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449 lines
15 KiB
449 lines
15 KiB
From 709646d59d96cb73a7e70347f37de9823e4e5f14 Mon Sep 17 00:00:00 2001
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From: Leonid Evdokimov <leon@darkk.net.ru>
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Date: Fri, 13 Apr 2012 01:57:23 +0400
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Subject: [PATCH 03/12] Initial support for UDP + TPROXY redirection. No more
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dest_ip in redudp.
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* TPROXY requires Linux 2.6.29+ (see man 7 ip[1]).
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* all redsocks code is running as root to bind to arbitrary port.
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* Non-Linux and old-Linux builds are broken at the moment.
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[1] http://www.kernel.org/doc/man-pages/online/pages/man7/ip.7.html
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---
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dnstc.c | 2 +-
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redudp.c | 197 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
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redudp.h | 2 +
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utils.c | 43 +++++++++++++-
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utils.h | 2 +-
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5 files changed, 227 insertions(+), 19 deletions(-)
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diff --git a/dnstc.c b/dnstc.c
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index 43881d8..5f9fedd 100644
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--- a/dnstc.c
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+++ b/dnstc.c
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@@ -68,7 +68,7 @@ static void dnstc_pkt_from_client(int fd, short what, void *_arg)
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ssize_t pktlen, outgoing;
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assert(fd == EVENT_FD(&self->listener));
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- pktlen = red_recv_udp_pkt(fd, buf.raw, sizeof(buf), &clientaddr);
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+ pktlen = red_recv_udp_pkt(fd, buf.raw, sizeof(buf), &clientaddr, NULL);
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if (pktlen == -1)
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return;
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diff --git a/redudp.c b/redudp.c
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index 9516a50..262af3e 100644
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--- a/redudp.c
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+++ b/redudp.c
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@@ -15,6 +15,7 @@
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*/
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#include <stdlib.h>
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+#include <search.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/uio.h>
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@@ -33,30 +34,157 @@
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#include "redudp.h"
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#define redudp_log_error(client, prio, msg...) \
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- redsocks_log_write_plain(__FILE__, __LINE__, __func__, 0, &(client)->clientaddr, &(client)->instance->config.destaddr, prio, ## msg)
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+ redsocks_log_write_plain(__FILE__, __LINE__, __func__, 0, &(client)->clientaddr, get_destaddr(client), prio, ## msg)
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#define redudp_log_errno(client, prio, msg...) \
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- redsocks_log_write_plain(__FILE__, __LINE__, __func__, 1, &(client)->clientaddr, &(client)->instance->config.destaddr, prio, ## msg)
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+ redsocks_log_write_plain(__FILE__, __LINE__, __func__, 1, &(client)->clientaddr, get_destaddr(client), prio, ## msg)
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static void redudp_pkt_from_socks(int fd, short what, void *_arg);
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static void redudp_drop_client(redudp_client *client);
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static void redudp_fini_instance(redudp_instance *instance);
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static int redudp_fini();
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+static int redudp_transparent(int fd);
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typedef struct redudp_expected_assoc_reply_t {
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socks5_reply h;
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socks5_addr_ipv4 ip;
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} PACKED redudp_expected_assoc_reply;
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+struct bound_udp4_key {
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+ struct in_addr sin_addr;
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+ uint16_t sin_port;
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+};
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+
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+struct bound_udp4 {
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+ struct bound_udp4_key key;
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+ int ref;
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+ int fd;
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+};
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+
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/***********************************************************************
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* Helpers
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*/
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+// TODO: separate binding to privileged process (this operation requires uid-0)
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+static void* root_bound_udp4 = NULL; // to avoid two binds to same IP:port
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+
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+static int bound_udp4_cmp(const void *a, const void *b)
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+{
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+ return memcmp(a, b, sizeof(struct bound_udp4_key));
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+}
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+
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+static void bound_udp4_mkkey(struct bound_udp4_key *key, const struct sockaddr_in *addr)
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+{
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+ memset(key, 0, sizeof(*key));
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+ key->sin_addr = addr->sin_addr;
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+ key->sin_port = addr->sin_port;
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+}
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+
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+static int bound_udp4_get(const struct sockaddr_in *addr)
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+{
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+ struct bound_udp4_key key;
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+ struct bound_udp4 *node, **pnode;
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+
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+ bound_udp4_mkkey(&key, addr);
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+ // I assume, that memory allocation for lookup is awful, so I use
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+ // tfind/tsearch pair instead of tsearch/check-result.
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+ pnode = tfind(&key, &root_bound_udp4, bound_udp4_cmp);
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+ if (pnode) {
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+ assert((*pnode)->ref > 0);
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+ (*pnode)->ref++;
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+ return (*pnode)->fd;
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+ }
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+
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+ node = calloc(1, sizeof(*node));
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+ if (!node) {
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+ log_errno(LOG_ERR, "calloc");
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+ goto fail;
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+ }
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+
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+ node->key = key;
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+ node->ref = 1;
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+ node->fd = socket(AF_INET, SOCK_DGRAM, 0);
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+ if (node->fd == -1) {
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+ log_errno(LOG_ERR, "socket");
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+ goto fail;
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+ }
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+
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+ if (0 != redudp_transparent(node->fd))
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+ goto fail;
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+
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+ if (0 != bind(node->fd, (struct sockaddr*)addr, sizeof(*addr))) {
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+ log_errno(LOG_ERR, "bind");
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+ goto fail;
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+ }
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+
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+ pnode = tsearch(node, &root_bound_udp4, bound_udp4_cmp);
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+ if (!pnode) {
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+ log_errno(LOG_ERR, "tsearch(%p) == %p", node, pnode);
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+ goto fail;
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+ }
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+ assert(node == *pnode);
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+
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+ return node->fd;
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+
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+fail:
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+ if (node) {
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+ if (node->fd != -1)
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+ redsocks_close(node->fd);
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+ free(node);
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+ }
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+ return -1;
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+}
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+
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+static void bound_udp4_put(const struct sockaddr_in *addr)
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+{
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+ struct bound_udp4_key key;
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+ struct bound_udp4 **pnode, *node;
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+ void *parent;
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+
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+ bound_udp4_mkkey(&key, addr);
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+ pnode = tfind(&key, &root_bound_udp4, bound_udp4_cmp);
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+ assert(pnode && (*pnode)->ref > 0);
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+
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+ node = *pnode;
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+
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+ node->ref--;
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+ if (node->ref)
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+ return;
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+
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+ parent = tdelete(node, &root_bound_udp4, bound_udp4_cmp);
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+ assert(parent);
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+
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+ redsocks_close(node->fd); // expanding `pnode` to avoid use after free
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+ free(node);
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+}
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+
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+static int redudp_transparent(int fd)
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+{
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+ int on = 1;
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+ int error = setsockopt(fd, SOL_IP, IP_TRANSPARENT, &on, sizeof(on));
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+ if (error)
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+ log_errno(LOG_ERR, "setsockopt(..., SOL_IP, IP_TRANSPARENT)");
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+ return error;
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+}
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+
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+static int do_tproxy(redudp_instance* instance)
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+{
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+ return instance->config.destaddr.sin_addr.s_addr == 0;
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+}
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+
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+static struct sockaddr_in* get_destaddr(redudp_client *client)
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+{
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+ if (do_tproxy(client->instance))
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+ return &client->destaddr;
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+ else
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+ return &client->instance->config.destaddr;
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+}
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+
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static void redudp_fill_preamble(socks5_udp_preabmle *preamble, redudp_client *client)
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{
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preamble->reserved = 0;
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preamble->frag_no = 0; /* fragmentation is not supported */
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preamble->addrtype = socks5_addrtype_ipv4;
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- preamble->ip.addr = client->instance->config.destaddr.sin_addr.s_addr;
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- preamble->ip.port = client->instance->config.destaddr.sin_port;
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+ preamble->ip.addr = get_destaddr(client)->sin_addr.s_addr;
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+ preamble->ip.port = get_destaddr(client)->sin_port;
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}
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static struct evbuffer* socks5_mkmethods_plain_wrapper(void *p)
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@@ -104,6 +232,8 @@ static void redudp_drop_client(redudp_client *client)
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redudp_log_errno(client, LOG_ERR, "event_del");
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redsocks_close(fd);
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}
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+ if (client->sender_fd != -1)
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+ bound_udp4_put(&client->destaddr);
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list_for_each_entry_safe(q, tmp, &client->queue, list) {
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list_del(&q->list);
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free(q);
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@@ -344,7 +474,8 @@ static void redudp_relay_connected(struct bufferevent *buffev, void *_arg)
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redudp_client *client = _arg;
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int do_password = socks5_is_valid_cred(client->instance->config.login, client->instance->config.password);
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int error;
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- redudp_log_error(client, LOG_DEBUG, "<trace>");
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+ char relayaddr_str[RED_INET_ADDRSTRLEN];
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+ redudp_log_error(client, LOG_DEBUG, "via %s", red_inet_ntop(&client->instance->config.relayaddr, relayaddr_str, sizeof(relayaddr_str)));
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if (!red_is_socket_connected_ok(buffev)) {
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redudp_log_errno(client, LOG_NOTICE, "red_is_socket_connected_ok");
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@@ -382,7 +513,7 @@ static void redudp_timeout(int fd, short what, void *_arg)
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redudp_drop_client(client);
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}
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-static void redudp_first_pkt_from_client(redudp_instance *self, struct sockaddr_in *clientaddr, char *buf, size_t pktlen)
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+static void redudp_first_pkt_from_client(redudp_instance *self, struct sockaddr_in *clientaddr, struct sockaddr_in *destaddr, char *buf, size_t pktlen)
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{
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redudp_client *client = calloc(1, sizeof(*client));
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@@ -395,9 +526,13 @@ static void redudp_first_pkt_from_client(redudp_instance *self, struct sockaddr_
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INIT_LIST_HEAD(&client->queue);
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client->instance = self;
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memcpy(&client->clientaddr, clientaddr, sizeof(*clientaddr));
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+ if (destaddr)
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+ memcpy(&client->destaddr, destaddr, sizeof(client->destaddr));
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evtimer_set(&client->timeout, redudp_timeout, client);
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// XXX: self->relay_ss->init(client);
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+ client->sender_fd = -1; // it's postponed until socks-server replies to avoid trivial DoS
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+
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client->relay = red_connect_relay(&client->instance->config.relayaddr,
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redudp_relay_connected, redudp_relay_error, client);
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if (!client->relay)
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@@ -431,7 +566,7 @@ static void redudp_pkt_from_socks(int fd, short what, void *_arg)
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assert(fd == EVENT_FD(&client->udprelay));
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- pktlen = red_recv_udp_pkt(fd, pkt.buf, sizeof(pkt.buf), &udprelayaddr);
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+ pktlen = red_recv_udp_pkt(fd, pkt.buf, sizeof(pkt.buf), &udprelayaddr, NULL);
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if (pktlen == -1)
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return;
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@@ -455,8 +590,8 @@ static void redudp_pkt_from_socks(int fd, short what, void *_arg)
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return;
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}
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- if (pkt.header.ip.port != client->instance->config.destaddr.sin_port ||
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- pkt.header.ip.addr != client->instance->config.destaddr.sin_addr.s_addr)
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+ if (pkt.header.ip.port != get_destaddr(client)->sin_port ||
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+ pkt.header.ip.addr != get_destaddr(client)->sin_addr.s_addr)
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{
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char buf[RED_INET_ADDRSTRLEN];
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struct sockaddr_in pktaddr = {
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@@ -472,8 +607,18 @@ static void redudp_pkt_from_socks(int fd, short what, void *_arg)
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redsocks_time(&client->last_relay_event);
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redudp_bump_timeout(client);
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+ if (do_tproxy(client->instance) && client->sender_fd == -1) {
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+ client->sender_fd = bound_udp4_get(&client->destaddr);
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+ if (client->sender_fd == -1) {
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+ redudp_log_error(client, LOG_WARNING, "bound_udp4_get failure");
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+ return;
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+ }
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+ }
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+
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fwdlen = pktlen - sizeof(pkt.header);
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- outgoing = sendto(EVENT_FD(&client->instance->listener),
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+ outgoing = sendto(do_tproxy(client->instance)
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+ ? client->sender_fd
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+ : EVENT_FD(&client->instance->listener),
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pkt.buf + sizeof(pkt.header), fwdlen, 0,
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(struct sockaddr*)&client->clientaddr, sizeof(client->clientaddr));
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if (outgoing != fwdlen) {
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@@ -486,18 +631,21 @@ static void redudp_pkt_from_socks(int fd, short what, void *_arg)
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static void redudp_pkt_from_client(int fd, short what, void *_arg)
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{
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redudp_instance *self = _arg;
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- struct sockaddr_in clientaddr;
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+ struct sockaddr_in clientaddr, destaddr, *pdestaddr;
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char buf[0xFFFF]; // UDP packet can't be larger then that
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ssize_t pktlen;
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redudp_client *tmp, *client = NULL;
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+ pdestaddr = do_tproxy(self) ? &destaddr : NULL;
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+
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assert(fd == EVENT_FD(&self->listener));
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- pktlen = red_recv_udp_pkt(fd, buf, sizeof(buf), &clientaddr);
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+ pktlen = red_recv_udp_pkt(fd, buf, sizeof(buf), &clientaddr, pdestaddr);
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if (pktlen == -1)
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return;
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// TODO: this lookup may be SLOOOOOW.
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list_for_each_entry(tmp, &self->clients, list) {
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+ // TODO: check destaddr
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if (0 == memcmp(&clientaddr, &tmp->clientaddr, sizeof(clientaddr))) {
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client = tmp;
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break;
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@@ -515,7 +663,7 @@ static void redudp_pkt_from_client(int fd, short what, void *_arg)
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}
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}
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else {
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- redudp_first_pkt_from_client(self, &clientaddr, buf, pktlen);
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+ redudp_first_pkt_from_client(self, &clientaddr, pdestaddr, buf, pktlen);
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}
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}
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@@ -554,7 +702,6 @@ static int redudp_onenter(parser_section *section)
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instance->config.relayaddr.sin_family = AF_INET;
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instance->config.relayaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
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instance->config.destaddr.sin_family = AF_INET;
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- instance->config.destaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
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instance->config.max_pktqueue = 5;
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instance->config.udp_timeout = 30;
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instance->config.udp_timeout_stream = 180;
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@@ -614,6 +761,28 @@ static int redudp_init_instance(redudp_instance *instance)
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goto fail;
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}
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+ if (do_tproxy(instance)) {
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+ int on = 1;
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+ char buf[RED_INET_ADDRSTRLEN];
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+ // iptables TPROXY target does not send packets to non-transparent sockets
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+ if (0 != redudp_transparent(fd))
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+ goto fail;
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+
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+ error = setsockopt(fd, SOL_IP, IP_RECVORIGDSTADDR, &on, sizeof(on));
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+ if (error) {
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+ log_errno(LOG_ERR, "setsockopt(listener, SOL_IP, IP_RECVORIGDSTADDR)");
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+ goto fail;
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+ }
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+
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+ log_error(LOG_DEBUG, "redudp @ %s: TPROXY", red_inet_ntop(&instance->config.bindaddr, buf, sizeof(buf)));
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+ }
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+ else {
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+ char buf1[RED_INET_ADDRSTRLEN], buf2[RED_INET_ADDRSTRLEN];
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+ log_error(LOG_DEBUG, "redudp @ %s: destaddr=%s",
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+ red_inet_ntop(&instance->config.bindaddr, buf1, sizeof(buf1)),
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+ red_inet_ntop(&instance->config.destaddr, buf2, sizeof(buf2)));
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+ }
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+
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error = bind(fd, (struct sockaddr*)&instance->config.bindaddr, sizeof(instance->config.bindaddr));
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if (error) {
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log_errno(LOG_ERR, "bind");
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diff --git a/redudp.h b/redudp.h
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index 308bd33..3f1d9d1 100644
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--- a/redudp.h
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+++ b/redudp.h
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@@ -24,6 +24,8 @@ typedef struct redudp_client_t {
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list_head list;
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redudp_instance *instance;
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struct sockaddr_in clientaddr;
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+ struct sockaddr_in destaddr;
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+ int sender_fd; // shared between several clients socket (bound to `destaddr`)
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struct event timeout;
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struct bufferevent *relay;
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struct event udprelay;
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diff --git a/utils.c b/utils.c
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index 6e1f3af..afdeea8 100644
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--- a/utils.c
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+++ b/utils.c
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@@ -26,17 +26,54 @@
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#include "utils.h"
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#include "redsocks.h" // for redsocks_close
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|
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-int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *inaddr)
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+int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *inaddr, struct sockaddr_in *toaddr)
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{
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socklen_t addrlen = sizeof(*inaddr);
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ssize_t pktlen;
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-
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- pktlen = recvfrom(fd, buf, buflen, 0, (struct sockaddr*)inaddr, &addrlen);
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+ struct msghdr msg;
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+ struct iovec io;
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+ char control[1024];
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+
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+ memset(&msg, 0, sizeof(msg));
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+ msg.msg_name = inaddr;
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+ msg.msg_namelen = sizeof(*inaddr);
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+ msg.msg_iov = &io;
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+ msg.msg_iovlen = 1;
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+ msg.msg_control = control;
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+ msg.msg_controllen = sizeof(control);
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+ io.iov_base = buf;
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+ io.iov_len = buflen;
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+
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+ pktlen = recvmsg(fd, &msg, 0);
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if (pktlen == -1) {
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log_errno(LOG_WARNING, "recvfrom");
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return -1;
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}
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|
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+ if (toaddr) {
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+ memset(toaddr, 0, sizeof(*toaddr));
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+ for (struct cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
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+ if (
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+ cmsg->cmsg_level == SOL_IP &&
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+ cmsg->cmsg_type == IP_ORIGDSTADDR &&
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+ cmsg->cmsg_len >= CMSG_LEN(sizeof(*toaddr))
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+ ) {
|
|
+ struct sockaddr_in* cmsgaddr = (struct sockaddr_in*)CMSG_DATA(cmsg);
|
|
+ char buf[RED_INET_ADDRSTRLEN];
|
|
+ log_error(LOG_DEBUG, "IP_ORIGDSTADDR: %s", red_inet_ntop(cmsgaddr, buf, sizeof(buf)));
|
|
+ memcpy(toaddr, cmsgaddr, sizeof(*toaddr));
|
|
+ }
|
|
+ else {
|
|
+ log_error(LOG_WARNING, "unexepcted cmsg (level,type) = (%d,%d)",
|
|
+ cmsg->cmsg_level, cmsg->cmsg_type);
|
|
+ }
|
|
+ }
|
|
+ if (toaddr->sin_family != AF_INET) {
|
|
+ log_error(LOG_WARNING, "(SOL_IP, IP_ORIGDSTADDR) not found");
|
|
+ return -1;
|
|
+ }
|
|
+ }
|
|
+
|
|
if (addrlen != sizeof(*inaddr)) {
|
|
log_error(LOG_WARNING, "unexpected address length %u instead of %zu", addrlen, sizeof(*inaddr));
|
|
return -1;
|
|
diff --git a/utils.h b/utils.h
|
|
index d3af00f..c2277e9 100644
|
|
--- a/utils.h
|
|
+++ b/utils.h
|
|
@@ -44,7 +44,7 @@ char *redsocks_evbuffer_readline(struct evbuffer *buf);
|
|
struct bufferevent* red_connect_relay(struct sockaddr_in *addr, evbuffercb writecb, everrorcb errorcb, void *cbarg);
|
|
int red_socket_geterrno(struct bufferevent *buffev);
|
|
int red_is_socket_connected_ok(struct bufferevent *buffev);
|
|
-int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *inaddr);
|
|
+int red_recv_udp_pkt(int fd, char *buf, size_t buflen, struct sockaddr_in *fromaddr, struct sockaddr_in *toaddr);
|
|
|
|
int fcntl_nonblock(int fd);
|
|
|
|
--
|
|
1.9.1
|
|
|