C++ 如何在 GCC 中使用 OpenSSL？
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How to use OpenSSL with GCC?
提问by Jondo Zaro
I'm trying to use openssl in a gcc program but it isn't working.
我正在尝试在 gcc 程序中使用 openssl 但它不起作用。
g++ server.cpp /usr/lib/libssl.a -o server
gives an error message, as does anything with the -loption. What must I type on the command line to link with openssl? The file /usr/lib/libssl.aexists, but nevertheless I still get the linker error no such function MD5() exists.
给出一条错误消息，与该-l选项的任何内容一样。我必须在命令行上输入什么才能与 openssl 链接？该文件/usr/lib/libssl.a存在，但我仍然收到链接器错误no such function MD5() exists。
回答by jschmier
Without knowing the exact errors you are seeing, it is difficult to provide an exact solution. Here is my best attempt.
在不知道您看到的确切错误的情况下，很难提供准确的解决方案。这是我最好的尝试。
From the information you provided, it sounds as though the linker is failing because it cannot find a reference to the md5function in libssl.a. I believe this function is actually in libcryptoso you may need to specify this library as well.
根据您提供的信息，听起来好像链接器失败了，因为它md5在libssl.a. 我相信这个函数实际上是在libcrypto所以你可能需要指定这个库。
g++ server.cpp -L/usr/lib -lssl -lcrypto -o server
g++ server.cpp -L/usr/lib -lssl -lcrypto -o server
回答by will
You or othersmay find this article developerWorksarticle helpful.
您或其他人可能会发现这篇developerWorks文章很有帮助。
It describes most things you need to know to get off the ground with OpenSSL and C/C++. If you find you are following most of the same steps, it might help you see what needs doing.
它描述了使用 OpenSSL 和 C/C++ 需要知道的大多数事情。如果您发现您正在遵循大多数相同的步骤，它可能会帮助您了解需要做什么。
Good luck.
祝你好运。
update
更新
- revised link: https://developer.ibm.com/technologies/linux/tutorials/l-openssl
- Which has been shuffled around
- original link: http://www.ibm.com/developerworks/linux/library/l-openssl.html
- Which now goes to a digest page including the article.
- 修改后的链接：https: //developer.ibm.com/technologies/linux/tutorials/l-openssl
- 已被洗牌
- 原始链接：http: //www.ibm.com/developerworks/linux/library/l-openssl.html
- 现在转到包含文章的摘要页面。
Note: keeping both links because they be used to find new discoveries.
注意：保留这两个链接是因为它们被用来寻找新的发现。
回答by user3343214
In Eclipse IDE select Your Project property --> c/c++ Build --> Settings gcc c linker(from tools settings)--> add to Library Search Path (-L)
在 Eclipse IDE 中选择 Your Project property --> c/c++ Build --> Settings gcc c linker(from tools settings)--> add to Library Search Path (-L)
/usr/lib -lssl -lcrypto
/usr/lib -lssl -lcrypto
回答by Alt Eisen
The location of the library is not fixed. In my case (Ubuntu 18.04), the .a files are located in /usr/lib/x86_64-linux-gnu/. So here are the complete steps:
图书馆的位置不固定。在我的情况下（Ubuntu 18.04），.a 文件位于/usr/lib/x86_64-linux-gnu/. 所以这里是完整的步骤：
1）安装库，
sudo apt install libss-dev
2）检查安装的文件，
dpkg-query -L libssl-dev
3) change the gcc flags -L(library directory) -l(library name), e.g.,
3）更改gcc标志-L(library directory) -l(library name)，例如，
gcc XXX.c XXXXX.c -L/usr/lib/x86_64-linux-gnu/ -lcrypto -lssl
回答by renzoe
On top of the accepted answers, I could not make compile the OpenSSL example for AES-CCM:
除了接受的答案之外，我无法编译 AES-CCM 的 OpenSSL 示例：
https://github.com/openssl/openssl/blob/master/demos/evp/aesccm.c
https://github.com/openssl/openssl/blob/master/demos/evp/aesccm.c
To make it work I needed to add two more things:
为了使它工作，我需要再添加两件事：
- The Dinamic Linking Library :
-ldl - The PThread library to use POSIX threading support:
-pthread(Adding directly the library with -lpthread is not recommended)
- 动态链接库：
-ldl - 使用 POSIX 线程支持的 PThread 库：（不推荐
-pthread使用 -lpthread 直接添加库）
