From f1bc7ee6be5aed2d4ed7db24a1c3b0d172e43d98 Mon Sep 17 00:00:00 2001
From: hev <git@hev.cc>
Date: Mon, 12 May 2025 23:02:09 +0800
Subject: [PATCH] HevSock: Break busy loop and log error if requested address
 is unavailable.

On MSYS2, when the requested address is unavailable, connect() may repeatedly
return EINPROGRESS instead of the expected EADDRNOTAVAIL. This can cause the
program to enter a busy loop without reporting the underlying error.
As a workaround, we impose a retry limit of 100 attempts --
if exceeded, an EADDRNOTAVAIL error is raised to break the loop and signal
the failure.
---
 src/hev-sock.c | 66 +++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 52 insertions(+), 14 deletions(-)

diff --git a/src/hev-sock.c b/src/hev-sock.c
index 1312b44..926f23e 100644
--- a/src/hev-sock.c
+++ b/src/hev-sock.c
@@ -24,6 +24,51 @@
 
 #include "hev-sock.h"
 
+typedef struct _SockConnectCtx SockConnectCtx;
+
+struct _SockConnectCtx
+{
+    int retries;
+    void *data;
+};
+
+static int
+connect_io_yielder (HevTaskYieldType type, void *data)
+{
+    SockConnectCtx *ctx = data;
+
+    ctx->retries++;
+    if (ctx->retries >= 100) {
+        errno = EADDRNOTAVAIL;
+        return -1;
+    }
+
+    return io_yielder (type, ctx->data);
+}
+
+static int
+sock_connect (int fd, const struct sockaddr *addr, socklen_t addr_len,
+              SockConnectCtx *ctx)
+{
+    int res;
+
+    ctx->retries = 0;
+    res = hev_task_io_socket_connect (fd, addr, addr_len, connect_io_yielder,
+                                      ctx);
+    if (res < 0) {
+        if (errno == EADDRNOTAVAIL) {
+            LOGV (E, "%s",
+                  "Cannot assign requested address, "
+                  "Please check is another instance exists or wait a minute. "
+                  "More: https://github.com/heiher/natmap/issues/27");
+        } else {
+            LOGV (E, "%s", strerror (errno));
+        }
+    }
+
+    return res;
+}
+
 static struct addrinfo *
 get_addr (int family, int type, const char *addr, const char *port, int passive)
 {
@@ -126,6 +171,7 @@ hev_sock_client_base (int family, int type, const char *saddr,
     struct addrinfo *sai;
     struct addrinfo *dai;
     int timeout = 30000;
+    SockConnectCtx ctx;
     socklen_t addrlen;
     int res;
     int fd;
@@ -183,18 +229,10 @@ hev_sock_client_base (int family, int type, const char *saddr,
 
     hev_task_add_fd (task, fd, POLLIN | POLLOUT);
 
-    res = hev_task_io_socket_connect (fd, dai->ai_addr, dai->ai_addrlen,
-                                      io_yielder, &timeout);
+    ctx.data = &timeout;
+    res = sock_connect (fd, dai->ai_addr, dai->ai_addrlen, &ctx);
     freeaddrinfo (dai);
     if (res < 0) {
-        if (errno == EADDRNOTAVAIL) {
-            LOGV (E, "%s",
-                  "Cannot assign requested address, "
-                  "Please check is another instance exists or wait a minute. "
-                  "More: https://github.com/heiher/natmap/issues/27");
-        } else {
-            LOGV (E, "%s", strerror (errno));
-        }
         hev_task_del_fd (task, fd);
         close (fd);
         return -1;
@@ -220,8 +258,9 @@ hev_sock_client_stun (struct sockaddr *saddr, int type, const char *daddr,
     HevTask *task = hev_task_self ();
     struct sockaddr_storage taddr;
     struct addrinfo sai, *dai;
-    socklen_t addrlen;
     int timeout = 30000;
+    SockConnectCtx ctx;
+    socklen_t addrlen;
     int res;
     int fd;
 
@@ -271,11 +310,10 @@ hev_sock_client_stun (struct sockaddr *saddr, int type, const char *daddr,
 
     hev_task_add_fd (task, fd, POLLIN | POLLOUT);
 
-    res = hev_task_io_socket_connect (fd, dai->ai_addr, dai->ai_addrlen,
-                                      io_yielder, &timeout);
+    ctx.data = &timeout;
+    res = sock_connect (fd, dai->ai_addr, dai->ai_addrlen, &ctx);
     freeaddrinfo (dai);
     if (res < 0) {
-        LOG (E);
         hev_task_del_fd (task, fd);
         close (fd);
         return -1;