警告

This document is not updated for ESP32C5 yet, so some of the content may not be correct.

This warning was automatically inserted due to the source file being in the add_warnings_pages list.

ICMP 回显

概述

网际控制报文协议 (ICMP) 通常用于诊断或控制目的，或响应 IP 操作中的错误。常用的网络工具 ping 的应答，即 Echo Reply，就是基于类型字段值为 0 的 ICMP 数据包实现的。

在 ping 会话中，首先由源主机发出请求包 (ICMP echo request)，然后等待应答包 (ICMP echo reply)，等待具有超时限制。通过这一过程，还能测量出信息的往返用时。收到有效的应答包后，源主机会生成 IP 链路层的统计数据（如失包率、运行时间等）。

IoT 设备通常需要检查远程服务器是否可用。如果服务器离线，设备应向用户发出警告。通过创建 ping 会话，定期发送或解析 ICMP echo 数据包，就能实现这一功能。

为简化这一过程方便用户操作，ESP-IDF 提供了一些好用的 API。

创建 ping 会话

要创建 ping 会话，首先需填写 esp_ping_config_t，指定目标芯片 IP 地址、间隔时间等配置。此外，还可以通过 esp_ping_callbacks_t 注册回调函数。

创建 ping 会话并注册回调函数示例：

static void test_on_ping_success(esp_ping_handle_t hdl, void *args)
{
    // optionally, get callback arguments
    // const char* str = (const char*) args;
    // printf("%s\r\n", str); // "foo"
    uint8_t ttl;
    uint16_t seqno;
    uint32_t elapsed_time, recv_len;
    ip_addr_t target_addr;
    esp_ping_get_profile(hdl, ESP_PING_PROF_SEQNO, &seqno, sizeof(seqno));
    esp_ping_get_profile(hdl, ESP_PING_PROF_TTL, &ttl, sizeof(ttl));
    esp_ping_get_profile(hdl, ESP_PING_PROF_IPADDR, &target_addr, sizeof(target_addr));
    esp_ping_get_profile(hdl, ESP_PING_PROF_SIZE, &recv_len, sizeof(recv_len));
    esp_ping_get_profile(hdl, ESP_PING_PROF_TIMEGAP, &elapsed_time, sizeof(elapsed_time));
    printf("%d bytes from %s icmp_seq=%d ttl=%d time=%d ms\n",
           recv_len, inet_ntoa(target_addr.u_addr.ip4), seqno, ttl, elapsed_time);
}

static void test_on_ping_timeout(esp_ping_handle_t hdl, void *args)
{
    uint16_t seqno;
    ip_addr_t target_addr;
    esp_ping_get_profile(hdl, ESP_PING_PROF_SEQNO, &seqno, sizeof(seqno));
    esp_ping_get_profile(hdl, ESP_PING_PROF_IPADDR, &target_addr, sizeof(target_addr));
    printf("From %s icmp_seq=%d timeout\n", inet_ntoa(target_addr.u_addr.ip4), seqno);
}

static void test_on_ping_end(esp_ping_handle_t hdl, void *args)
{
    uint32_t transmitted;
    uint32_t received;
    uint32_t total_time_ms;

    esp_ping_get_profile(hdl, ESP_PING_PROF_REQUEST, &transmitted, sizeof(transmitted));
    esp_ping_get_profile(hdl, ESP_PING_PROF_REPLY, &received, sizeof(received));
    esp_ping_get_profile(hdl, ESP_PING_PROF_DURATION, &total_time_ms, sizeof(total_time_ms));
    printf("%d packets transmitted, %d received, time %dms\n", transmitted, received, total_time_ms);
}

void initialize_ping()
{
    /* convert URL to IP address */
    ip_addr_t target_addr;
    struct addrinfo hint;
    struct addrinfo *res = NULL;
    memset(&hint, 0, sizeof(hint));
    memset(&target_addr, 0, sizeof(target_addr));
    getaddrinfo("www.espressif.com", NULL, &hint, &res);
    struct in_addr addr4 = ((struct sockaddr_in *) (res->ai_addr))->sin_addr;
    inet_addr_to_ip4addr(ip_2_ip4(&target_addr), &addr4);
    freeaddrinfo(res);

    esp_ping_config_t ping_config = ESP_PING_DEFAULT_CONFIG();
    ping_config.target_addr = target_addr;          // target IP address
    ping_config.count = ESP_PING_COUNT_INFINITE;    // ping in infinite mode, esp_ping_stop can stop it

    /* set callback functions */
    esp_ping_callbacks_t cbs;
    cbs.on_ping_success = test_on_ping_success;
    cbs.on_ping_timeout = test_on_ping_timeout;
    cbs.on_ping_end = test_on_ping_end;
    cbs.cb_args = "foo";  // arguments that will feed to all callback functions, can be NULL
    cbs.cb_args = eth_event_group;

    esp_ping_handle_t ping;
    esp_ping_new_session(&ping_config, &cbs, &ping);
}

启动和停止 ping 会话

使用 esp_ping_new_session 返回的句柄可以启动或停止 ping 会话。注意，ping 会话在创建后不会自动启动。如果 ping 会话停止后重启，ICMP 数据包的序列号会归零重新计数。

删除 ping 会话

如果不再使用 ping 会话，可用 esp_ping_delete_session 将其删除。在删除 ping 会话时，确保该会话已处于停止状态（即已调用了 esp_ping_stop ，或该会话已完成所有步骤）。

获取运行时间数据

在回调函数中调用 esp_ping_get_profile，可获取 ping 会话的不同运行时间数据，如上文代码示例所示。

应用示例

ICMP echo 示例： protocols/icmp_echo

API 参考

Header File

components/lwip/include/apps/ping/ping_sock.h
This header file can be included with:
#include "ping/ping_sock.h"
This header file is a part of the API provided by the lwip component. To declare that your component depends on lwip, add the following to your CMakeLists.txt:
REQUIRES lwip
or
PRIV_REQUIRES lwip

Functions

esp_err_t esp_ping_new_session(const esp_ping_config_t *config, const esp_ping_callbacks_t *cbs, esp_ping_handle_t *hdl_out)

Create a ping session.

参数

config -- ping configuration
cbs -- a bunch of callback functions invoked by internal ping task
hdl_out -- handle of ping session

返回

ESP_ERR_INVALID_ARG: invalid parameters (e.g. configuration is null, etc)
ESP_ERR_NO_MEM: out of memory
ESP_FAIL: other internal error (e.g. socket error)
ESP_OK: create ping session successfully, user can take the ping handle to do follow-on jobs

esp_err_t esp_ping_delete_session(esp_ping_handle_t hdl)

Delete a ping session.

参数

hdl -- handle of ping session

返回

ESP_ERR_INVALID_ARG: invalid parameters (e.g. ping handle is null, etc)
ESP_OK: delete ping session successfully

esp_err_t esp_ping_start(esp_ping_handle_t hdl)

Start the ping session.

参数

hdl -- handle of ping session

返回

ESP_ERR_INVALID_ARG: invalid parameters (e.g. ping handle is null, etc)
ESP_OK: start ping session successfully

esp_err_t esp_ping_stop(esp_ping_handle_t hdl)

Stop the ping session.

参数

hdl -- handle of ping session

返回

ESP_ERR_INVALID_ARG: invalid parameters (e.g. ping handle is null, etc)
ESP_OK: stop ping session successfully

esp_err_t esp_ping_get_profile(esp_ping_handle_t hdl, esp_ping_profile_t profile, void *data, uint32_t size)

Get runtime profile of ping session.

参数

hdl -- handle of ping session
profile -- type of profile
data -- profile data
size -- profile data size

返回

ESP_ERR_INVALID_ARG: invalid parameters (e.g. ping handle is null, etc)
ESP_ERR_INVALID_SIZE: the actual profile data size doesn't match the "size" parameter
ESP_OK: get profile successfully

Structures

struct esp_ping_callbacks_t

Type of "ping" callback functions.

Public Members

void *cb_args: arguments for callback functions

void (*on_ping_success)(esp_ping_handle_t hdl, void *args): Invoked by internal ping thread when received ICMP echo reply packet.

void (*on_ping_timeout)(esp_ping_handle_t hdl, void *args): Invoked by internal ping thread when receive ICMP echo reply packet timeout.

void (*on_ping_end)(esp_ping_handle_t hdl, void *args): Invoked by internal ping thread when a ping session is finished.

struct esp_ping_config_t

Type of "ping" configuration.

Public Members

uint32_t count: A "ping" session contains count procedures

uint32_t interval_ms: Milliseconds between each ping procedure

uint32_t timeout_ms: Timeout value (in milliseconds) of each ping procedure

uint32_t data_size: Size of the data next to ICMP packet header

int tos: Type of Service, a field specified in the IP header

int ttl: Time to Live,a field specified in the IP header

ip_addr_t target_addr: Target IP address, either IPv4 or IPv6

uint32_t task_stack_size: Stack size of internal ping task

uint32_t task_prio: Priority of internal ping task

uint32_t interface: Netif index, interface=0 means NETIF_NO_INDEX

Macros

ESP_PING_DEFAULT_CONFIG(): Default ping configuration.

ESP_PING_COUNT_INFINITE: Set ping count to zero will ping target infinitely

Type Definitions

typedef void *esp_ping_handle_t: Type of "ping" session handle.

Enumerations

enum esp_ping_profile_t

Profile of ping session.

Values:

enumerator ESP_PING_PROF_SEQNO: Sequence number of a ping procedure

enumerator ESP_PING_PROF_TOS: Type of service of a ping procedure

enumerator ESP_PING_PROF_TTL: Time to live of a ping procedure

enumerator ESP_PING_PROF_REQUEST: Number of request packets sent out

enumerator ESP_PING_PROF_REPLY: Number of reply packets received

enumerator ESP_PING_PROF_IPADDR: IP address of replied target

enumerator ESP_PING_PROF_SIZE: Size of received packet

enumerator ESP_PING_PROF_TIMEGAP: Elapsed time between request and reply packet

enumerator ESP_PING_PROF_DURATION: Elapsed time of the whole ping session

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