What should I do if php curl cannot obtain data?

Since PHP 5.5, the cURL library has been bundled into the core and opened by default. Therefore, one can use cURL function in PHP to get the data.

However, in practice, it is sometimes found that cURL cannot obtain data from the target website. These problems may be caused by the following reasons:

1. The website has restricted requests
2. The proxy server is incorrect or cannot be connected
3. HTTPS certificate verification failed
4. Request timeout or failure

In this article, we will discuss some reasons that may cause cURL to be unable to obtain data, and how to solve these problems.

1. Website limits requests

Some websites restrict requests from certain IP addresses. Illegal requests or requests that are too frequent may be rejected. Such limitations may prevent cURL from fetching data. At this point, if you are sure that your IP address has been restricted, then you can solve the problem by the following methods:

1) Make sure your IP address is back to normal
2) Adjust the cURL code to The access is simulated as a regular browser access
3) Use the proxy IP address to access the target website

2. The proxy server is incorrect or cannot be connected

When you access through the proxy server When targeting a website, there may be an issue where the proxy server is incorrect or cannot be connected. If you encounter this situation, you can solve this problem through the following methods:

1) Check whether the IP address and port number of the proxy server are correct
2) Check whether the access method of the proxy server is correct, such as whether Username and password authentication is required
3) Check whether the proxy server is restricted by firewalls or other network protection systems

3. HTTPS certificate verification failed

When using cURL to download HTTPS When accessing a web page, certificate verification may fail. This is because cURL uses a default set of certificates to verify the target website's SSL certificate. If the target website's certificate is not in this certificate set, verification fails and cURL will not be able to download the web page.

To resolve this issue, you can do one of the following:

1) Manually specify the SSL certificate from the target website
2) Disable certificate verification
3) Update cURL Certificate

4. The request times out or fails

When the cURL request times out or fails, it may be caused by the following reasons:

1) Request the target website There is a problem
2) There is a network failure
3) There is an error in the PHP program
4) The request has been rejected by the target website

In order to solve this problem, you can use the following methods:

1) Check if there is a problem with the target website
2) Check if the network is working properly
3) Check if there are any errors in the PHP program
4) Determine the reason why the request was rejected

If When encountering the above problems, we can try to solve them according to the specific situation. You can debug the code and logs to determine the cause of the problem and take appropriate resolutions.

Summary

When using cURL in PHP, if the data cannot be obtained, the problem may be caused by multiple reasons. Common problems include websites throttling requests, incorrect or unreachable proxy servers, failed HTTPS certificate verification, and request timeouts or failures. By taking appropriate workarounds based on the specific situation, the above issues can be resolved so that cURL can work properly.

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