path: root/src/client.c

#include "internal.h"

#include <curl/curl.h>
#include <errno.h>
#include <math.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <time.h>

#define CEPIS_ACCEPT_HEADER \
        "Accept: application/json, text/csv;q=0.9, */*;q=0.1"

static const long RETRIABLE_STATUS[] = {429, 500, 502, 503, 504};

#define RETRIABLE_COUNT (sizeof(RETRIABLE_STATUS) / sizeof(RETRIABLE_STATUS[0]))

struct cepis_client {
        char *base_url;
        char *user_agent;
        double timeout;
        double backoff_base;
        double backoff_max;
        double total_timeout;
        int max_attempts;
        uint64_t rng;
        CURL *curl;
        struct curl_slist *headers;
};

typedef struct {
        long status;
        double retry_after;
        cepis_buf_t body;
} cepis_response_t;

const char *cepis_status_str(cepis_status_t status)
{
        switch (status) {
        case CEPIS_OK:
                return "ok";
        case CEPIS_ERR_INVALID_CEP:
                return "invalid CEP";
        case CEPIS_ERR_NOT_FOUND:
                return "CEP not found";
        case CEPIS_ERR_RATE_LIMITED:
                return "rate limited";
        case CEPIS_ERR_SERVER:
                return "server error";
        case CEPIS_ERR_NETWORK:
                return "network error";
        case CEPIS_ERR_INVALID_RESPONSE:
                return "invalid response";
        case CEPIS_ERR_CONFIG:
                return "invalid configuration";
        case CEPIS_ERR_NOMEM:
                return "out of memory";
        }
        return "unknown error";
}

cepis_status_t cepis_global_init(void)
{
        if (curl_global_init(CURL_GLOBAL_DEFAULT) != CURLE_OK)
                return CEPIS_ERR_NETWORK;
        return CEPIS_OK;
}

void cepis_global_cleanup(void)
{
        curl_global_cleanup();
}

cepis_status_t cepis_normalize_cep(const char *value,
                                   char out[CEPIS_CEP_LEN + 1])
{
        char digits[CEPIS_CEP_LEN + 1];
        size_t n = 0;
        size_t i;

        if (value == NULL || out == NULL)
                return CEPIS_ERR_INVALID_CEP;

        for (i = 0; value[i] != '\0'; i++) {
                char c = value[i];
                if (c == ' ' || c == '\t' || c == '\n' || c == '\r' ||
                    c == '-' || c == '.')
                        continue;
                if (c < '0' || c > '9')
                        return CEPIS_ERR_INVALID_CEP;
                if (n >= CEPIS_CEP_LEN)
                        return CEPIS_ERR_INVALID_CEP;
                digits[n++] = c;
        }
        if (n != CEPIS_CEP_LEN)
                return CEPIS_ERR_INVALID_CEP;

        digits[CEPIS_CEP_LEN] = '\0';
        memcpy(out, digits, CEPIS_CEP_LEN + 1);
        return CEPIS_OK;
}

cepis_status_t cepis_format_cep(const char *cep, char out[CEPIS_CEP_LEN + 2])
{
        char digits[CEPIS_CEP_LEN + 1];
        cepis_status_t status = cepis_normalize_cep(cep, digits);

        if (status != CEPIS_OK)
                return status;
        memcpy(out, digits, 5);
        out[5] = '-';
        memcpy(out + 6, digits + 5, 3);
        out[CEPIS_CEP_LEN + 1] = '\0';
        return CEPIS_OK;
}

void cepis_config_init(cepis_config_t *config)
{
        if (config == NULL)
                return;
        config->base_url = CEPIS_DEFAULT_BASE_URL;
        config->user_agent = NULL;
        config->timeout = 10.0;
        config->max_attempts = 3;
        config->backoff_base = 0.5;
        config->backoff_max = 8.0;
        config->total_timeout = 0.0;
}

static char *trim_base_url(const char *base_url)
{
        size_t len = strlen(base_url);
        char *copy;

        while (len > 0 && base_url[len - 1] == '/')
                len--;
        copy = malloc(len + 1);
        if (copy == NULL)
                return NULL;
        memcpy(copy, base_url, len);
        copy[len] = '\0';
        return copy;
}

cepis_status_t cepis_client_new(const cepis_config_t *config,
                                cepis_client_t **out, cepis_error_t *err)
{
        cepis_config_t defaults;
        cepis_client_t *client;

        if (out == NULL)
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "out must not be NULL");
        if (config == NULL) {
                cepis_config_init(&defaults);
                config = &defaults;
        }
        if (config->base_url == NULL || config->base_url[0] == '\0')
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "base_url must not be empty");
        if (config->max_attempts < 1)
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "max_attempts must be >= 1");
        if (!(config->timeout > 0.0))
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "timeout must be > 0");
        if (config->backoff_base < 0.0 || config->backoff_max < 0.0)
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "backoff values must be >= 0");
        if (config->total_timeout < 0.0)
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "total_timeout must be >= 0");

        if (curl_global_init(CURL_GLOBAL_DEFAULT) != CURLE_OK)
                return cepis_set_error(err, CEPIS_ERR_NETWORK, 0, -1.0,
                                       "could not initialise libcurl");

        client = calloc(1, sizeof(*client));
        if (client == NULL) {
                curl_global_cleanup();
                return cepis_set_error(err, CEPIS_ERR_NOMEM, 0, -1.0,
                                       "out of memory");
        }

        client->timeout = config->timeout;
        client->max_attempts = config->max_attempts;
        client->backoff_base = config->backoff_base;
        client->backoff_max = config->backoff_max;
        client->total_timeout = config->total_timeout;
        client->rng =
                (uint64_t)time(NULL) ^ ((uint64_t)(uintptr_t)client << 16);
        if (client->rng == 0)
                client->rng = 0x9E3779B97F4A7C15ULL;

        client->base_url = trim_base_url(config->base_url);
        if (config->user_agent != NULL && config->user_agent[0] != '\0') {
                client->user_agent = cepis_strdup(config->user_agent);
        } else {
                client->user_agent = cepis_strdup("cepis-c/" CEPIS_VERSION
                                                  " (+https://cep.is)");
        }
        client->curl = curl_easy_init();
        client->headers = curl_slist_append(NULL, CEPIS_ACCEPT_HEADER);

        if (client->base_url == NULL || client->user_agent == NULL ||
            client->curl == NULL || client->headers == NULL) {
                cepis_client_free(client);
                return cepis_set_error(err, CEPIS_ERR_NOMEM, 0, -1.0,
                                       "out of memory");
        }

        *out = client;
        return CEPIS_OK;
}

void cepis_client_free(cepis_client_t *client)
{
        if (client == NULL)
                return;
        if (client->curl != NULL)
                curl_easy_cleanup(client->curl);
        if (client->headers != NULL)
                curl_slist_free_all(client->headers);
        free(client->base_url);
        free(client->user_agent);
        free(client);
        curl_global_cleanup();
}

const char *cepis_client_base_url(const cepis_client_t *client)
{
        return client == NULL ? NULL : client->base_url;
}

const char *cepis_client_user_agent(const cepis_client_t *client)
{
        return client == NULL ? NULL : client->user_agent;
}

static double monotonic_now(void)
{
        struct timespec ts;

        if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
                return 0.0;
        return (double)ts.tv_sec + (double)ts.tv_nsec / 1e9;
}

static void sleep_seconds(double seconds)
{
        struct timespec request;

        if (seconds <= 0.0)
                return;
        if (seconds > 3600.0)
                seconds = 3600.0;
        request.tv_sec = (time_t)seconds;
        request.tv_nsec = (long)((seconds - (double)request.tv_sec) * 1e9);
        if (request.tv_nsec < 0)
                request.tv_nsec = 0;
        if (request.tv_nsec > 999999999L)
                request.tv_nsec = 999999999L;
        while (nanosleep(&request, &request) == -1 && errno == EINTR)
                ;
}

static double next_uniform(cepis_client_t *client)
{
        uint64_t x = client->rng;

        x ^= x >> 12;
        x ^= x << 25;
        x ^= x >> 27;
        client->rng = x;
        x *= 0x2545F4914F6CDD1DULL;
        return (double)(x >> 11) / 9007199254740992.0;
}

static double backoff_delay(cepis_client_t *client, int attempt,
                            double retry_after)
{
        double ceiling;

        if (retry_after >= 0.0)
                return retry_after < client->backoff_max ? retry_after
                                                         : client->backoff_max;
        ceiling = client->backoff_base * pow(2.0, (double)(attempt - 1));
        if (ceiling > client->backoff_max)
                ceiling = client->backoff_max;
        return next_uniform(client) * ceiling;
}

static double parse_retry_after(const char *value, size_t len)
{
        char text[128];
        const char *formats[] = {"%a, %d %b %Y %H:%M:%S",
                                 "%A, %d-%b-%y %H:%M:%S",
                                 "%a %b %d %H:%M:%S %Y"};
        char *stop = NULL;
        double seconds;
        size_t i;

        while (len > 0 && (*value == ' ' || *value == '\t')) {
                value++;
                len--;
        }
        while (len > 0 && (value[len - 1] == ' ' || value[len - 1] == '\t' ||
                           value[len - 1] == '\r' || value[len - 1] == '\n'))
                len--;
        if (len == 0 || len >= sizeof(text))
                return -1.0;
        memcpy(text, value, len);
        text[len] = '\0';

        seconds = strtod(text, &stop);
        if (stop != NULL && *stop == '\0' && stop != text)
                return seconds < 0.0 ? 0.0 : seconds;

        for (i = 0; i < sizeof(formats) / sizeof(formats[0]); i++) {
                struct tm parsed;
                time_t target;

                memset(&parsed, 0, sizeof(parsed));
                if (strptime(text, formats[i], &parsed) == NULL)
                        continue;
                target = timegm(&parsed);
                if (target == (time_t)-1)
                        continue;
                seconds = difftime(target, time(NULL));
                return seconds < 0.0 ? 0.0 : seconds;
        }
        return -1.0;
}

static size_t write_body(char *ptr, size_t size, size_t nmemb, void *userdata)
{
        cepis_buf_t *body = userdata;
        size_t total = size * nmemb;

        if (!cepis_buf_append(body, ptr, total))
                return 0;
        return total;
}

static size_t read_header(char *ptr, size_t size, size_t nmemb, void *userdata)
{
        cepis_response_t *response = userdata;
        size_t total = size * nmemb;
        static const char name[] = "Retry-After:";
        size_t name_len = sizeof(name) - 1;

        if (total > name_len && strncasecmp(ptr, name, name_len) == 0)
                response->retry_after =
                        parse_retry_after(ptr + name_len, total - name_len);
        return total;
}

static bool is_retriable(long status)
{
        size_t i;

        for (i = 0; i < RETRIABLE_COUNT; i++)
                if (RETRIABLE_STATUS[i] == status)
                        return true;
        return false;
}

static bool is_accepted(long status, const long *accepted, size_t count)
{
        size_t i;

        for (i = 0; i < count; i++)
                if (accepted[i] == status)
                        return true;
        return false;
}

static void apply_options(cepis_client_t *client, const char *url,
                          cepis_response_t *response, char *error_buffer,
                          double budget)
{
        CURL *curl = client->curl;
        long low_speed_time = (long)ceil(client->timeout);

        if (low_speed_time < 1)
                low_speed_time = 1;

        curl_easy_reset(curl);
        curl_easy_setopt(curl, CURLOPT_URL, url);
        curl_easy_setopt(curl, CURLOPT_HTTPGET, 1L);
        curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1L);
        curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
        curl_easy_setopt(curl, CURLOPT_MAXREDIRS, 5L);
        curl_easy_setopt(curl, CURLOPT_USERAGENT, client->user_agent);
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, client->headers);
        curl_easy_setopt(curl, CURLOPT_ACCEPT_ENCODING, "identity");
        curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT_MS,
                         (long)(client->timeout * 1000.0));
        curl_easy_setopt(curl, CURLOPT_LOW_SPEED_LIMIT, 1L);
        curl_easy_setopt(curl, CURLOPT_LOW_SPEED_TIME, low_speed_time);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_body);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response->body);
        curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, read_header);
        curl_easy_setopt(curl, CURLOPT_HEADERDATA, response);
        curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, error_buffer);
        if (budget > 0.0) {
                long ms = (long)(budget * 1000.0);
                curl_easy_setopt(curl, CURLOPT_TIMEOUT_MS, ms > 1 ? ms : 1L);
        }
}

static cepis_status_t client_request(cepis_client_t *client, const char *url,
                                     const long *accepted,
                                     size_t accepted_count,
                                     cepis_response_t *response,
                                     cepis_error_t *err)
{
        char error_buffer[CURL_ERROR_SIZE];
        double deadline = client->total_timeout > 0.0
                                  ? monotonic_now() + client->total_timeout
                                  : 0.0;
        long last_status = 0;
        double last_retry_after = -1.0;
        int attempt;

        error_buffer[0] = '\0';
        response->status = 0;
        response->retry_after = -1.0;
        cepis_buf_init(&response->body);

        for (attempt = 1; attempt <= client->max_attempts; attempt++) {
                double budget = 0.0;
                CURLcode code;
                double wait;

                if (deadline > 0.0) {
                        budget = deadline - monotonic_now();
                        if (budget <= 0.0)
                                break;
                }

                response->body.len = 0;
                if (response->body.data != NULL)
                        response->body.data[0] = '\0';
                response->retry_after = -1.0;
                error_buffer[0] = '\0';

                apply_options(client, url, response, error_buffer, budget);
                code = curl_easy_perform(client->curl);

                if (code == CURLE_OK) {
                        long status = 0;
                        curl_easy_getinfo(client->curl, CURLINFO_RESPONSE_CODE,
                                          &status);
                        if (is_accepted(status, accepted, accepted_count) ||
                            !is_retriable(status)) {
                                response->status = status;
                                return CEPIS_OK;
                        }
                        last_status = status;
                        last_retry_after = response->retry_after;
                } else {
                        last_status = 0;
                        last_retry_after = -1.0;
                        if (error_buffer[0] == '\0')
                                snprintf(error_buffer, sizeof(error_buffer),
                                         "%s", curl_easy_strerror(code));
                }

                if (attempt == client->max_attempts)
                        break;

                wait = backoff_delay(client, attempt, last_retry_after);
                if (deadline > 0.0) {
                        double remaining = deadline - monotonic_now();
                        if (remaining <= 0.0)
                                break;
                        if (wait > remaining)
                                wait = remaining;
                }
                sleep_seconds(wait);
        }

        cepis_buf_free(&response->body);

        if (last_status == 429)
                return cepis_set_error(err, CEPIS_ERR_RATE_LIMITED, last_status,
                                       last_retry_after,
                                       "rate limit reached at %s (after %d "
                                       "attempt(s))",
                                       url, client->max_attempts);
        if (last_status != 0)
                return cepis_set_error(err, CEPIS_ERR_SERVER, last_status, -1.0,
                                       "the API answered %ld at %s (after %d "
                                       "attempt(s))",
                                       last_status, url, client->max_attempts);
        return cepis_set_error(err, CEPIS_ERR_NETWORK, 0, -1.0,
                               "could not reach %s (after %d attempt(s)): %s",
                               url, client->max_attempts,
                               error_buffer[0] != '\0' ? error_buffer
                                                       : "request aborted");
}

static void api_message(const cepis_buf_t *body, char *out, size_t out_size,
                        const char *fallback)
{
        json_value_t *root = json_parse(body->data, body->len);
        const char *message = json_as_string(json_object_get(root, "mensagem"));

        snprintf(out, out_size, "%s", message != NULL ? message : fallback);
        json_free(root);
}

/*
 * A 404 body may carry a `faixa` block naming the municipality the CEP would
 * have belonged to. Nothing here can fail: an unparseable body just means the
 * API named no municipality, which is also what an absent block means.
 */
static bool faixa_from_body(const cepis_buf_t *body, cepis_faixa_t *out)
{
        json_value_t *root = json_parse(body->data, body->len);
        bool named = cepis_faixa_from_json(root, out);

        json_free(root);
        return named;
}

static cepis_status_t build_url(const cepis_client_t *client, const char *path,
                                cepis_buf_t *out)
{
        cepis_buf_init(out);
        if (!cepis_buf_append_str(out, client->base_url) ||
            !cepis_buf_append_str(out, path)) {
                cepis_buf_free(out);
                return CEPIS_ERR_NOMEM;
        }
        return CEPIS_OK;
}

cepis_status_t cepis_lookup(cepis_client_t *client, const char *cep,
                            cepis_address_t **out, cepis_error_t *err)
{
        char number[CEPIS_CEP_LEN + 1];
        char path[CEPIS_CEP_LEN + 2];
        char message[CEPIS_ERROR_MESSAGE_MAX];
        char fallback[CEPIS_ERROR_MESSAGE_MAX];
        static const long accepted[] = {200};
        cepis_response_t response;
        cepis_address_t *address;
        cepis_buf_t url;
        json_value_t *root;
        cepis_status_t status;

        if (client == NULL || out == NULL)
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "client and out must not be NULL");
        if (cepis_normalize_cep(cep, number) != CEPIS_OK)
                return cepis_set_error(err, CEPIS_ERR_INVALID_CEP, 0, -1.0,
                                       "CEP must be 8 digits, got \"%s\"",
                                       cep != NULL ? cep : "(null)");

        snprintf(path, sizeof(path), "/%s", number);
        status = build_url(client, path, &url);
        if (status != CEPIS_OK)
                return cepis_set_error(err, status, 0, -1.0, "out of memory");

        status = client_request(client, url.data, accepted, 1, &response, err);
        cepis_buf_free(&url);
        if (status != CEPIS_OK)
                return status;

        if (response.status == 404) {
                cepis_faixa_t faixa;
                bool named = faixa_from_body(&response.body, &faixa);

                cepis_buf_free(&response.body);
                status = cepis_set_error(
                        err, CEPIS_ERR_NOT_FOUND, 404, -1.0,
                        "CEP %s does not exist in the DNE database", number);
                /*
                 * After cepis_set_error, which clears has_faixa: the block is
                 * extra detail about the failure, never a reason to report a
                 * different one.
                 */
                if (named && err != NULL) {
                        err->faixa = faixa;
                        err->has_faixa = true;
                }
                return status;
        }
        if (response.status == 400) {
                snprintf(fallback, sizeof(fallback), "CEP %s rejected", number);
                api_message(&response.body, message, sizeof(message), fallback);
                cepis_buf_free(&response.body);
                return cepis_set_error(err, CEPIS_ERR_INVALID_CEP, 400, -1.0,
                                       "%s", message);
        }
        if (response.status != 200) {
                long seen = response.status;
                cepis_buf_free(&response.body);
                return cepis_set_error(err, CEPIS_ERR_INVALID_RESPONSE, seen,
                                       -1.0, "the API answered %ld", seen);
        }

        root = json_parse(response.body.data, response.body.len);
        if (root == NULL || root->type != JSON_OBJECT) {
                json_free(root);
                status = cepis_set_error(err, CEPIS_ERR_INVALID_RESPONSE, 200,
                                         -1.0,
                                         "response is not a JSON object - "
                                         "something between you and "
                                         "the API is answering instead of it");
                cepis_buf_free(&response.body);
                return status;
        }

        address = cepis_address_from_json(root, response.body.data,
                                          response.body.len);
        json_free(root);
        cepis_buf_free(&response.body);
        if (address == NULL)
                return cepis_set_error(err, CEPIS_ERR_NOMEM, 0, -1.0,
                                       "out of memory");

        *out = address;
        return CEPIS_OK;
}

cepis_status_t cepis_health(cepis_client_t *client, cepis_health_t **out,
                            cepis_error_t *err)
{
        static const long accepted[] = {200, 503};
        cepis_response_t response;
        cepis_health_t *health;
        cepis_buf_t url;
        json_value_t *root;
        cepis_status_t status;

        if (client == NULL || out == NULL)
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "client and out must not be NULL");

        status = build_url(client, "/health", &url);
        if (status != CEPIS_OK)
                return cepis_set_error(err, status, 0, -1.0, "out of memory");

        status = client_request(client, url.data, accepted, 2, &response, err);
        cepis_buf_free(&url);
        if (status != CEPIS_OK)
                return status;

        root = json_parse(response.body.data, response.body.len);
        health = cepis_health_from_json(root);
        json_free(root);
        cepis_buf_free(&response.body);

        if (health == NULL)
                return cepis_set_error(err, CEPIS_ERR_INVALID_RESPONSE,
                                       response.status, -1.0,
                                       "health response is not a JSON object");

        *out = health;
        return CEPIS_OK;
}

static bool blank(const char *text)
{
        size_t i;

        if (text == NULL)
                return true;
        for (i = 0; text[i] != '\0'; i++)
                if (text[i] != ' ' && text[i] != '\t' && text[i] != '\r' &&
                    text[i] != '\n')
                        return false;
        return true;
}

static size_t column_index(const csv_row_t *header, const char *name)
{
        size_t i;

        for (i = 0; i < header->count; i++)
                if (strcmp(header->fields[i], name) == 0)
                        return i;
        return (size_t)-1;
}

static cepis_status_t chunk_url(cepis_client_t *client, const char *const *ceps,
                                size_t count, cepis_buf_t *out)
{
        cepis_buf_t joined;
        char *escaped;
        size_t i;

        cepis_buf_init(&joined);
        for (i = 0; i < count; i++) {
                const char *value = ceps[i] != NULL ? ceps[i] : "";
                if ((i > 0 && !cepis_buf_append_str(&joined, ",")) ||
                    !cepis_buf_append_str(&joined, value)) {
                        cepis_buf_free(&joined);
                        return CEPIS_ERR_NOMEM;
                }
        }

        escaped = curl_easy_escape(client->curl, joined.data ? joined.data : "",
                                   (int)joined.len);
        cepis_buf_free(&joined);
        if (escaped == NULL)
                return CEPIS_ERR_NOMEM;

        cepis_buf_init(out);
        if (!cepis_buf_append_str(out, client->base_url) ||
            !cepis_buf_append_str(out, "/csv?ceps=") ||
            !cepis_buf_append_str(out, escaped)) {
                cepis_buf_free(out);
                curl_free(escaped);
                return CEPIS_ERR_NOMEM;
        }
        curl_free(escaped);
        return CEPIS_OK;
}

static cepis_status_t fill_chunk(cepis_client_t *client,
                                 const char *const *ceps, size_t count,
                                 cepis_address_t **slots, cepis_error_t *err)
{
        static const long accepted[] = {200};
        char message[CEPIS_ERROR_MESSAGE_MAX];
        cepis_response_t response;
        csv_reader_t *reader;
        csv_row_t header;
        cepis_buf_t url;
        size_t localidade;
        size_t index;
        cepis_status_t status;

        status = chunk_url(client, ceps, count, &url);
        if (status != CEPIS_OK)
                return cepis_set_error(err, status, 0, -1.0, "out of memory");

        status = client_request(client, url.data, accepted, 1, &response, err);
        cepis_buf_free(&url);
        if (status != CEPIS_OK)
                return status;

        if (response.status == 400) {
                api_message(&response.body, message, sizeof(message),
                            "the batch was rejected");
                cepis_buf_free(&response.body);
                return cepis_set_error(err, CEPIS_ERR_INVALID_CEP, 400, -1.0,
                                       "%s", message);
        }
        if (response.status != 200) {
                long seen = response.status;
                cepis_buf_free(&response.body);
                return cepis_set_error(err, CEPIS_ERR_INVALID_RESPONSE, seen,
                                       -1.0, "the API answered %ld", seen);
        }

        reader = csv_reader_new(response.body.data ? response.body.data : "",
                                response.body.len);
        if (reader == NULL) {
                cepis_buf_free(&response.body);
                return cepis_set_error(err, CEPIS_ERR_NOMEM, 0, -1.0,
                                       "out of memory");
        }

        if (csv_reader_next(reader, &header) != 1) {
                csv_reader_free(reader);
                cepis_buf_free(&response.body);
                return cepis_set_error(err, CEPIS_ERR_INVALID_RESPONSE, 200,
                                       -1.0,
                                       "the batch response has no header");
        }

        localidade = column_index(&header, "localidade");
        status = CEPIS_OK;

        for (index = 0; index < count; index++) {
                csv_row_t record;
                int read = csv_reader_next(reader, &record);

                if (read != 1)
                        break;
                if (localidade != (size_t)-1 && localidade < record.count &&
                    !blank(record.fields[localidade])) {
                        slots[index] = cepis_address_from_csv(&header, &record);
                        if (slots[index] == NULL) {
                                csv_row_free(&record);
                                status =
                                        cepis_set_error(err, CEPIS_ERR_NOMEM, 0,
                                                        -1.0, "out of memory");
                                break;
                        }
                }
                csv_row_free(&record);
        }

        csv_row_free(&header);
        csv_reader_free(reader);
        cepis_buf_free(&response.body);
        return status;
}

cepis_status_t cepis_lookup_many(cepis_client_t *client,
                                 const char *const *ceps, size_t count,
                                 cepis_address_list_t *out, cepis_error_t *err)
{
        cepis_address_list_t list = {NULL, 0};
        size_t start;

        if (client == NULL || out == NULL)
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "client and out must not be NULL");
        if (count == 0) {
                out->items = NULL;
                out->count = 0;
                return CEPIS_OK;
        }
        if (ceps == NULL)
                return cepis_set_error(err, CEPIS_ERR_CONFIG, 0, -1.0,
                                       "ceps must not be NULL");

        list.items = calloc(count, sizeof(*list.items));
        if (list.items == NULL)
                return cepis_set_error(err, CEPIS_ERR_NOMEM, 0, -1.0,
                                       "out of memory");
        list.count = count;

        for (start = 0; start < count; start += CEPIS_MAX_BATCH) {
                size_t size = count - start;
                cepis_status_t status;

                if (size > CEPIS_MAX_BATCH)
                        size = CEPIS_MAX_BATCH;
                status = fill_chunk(client, ceps + start, size,
                                    list.items + start, err);
                if (status != CEPIS_OK) {
                        cepis_address_list_free(&list);
                        return status;
                }
        }

        *out = list;
        return CEPIS_OK;
}