connector: Add checks if file descriptor is a socket

Fixes T104

Signed-off-by: David Wedderwille <davidwe@posteo.de>

src/connector.c

@@ -26,6 +26,10 @@
 #include "libssh/callbacks.h"
 #include "libssh/session.h"
 #include <stdlib.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+
 #define CHUNKSIZE 4096
 
 #ifdef _WIN32
@@ -40,6 +44,9 @@
 #  undef unlink
 #  define unlink _unlink
 # endif /* HAVE_IO_H */
+#else
+# include <sys/types.h>
+# include <sys/socket.h>
 #endif
 
 struct ssh_connector_struct {
@@ -51,6 +58,8 @@ struct ssh_connector_struct {
     socket_t in_fd;
     socket_t out_fd;
 
+    bool fd_is_socket;
+
     ssh_poll_handle in_poll;
     ssh_poll_handle out_poll;
 
@@ -76,6 +85,13 @@ static int ssh_connector_channel_write_wontblock_cb(ssh_session session,
                                                     ssh_channel channel,
                                                     size_t bytes,
                                                     void *userdata);
+static ssize_t ssh_connector_fd_read(ssh_connector connector,
+                                     void *buffer,
+                                     uint32_t len);
+static ssize_t ssh_connector_fd_write(ssh_connector connector,
+                                      const void *buffer,
+                                      uint32_t len);
+static bool ssh_connector_fd_is_socket(socket_t socket);
 
 ssh_connector ssh_connector_new(ssh_session session)
 {
@@ -91,6 +107,8 @@ ssh_connector ssh_connector_new(ssh_session session)
     connector->in_fd = SSH_INVALID_SOCKET;
     connector->out_fd = SSH_INVALID_SOCKET;
 
+    connector->fd_is_socket = false;
+
     ssh_callbacks_init(&connector->in_channel_cb);
     ssh_callbacks_init(&connector->out_channel_cb);
 
@@ -167,12 +185,14 @@ int ssh_connector_set_out_channel(ssh_connector connector,
 void ssh_connector_set_in_fd(ssh_connector connector, socket_t fd)
 {
     connector->in_fd = fd;
+    connector->fd_is_socket = ssh_connector_fd_is_socket(fd);
     connector->in_channel = NULL;
 }
 
 void ssh_connector_set_out_fd(ssh_connector connector, socket_t fd)
 {
     connector->out_fd = fd;
+    connector->fd_is_socket = ssh_connector_fd_is_socket(fd);
     connector->out_channel = NULL;
 }
 
@@ -223,9 +243,9 @@ static void ssh_connector_reset_pollevents(ssh_connector connector)
 static void ssh_connector_fd_in_cb(ssh_connector connector)
 {
     unsigned char buffer[CHUNKSIZE];
-    int r;
+    uint32_t toread = CHUNKSIZE;
-    int toread = CHUNKSIZE;
+    ssize_t r;
-    int w;
+    ssize_t w;
     int total = 0;
     int rc;
 
@@ -239,7 +259,7 @@ static void ssh_connector_fd_in_cb(ssh_connector connector)
             toread = MIN(size, CHUNKSIZE);
         }
 
-        r = read(connector->in_fd, buffer, toread);
+        r = ssh_connector_fd_read(connector, buffer, toread);
         if (r < 0) {
             ssh_connector_except(connector, connector->in_fd);
             return;
@@ -277,7 +297,7 @@ static void ssh_connector_fd_in_cb(ssh_connector connector)
                  * bytes
                  */
                 while (total != r) {
-                    w = write(connector->out_fd, buffer + total, r - total);
+                    w = ssh_connector_fd_write(connector, buffer + total, r - total);
                     if (w < 0){
                         ssh_connector_except(connector, connector->out_fd);
                         return;
@@ -319,7 +339,7 @@ static void ssh_connector_fd_out_cb(ssh_connector connector){
             } else if(r>0) {
                 /* loop around write in case the write blocks even for CHUNKSIZE bytes */
                 while (total != r){
-                    w = write(connector->out_fd, buffer + total, r - total);
+                        w = ssh_connector_fd_write(connector, buffer + total, r - total);
                     if (w < 0){
                         ssh_connector_except(connector, connector->out_fd);
                         return;
@@ -451,7 +471,7 @@ static int ssh_connector_channel_data_cb(ssh_session session,
                 ssh_connector_except_channel(connector, connector->out_channel);
             }
         } else if (connector->out_fd != SSH_INVALID_SOCKET) {
-            w = write(connector->out_fd, data, len);
+                w = ssh_connector_fd_write(connector, data, len);
             if (w < 0)
                 ssh_connector_except(connector, connector->out_fd);
         } else {
@@ -634,3 +654,96 @@ int ssh_connector_remove_event(ssh_connector connector) {
 
     return SSH_OK;
 }
+
+/**
+ * @internal
+ *
+ * @brief Check the file descriptor to check if it is a Windows socket handle.
+ *
+ */
+static bool ssh_connector_fd_is_socket(socket_t s)
+{
+#ifdef _WIN32
+    struct sockaddr_storage ss;
+    int len = sizeof(struct sockaddr_storage);
+    int rc;
+
+    rc = getsockname(s, (struct sockaddr *)&ss, &len);
+    if (rc == 0) {
+        return true;
+    }
+
+    SSH_LOG(SSH_LOG_TRACE,
+            "Error %i in getsockname() for fd %d",
+            WSAGetLastError(),
+            s);
+
+    return false;
+#else
+    struct stat sb;
+    int rc;
+
+    rc = fstat(s, &sb);
+    if (rc != 0) {
+        SSH_LOG(SSH_LOG_TRACE,
+                "error %i in fstat() for fd %d",
+                errno,
+                s);
+        return false;
+    }
+
+    /* The descriptor is a socket */
+    if (S_ISSOCK(sb.st_mode)) {
+          return true;
+    }
+
+    return false;
+#endif /* _WIN32 */
+}
+
+/**
+ * @internal
+ *
+ * @brief read len bytes from socket into buffer
+ *
+ */
+static ssize_t ssh_connector_fd_read(ssh_connector connector,
+                                     void *buffer,
+                                     uint32_t len)
+{
+    ssize_t nread = -1;
+
+    if (connector->fd_is_socket) {
+        nread = recv(connector->in_fd,buffer, len, 0);
+    } else {
+        nread = read(connector->in_fd,buffer, len);
+    }
+
+    return nread;
+}
+
+/**
+ * @internal
+ *
+ * @brief brief writes len bytes from buffer to socket
+ *
+ */
+static ssize_t ssh_connector_fd_write(ssh_connector connector,
+                                      const void *buffer,
+                                      uint32_t len)
+{
+    ssize_t bwritten = -1;
+    int flags = 0;
+
+#ifdef MSG_NOSIGNAL
+    flags |= MSG_NOSIGNAL;
+#endif
+
+    if (connector->fd_is_socket) {
+        bwritten = send(connector->out_fd,buffer, len, flags);
+    } else {
+        bwritten = write(connector->out_fd, buffer, len);
+    }
+
+    return bwritten;
+}