Why doesn't my Go program use the TCP server library correctly?

In recent years, Go language has become one of the most popular programming languages. However, many people run into problems when writing TCP servers in Go. Especially those without network programming experience often face the challenges that come with writing a TCP server. In this article, we will explore some common problems and solutions involved when writing TCP servers in Go.

Question 1: Why can't I run a TCP server locally?

If you have just started writing a TCP server in Go, and you are unable to run the server locally, then you should check your code, to make sure you are listening on the correct port. Also, you should check your firewall to see if inbound connections are allowed.

Another common problem is that if you are using an IPv6 address instead of an IPv4 address, you need to bind your server to the IPv6 address instead of the IPv4 address. If you still can't run the TCP server locally, you may want to check if there are other processes listening on the same port. You can use the UNIX/Linux command "netstat -tulpn" to find other processes that are listening on the same port.

Question 2: Why can’t my server receive client connections?

Your TCP server may be unable to accept connections from clients for the following reasons:

• The server is not bound to the correct IP address and port.
• The server is running a firewall that does not allow connections from clients.
• The server is running anti-virus or other security software that may be blocking client connections.
• The server may have reached its maximum number of connections limit.

In addition to the reasons listed above, there may be other factors that prevent your server from accepting connections from clients. If you cannot identify the cause and your problem persists, it is recommended that you refer to the documentation or consult a network programming expert.

Question 3: Why can’t my server handle client data correctly?

If your server cannot handle client data correctly, it may be because your server's read buffer length is not large enough and the client is sending a large amount of data. The solution is to increase the buffer size. To do this, you need to consider using a buffer pool.

Another possible cause is that your server is not handling terminators in the byte stream correctly. In the TCP protocol, data does not have any boundaries, so you need to handle requests from clients specially. For example, you can end with a specific character or a specific sequence of bytes to indicate the end of the data.

Question 4: How do I add security to my TCP server?

When building a TCP server, you need to consider how to add security. Here are a few ways to achieve security:

• Use SSL/TLS to secure your connection.
• Limit connection speed. This can help reduce DOS attacks.
• Restrict the client's IP address. This can help prevent DDOS attacks.
• Validate and filter data from the client. This can help prevent SQL injection attacks and other types of attacks.

Question 5: Why does my server crash when there are a large number of concurrent connections?

One of the most common problems in TCP servers is program crash due to too many concurrent connections. This can be solved by managing connection pooling. Connection pooling maintains a set of established connections so that they can be reused when needed. However, if your server receives more concurrent connections than your connection pool can handle, it can cause a crash.

In addition to using a connection pool, you can also take the following measures to deal with high concurrent connections:

• Limit the connection speed and enable DDOS protection.
• Set the connection timeout to a short time to allow inactive connections to be cleared.
• Use polling model to manage connections. By asking for the status of each connection, you can quickly detect connections that are dead or no longer in use.

Summary

The problems involved in using the TCP server library in the Go language are not limited to the above. This requires you to spend time and energy to solve these problems, and requires a certain knowledge of network programming. As long as you master the correct techniques and methods, you can build a powerful TCP server that can handle a large number of concurrent connections and ensure security.

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