webserver - how to get incoming http request IP address

[J00003]

I am using the webserver component as documented here: https://docs.espressif.com/projects/esp ... erver.html, and have the basics working.
But am wondering how to retrieve the IP address of the far-end or client for an incoming http request. Is it available some how thru the session or transport context?
The docs and example code don't give any clues...
Thanks,

[ESP_Anurag]

Hi,

You need to use the httpd_req_to_sockfd() function to obtain the sockfd of a client inside a request handler, then use getpeername() function (include <sys/socket.h>) to get the IP address from the sockfd.

Here is an example function that you can try invoking inside your request handler for printing the IP address:

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void print_client_ip(httpd_req_t *req)
{
    int sockfd = httpd_req_to_sockfd(req);
    char ipstr[INET6_ADDRSTRLEN];
    struct sockaddr_in6 addr;   // esp_http_server uses IPv6 addressing
    socklen_t addr_size = sizeof(addr);
    
    if (getpeername(sockfd, (struct sockaddr *)&addr, &addr_size) < 0) {
        ESP_LOGE(TAG, "Error getting client IP");
        return;
    }
    
    // Convert to IPv6 string
    inet_ntop(AF_INET, &addr.sin6_addr, ipstr, sizeof(ipstr));
    ESP_LOGI(TAG, "Client IP => %s", ipstr);
}

Now, you may prefer to print the IPv4 part of the address, in which case you can do (as described in this post http://bbs.esp32.com/viewtopic.php?t=8317):

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    // Convert to IPv4 string
    inet_ntop(AF_INET, &addr.sin6_addr.un.u32_addr[3], ipstr, sizeof(ipstr));
    ESP_LOGI(TAG, "Client IP => %s", ipstr);

[J00003]

Thank you @ESP_Anurag, I'll give that a try.

[Craige Hales]

Thanks!
Pretty sure the IPv6 call should use AF_INET6:

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inet_ntop(AF_INET6, &addr.sin6_addr, ipstr, sizeof(ipstr));

I wanted to understand the [3] for the IPv4 call, here's some info:

https://datatracker.ietf.org/doc/html/r ... on-2.5.5.2 :
IPv4-Mapped IPv6 Address
A second type of IPv6 address that holds an embedded IPv4 address is
defined. This address type is used to represent the addresses of
IPv4 nodes as IPv6 addresses. The format of the "IPv4-mapped IPv6
address" is as follows:

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   |                80 bits               | 16 |      32 bits        |
   +--------------------------------------+--------------------------+
   |0000..............................0000|FFFF|    IPv4 address     |
   +--------------------------------------+----+---------------------+

which is what I see with AF_INET6:

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I (183749) file_server: Client IP => ::FFFF:192.168.4.121

[sinmosh]

@ESP_Anurag Thank you for the great hint!