From 15e22fa1bdf36820aa54fb264006ce9dbfb1afb7 Mon Sep 17 00:00:00 2001
From: bol-van <none@none.none>
Date: Fri, 14 Mar 2025 11:35:26 +0300
Subject: [PATCH] tpws: detect WSL 1 and warn about non-working options

---
 tpws/helpers.c | 23 +++++++++++++++++++++++
 tpws/helpers.h |  5 +++++
 tpws/tpws.c    | 21 ++++++++++++++++++++-
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/tpws/helpers.c b/tpws/helpers.c
index 47e8f2b2..23b5273d 100644
--- a/tpws/helpers.c
+++ b/tpws/helpers.c
@@ -78,6 +78,13 @@ char *strncasestr(const char *s, const char *find, size_t slen)
 	return (char *)s;
 }
 
+bool str_ends_with(const char *s, const char *suffix)
+{
+    size_t slen = strlen(s);
+    size_t suffix_len = strlen(suffix);
+    return suffix_len <= slen && !strcmp(s + slen - suffix_len, suffix);
+}
+
 bool load_file(const char *filename, void *buffer, size_t *buffer_size)
 {
 	FILE *F;
@@ -565,4 +572,20 @@ bool socket_wait_notsent(int sfd, unsigned int delay_ms, unsigned int *wasted_ms
 	}
 	return false;
 }
+
+int is_wsl(void)
+{
+  struct utsname buf;
+  if (uname(&buf) != 0)
+    return -1;
+
+  if (strcmp(buf.sysname, "Linux") != 0)
+    return 0;
+  if (str_ends_with(buf.release, "microsoft-standard-WSL2"))
+    return 2;
+  if (str_ends_with(buf.release, "-Microsoft"))
+    return 1;
+
+  return 0;
+}
 #endif
diff --git a/tpws/helpers.h b/tpws/helpers.h
index 3c9c1536..c0301c2e 100644
--- a/tpws/helpers.h
+++ b/tpws/helpers.h
@@ -7,6 +7,7 @@
 #include <netdb.h>
 #include <stdio.h>
 #include <time.h>
+#include <sys/utsname.h>
 
 // this saves memory. sockaddr_storage is larger than required. it can be 128 bytes. sockaddr_in6 is 28 bytes.
 typedef union
@@ -22,6 +23,8 @@ void rtrim(char *s);
 void replace_char(char *s, char from, char to);
 char *strncasestr(const char *s,const char *find, size_t slen);
 
+bool str_ends_with(const char *s, const char *suffix);
+
 bool load_file(const char *filename,void *buffer,size_t *buffer_size);
 bool append_to_list_file(const char *filename, const char *s);
 
@@ -133,4 +136,6 @@ void msleep(unsigned int ms);
 bool socket_supports_notsent();
 bool socket_has_notsent(int sfd);
 bool socket_wait_notsent(int sfd, unsigned int delay_ms, unsigned int *wasted_ms);
+
+int is_wsl();
 #endif
diff --git a/tpws/tpws.c b/tpws/tpws.c
index ff6bfc86..0256f42c 100644
--- a/tpws/tpws.c
+++ b/tpws/tpws.c
@@ -1474,7 +1474,7 @@ void parse_params(int argc, char *argv[])
 		params.binds_last=0; // default bind to all
 	}
 	if (!params.resolver_threads) params.resolver_threads = 5 + params.maxconn/50;
-	
+
 	VPRINT("adding low-priority default empty desync profile\n");
 	// add default empty profile
 	if (!(dpl = dp_list_add(&params.desync_profiles)))
@@ -1490,6 +1490,10 @@ void parse_params(int argc, char *argv[])
 		fprintf(stderr, "could not chown %s. log file may not be writable after privilege drop\n", params.debug_logfile);
 	if (params.droproot && *params.hostlist_auto_debuglog && chown(params.hostlist_auto_debuglog, params.uid, -1))
 		DLOG_ERR("could not chown %s. auto hostlist debug log may not be writable after privilege drop\n", params.hostlist_auto_debuglog);
+
+#ifdef __linux__
+	bool bHasMSS=false, bHasOOB=false, bHasDisorder=false;
+#endif
 	LIST_FOREACH(dpl, &params.desync_profiles, next)
 	{
 		dp = &dpl->dp;
@@ -1500,7 +1504,22 @@ void parse_params(int argc, char *argv[])
 		}
 		if (params.droproot && dp->hostlist_auto && chown(dp->hostlist_auto->filename, params.uid, -1))
 			DLOG_ERR("could not chown %s. auto hostlist file may not be writable after privilege drop\n", dp->hostlist_auto->filename);
+#ifdef __linux__
+		if (dp->mss) bHasMSS=true;
+		if (dp->oob || dp->oob_http || dp->oob_tls) bHasOOB=true;
+		if (dp->disorder || dp->disorder_http || dp->disorder_tls) bHasDisorder=true;
+#endif
 	}
+#ifdef __linux__
+	if (is_wsl()==1)
+	{
+		if (!params.nosplice) DLOG_CONDUP("WARNING ! WSL1 may have problems with splice. Consider using `--nosplice`.\n");
+		if (bHasMSS) DLOG_CONDUP("WARNING ! WSL1 does not support MSS socket option. MSS will likely fail.\n");
+		if (bHasOOB) DLOG_CONDUP("WARNING ! WSL1 does not support OOB. OOB will likely fail.\n");
+		if (bHasDisorder) DLOG_CONDUP("WARNING ! Windows retransmits whole TCP segment. Disorder will not function properly.\n");
+		fflush(stdout);
+	}
+#endif
 
 	if (!LoadAllHostLists())
 	{