在Arduino下的Slack bot上找不到通道，但在Bash上找不到

如何解决在Arduino下的Slack bot上找不到通道，但在Bash上找不到

我正在尝试使用Arduino在Slack上发布消息，但是它总是返回"channel_not_found"错误。 我试图用不同的格式定义频道：

    client.println("POST " PATH " HTTP/1.1");
    client.println("Content-type: application/json");
    client.println("Authorization: Bearer " TOKEN);
    client.println("Host: " SERVER);
    client.println("Connection: close");
    client.println();  // Separate header from content. Important!
    client.println("{\"channel\":\"C01750LNGAU\",\"text\":\":tada:\"}");
    //OR: client.println("{\"channel\":\"#project-coffee\",\"text\":\":tada:\"}");
    //OR: client.println("{\"channel\":C01750LNGAU,\"text\":\":tada:\"}");

也使用URL编码内容类型：

    client.println("POST " PATH " HTTP/1.1");
    client.println("Content-type: application/x-www-form-urlencoded");
    client.println("Authorization: Bearer " TOKEN);
    client.println("Host: " SERVER);
    client.println("Connection: close");
    client.println();
    client.println("channel=C01750LNGAU&text=:tada:");
    //OR client.println("channel=project-coffee&text=:tada:");
    //OR client.println("channel=#project-coffee&text=:tada:");
    //OR client.println("channel=\\#project-coffee&text=:tada:");

为了进行比较，使用具有相同参数的Bash，它可以工作： curl -F token=xoxb-12... -F channel=project-coffee -F text="Blabla" https://slack.com/api/chat.postMessage，因此漫游器的权限是正确的。 我怀疑自己在做些微妙的蠢事，但我看不到。

该频道为公开频道，并且该漫游器具有权限。

作为参考，here是postMessage的文档，here是示例。

完整代码包含在此处：

#include <SPI.h>
#include <WiFiNINA.h>
#include "arduino_secrets.h"


char ssid[] = SECRET_SSID; 
const char password[] = SECRET_PASS;
int status = WL_IDLE_STATUS;

// POST parameters
// curl -F token=xoxb-12... -F channel=project-coffee -F text="Blabla" https://slack.com/api/chat.postMessage

const char* serverName = "slack.com/api/chat.postMessage";
const char* post_channel="project-coffee";
const int port = 443;


#define SERVER "slack.com"
#define PATH   "/api/chat.postMessage"

WiFiSSLClient client;


void setup() {
  Serial.begin(115200);

  // attempt to connect to Wifi network:
  while (status != WL_CONNECTED) {
    Serial.print("Attempting to connect to WPA SSID: ");
    Serial.println(ssid);
    Serial.flush();

    // Connect to WPA/WPA2 network:
    status = WiFi.begin(ssid,password);
  }

  // you're connected now,so print out the data:
  Serial.println("You are connected to the network");
  Serial.flush();

  if (client.connect(SERVER,443)) {
    Serial.println("connected to Slack");

    client.println("POST " PATH " HTTP/1.1");
    client.println("Content-type: application/json");
    //client.println("Content-type: application/x-www-form-urlencoded");
    client.println("Authorization: Bearer " TOKEN);
    client.println("Host: " SERVER);
    client.println("Connection: close");
    client.println();  // Separate header from content. Important!
    //client.println("{\"channel\": \"#project-coffee\",\"text\": \":tada:\"}");
    client.println("{\"channel\": \"C01750LNGAU\",\"text\": \":tada:\"}");
    //client.println("{\"channel\": C01750LNGAU,\"text\": \":tada:\"}");
    //client.println("channel=C01750LNGAU&text=:tada:");
    //client.println("channel=project-coffee&text=:tada:");
    //client.println("channel=#project-coffee&text=:tada:");
    //client.println("channel=\\#project-coffee&text=:tada:");
    Serial.println();

  }
}


uint32_t bytes = 0;
void loop() {

  while (client.available()) {
    char c = client.read();
    Serial.write(c);
    bytes++;
  }
  if (!client.connected()) {
  Serial.println();
  Serial.println("disconnecting from server.");
  client.stop();
  Serial.print("Read "); Serial.print(bytes); Serial.println(" bytes");

  // do nothing forevermore:
  while (true);
  }
}

完整的答复是：

date: Sun,06 Sep 2020 13:46:30 GMT
server: Apache
x-slack-req-id: ****
x-oauth-scopes: chat:write,channels:read,groups:read,mpim:read,im:read
x-accepted-oauth-scopes: chat:write
access-control-expose-headers: x-slack-req-id,retry-after
x-slack-backend: r
x-content-type-options: nosniff
expires: Mon,26 Jul 1997 05:00:00 GMT
cache-control: private,no-cache,no-store,must-revalidate
x-xss-protection: 0
vary: Accept-Encoding
pragma: no-cache
access-control-allow-headers: slack-route,x-slack-version-ts,x-b3-traceid,x-b3-spanid,x-b3-parentspanid,x-b3-sampled,x-b3-flags
strict-transport-security: max-age=31536000; includeSubDomains; preload
referrer-policy: no-referrer
access-control-allow-origin: *
connection: close
transfer-encoding: chunked
content-type: application/json; charset=utf-8
x-via: haproxy-www-3rug,haproxy-edge-fra-eynl

{"ok":false,"error":"channel_not_found"}

解决方法

将POST发送到postman-echo.com，它以您发送的请求作为响应，我可以看到正文为空。

原来我在标头Content-Length中缺少一个必填字段。丢失时，似乎Slack和邮递员默认为0。 解决方案？添加标题：

client.println("Content-Length: 42");