[tor-commits] [torsocks/master] Implement gethostbyaddr libc call
dgoulet at torproject.org
dgoulet at torproject.org
Fri Apr 4 22:40:25 UTC 2014
commit 4c90e9e112cd1f72bc7f90af9f3d59dc37c832dc
Author: David Goulet <dgoulet at ev0ke.net>
Date: Sun Jun 23 22:38:40 2013 -0400
Implement gethostbyaddr libc call
Also add the tor resolve ptr function call in torsocks used by
gethostbyaddr().
Signed-off-by: David Goulet <dgoulet at ev0ke.net>
---
src/lib/gethostbyname.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++
src/lib/torsocks.c | 48 ++++++++++++++++++++++++++++++++++
src/lib/torsocks.h | 19 +++++++++++++-
3 files changed, 132 insertions(+), 1 deletion(-)
diff --git a/src/lib/gethostbyname.c b/src/lib/gethostbyname.c
index d9afec9..3e89e9b 100644
--- a/src/lib/gethostbyname.c
+++ b/src/lib/gethostbyname.c
@@ -24,6 +24,7 @@
#include <common/log.h>
#include "torsocks.h"
+
/*
* Torsocks call for gethostbyname(3).
*
@@ -113,3 +114,68 @@ LIBC_GETHOSTBYNAME2_DECL
{
return tsocks_gethostbyname2(LIBC_GETHOSTBYNAME2_ARGS);
}
+
+/*
+ * Torsocks call for gethostbyaddr(3).
+ *
+ * NOTE: This call is OBSOLETE in the glibc. Also, this call returns a pointer
+ * to a static pointer.
+ */
+LIBC_GETHOSTBYADDR_RET_TYPE tsocks_gethostbyaddr(LIBC_GETHOSTBYADDR_SIG)
+{
+ int ret;
+ char *hostname;
+
+ /*
+ * Tor does not allow to resolve to an IPv6 pointer so only accept inet
+ * return address.
+ */
+ if (!__addr || __type != AF_INET) {
+ h_errno = HOST_NOT_FOUND;
+ goto error;
+ }
+
+ DBG("[gethostbyaddr] Requesting address %s of len %d and type %d",
+ inet_ntoa(*((struct in_addr *) __addr)), __len, __type);
+
+ /* Reset static host entry of tsocks. */
+ memset(&tsocks_he, 0, sizeof(tsocks_he));
+ memset(tsocks_he_addr_list, 0, sizeof(tsocks_he_addr_list));
+ memset(tsocks_he_name, 0, sizeof(tsocks_he_name));
+
+ ret = tsocks_tor_resolve_ptr(__addr, &hostname, __type);
+ if (ret < 0) {
+ const char *ret_str;
+
+ ret_str = inet_ntop(__type, __addr, tsocks_he_name,
+ sizeof(tsocks_he_name));
+ if (!ret_str) {
+ h_errno = HOST_NOT_FOUND;
+ goto error;
+ }
+ } else {
+ memcpy(tsocks_he_name, hostname, sizeof(tsocks_he_name));
+ free(hostname);
+ tsocks_he_addr_list[0] = (char *) __addr;
+ }
+
+ tsocks_he.h_name = tsocks_he_name;
+ tsocks_he.h_aliases = NULL;
+ tsocks_he.h_length = strlen(tsocks_he_name);
+ tsocks_he.h_addrtype = __type;
+ tsocks_he.h_addr_list = tsocks_he_addr_list;
+
+ errno = 0;
+ return &tsocks_he;
+
+error:
+ return NULL;
+}
+
+/*
+ * Libc hijacked symbol gethostbyaddr(3).
+ */
+LIBC_GETHOSTBYADDR_DECL
+{
+ return tsocks_gethostbyaddr(LIBC_GETHOSTBYADDR_ARGS);
+}
diff --git a/src/lib/torsocks.c b/src/lib/torsocks.c
index 6b657ef..bc5959a 100644
--- a/src/lib/torsocks.c
+++ b/src/lib/torsocks.c
@@ -19,6 +19,7 @@
#include <assert.h>
#include <dlfcn.h>
+#include <inttypes.h>
#include <stdlib.h>
#include <common/config-file.h>
@@ -305,6 +306,53 @@ error:
}
/*
+ * Resolve a hostname through Tor and set the ip address in the given pointer.
+ *
+ * Return 0 on success else a negative value and the result addr is untouched.
+ */
+int tsocks_tor_resolve_ptr(const char *addr, char **ip, int af)
+{
+ int ret;
+ struct connection conn;
+
+ assert(addr);
+ assert(ip);
+
+ DBG("Resolving %" PRIu32 " on the Tor network", addr);
+
+ conn.fd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+ if (conn.fd < 0) {
+ PERROR("socket");
+ ret = -errno;
+ goto error;
+ }
+
+ ret = setup_tor_connection(&conn);
+ if (ret < 0) {
+ goto error;
+ }
+
+ ret = socks5_send_resolve_ptr_request(addr, &conn);
+ if (ret < 0) {
+ goto error;
+ }
+
+ /* Force IPv4 resolution for now. */
+ ret = socks5_recv_resolve_ptr_reply(&conn, ip);
+ if (ret < 0) {
+ goto error;
+ }
+
+ ret = close(conn.fd);
+ if (ret < 0) {
+ PERROR("close");
+ }
+
+error:
+ return ret;
+}
+
+/*
* Lookup symbol in the loaded libraries of the binary.
*
* Return the function pointer or NULL on error.
diff --git a/src/lib/torsocks.h b/src/lib/torsocks.h
index 0121716..2e6fd50 100644
--- a/src/lib/torsocks.h
+++ b/src/lib/torsocks.h
@@ -45,7 +45,7 @@
#define LIBC_CONNECT_ARGS \
__sockfd, __addr, __addrlen
-/* gethostbyname(3) */
+/* gethostbyname(3) - DEPRECATED in glibc. */
#include <netdb.h>
/*
@@ -57,6 +57,7 @@
struct hostent tsocks_he;
char *tsocks_he_addr_list[2];
char tsocks_he_addr[INET_ADDRSTRLEN];
+char tsocks_he_name[255];
#define LIBC_GETHOSTBYNAME_NAME gethostbyname
#define LIBC_GETHOSTBYNAME_NAME_STR XSTR(LIBC_GETHOSTBYNAME_NAME)
@@ -71,6 +72,15 @@ char tsocks_he_addr[INET_ADDRSTRLEN];
#define LIBC_GETHOSTBYNAME2_SIG const char *__name, int __af
#define LIBC_GETHOSTBYNAME2_ARGS __name, __af
+/* gethostbyaddr(3) - DEPRECATED in glibc. */
+#include <sys/socket.h>
+
+#define LIBC_GETHOSTBYADDR_NAME gethostbyaddr
+#define LIBC_GETHOSTBYADDR_NAME_STR XSTR(LIBC_GETHOSTBYADDR_NAME)
+#define LIBC_GETHOSTBYADDR_RET_TYPE struct hostent *
+#define LIBC_GETHOSTBYADDR_SIG const void *__addr, socklen_t __len, int __type
+#define LIBC_GETHOSTBYADDR_ARGS __addr, __len, __type
+
/* getaddrinfo(3) */
#include <netdb.h>
@@ -108,6 +118,12 @@ TSOCKS_LIBC_DECL(gethostbyname2, LIBC_GETHOSTBYNAME2_RET_TYPE,
#define LIBC_GETHOSTBYNAME2_DECL LIBC_GETHOSTBYNAME2_RET_TYPE \
LIBC_GETHOSTBYNAME2_NAME(LIBC_GETHOSTBYNAME2_SIG)
+/* gethostbyaddr(3) */
+TSOCKS_LIBC_DECL(gethostbyaddr, LIBC_GETHOSTBYADDR_RET_TYPE,
+ LIBC_GETHOSTBYADDR_SIG)
+#define LIBC_GETHOSTBYADDR_DECL LIBC_GETHOSTBYADDR_RET_TYPE \
+ LIBC_GETHOSTBYADDR_NAME(LIBC_GETHOSTBYADDR_SIG)
+
/* getaddrinfo(3) */
TSOCKS_LIBC_DECL(getaddrinfo, LIBC_GETADDRINFO_RET_TYPE,
LIBC_GETADDRINFO_SIG)
@@ -131,5 +147,6 @@ int tsocks_connect_to_tor(struct connection *conn);
void *tsocks_find_libc_symbol(const char *symbol,
enum tsocks_sym_action action);
int tsocks_tor_resolve(const char *hostname, uint32_t *ip_addr);
+int tsocks_tor_resolve_ptr(const char *addr, char **ip, int af);
#endif /* TORSOCKS_H */
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