAX);
#else /* _WIN32 */
len = res_query(fulldomain, MESSAGE_C_IN, MESSAGE_T_SRV, buf,
RESOLVER_BUF_MAX);
#endif /* _WIN32 */
if (len > 0)
set = resolver_srv_lookup_buf(ctx, buf, (size_t)len, srv_rr_list);
xmpp_free(ctx, buf);
#endif /* HAVE_CARES */
return set;
}
void resolver_srv_free(xmpp_ctx_t *ctx, resolver_srv_rr_t *srv_rr_list)
{
resolver_srv_rr_t *rr;
while (srv_rr_list != NULL) {
rr = srv_rr_list->next;
xmpp_free(ctx, srv_rr_list);
srv_rr_list = rr;
}
}
#ifndef HAVE_CARES
/*******************************************************************************
* Resolver raw implementation.
*
* This code is common for both unix and win32.
******************************************************************************/
struct message_header {
uint16_t id;
uint8_t octet2;
@@ -41,13 +228,6 @@ struct message_header {
uint16_t arcount;
};
#ifdef _WIN32
static int resolver_win32_srv_lookup(xmpp_ctx_t *ctx, const char *fulldomain,
resolver_srv_rr_t **srv_rr_list);
static int resolver_win32_srv_query(const char *fulldomain,
unsigned char *buf, size_t len);
#endif /* _WIN32 */
/* the same as ntohs(), but receives pointer to the value */
static uint16_t xmpp_ntohs_ptr(const void *ptr)
{
@@ -160,63 +340,6 @@ static unsigned message_name_len(const unsigned char *buf, size_t buf_len,
return message_name_get(buf, buf_len, buf_offset, NULL, SIZE_MAX);
}
static void resolver_srv_list_sort(resolver_srv_rr_t **srv_rr_list)
{
resolver_srv_rr_t * rr_head;
resolver_srv_rr_t * rr_current;
resolver_srv_rr_t * rr_next;
resolver_srv_rr_t * rr_prev;
int swap;
rr_head = *srv_rr_list;
if ((rr_head == NULL) || (rr_head->next == NULL)) {
/* Empty or single record list */
return;
}
do {
rr_prev = NULL;
rr_current = rr_head;
rr_next = rr_head->next;
swap = 0;
while (rr_next != NULL) {
/*
* RFC2052: A client MUST attempt to contact the target host
* with the lowest-numbered priority it can reach.
* RFC2052: When selecting a target host among the
* those that have the same priority, the chance of trying
* this one first SHOULD be proportional to its weight.
*/
if ((rr_current->priority > rr_next->priority) ||
(rr_current->priority == rr_next->priority &&
rr_current->weight < rr_next->weight))
{
/* Swap node */
swap = 1;
if (rr_prev != NULL) {
rr_prev->next = rr_next;
} else {
/* Swap head node */
rr_head = rr_next;
}
rr_current->next = rr_next->next;
rr_next->next = rr_current;
rr_prev = rr_next;
rr_next = rr_current->next;
} else {
/* Next node */
rr_prev = rr_current;
rr_current = rr_next;
rr_next = rr_next->next;
}
}
} while (swap != 0);
*srv_rr_list = rr_head;
}
#define BUF_OVERFLOW_CHECK(ptr, len) do { \
if ((ptr) >= (len)) { \
if (*srv_rr_list != NULL) \
@@ -226,8 +349,10 @@ static void resolver_srv_list_sort(resolver_srv_rr_t **srv_rr_list)
} \
} while (0)
int resolver_srv_lookup_buf(xmpp_ctx_t *ctx, const unsigned char *buf,
size_t len, resolver_srv_rr_t **srv_rr_list)
static int resolver_raw_srv_lookup_buf(xmpp_ctx_t *ctx,
const unsigned char *buf,
size_t len,
resolver_srv_rr_t **srv_rr_list)
{
unsigned i;
unsigned j;
@@ -292,52 +417,110 @@ int resolver_srv_lookup_buf(xmpp_ctx_t *ctx, const unsigned char *buf,
}
j += rdlength;
}
resolver_srv_list_sort(srv_rr_list);
return *srv_rr_list != NULL ? XMPP_DOMAIN_FOUND : XMPP_DOMAIN_NOT_FOUND;
}
int resolver_srv_lookup(xmpp_ctx_t *ctx, const char *service, const char *proto,
const char *domain, resolver_srv_rr_t **srv_rr_list)
{
char fulldomain[2048];
unsigned char buf[65535];
int len;
int set = XMPP_DOMAIN_NOT_FOUND;
#endif /* !HAVE_CARES */
xmpp_snprintf(fulldomain, sizeof(fulldomain),
"_%s._%s.%s", service, proto, domain);
#ifdef HAVE_CARES
/*******************************************************************************
* Resolver implementation using c-ares library.
******************************************************************************/
struct resolver_ares_ctx {
xmpp_ctx_t *ctx;
int result;
resolver_srv_rr_t *srv_rr_list;
};
static int resolver_ares_srv_lookup_buf(xmpp_ctx_t *ctx,
const unsigned char *buf,
size_t len,
resolver_srv_rr_t **srv_rr_list)
{
struct ares_srv_reply *srv;
struct ares_srv_reply *item;
resolver_srv_rr_t *rr;
int rc;
*srv_rr_list = NULL;
#ifdef _WIN32
set = resolver_win32_srv_lookup(ctx, fulldomain, srv_rr_list);
if (set == XMPP_DOMAIN_FOUND)
return set;
len = resolver_win32_srv_query(fulldomain, buf, sizeof(buf));
#else /* _WIN32 */
len = res_query(fulldomain, MESSAGE_C_IN, MESSAGE_T_SRV, buf, sizeof(buf));
#endif /* _WIN32 */
rc = ares_parse_srv_reply(buf, len, &srv);
if (rc != ARES_SUCCESS)
return XMPP_DOMAIN_NOT_FOUND;
if (len > 0)
set = resolver_srv_lookup_buf(ctx, buf, (size_t)len, srv_rr_list);
return set;
}
void resolver_srv_free(xmpp_ctx_t *ctx, resolver_srv_rr_t *srv_rr_list)
{
resolver_srv_rr_t *rr;
while (srv_rr_list != NULL) {
rr = srv_rr_list->next;
xmpp_free(ctx, srv_rr_list);
srv_rr_list = rr;
item = srv;
while (item != NULL) {
rr = xmpp_alloc(ctx, sizeof(*rr));
if (rr == NULL)
break;
rr->next = *srv_rr_list;
rr->priority = item->priority;
rr->weight = item->weight;
rr->port = item->port;
strncpy(rr->target, item->host, sizeof(rr->target) - 1);
rr->target[sizeof(rr->target) - 1] = '\0';
*srv_rr_list = rr;
item = item->next;
}
ares_free_data(srv);
return *srv_rr_list == NULL ? XMPP_DOMAIN_NOT_FOUND : XMPP_DOMAIN_FOUND;
}
#ifdef _WIN32
static void ares_srv_lookup_callback(void *arg, int status, int timeouts,
unsigned char *buf, int len)
{
struct resolver_ares_ctx *actx = arg;
if (status != ARES_SUCCESS)
actx->result = XMPP_DOMAIN_NOT_FOUND;
else
actx->result = resolver_ares_srv_lookup_buf(actx->ctx, buf, len,
&actx->srv_rr_list);
}
static int resolver_ares_srv_lookup(xmpp_ctx_t *ctx, const char *fulldomain,
resolver_srv_rr_t **srv_rr_list)
{
struct resolver_ares_ctx actx;
ares_channel chan;
struct timeval tv;
struct timeval *tvp;
fd_set rfds;
fd_set wfds;
int nfds;
int rc;
actx.ctx = ctx;
actx.result = XMPP_DOMAIN_NOT_FOUND;
actx.srv_rr_list = NULL;
rc = ares_init(&chan);
if (rc == ARES_SUCCESS) {
ares_query(chan, fulldomain, MESSAGE_C_IN, MESSAGE_T_SRV,
ares_srv_lookup_callback, &actx);
while (1) {
FD_ZERO(&rfds);
FD_ZERO(&wfds);
nfds = ares_fds(chan, &rfds, &wfds);
if (nfds == 0)
break;
tvp = ares_timeout(chan, NULL, &tv);
select(nfds, &rfds, &wfds, NULL, tvp);
ares_process(chan, &rfds, &wfds);
}
ares_destroy(chan);
}
*srv_rr_list = actx.srv_rr_list;
return actx.result;
}
#endif /* HAVE_CARES */
#ifdef _WIN32
/*******************************************************************************
* Next part was copied from sock.c and contains old win32 code.
*

3
src/resolver.h
View File

@@ -33,6 +33,9 @@ typedef struct resolver_srv_rr_struc {
struct resolver_srv_rr_struc *next;
} resolver_srv_rr_t;
void resolver_initialize(void);
void resolver_shutdown(void);
/** Perform lookup for RFC1035 message format.
* This function allocates all elements.
*