c++ libssh - ssh_channel_read() 不断返回 0 和 ssh_channel_is_open() returns false
c++ libssh - ssh_channel_read() keeps returning 0 and ssh_channel_is_open() returns false
这是我第一次以编程方式实现 ssh，我很困惑为什么我的代码不起作用——更具体地说，ssh_channel_read()不断返回 0 字节读取。我不知道我做错了什么！我一直在逐步遵循 API 说明，但显然我无意中遗漏了一些东西。
我正在尝试使用用户名 + 密码连接到我的 Pi。这是完整的代码，您可以复制粘贴并编译它：
g++ main.cpp -lssh -o myapp
在代码之后，你可以看到我得到的输出。请不要苛刻，就像我说的，这是我第一次与 SSH 打交道：
#include <iostream>
#include <string>
#include <libssh/libsshpp.hpp>
int main(int argc, const char **argv)
{
int vbs = SSH_LOG_RARE;
int timeout_ms = 1000;
ssh_session session = ssh_new();
ssh_channel channel;
char buffer[256];
int bytes_red;
if (session == NULL)
{
std::cout << "Failed to create ssh session." << std::endl;
exit(-1);
}
ssh_set_blocking(session, 1);
std::cout << "Created SSH session..." << std::endl;
ssh_options_set(session, SSH_OPTIONS_HOST, "192.168.1.5");
ssh_options_set(session, SSH_OPTIONS_PORT_STR, "22");
ssh_options_set(session, SSH_OPTIONS_USER, "pi@192.168.1.5");
ssh_options_set(session,SSH_OPTIONS_LOG_VERBOSITY, &vbs);
int con_result = ssh_connect(session);
int auth_result = ssh_userauth_password(session, "pi", "1234");
std::cout << "Connecton Result is: " << con_result << std::endl;
std::cout << "Auth Result is: " << auth_result << std::endl;
///////////////////////////////////////////
// Did we create the session successfully?
///////////////////////////////////////////
if (con_result != SSH_OK)
{
std::cout << "SSH connection failed. Error code is: " << con_result << std::endl;
ssh_free(session);
return con_result;
}
///////////////////////////////////////////
// Did we authenticate?
///////////////////////////////////////////
if (auth_result != SSH_AUTH_SUCCESS)
{
std::cout << "SSH authentication failed. Error code is: " << auth_result << std::endl;
ssh_free(session);
return auth_result;
}
///////////////////////////////////////////
// Create a new ssh_channel
///////////////////////////////////////////
channel = ssh_channel_new(session);
if (channel == NULL)
{
std::cout << "Failed to create SSH channel." << std::endl;
ssh_free(session);
return SSH_ERROR;
}
if (ssh_channel_is_open(channel))
std::cout << "Channel is open" << std::endl;
else
std::cout << "Channel is closed" << std::endl;
while(!ssh_channel_is_eof(channel))
{
bytes_red = ssh_channel_read_timeout(channel, buffer, sizeof(buffer), 0, timeout_ms);
// if (bytes_red)
std::cout << "Bytes read: " << bytes_red << std::endl;
}
std::cout << "Exiting ..." << std::endl;
ssh_channel_close(channel);
ssh_channel_free(channel);
ssh_free(session);
return 0;
}
这是我在 运行 对其进行设置时得到的输出：
$./myapp
Created SSH session...
[2018/05/19 14:57:14.246759, 1] socket_callback_connected: Socket connection callback: 1 (0)
[2018/05/19 14:57:14.301270, 1] ssh_client_connection_callback: SSH server banner: SSH-2.0-OpenSSH_7.4p1 Raspbian-10+deb9u1
[2018/05/19 14:57:14.301321, 1] ssh_analyze_banner: Analyzing banner: SSH-2.0-OpenSSH_7.4p1 Raspbian-10+deb9u1
[2018/05/19 14:57:14.301337, 1] ssh_analyze_banner: We are talking to an OpenSSH client version: 7.4 (70400)
Connecton Result is: 0
Auth Result is: 0
Channel is closed
[2018/05/19 14:57:14.669298, 1] ssh_packet_process: Couldn't do anything with packet type 80
Bytes read: 0
Bytes read: 0
Bytes read: 0
Bytes read: 0
Bytes read: 0
^C
$
我可以看到错误，"Channel is closed"但是为什么？我究竟做错了什么？
在此之后，我也想向服务器发送数据，显然得到反馈。根据我的阅读，ssh_channel_write() 是要使用的函数。
我以前没有以编程方式处理过 SSH，我在写这篇文章的时候正在学习它。
非常感谢您的帮助。
更新
感谢 Jarra，我解决了这个问题！这是有效的最终代码！
#include <iostream>
#include <string>
#include <libssh/libsshpp.hpp>
int main(int argc, const char **argv)
{
int vbs = SSH_LOG_RARE;
int timeout_ms = 1000;
ssh_session session = ssh_new();
ssh_channel channel;
char buffer[256];
int bytes_red;
if (session == NULL)
{
std::cout << "Failed to create ssh session." << std::endl;
exit(-1);
}
ssh_set_blocking(session, 1);
std::cout << "Created SSH session..." << std::endl;
ssh_options_set(session, SSH_OPTIONS_HOST, "192.168.1.5");
ssh_options_set(session, SSH_OPTIONS_PORT_STR, "22");
ssh_options_set(session, SSH_OPTIONS_USER, "pi@192.168.1.5");
ssh_options_set(session, SSH_OPTIONS_LOG_VERBOSITY, &vbs);
int con_result = ssh_connect(session);
int auth_result = ssh_userauth_password(session, "pi", "1234");
std::cout << "Connecton Result is: " << con_result << std::endl;
std::cout << "Auth Result is: " << auth_result << std::endl;
///////////////////////////////////////////
// Did we create the session successfully?
///////////////////////////////////////////
if (con_result != SSH_OK)
{
std::cout << "SSH connection failed. Error code is: " << con_result << std::endl;
ssh_free(session);
return con_result;
}
///////////////////////////////////////////
// Did we authenticate?
///////////////////////////////////////////
if (auth_result != SSH_AUTH_SUCCESS)
{
std::cout << "SSH authentication failed. Error code is: " << auth_result << std::endl;
ssh_free(session);
return auth_result;
}
///////////////////////////////////////////
// Create a new ssh_channel
///////////////////////////////////////////
channel = ssh_channel_new(session);
if (channel == NULL)
{
std::cout << "Failed to create SSH channel." << std::endl;
ssh_free(session);
return SSH_ERROR;
}
ssh_channel_open_session(channel);
if (ssh_channel_is_open(channel))
std::cout << "Channel is open" << std::endl;
else
std::cout << "Channel is closed" << std::endl;
int rc = ssh_channel_request_exec(channel, "ls");
while(!ssh_channel_is_eof(channel))
{
bytes_red = ssh_channel_read_timeout(channel, buffer, sizeof(buffer), 0, timeout_ms);
// if (bytes_red)
// std::cout << "Bytes read: " << bytes_red << std::endl;
std::cout << buffer << std::endl;
}
std::cout << "Exiting ..." << std::endl;
ssh_channel_close(channel);
ssh_channel_free(channel);
ssh_free(session);
return 0;
}
要编译：g++ main.cpp -lssh -o myapp 这是我 运行 时得到的结果：
./myapp
Created SSH session...
[2018/05/19 16:01:41.830861, 1] socket_callback_connected: Socket connection callback: 1 (0)
[2018/05/19 16:01:41.884875, 1] ssh_client_connection_callback: SSH server banner: SSH-2.0-OpenSSH_7.4p1 Raspbian-10+deb9u1
[2018/05/19 16:01:41.884929, 1] ssh_analyze_banner: Analyzing banner: SSH-2.0-OpenSSH_7.4p1 Raspbian-10+deb9u1
[2018/05/19 16:01:41.884945, 1] ssh_analyze_banner: We are talking to an OpenSSH client version: 7.4 (70400)
Connecton Result is: 0
Auth Result is: 0
[2018/05/19 16:01:42.258668, 1] ssh_packet_process: Couldn't do anything with packet type 80
Channel is open
Desktop
Documents
Downloads
Music
Pictures
Public
python_games
Templates
Videos
����s
Exiting ...
我只需要处理最后一点有趣的字符。这是我刚开始使用时直接从我的源代码编辑器中取出来的，所以代码并不完美。
ssh_channel_new 为新频道分配了资源。它打不开。
根据您要实现的目标，您应该在该频道上调用适当的 ssh_channel_open_XXXX 函数。
可以在这里找到一个简单的例子：https://github.com/substack/libssh/blob/c073979235eb0d0587ac9cb3c192e91e32d34b06/examples/exec.c
首先调用ssh_channel_open_session打开会话(shell)通道，然后调用ssh_channel_request_exec执行lsof命令
How/when您将写入频道取决于您打开的频道类型。可以在此处看到写入会话通道的示例（在主机上调用 cat > /dev/null 以将写入的数据传输到 /dev/null 之后）：https://github.com/substack/libssh/blob/c073979235eb0d0587ac9cb3c192e91e32d34b06/examples/senddata.c
这是我第一次以编程方式实现 ssh，我很困惑为什么我的代码不起作用——更具体地说，ssh_channel_read()不断返回 0 字节读取。我不知道我做错了什么！我一直在逐步遵循 API 说明，但显然我无意中遗漏了一些东西。
我正在尝试使用用户名 + 密码连接到我的 Pi。这是完整的代码，您可以复制粘贴并编译它：
g++ main.cpp -lssh -o myapp
在代码之后，你可以看到我得到的输出。请不要苛刻，就像我说的，这是我第一次与 SSH 打交道：
#include <iostream>
#include <string>
#include <libssh/libsshpp.hpp>
int main(int argc, const char **argv)
{
int vbs = SSH_LOG_RARE;
int timeout_ms = 1000;
ssh_session session = ssh_new();
ssh_channel channel;
char buffer[256];
int bytes_red;
if (session == NULL)
{
std::cout << "Failed to create ssh session." << std::endl;
exit(-1);
}
ssh_set_blocking(session, 1);
std::cout << "Created SSH session..." << std::endl;
ssh_options_set(session, SSH_OPTIONS_HOST, "192.168.1.5");
ssh_options_set(session, SSH_OPTIONS_PORT_STR, "22");
ssh_options_set(session, SSH_OPTIONS_USER, "pi@192.168.1.5");
ssh_options_set(session,SSH_OPTIONS_LOG_VERBOSITY, &vbs);
int con_result = ssh_connect(session);
int auth_result = ssh_userauth_password(session, "pi", "1234");
std::cout << "Connecton Result is: " << con_result << std::endl;
std::cout << "Auth Result is: " << auth_result << std::endl;
///////////////////////////////////////////
// Did we create the session successfully?
///////////////////////////////////////////
if (con_result != SSH_OK)
{
std::cout << "SSH connection failed. Error code is: " << con_result << std::endl;
ssh_free(session);
return con_result;
}
///////////////////////////////////////////
// Did we authenticate?
///////////////////////////////////////////
if (auth_result != SSH_AUTH_SUCCESS)
{
std::cout << "SSH authentication failed. Error code is: " << auth_result << std::endl;
ssh_free(session);
return auth_result;
}
///////////////////////////////////////////
// Create a new ssh_channel
///////////////////////////////////////////
channel = ssh_channel_new(session);
if (channel == NULL)
{
std::cout << "Failed to create SSH channel." << std::endl;
ssh_free(session);
return SSH_ERROR;
}
if (ssh_channel_is_open(channel))
std::cout << "Channel is open" << std::endl;
else
std::cout << "Channel is closed" << std::endl;
while(!ssh_channel_is_eof(channel))
{
bytes_red = ssh_channel_read_timeout(channel, buffer, sizeof(buffer), 0, timeout_ms);
// if (bytes_red)
std::cout << "Bytes read: " << bytes_red << std::endl;
}
std::cout << "Exiting ..." << std::endl;
ssh_channel_close(channel);
ssh_channel_free(channel);
ssh_free(session);
return 0;
}
这是我在 运行 对其进行设置时得到的输出：
$./myapp
Created SSH session...
[2018/05/19 14:57:14.246759, 1] socket_callback_connected: Socket connection callback: 1 (0)
[2018/05/19 14:57:14.301270, 1] ssh_client_connection_callback: SSH server banner: SSH-2.0-OpenSSH_7.4p1 Raspbian-10+deb9u1
[2018/05/19 14:57:14.301321, 1] ssh_analyze_banner: Analyzing banner: SSH-2.0-OpenSSH_7.4p1 Raspbian-10+deb9u1
[2018/05/19 14:57:14.301337, 1] ssh_analyze_banner: We are talking to an OpenSSH client version: 7.4 (70400)
Connecton Result is: 0
Auth Result is: 0
Channel is closed
[2018/05/19 14:57:14.669298, 1] ssh_packet_process: Couldn't do anything with packet type 80
Bytes read: 0
Bytes read: 0
Bytes read: 0
Bytes read: 0
Bytes read: 0
^C
$
我可以看到错误，"Channel is closed"但是为什么？我究竟做错了什么？
在此之后，我也想向服务器发送数据，显然得到反馈。根据我的阅读，ssh_channel_write() 是要使用的函数。
我以前没有以编程方式处理过 SSH，我在写这篇文章的时候正在学习它。
非常感谢您的帮助。
更新
感谢 Jarra，我解决了这个问题！这是有效的最终代码！
#include <iostream>
#include <string>
#include <libssh/libsshpp.hpp>
int main(int argc, const char **argv)
{
int vbs = SSH_LOG_RARE;
int timeout_ms = 1000;
ssh_session session = ssh_new();
ssh_channel channel;
char buffer[256];
int bytes_red;
if (session == NULL)
{
std::cout << "Failed to create ssh session." << std::endl;
exit(-1);
}
ssh_set_blocking(session, 1);
std::cout << "Created SSH session..." << std::endl;
ssh_options_set(session, SSH_OPTIONS_HOST, "192.168.1.5");
ssh_options_set(session, SSH_OPTIONS_PORT_STR, "22");
ssh_options_set(session, SSH_OPTIONS_USER, "pi@192.168.1.5");
ssh_options_set(session, SSH_OPTIONS_LOG_VERBOSITY, &vbs);
int con_result = ssh_connect(session);
int auth_result = ssh_userauth_password(session, "pi", "1234");
std::cout << "Connecton Result is: " << con_result << std::endl;
std::cout << "Auth Result is: " << auth_result << std::endl;
///////////////////////////////////////////
// Did we create the session successfully?
///////////////////////////////////////////
if (con_result != SSH_OK)
{
std::cout << "SSH connection failed. Error code is: " << con_result << std::endl;
ssh_free(session);
return con_result;
}
///////////////////////////////////////////
// Did we authenticate?
///////////////////////////////////////////
if (auth_result != SSH_AUTH_SUCCESS)
{
std::cout << "SSH authentication failed. Error code is: " << auth_result << std::endl;
ssh_free(session);
return auth_result;
}
///////////////////////////////////////////
// Create a new ssh_channel
///////////////////////////////////////////
channel = ssh_channel_new(session);
if (channel == NULL)
{
std::cout << "Failed to create SSH channel." << std::endl;
ssh_free(session);
return SSH_ERROR;
}
ssh_channel_open_session(channel);
if (ssh_channel_is_open(channel))
std::cout << "Channel is open" << std::endl;
else
std::cout << "Channel is closed" << std::endl;
int rc = ssh_channel_request_exec(channel, "ls");
while(!ssh_channel_is_eof(channel))
{
bytes_red = ssh_channel_read_timeout(channel, buffer, sizeof(buffer), 0, timeout_ms);
// if (bytes_red)
// std::cout << "Bytes read: " << bytes_red << std::endl;
std::cout << buffer << std::endl;
}
std::cout << "Exiting ..." << std::endl;
ssh_channel_close(channel);
ssh_channel_free(channel);
ssh_free(session);
return 0;
}
要编译：g++ main.cpp -lssh -o myapp 这是我 运行 时得到的结果：
./myapp
Created SSH session...
[2018/05/19 16:01:41.830861, 1] socket_callback_connected: Socket connection callback: 1 (0)
[2018/05/19 16:01:41.884875, 1] ssh_client_connection_callback: SSH server banner: SSH-2.0-OpenSSH_7.4p1 Raspbian-10+deb9u1
[2018/05/19 16:01:41.884929, 1] ssh_analyze_banner: Analyzing banner: SSH-2.0-OpenSSH_7.4p1 Raspbian-10+deb9u1
[2018/05/19 16:01:41.884945, 1] ssh_analyze_banner: We are talking to an OpenSSH client version: 7.4 (70400)
Connecton Result is: 0
Auth Result is: 0
[2018/05/19 16:01:42.258668, 1] ssh_packet_process: Couldn't do anything with packet type 80
Channel is open
Desktop
Documents
Downloads
Music
Pictures
Public
python_games
Templates
Videos
����s
Exiting ...
我只需要处理最后一点有趣的字符。这是我刚开始使用时直接从我的源代码编辑器中取出来的，所以代码并不完美。
ssh_channel_new 为新频道分配了资源。它打不开。
根据您要实现的目标，您应该在该频道上调用适当的 ssh_channel_open_XXXX 函数。
可以在这里找到一个简单的例子：https://github.com/substack/libssh/blob/c073979235eb0d0587ac9cb3c192e91e32d34b06/examples/exec.c
首先调用ssh_channel_open_session打开会话(shell)通道，然后调用ssh_channel_request_exec执行lsof命令
How/when您将写入频道取决于您打开的频道类型。可以在此处看到写入会话通道的示例（在主机上调用 cat > /dev/null 以将写入的数据传输到 /dev/null 之后）：https://github.com/substack/libssh/blob/c073979235eb0d0587ac9cb3c192e91e32d34b06/examples/senddata.c