Re-implemented the Windows version of socketpair(). In particular there are two versions, one that build a packet-oriented socketpair and another one for stream-oriented pairs.

libc/sock/internal.h

@@ -105,7 +105,8 @@ int sys_bind_nt(struct Fd *, const void *, uint32_t);
 int sys_accept_nt(struct Fd *, void *, uint32_t *, int) hidden;
 int sys_closesocket_nt(struct Fd *) hidden;
 int sys_socket_nt(int, int, int) hidden;
-int sys_socketpair_nt(int, int, int, int[2]) hidden;
+int sys_socketpair_nt_stream(int, int, int, int[2]) hidden;
+int sys_socketpair_nt_dgram(int, int, int, int[2]) hidden;
 int sys_select_nt(int, fd_set *, fd_set *, fd_set *, struct timeval *) hidden;
 int sys_shutdown_nt(struct Fd *, int) hidden;
 

libc/sock/socketpair-nt.c

@@ -29,31 +29,36 @@
 #include "libc/sysv/consts/sock.h"
 #include "libc/sysv/consts/af.h"
 #include "libc/sysv/consts/ipproto.h"
+#include "libc/sysv/consts/inaddr.h"
 
-textwindows int sys_socketpair_nt(int family, int type, int protocol, int sv[2]) {
+/* Polyfill for socketpair() on Windows with family=AF_INET and 
+ * type=SOCK_STREAM or SOCK_SEQPACKET
+ */
+textwindows int sys_socketpair_nt_stream(int family, int type, int proto, int sv[2]) {
   struct sockaddr_storage ss;
   struct sockaddr_in *sa = (struct sockaddr_in *)&ss;
   uint32_t ss_len;
   int spR = -1, spW = -1;
   int opt;
   int rc = -1;
-
   int listensock = -1;
+
+  /* Avoid warnings for unused parameters */
+  (void)family;
+  (void)proto;
+
   sv[0] = -1;     /* INVALID_SOCKET */
   sv[1] = -1;     /* INVALID_SOCKET */
 
   memset(&ss, 0, sizeof(ss));
-    if (family == AF_INET){
+  sa->sin_family = AF_INET;
-        sa->sin_family = family;
+  sa->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
-        sa->sin_addr.s_addr = htonl(0x7f000001);
   sa->sin_port = 0;
   ss_len = sizeof(struct sockaddr_in);
-    } else {
-        return -1;
-    }
 
-    listensock = sys_socket_nt(family, SOCK_STREAM, IPPROTO_TCP);
+  listensock = sys_socket_nt(AF_INET, type, IPPROTO_TCP);
   if (listensock == -1) {
+    errno = WSAGetLastError();
     goto done;
   }
 
@@ -71,11 +76,11 @@ textwindows int sys_socketpair_nt(int family, int type, int protocol, int sv[2])
     goto done;
   }
 
-    sa->sin_family = family;
+  sa->sin_family = AF_INET;
-    sa->sin_addr.s_addr = htonl(0x7f000001);
+  sa->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
   ss_len = sizeof(struct sockaddr_in);
 
-    spR = socket(family, SOCK_STREAM, IPPROTO_TCP);
+  spR = socket(AF_INET, type, IPPROTO_TCP);
   if (spR == -1) {
     goto done;
   }
@@ -116,7 +121,6 @@ textwindows int sys_socketpair_nt(int family, int type, int protocol, int sv[2])
 
 done:
   if (rc == -1) {
-        errno = WSAGetLastError();
     if (spR != -1) {
       close(spR);
     }
@@ -134,3 +138,116 @@ done:
   }
   return rc;
 }
+
+
+int sys_socketpair_nt_dgram(int family, int type, int proto, int sv[2]) {
+  struct sockaddr_in sa;
+  uint32_t sa_len;
+  int opt;
+  int spR = -1, spW = -1;
+  int rc = -1;
+
+  /* Avoid warnings for unused parameters */
+  (void)family;
+  (void)proto;
+
+  sv[0] = -1;     /* INVALID_SOCKET */
+  sv[1] = -1;     /* INVALID_SOCKET */
+  memset(&sa, 0, sizeof(sa));
+  sa.sin_family = AF_INET;
+  sa.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+  sa.sin_port = 0;
+  sa_len = sizeof(struct sockaddr_in);
+
+  /* Creates a read socket */
+  spR = sys_socket_nt(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+  if (spR == -1) {
+    errno = WSAGetLastError();
+    goto done;
+  }
+
+  /* ... and bind it to whatever port is available on localhost */
+  if (bind(spR, (struct sockaddr *)&sa, sa_len) < 0) {
+    goto done;
+  }
+
+  /* Read the port # that bind obtained */
+  memset(&sa, 0, sizeof(sa));
+  sa_len = sizeof(sa);
+  if (getsockname(spR, (struct sockaddr *)&sa, &sa_len) < 0) {
+    goto done;
+  }
+  // The port # is on: sa.sin_port
+  // printf("RD Bound: port=%d, addr=%08x\n", sa.sin_port, sa.sin_addr.s_addr);
+
+  /* Creates a write socket */
+  spW = sys_socket_nt(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+  if (spW == -1) {
+    errno = WSAGetLastError();
+    goto done;
+  }
+  /* ... and connect it to the read socket port */
+  if (connect(spW, (struct sockaddr *)&sa, sa_len) < 0) {
+    goto done;
+  }
+
+  /* So far we got connection only in one way:
+   *      WR ----> RD
+   * To ensure symmetric behavior, read back the port bound of the 
+   * write socket */
+  memset(&sa, 0, sizeof(sa));
+  sa_len = sizeof(sa);
+  if (getsockname(spW, (struct sockaddr *)&sa, &sa_len) < 0) {
+    goto done;
+  }
+
+  // The write socket is bound at: sa.sin_port
+  //printf("WR Bound: port=%d, addr=%08x\n", sa.sin_port, sa.sin_addr.s_addr);
+
+  // ... finally connect the READ socket to the WRITE socket
+  if (connect(spR, (struct sockaddr *)&sa, sa_len) < 0) {
+    goto done;
+  }
+
+  /* Now we finally got both bi-directional sockets: RD <---> WR */
+
+  /* Finally set both sockets as non-blocking */
+  opt = fcntl(spW, F_GETFL, 0);
+  if (opt == -1) {
+    goto done;
+  }
+  if(fcntl(spW, F_SETFL, opt | O_NONBLOCK) == -1) {
+    goto done;
+  }
+
+  opt = fcntl(spR, F_GETFL, 0);
+  if (opt == -1) {
+    goto done;
+  }
+  if(fcntl(spR, F_SETFL, opt | O_NONBLOCK) == -1) {
+    goto done;
+  }
+
+  rc = 0;
+
+done:
+  if (rc == -1) {
+    errno = WSAGetLastError();
+    if (spR != -1) {
+      close(spR);
+    }
+    if (spW != -1) {
+      close(spW);
+    }
+  } else {
+    sv[0] = spR;
+    sv[1] = spW;
+  }
+
+  return rc;
+}
+
+
+
+
+

libc/sock/socketpair.c

@@ -20,6 +20,7 @@
 #include "libc/sock/internal.h"
 #include "libc/sock/sock.h"
 #include "libc/sysv/consts/af.h"
+#include "libc/sysv/consts/sock.h"
 #include "libc/sysv/errfuns.h"
 
 /**
@@ -43,11 +44,39 @@ int socketpair(int family, int type, int protocol, int sv[2]) {
     /* Recommend IPv6 on frontend serving infrastructure only. That's
        what Google Cloud does. It's more secure. It also means poll()
        will work on Windows, which doesn't allow mixing third layers. */
+    errno = EAFNOSUPPORT;
     return epfnosupport();
   }
   if (!IsWindows()) {
     return sys_socketpair(family, type, protocol, sv);
   } else {
-    return sys_socketpair_nt(family, type, protocol, sv);
+    /* Not all the version of Windows support AF_UNIX
+     */
+    if (family == AF_UNIX) {
+        /* TODO: Not all the version of Windows support AF_UNIX. 
+         *       we should figure out a way to detect if AF_UNIX is
+         *       supported.
+         *       Note that although AF_UNIX may be supported, it only
+         *       works with type==SOCK_STREAM and not with
+         *       SOCK_DGRAM (as well as SOCK_SEQPACKET)
+         */
+        return sys_socketpair_nt_stream(AF_INET, SOCK_STREAM, 0, sv);
+        /* 
+        errno = EAFNOSUPPORT;
+        return -1;
+        */
+    }
+    if (family != AF_INET) {
+        errno = EAFNOSUPPORT;
+        return -1;
+    }
+    if ((type == SOCK_STREAM) || (type == SOCK_SEQPACKET)) {
+        return sys_socketpair_nt_stream(family, type, protocol, sv);
+    }
+    if (type == SOCK_DGRAM) {
+        return sys_socketpair_nt_dgram(family, type, protocol, sv);
+    }
+    errno = EOPNOTSUPP;
+    return -1;
   }
 }