From b23520dcddbdf088ededeac7a0a1611db73db191 Mon Sep 17 00:00:00 2001
From: kircher <[email protected]>
Date: Mon, 19 Dec 2022 19:23:42 +0800
Subject: [PATCH] skip unnecessary tcp_route

---
 src/core/tcp.c         |  1 +
 src/core/tcp_out.c     | 20 ++++++++++++++++----
 src/include/lwip/tcp.h |  1 +
 src/include/lwipsock.h |  1 +
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/core/tcp.c b/src/core/tcp.c
index 252f27f..abfcc00 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -2294,6 +2294,7 @@ tcp_pcb_purge(struct tcp_pcb *pcb)
     tcp_segs_free(pcb->unacked);
     pcb->unacked = pcb->unsent = NULL;
     pcb->last_unacked = pcb->last_unsent = NULL;
+    pcb->pcb_if = NULL;
 #if TCP_OVERSIZE
     pcb->unsent_oversize = 0;
 #endif /* TCP_OVERSIZE */
diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index 25aeb23..1c5734b 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -1425,7 +1425,12 @@ tcp_output(struct tcp_pcb *pcb)
                  lwip_ntohl(seg->tcphdr->seqno), pcb->lastack));
   }
 
-  netif = tcp_route(pcb, &pcb->local_ip, &pcb->remote_ip);
+  if (pcb->pcb_if == NULL) {
+    netif = tcp_route(pcb, &pcb->local_ip, &pcb->remote_ip);
+    pcb->pcb_if = netif;
+  } else {
+    netif = pcb->pcb_if;
+  }
   if (netif == NULL) {
     return ERR_RTE;
   }
@@ -2220,7 +2225,7 @@ tcp_output_fill_options(const struct tcp_pcb *pcb, struct pbuf *p, u8_t optflags
  * header checksum and calling ip_output_if while handling netif hints and stats.
  */
 static err_t
-tcp_output_control_segment(const struct tcp_pcb *pcb, struct pbuf *p,
+tcp_output_control_segment(struct tcp_pcb *pcb, struct pbuf *p,
                            const ip_addr_t *src, const ip_addr_t *dst)
 {
   err_t err;
@@ -2228,7 +2233,14 @@ tcp_output_control_segment(const struct tcp_pcb *pcb, struct pbuf *p,
 
   LWIP_ASSERT("tcp_output_control_segment: invalid pbuf", p != NULL);
 
-  netif = tcp_route(pcb, src, dst);
+  if (pcb == NULL || pcb->pcb_if == NULL) {
+    netif = tcp_route(pcb, src, dst);
+    if (pcb) {
+      pcb->pcb_if = netif;
+    }
+  } else {
+    netif = pcb->pcb_if;
+  }
   if (netif == NULL) {
     err = ERR_RTE;
   } else {
@@ -2318,7 +2330,7 @@ tcp_rst(const struct tcp_pcb *pcb, u32_t seqno, u32_t ackno,
 
   MIB2_STATS_INC(mib2.tcpoutrsts);
 
-  tcp_output_control_segment(pcb, p, local_ip, remote_ip);
+  tcp_output_control_segment((struct tcp_pcb*)pcb, p, local_ip, remote_ip);
   LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
 }
 
diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index b0ae02c..2a61776 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -408,6 +408,7 @@ struct tcp_pcb {
   u8_t snd_scale;
   u8_t rcv_scale;
 #endif
+  struct netif* pcb_if;
 };
 
 #if TCP_PCB_HASH
diff --git a/src/include/lwipsock.h b/src/include/lwipsock.h
index 62e5bf1..ec4d78c 100644
--- a/src/include/lwipsock.h
+++ b/src/include/lwipsock.h
@@ -111,6 +111,7 @@ struct lwip_sock {
   /* stack thread all use */
   struct list_node recv_list;
   struct list_node send_list;
+  struct pbuf *lwip_lastdata;
   struct pbuf *send_lastdata;
   struct pbuf *send_pre_del;
 
-- 
2.33.0