Merge 864e8090ba1b473479966a1419630109ffd64210 into e42f0e573221c5e0146c02fd5d71f32aa93c7221

README.md

@@ -81,7 +81,7 @@ Assume your UDP is blocked or being QOS-ed or just poorly supported. Assume your
 Now,an encrypted raw tunnel has been established between client and server through TCP port 4096. Connecting to UDP port 3333 at the client side is equivalent to connecting to port 7777 at the server side. No UDP traffic will be exposed.
 
 ### Note
-To run on Android, check [Android_Guide](/doc/android_guide.md)
+To run on Android, check [Android_Guide](https://github.com/wangyu-/udp2raw/wiki/Android-Guide)
 
 `-a` option automatically adds an iptables rule (or a few iptables rules) for you, udp2raw relies on this iptables rule to work stably. Be aware you dont forget `-a` (its a common mistake). If you dont want udp2raw to add iptables rule automatically, you can add it manually(take a look at `-g` option) and omit `-a`.
 

common.cpp

@@ -11,6 +11,7 @@
 
 #include <random>
 #include <cmath>
+#include <stdint.h>
 
 // static int random_number_fd=-1;
 int force_socket_buf = 0;
@@ -190,6 +191,8 @@ int address_t::from_sockaddr(sockaddr *addr, socklen_t slen) {
     return 0;
 }
 
+int g_randomize_local_addr = 0;
+static uint32_t g_lo_ip = 0x7f010001u;
 int address_t::new_connected_udp_fd() {
     int new_udp_fd;
     new_udp_fd = socket(get_type(), SOCK_DGRAM, IPPROTO_UDP);
@@ -200,6 +203,20 @@ int address_t::new_connected_udp_fd() {
     setnonblocking(new_udp_fd);
     set_buf_size(new_udp_fd, socket_buf_size);
 
+    struct sockaddr_in *paddr_inet = (struct sockaddr_in *)&inner;
+    if (paddr_inet->sin_family == AF_INET && g_randomize_local_addr && 
+    (ntohl(paddr_inet->sin_addr.s_addr) & 0xff000000u) == 0x7f000000u) {
+        // wireguard allows only one port number per address, so change source address on reconnection
+        struct sockaddr_in addr_bound;
+        memset(&addr_bound, 0, sizeof(addr_bound));
+        addr_bound.sin_family = AF_INET;
+        addr_bound.sin_addr.s_addr = htonl(g_lo_ip);
+        g_lo_ip += 0x2u;
+        mylog(log_debug, "randomizing local address when connecting to localhost, binding local ip %s\n", my_ntoa(g_lo_ip));
+        if (bind(new_udp_fd, (struct sockaddr *)&addr_bound, sizeof(addr_bound)) != 0) {
+            mylog(log_warn, "lo addr: bind failed\n");
+        }
+    }
     mylog(log_debug, "created new udp_fd %d\n", new_udp_fd);
     int ret = connect(new_udp_fd, (struct sockaddr *)&inner, get_len());
     if (ret != 0) {

common.h

@@ -163,6 +163,8 @@ extern int force_socket_buf;
 
 extern int g_fix_gro;
 
+extern int g_randomize_local_addr;
+
 /*
 struct ip_port_t
 {

misc.cpp

@@ -296,6 +296,9 @@ void process_arg(int argc, char *argv[])  // process all options
             {"no-pcap-mutex", no_argument, 0, 1},
 #endif
             {"fix-gro", no_argument, 0, 1},
+            {"do-fragment", no_argument, 0, 1},
+            {"rand-addr", no_argument, 0, 1},
+            {"wireguard", no_argument, 0, 1},
             {NULL, 0, 0, 0}};
 
     process_log_level(argc, argv);
@@ -677,6 +680,16 @@ void process_arg(int argc, char *argv[])  // process all options
                 } else if (strcmp(long_options[option_index].name, "fix-gro") == 0) {
                     mylog(log_info, "--fix-gro enabled\n");
                     g_fix_gro = 1;
+                } else if (strcmp(long_options[option_index].name, "do-fragment") == 0) {
+                    mylog(log_info, "--do-fragment enabled\n");
+                    g_should_fragment = 1;
+                } else if (strcmp(long_options[option_index].name, "rand-addr") == 0) {
+                    mylog(log_info, "--rand-addr enabled\n");
+                    g_randomize_local_addr = 1;
+                } else if (strcmp(long_options[option_index].name, "wireguard") == 0) {
+                    mylog(log_info, "--wireguard mode enabled, turning on --do-fragment and --rand-addr\n");
+                    g_should_fragment = 1;
+                    g_randomize_local_addr = 1;
                 } else {
                     mylog(log_warn, "ignored unknown long option ,option_index:%d code:<%x>\n", option_index, optopt);
                 }

network.cpp

@@ -1159,6 +1159,7 @@ printf("pcap send!\n");*/
 }
 #endif
 
+int g_should_fragment = 0;
 int send_raw_ip(raw_info_t &raw_info, const char *payload, int payloadlen) {
     const packet_info_t &send_info = raw_info.send_info;
     const packet_info_t &recv_info = raw_info.recv_info;
@@ -1188,8 +1189,11 @@ int send_raw_ip(raw_info_t &raw_info, const char *payload, int payloadlen) {
             // iph->id = 0; //Id of this packet  ,kernel will auto fill this if id is zero  ,or really?????// todo //seems like there is a problem
         }
 
-        iph->frag_off = htons(0x4000);  // DF set,others are zero
-        // iph->frag_off = htons(0x0000); //DF set,others are zero
+        if (g_should_fragment) {
+            iph->frag_off = htons(0x0000);  //DF cleared,others are zero
+        } else {
+            iph->frag_off = htons(0x4000);  // DF set,others are zero
+        }
         iph->ttl = (unsigned char)ttl_value;
         iph->protocol = send_info.protocol;
         iph->check = 0;                        // Set to 0 before calculating checksum

network.h

@@ -56,6 +56,8 @@ struct icmphdr {
 };
 #endif
 
+extern int g_should_fragment;
+
 struct my_iphdr {
 #ifdef UDP2RAW_LITTLE_ENDIAN
     unsigned char ihl : 4;