Hiredis SO_BINDTODEVICE example.

bind-to-device.c

#include "hiredis.h"
#include <assert.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <linux/if.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>

char device[IFNAMSIZ];

int bindToDevice(redisFD fd, void *privdata, char **user_errstr) {
    (void)privdata;


    if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, &device, sizeof(device)) != 0) {
        *user_errstr = strerror(errno);
        return REDIS_ERR;
    }

    return REDIS_OK;
}

int main(int argc, const char **argv) {
    redisOptions opt = {0};
    const char *host;
    int port;
    redisContext *c;
    redisReply *r;

    if (argc > 1) {
        strcpy(device, argv[1]);
    } else {
        strncpy(device, "lo", sizeof(device));
    }

    host = argc > 2 ? argv[2] : "localhost";
    port = argc > 3 ? atoi(argv[3]) : 6379;

    printf("Attempting to connect to %s:%d; device: %s\n", host, port, device);

    REDIS_OPTIONS_SET_TCP(&opt, host, port);
    REDIS_OPTIONS_SET_SOCKET_CB(&opt, bindToDevice);
    REDIS_OPTIONS_SET_PRIVDATA(&opt, (void*)0xdeadbeef, NULL);

    c = redisConnectWithOptions(&opt);
    if (c == NULL || c->err) {
        fprintf(stderr, "Failed to connect: (error: %s)\n", c->errstr);
        exit(1);
    }

    r = redisCommand(c, "PING");
    assert(r != NULL && !c->err && r->type == REDIS_REPLY_STATUS);

    printf("PING: %s\n", r->str);

    return 0;
}