Add basic ssh/sftp code to SocketCore and introduce SSHSession

We use libssh2 to implement sftp feature.  SSHSession is closely
designed to TLSSession, but it differs in several aspects.  In this
code, we only implements read part of sftp, since aria2 won't offer
uploading feature.  Adding SSH/sftp to SocketCore is a bit bloat.  But
by doing this we can reuse DownloadCommand, without mostly no
modification.  We can just create SSHDownloadCommand by inheriting it,
just like existing ftp.

1 files changed, 207 insertions, 0 deletions

diff --git a/src/SSHSession.cc b/src/SSHSession.cc
new file mode 100644
index 00000000..d320b02b
--- /dev/null
+++ b/src/SSHSession.cc
@@ -0,0 +1,207 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * Copyright (C) 2015 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#include "SSHSession.h"
+
+#include <cassert>
+
+namespace aria2 {
+
+SSHSession::SSHSession()
+  : ssh2_(nullptr),
+    sftp_(nullptr),
+    sftph_(nullptr),
+    fd_(-1)
+{}
+
+SSHSession::~SSHSession()
+{
+  closeConnection();
+}
+
+int SSHSession::closeConnection()
+{
+  if (sftph_) {
+    // TODO this could return LIBSSH2_ERROR_EAGAIN
+    libssh2_sftp_close(sftph_);
+    sftph_ = nullptr;
+  }
+  if (sftp_) {
+    // TODO this could return LIBSSH2_ERROR_EAGAIN
+    libssh2_sftp_shutdown(sftp_);
+    sftp_ = nullptr;
+  }
+  if (ssh2_) {
+    // TODO this could return LIBSSH2_ERROR_EAGAIN
+    libssh2_session_disconnect(ssh2_, "bye");
+    libssh2_session_free(ssh2_);
+    ssh2_ = nullptr;
+  }
+  return SSH_ERR_OK;
+}
+
+int SSHSession::gracefulShutdown()
+{
+  if (sftph_) {
+    auto rv = libssh2_sftp_close(sftph_);
+    if (rv == LIBSSH2_ERROR_EAGAIN) {
+      return SSH_ERR_WOULDBLOCK;
+    }
+    if (rv != 0) {
+      return SSH_ERR_ERROR;
+    }
+    sftph_ = nullptr;
+  }
+  if (sftp_) {
+    auto rv = libssh2_sftp_shutdown(sftp_);
+    if (rv == LIBSSH2_ERROR_EAGAIN) {
+      return SSH_ERR_WOULDBLOCK;
+    }
+    if (rv != 0) {
+      return SSH_ERR_ERROR;
+    }
+    sftp_ = nullptr;
+  }
+  if (ssh2_) {
+    auto rv = libssh2_session_disconnect(ssh2_, "bye");
+    if (rv == LIBSSH2_ERROR_EAGAIN) {
+      return SSH_ERR_WOULDBLOCK;
+    }
+    if (rv != 0) {
+      return SSH_ERR_ERROR;
+    }
+    libssh2_session_free(ssh2_);
+    ssh2_ = nullptr;
+  }
+  return SSH_ERR_OK;
+}
+
+int SSHSession::init(sock_t sockfd)
+{
+  ssh2_ = libssh2_session_init();
+  if (!ssh2_) {
+    return SSH_ERR_ERROR;
+  }
+  fd_ = sockfd;
+  return SSH_ERR_OK;
+}
+
+
+int SSHSession::checkDirection()
+{
+  auto dir = libssh2_session_block_directions(ssh2_);
+  if (dir & LIBSSH2_SESSION_BLOCK_OUTBOUND) {
+    return SSH_WANT_WRITE;
+  }
+  return SSH_WANT_READ;
+}
+
+ssize_t SSHSession::writeData(const void* data, size_t len)
+{
+  // net implemented yet
+  assert(0);
+}
+
+ssize_t SSHSession::readData(void* data, size_t len)
+{
+  auto nread = libssh2_sftp_read(sftph_, static_cast<char*>(data), len);
+  if (nread == LIBSSH2_ERROR_EAGAIN) {
+    return SSH_ERR_WOULDBLOCK;
+  }
+  if (nread < 0) {
+    return SSH_ERR_ERROR;
+  }
+  return nread;
+}
+
+int SSHSession::handshake()
+{
+  auto rv = libssh2_session_handshake(ssh2_, fd_);
+  if (rv == LIBSSH2_ERROR_EAGAIN) {
+    return SSH_ERR_WOULDBLOCK;
+  }
+  if (rv != 0) {
+    return SSH_ERR_ERROR;
+  }
+  // TODO we have to validate server's fingerprint
+  return SSH_ERR_OK;
+}
+
+int SSHSession::authPassword(const std::string& user,
+                                const std::string& password)
+{
+  auto rv = libssh2_userauth_password(ssh2_, user.c_str(), password.c_str());
+  if (rv == LIBSSH2_ERROR_EAGAIN) {
+    return SSH_ERR_WOULDBLOCK;
+  }
+  if (rv != 0) {
+    return SSH_ERR_ERROR;
+  }
+  return SSH_ERR_OK;
+}
+
+int SSHSession::sftpOpen(const std::string& path)
+{
+  if (!sftp_) {
+    sftp_ = libssh2_sftp_init(ssh2_);
+    if (!sftp_) {
+      if (libssh2_session_last_errno(ssh2_) == LIBSSH2_ERROR_EAGAIN) {
+        return SSH_ERR_WOULDBLOCK;
+      }
+      return SSH_ERR_ERROR;
+    }
+  }
+  if (!sftph_) {
+    sftph_ = libssh2_sftp_open(sftp_, path.c_str(), LIBSSH2_FXF_READ, 0);
+    if (!sftph_) {
+      if (libssh2_session_last_errno(ssh2_) == LIBSSH2_ERROR_EAGAIN) {
+        return SSH_ERR_WOULDBLOCK;
+      }
+      return SSH_ERR_ERROR;
+    }
+  }
+  return SSH_ERR_OK;
+}
+
+std::string SSHSession::getLastErrorString()
+{
+  if (!ssh2_) {
+    return "SSH session has not been initialized yet";
+  }
+  char* errmsg;
+  libssh2_session_last_error(ssh2_, &errmsg, nullptr, 0);
+  return errmsg;
+}
+
+} // namespace aria2