How to get json data from connection golang

I use a tcp connection written in golang to send a curl request from the console. So it's basically a data flow. I can successfully receive the data and store it in the buffer using the following code

func PushDataToBuffer(bufferedChannel chan []byte, conn net.Conn) {
    defer conn.Close()
    fmt.Println("pushing messages into buffer...")

    buffer := make([]byte, 2048) // 2048 = assumption for reasonable event byte size

    for {
        n, err := conn.Read(buffer)
        if err != nil {
            fmt.Println("read error: ", err)
            continue // to continue listening for connections
        }
        bufferedChannel <- buffer[:n]
    }
}

However, when I try to read this data using this code:

for data := range bufferedChannel {
    fmt.Println("The len of buffer is: ", len(bufferedChannel))
    dataObject := models.Event{}
    err := json.Unmarshal(data, &dataObject)
}

I get the following error

Invalid character 'P' looking for beginning of value
2024/01/29 09:40:31 syntax error at byte offset 1

When I print out the data itself, I see this

POST / HTTP/1.1
Host: localhost:8952
User-Agent: curl/7.77.0
Accept: */*
Content-Type: application/json
Content-Length: 232

{\"customer\":\"Ada\",\"eventtype\":\"BuyingApples\",\"time\":\"0001-01-01T00:00:00Z\",\"specifics\":[{\"Key\":\"Shop\",\"Value\":\"Bakery\"},{\"Key\":\"Location\",\"Value\":\"Downtown\"},{\"Key\":\"recommends\",\"Value\":\"yes\"}]}

From the above you can clearly see where the problem lies. It adds headers to the data, so the P in POST is what golang complains about. That's why I can't unmarshal it. So my question is this: How do I send the data to the server or trim it as it arrives, all I will use is the json part:

{\"customer\":\"Ada\",\"eventtype\":\"BuyingApples\",\"time\":\"0001-01-01T00:00:00Z\",\"specifics\":[{\"Key\":\"Shop\",\"Value\":\"Bakery\"},{\"Key\":\"Location\",\"Value\":\"Downtown\"},{\"Key\":\"recommends\",\"Value\":\"yes\"}]}

P.S - I am using tcp connection to get the data instead of http

I looked online for various solutions but didn't find one that fit my use case

Correct answer

cURL is not a TCP client. It is an HTTP client and naturally generates some headers native to the protocol (such as request method and path). This is what is ultimately sent over the TCP connection. Therefore, there is a mismatch between what the server expects (plain TCP) and what the client sends (HTTP).

You should update your server code to parse the raw data into an HTTP request, such as http .ReadRequest, or simply use a client that sends the expected payload over the wire - i.e. pure TCP. Netcat will make this easy. Without knowing much about the problem you're trying to solve, I'd recommend the latter approach by default (because why send HTTP when you need TCP in the first place?).

The above is the detailed content of How to get json data from connection golang. For more information, please follow other related articles on the PHP Chinese website!