dns.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "../io_ring_internal.h"
#include "../dns/dns_resolver.h"
#include "../dns/dns_ares.h"

#define MAX_TRY_COUNT 5
struct dns_arg {
        struct io_ring *ring;
        struct dns_resolver_result **result;
        struct io_ring_sqe sqe;
        uint8_t try_count;
};

static bool issue_sqe_dns_query(struct dns_arg *arg);

void gw_dns_cb(int code, struct dns_resolver_result *result, void *parg)
{
        struct dns_arg *arg = parg;
        struct io_ring *ring = arg->ring;
        struct io_ring_sqe *sqe = &arg->sqe;

        if (code == ARES_ECANCELLED && arg->try_count < MAX_TRY_COUNT) {
                dns_res_result_free(result);
                mutex_lock(&ring->sq_lock);
                issue_sqe_dns_query(arg);
                mutex_unlock(&ring->sq_lock);
                return;
        }

        *arg->result = result;
        gw_post_cqe(ring, code, sqe->user_data);
        free(arg->sqe.arg2_ptr);
        free(arg);
}

static bool issue_sqe_dns_query(struct dns_arg *arg)
        __must_hold(&ring->sq_lock)
{
        struct io_ring_sqe *sqe = &arg->sqe;
        struct io_ring *ring = arg->ring;
        int ret = -ENOSYS;

        arg->try_count++;
        switch (sqe->op) {
        case GW_RING_OP_DNS_QUERY:
                ret = dns_res_query(sqe->arg1_ptr, sqe->arg2_ptr, gw_dns_cb, arg);
                break;
        case GW_RING_OP_DNS_QUERY4:
                ret = dns_res_query4(sqe->arg1_ptr, sqe->arg2_ptr, gw_dns_cb, arg);
                break;
        case GW_RING_OP_DNS_QUERY6:
                ret = dns_res_query6(sqe->arg1_ptr, sqe->arg2_ptr, gw_dns_cb, arg);
                break;
        }

        if (unlikely(ret != 0)) {
                free(arg->sqe.arg2_ptr);
                free(arg);
                return gw_post_cqe(ring, ret, sqe->user_data);
        }

        return true;
}

bool gw_issue_sqe_dns_query(struct io_ring *ring, struct io_ring_sqe *sqe)
        __must_hold(&ring->sq_lock)
{
        struct dns_arg *arg;

        arg = malloc(sizeof(*arg));
        if (unlikely(!arg)) {
                return false;
        }

        arg->sqe = *sqe;
        arg->sqe.arg2_ptr = strdup(sqe->arg2_ptr);
        if (unlikely(!arg->sqe.arg2_ptr)) {
                free(arg);
                return false;
        }

        arg->ring = ring;
        arg->result = arg->sqe.arg3_ptr;
        arg->try_count = 0;

        return issue_sqe_dns_query(arg);
}