一、libSSH2介绍

libSSH2是一个开源的C函数库，用来实现SSH2协议。

SSH(Secure SHell)到目前为止有两个不兼容的版本——SSH1和SSH2。

SSH2避免了RSA的专利问题，并修补了CRC的缺陷，增加了AES和Twofish等对称加密算法。

二、文件下载

libSSH2网站：
libSSH2

下载压缩包：libssh2-1.10.0.tar.gz

三、文件分析

解压缩libssh2-1.10.0.tar.gz文件。
进入libssh2-1.10.0目录

CMakeLists.txt记录了要加载的文件目录。

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四、pro文件

windows环境下的libssh2_config.h文件：

从libssh2-1.10.0/win32目录下，拷贝libssh2_config.h，到win目录下：

linuxmac目录下的libssh2_config.h文件进行修改如下：

配置头文件：

#头文件
HEADERS +=  ./agent.h \
            ./blf.h \
            ./channel.h \
            ./comp.h \
            ./crypto.h \
            ./libssh2.h \
            ./libssh2_priv.h \
            ./mac.h \
            ./mbedtls.h \
            ./misc.h \
            ./openssl.h \
            ./packet.h \
            ./session.h \
            ./sftp.h \
            ./transport.h \
            ./userauth.h \
            ./wincng.h
win32 {
    HEADERS += ./win/libssh2_config.h
}
linux* {
    HEADERS += ./linuxmac/libssh2_config.h
}
macx {
    HEADERS += ./linuxmac/libssh2_config.h
}

配置源文件：

#源文件
SOURCES +=  ./agent.c \
            ./agent_win.c \
            ./bcrypt_pbkdf.c \
            ./blowfish.c \
            ./channel.c \
            ./comp.c \
            ./crypt.c \
            ./global.c \
            ./hostkey.c \
            ./keepalive.c \
            ./kex.c \
            ./knownhost.c \
            ./mac.c \
            ./mbedtls.c \
            ./misc.c \
            ./openssl.c \
            ./packet.c \
            ./pem.c \
            ./publickey.c \
            ./scp.c \
            ./session.c \
            ./sftp.c \
            ./transport.c \
            ./userauth.c \
            ./version.c \
            ./wincng.c

配置预定义项：

DEFINES -= UNICODE
DEFINES += LIBSSH2_OPENSSL
win32 {
    DEFINES += LIBSSH2_WIN32 _CRT_SECURE_NO_DEPRECATE _CRT_NONSTDC_NO_DEPRECATE
}

依赖库配置：

win32 {
    LIBS += -LD:/Qt/Tools/OpenSSL/Win_x64/lib
    LIBS += -llibcrypto
    LIBS += -luser32 -lws2_32
}
linux* {
    LIBS += -lcrypto
}
macx {
    LIBS += -L/usr/local/opt/openssl@3/lib
    LIBS += -lcrypto
}

形成003.libssh2-1.10.0.pro文件：

QT += core network

TEMPLATE = lib
CONFIG += c++17

DESTDIR = ../QGIS
CONFIG(debug, debug|release){
    MOC_DIR = ../build-QGIS/ssh2/Debug/moc
    RCC_DIR = ../build-QGIS/ssh2/Debug/rcc
    UI_DIR = ../build-QGIS/ssh2/Debug/ui
    OBJECTS_DIR = ../build-QGIS/ssh2/Debug/obj
}else{
    MOC_DIR = ../build-QGIS/ssh2/Release/moc
    RCC_DIR = ../build-QGIS/ssh2/Release/rcc
    UI_DIR = ../build-QGIS/ssh2/Release/ui
    OBJECTS_DIR = ../build-QGIS/ssh2/Release/obj
}

CONFIG(debug, debug|release){
    TARGET = ssh2d
}else{
    TARGET = ssh2
}
DEFINES -= UNICODE
DEFINES += LIBSSH2_OPENSSL
win32 {
    DEFINES += LIBSSH2_WIN32 _CRT_SECURE_NO_DEPRECATE _CRT_NONSTDC_NO_DEPRECATE
}

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
#当前目录
INCLUDEPATH += ./
#openssl路径
win32 {
    INCLUDEPATH += ./win
    INCLUDEPATH += D:/Qt/Tools/OpenSSL/Win_x64/include
    INCLUDEPATH += D:/Qt/Tools/OpenSSL/Win_x64/include/openssl
}
linux* {
    INCLUDEPATH += ./linuxmac
    INCLUDEPATH += /opt/Qt/Tools/OpenSSL/src/include
    INCLUDEPATH += /opt/Qt/Tools/OpenSSL/src/include/openssl
}
macx {
    INCLUDEPATH += ./linuxmac
    INCLUDEPATH += /usr/local/opt/openssl@3/include
    INCLUDEPATH += /usr/local/opt/openssl@3/include/openssl
}

#ZLIB路径
INCLUDEPATH += ../zlib-1.2.12
#LIBS
LIBS += -L../QGIS

CONFIG(debug, debug|release){
    LIBS += -lzlibd
}else{
    LIBS += -lzlib
}
win32 {
    LIBS += -LD:/Qt/Tools/OpenSSL/Win_x64/lib
    LIBS += -llibcrypto
    LIBS += -luser32 -lws2_32
}
linux* {
    LIBS += -lcrypto
}
macx {
    LIBS += -L/usr/local/opt/openssl@3/lib
    LIBS += -lcrypto
}

#头文件
HEADERS +=  ./agent.h \
            ./blf.h \
            ./channel.h \
            ./comp.h \
            ./crypto.h \
            ./libssh2.h \
            ./libssh2_priv.h \
            ./mac.h \
            ./mbedtls.h \
            ./misc.h \
            ./openssl.h \
            ./packet.h \
            ./session.h \
            ./sftp.h \
            ./transport.h \
            ./userauth.h \
            ./wincng.h
win32 {
    HEADERS += ./win/libssh2_config.h
}
linux* {
    HEADERS += ./linuxmac/libssh2_config.h
}
macx {
    HEADERS += ./linuxmac/libssh2_config.h
}

#源文件
SOURCES +=  ./agent.c \
            ./agent_win.c \
            ./bcrypt_pbkdf.c \
            ./blowfish.c \
            ./channel.c \
            ./comp.c \
            ./crypt.c \
            ./global.c \
            ./hostkey.c \
            ./keepalive.c \
            ./kex.c \
            ./knownhost.c \
            ./mac.c \
            ./mbedtls.c \
            ./misc.c \
            ./openssl.c \
            ./packet.c \
            ./pem.c \
            ./publickey.c \
            ./scp.c \
            ./session.c \
            ./sftp.c \
            ./transport.c \
            ./userauth.c \
            ./version.c \
            ./wincng.c

# Default rules for deployment.
#unix {
#    target.path = /usr/lib
#}
#!isEmpty(target.path): INSTALLS += target

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五、编译实践

用QtCreator程序，打开003.libssh2-1.10.0.pro文件。

在windows下编译，形成：

在linux下编译，形成：

在macos下编译，形成：