hiredis fails with username and password in hostname

I'm trying to run hiredis in C on CentOS.

The following code seems to run fine:

...
const char *hostname = "my.redis-as-a-service.com";
int port = 8765;

const char *cert = "-----BEGIN CERTIFICATE-----...-----END CERTIFICATE-----\n";
const char *key = "-----BEGIN PRIVATE KEY-----...-----END PRIVATE KEY-----\n";
const char *ca = "-----BEGIN CERTIFICATE-----...-----END CERTIFICATE-----\n";

struct timeval tv = { 1, 500000 }; // 1.5 seconds
redisOptions options = {0};
REDIS_OPTIONS_SET_TCP(&options, hostname, port);
options.timeout = &tv;
c = redisConnectWithOptions(&options);

if (c == NULL || c->err) {
    if (c) {
        printf("Connection error: %s\n", c->errstr);
        redisFree(c);
    } else {
        printf("Connection error: can't allocate redis context\n");
    }
    exit(1);
}

if (redisSecureConnection(c, ca, cert, key, "sni") != REDIS_OK) {
    printf("Couldn't initialize SSL!\n");
    printf("Error: %s\n", c->errstr);
    redisFree(c);
    exit(1);
}

But when I try to run it against Compose.com which require username and password in the url, like:

const char *hostname = "USERNAME:PASSWORD@my.redis-as-a-service.com";

then it fails without a specific error. Simple:

Connection error: Name or service not known

You cannot specify a username and passwort in the hostname string. This whole string is treated as the hostname and DNS lookup fails.

Instead you have to do it this way:

First, connect normally without authentication credentials.

After this succeeded, you can authenticate with

redisCommand(c, "AUTH password");

Note that usernames are not supported with redis, so you cannot specify one.