Is there any C socket function, which can look for datagrams from a specific UDP client?

Question

The server I am building uses the UDP transport layer protocol. I have a scenario where multiple clients can send datagrams to my server. But each client may send the data across multiple datagrams, and before starting to process the data, I need to have the entire data at the server. From the man page of recvfrom() , it sounds like it reads the datagrams from any UDP client. Are there any recv*() family functions that enable us to read from a specific UDP client?

#include <netinet/in.h>
#include <sys/socket.h>

int append_data(void* buf, int size);

int main()
{
    /* Create a UDP socket and bind to a port */
    int sockfd;
    char rd_buf[100];

    struct sockaddr_in cliaddr;

    for ( ; ; ) {
        /* Recvfrom any client */

        int addr_len = sizeof(cliaddr);
        int rd_status = recvfrom(sockfd, rd_buf, sizeof(rd_buf), 0, (struct sockaddr*) &cliaddr, &addr_len);

        if (append_data(rd_buf, rd_status) == DATA_COMPLETE)
            continue;

        /* Recvfrom a particular client */

        for ( ; ; ) {
            /* Any function similar to recvfromcli() ? */

            int rd_status = recvfromcli(sockfd, rd_buf, sizeof(rd_buf), 0, (struct sockaddr*) &cliaddr, addr_len);

            if (append_data(rd_buf, rd_status) == DATA_COMPLETE)
                 break;
        }
    }
}

If not what are my other alternatives?

Answer 1

You can create a separate UDP socket that is bind() 'ed to the local IP/Port and connect() 'ed to a specific client IP/Port, then you can recv() using that socket, and it will give you datagrams from only that client.