From fe53378596df213f4e1be079c59b4d23be24ee62 Mon Sep 17 00:00:00 2001
From: Vladimir Dubrovin <3proxy@3proxy.ru>
Date: Sat, 29 Nov 2025 15:05:29 +0300
Subject: [PATCH] maxseg / TCP_MAXSEG support added

---
 src/conf.c      | 12 +++++++++---
 src/proxymain.c |  9 +++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/conf.c b/src/conf.c
index 39219ac..bac80fd 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -466,6 +466,11 @@ static int h_rotate(int argc, unsigned char **argv){
 	return 0;
 }
 
+static int h_maxseg(int argc, unsigned char **argv){
+	conf.maxseg = atoi((char *)argv[1]);
+	return 0;
+}
+
 static int h_logformat(int argc, unsigned char **argv){
 	unsigned char * old = conf.logformat;
 	conf.logformat = (unsigned char *)mystrdup((char *)argv[1]);
@@ -1645,11 +1650,12 @@ struct commands commandhandlers[]={
 	{commandhandlers+61, "force", h_force, 1, 1},
 	{commandhandlers+62, "noforce", h_noforce, 1, 1},
 	{commandhandlers+63, "parentretries", h_parentretries, 2, 2},
-	{commandhandlers+64,  "auto", h_proxy, 1, 0},
+	{commandhandlers+64, "auto", h_proxy, 1, 0},
 	{commandhandlers+65, "backlog", h_backlog, 2, 2},
-	{commandhandlers+66,  "tlspr", h_proxy, 1, 0},
+	{commandhandlers+66, "tlspr", h_proxy, 1, 0},
+	{commandhandlers+67, "maxseg", h_maxseg, 2, 2},
 #ifndef NORADIUS
-	{commandhandlers+67, "radius", h_radius, 3, 0},
+	{commandhandlers+68, "radius", h_radius, 3, 0},
 #endif
 	{specificcommands, 	 "", h_noop, 1, 0}
 };
diff --git a/src/proxymain.c b/src/proxymain.c
index 2e11e97..43810eb 100644
--- a/src/proxymain.c
+++ b/src/proxymain.c
@@ -170,6 +170,9 @@ struct socketoptions sockopts[] = {
 #endif
 #ifdef TCP_FASTOPEN_CONNECT
 	{TCP_FASTOPEN_CONNECT, "TCP_FASTOPEN_CONNECT"},
+#endif
+#ifdef TCP_MAXSEG
+	{TCP_MAXSEG, "TCP_MAXSEG"},
 #endif
 	{0, NULL}
 };
@@ -193,6 +196,12 @@ void setopts(SOCKET s, int opts){
 	int i, opt, set;
 	for(i = 0; opts >= (opt = (1<<i)); i++){
 		set = 1;
+#ifdef TCP_MAXSEG
+		if(sockopts[i].opt == TCP_MAXSEG){
+		    if(!conf.maxseg) continue;
+		    set = conf.maxseg;
+		}
+#endif
 		if(opts & opt) setsockopt(s, *sockopts[i].optname == 'T'? IPPROTO_TCP:
 #ifdef SOL_IP
 			*sockopts[i].optname == 'I'? SOL_IP: