Analysis of the failure of php http submission request

When writing web applications using PHP, we usually need to interact with other web services. HTTP requests are one of the common forms of Web interaction, such as requesting APIs, communicating with external interfaces, etc. However, when we use the http request function provided in PHP, in some cases we may encounter the problem of http request failure, causing the application to not work properly.

This article will introduce in detail the problems that may be encountered when submitting http requests in PHP, and how to solve these problems.

1. Unable to resolve the domain name

When initiating an http request to the target server, you first need to establish a connection based on the server IP or domain name. If the domain name of the target server cannot be resolved, The connection cannot be established and the http request will fail at this time.

Solution:
Ensure that the domain name of the target server can be resolved correctly, which can be solved by configuring the DNS or hosts file.

2. DNS resolution failure

Even if the domain name of the target server can be resolved, sometimes the DNS server will fail and cannot correctly resolve the server IP address. At this time, http The request will also fail.

Solution:
Use another DNS server or modify the IP address in the hosts file.

3. Server port problem

Some servers may listen to multiple ports. If the port we use is inconsistent with the port the server listens on, it may also cause the http request to fail.

Solution:
Confirm the port that the target server is listening on, and specify the correct port in the request.

4. Server access restrictions

In some high-security servers, access may be restricted, such as: IP address whitelist, access token, etc., if we If the submitted http request fails to pass the server limit, the http request will also fail.

Solution:
Confirm the access restrictions of the target server, and according to the needs, lift the access restrictions or add valid access authentication information.

5. Time stamp issue

When making an http request, the timestamp is a very important parameter. It is used to verify whether the request has expired. If the timestamp is incorrect, will cause the request to fail.

Solution:
Make sure that when submitting the http request, the timestamp parameter is correct and synchronized with the server time.

6. SSL Certificate Issue

When using the https protocol to make an http request, the server will send an SSL certificate to the client to encrypt and protect the data transmission process. If the client cannot verify the validity of the certificate, the http request will fail.

Solution:
If the target server uses a self-signed SSL certificate, it can be solved by ignoring the certificate verification or adding the certificate to the trust list.

7. Proxy server problem

In the process of initiating an http request to the target server, if the connection process needs to go through a proxy server, then the proxy server setting problem may also cause http Request failed.

Solution:
Confirm the configuration information of the proxy server, and correctly specify the address and port information of the proxy server in the request.

Summary

When submitting HTTP requests in PHP, there are some basic rules to follow to ensure that the target server of the request is correctly reachable and use the correct request parameters. If you still cannot submit the request, you can consider the above seven possible problems and take corresponding solutions. This can better ensure the stability of our program and the efficiency of interaction with other web services.

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