Fix getpeername() bug on Windows

The WIN32 getpeername() function returns ENOTCONN when it uses connect()
the SOCK_NONBLOCK way. So we simply store the address, provided earlier.

Author: jart

libc/intrin/fds.h

@@ -1,5 +1,6 @@
 #ifndef COSMOPOLITAN_LIBC_CALLS_STRUCT_FD_INTERNAL_H_
 #define COSMOPOLITAN_LIBC_CALLS_STRUCT_FD_INTERNAL_H_
+#include "libc/sock/struct/sockaddr.h"
 #include "libc/thread/thread.h"
 COSMOPOLITAN_C_START_
 
@@ -37,6 +38,7 @@ struct Fd {
   unsigned sndtimeo; /* millis; 0 means wait forever */
   void *connect_op;
   struct Cursor *cursor;
+  struct sockaddr_storage peer;
 };
 
 struct Fds {

libc/sock/connect-nt.c

@@ -18,10 +18,11 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
 #include "libc/atomic.h"
-#include "libc/intrin/fds.h"
 #include "libc/calls/struct/sigset.internal.h"
 #include "libc/cosmo.h"
 #include "libc/errno.h"
+#include "libc/intrin/fds.h"
+#include "libc/macros.h"
 #include "libc/mem/mem.h"
 #include "libc/nt/enum/wsaid.h"
 #include "libc/nt/errors.h"
@@ -34,6 +35,7 @@
 #include "libc/sock/struct/sockaddr.h"
 #include "libc/sock/syscall_fd.internal.h"
 #include "libc/sock/wsaid.internal.h"
+#include "libc/sysv/consts/af.h"
 #include "libc/sysv/consts/o.h"
 #include "libc/sysv/consts/sol.h"
 #include "libc/sysv/errfuns.h"
@@ -109,6 +111,7 @@ static textwindows int sys_connect_nt_impl(struct Fd *f, const void *addr,
 
   // perform normal connect
   if (!(f->flags & O_NONBLOCK)) {
+    f->peer.ss_family = AF_UNSPEC;
     ssize_t rc = __winsock_block(f->handle, 0, false, f->sndtimeo, mask,
                                  sys_connect_nt_start,
                                  &(struct ConnectArgs){addr, addrsize});
@@ -122,6 +125,10 @@ static textwindows int sys_connect_nt_impl(struct Fd *f, const void *addr,
     return rc;
   }
 
+  // win32 getpeername() stops working in non-blocking connect mode
+  if (addrsize)
+    memcpy(&f->peer, addr, MIN(addrsize, sizeof(struct sockaddr_storage)));
+
   // perform nonblocking connect(), i.e.
   // 1. connect(O_NONBLOCK) → EINPROGRESS
   // 2. poll(POLLOUT)

libc/sock/getsockname.c

@@ -17,8 +17,8 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/internal.h"
-#include "libc/intrin/fds.h"
 #include "libc/dce.h"
+#include "libc/intrin/fds.h"
 #include "libc/intrin/strace.h"
 #include "libc/nt/errors.h"
 #include "libc/nt/thunk/msabi.h"
@@ -28,6 +28,7 @@
 #include "libc/sock/struct/sockaddr.h"
 #include "libc/sock/struct/sockaddr.internal.h"
 #include "libc/sock/syscall_fd.internal.h"
+#include "libc/sysv/consts/af.h"
 #include "libc/sysv/errfuns.h"
 
 __msabi extern typeof(__sys_getsockname_nt) *const __imp_getsockname;
@@ -45,7 +46,12 @@ static int __getsockpeername(int fd, struct sockaddr *out_addr,
   if (IsWindows()) {
     if (__isfdkind(fd, kFdSocket)) {
       if ((rc = impl_win32(g_fds.p[fd].handle, &ss, &size))) {
-        if (impl_win32 == __imp_getsockname && WSAGetLastError() == WSAEINVAL) {
+        if (impl_win32 == __imp_getpeername &&
+            g_fds.p[fd].peer.ss_family != AF_UNSPEC) {
+          ss = g_fds.p[fd].peer;
+          rc = 0;
+        } else if (impl_win32 == __imp_getsockname &&
+                   WSAGetLastError() == WSAEINVAL) {
           // The socket has not been bound to an address with bind, or
           // ADDR_ANY is specified in bind but connection has not yet
           // occurred. -MSDN

test/libc/sock/connect_test.c

@@ -34,6 +34,55 @@
 #include "libc/testlib/testlib.h"
 #include "libc/thread/thread.h"
 
+TEST(connect, blocking) {
+  char buf[16] = {0};
+  atomic_uint *sem = _mapshared(sizeof(unsigned));
+  uint32_t addrsize = sizeof(struct sockaddr_in);
+  struct sockaddr_in addr = {
+      .sin_family = AF_INET,
+      .sin_addr.s_addr = htonl(0x7f000001),
+  };
+  ASSERT_SYS(0, 3, socket(AF_INET, SOCK_STREAM, IPPROTO_TCP));
+  ASSERT_SYS(0, 0, bind(3, (struct sockaddr *)&addr, sizeof(addr)));
+  ASSERT_SYS(0, 0, getsockname(3, (struct sockaddr *)&addr, &addrsize));
+  ASSERT_SYS(0, 0, listen(3, SOMAXCONN));
+  SPAWN(fork);
+  while (!*sem)
+    pthread_yield();
+  ASSERT_SYS(0, 4, accept(3, (struct sockaddr *)&addr, &addrsize));
+  ASSERT_SYS(0, 2, read(4, buf, 16));  // hi
+  ASSERT_SYS(0, 5, write(4, "hello", 5));
+  ASSERT_SYS(0, 3, read(4, buf, 16));  // bye
+  PARENT();
+  ASSERT_SYS(0, 0, close(3));
+  ASSERT_SYS(0, 3, socket(AF_INET, SOCK_STREAM, IPPROTO_TCP));
+  ASSERT_SYS(0, 0, connect(3, (struct sockaddr *)&addr, sizeof(addr)));
+  *sem = 1;
+  {  // wait until connected
+    struct pollfd pfd = {3, POLLOUT};
+    ASSERT_SYS(0, 1, poll(&pfd, 1, -1));
+    ASSERT_TRUE(!!(POLLOUT & pfd.revents));
+  }
+  struct sockaddr_in peer;
+  uint32_t sz = sizeof(peer);
+  ASSERT_SYS(0, 0, getsockname(3, (struct sockaddr *)&peer, &sz));
+  ASSERT_EQ(htonl(0x7f000001), peer.sin_addr.s_addr);
+  ASSERT_SYS(0, 0, getpeername(3, (struct sockaddr *)&peer, &sz));
+  ASSERT_EQ(htonl(0x7f000001), peer.sin_addr.s_addr);
+  ASSERT_SYS(0, 2, write(3, "hi", 2));
+  {  // wait for other process to send us stuff
+    struct pollfd pfd = {3, POLLIN};
+    ASSERT_SYS(0, 1, poll(&pfd, 1, -1));
+    ASSERT_TRUE(!!(POLLIN & pfd.revents));
+  }
+  ASSERT_SYS(0, 5, read(3, buf, 16));
+  ASSERT_STREQ("hello", buf);
+  ASSERT_SYS(0, 3, write(3, "bye", 3));
+  ASSERT_SYS(0, 0, close(3));
+  WAIT(exit, 0);
+  munmap(sem, sizeof(unsigned));
+}
+
 TEST(connect, nonblocking) {
   if (IsFreebsd())
     return;  // TODO(jart): why did this start flaking?
@@ -74,6 +123,10 @@ TEST(connect, nonblocking) {
     ASSERT_SYS(0, 1, poll(&pfd, 1, -1));
     ASSERT_TRUE(!!(POLLOUT & pfd.revents));
   }
+  struct sockaddr_in peer;
+  uint32_t sz = sizeof(peer);
+  ASSERT_SYS(0, 0, getpeername(3, (struct sockaddr *)&peer, &sz));
+  ASSERT_EQ(htonl(0x7f000001), peer.sin_addr.s_addr);
   ASSERT_SYS(0, 2, write(3, "hi", 2));
   {  // wait for other process to send us stuff
     struct pollfd pfd = {3, POLLIN};