如何使用 Netcat 读取和处理 POST 请求

Question

I want to make a simple HTTP server with Bash & netcat, and have a problem with reading POST requests entirely - the last line is always missing.

The server is started like this:

netcat -l -p 8080 -e ./ncserver.sh

The ncserver.sh , reduced to bare minimum which displays the problem:

#!/bin/bash

while read INPUT; do
    echo "Req line: $INPUT" >&2
done;

I use Postman to make requests to the server, and expect the script to dump entire request data to stderr. The request is a simple JSON:

{
    name: "Eugene",
    age: 34
}

Update: Raw postman request data:

POST /foo/bar HTTP/1.1
Host: localhost:8080
Content-Type: application/json
Cache-Control: no-cache
Postman-Token: 7f5a57a7-1664-e79c-2242-7ba6b638e260

{
    name: "Eugene",
    age: 34
}

In the server's output I get all the headers and request body which is missing the last line, the } . The same holds for other content types, such as multipart/form-data - last line is always missing.

Note: if I add an empty line after JSON, I can see the } in terminal output.

I tried using cat /dev/stdin instead of read but get No such device or address .

The question probably can be generalized as how do I read HTTP requests in correct binary form in Bash?

Answer 1

Try as below.

#!/bin/bash

while IFS= read -r INPUT || [ "$INPUT" ]; do
    echo "Req line: $INPUT" >&2
done;   

Point to notice.

IFS= is to preserve any indentation.
-r is to prevent backslash interpretation.
Check for INPUT : When read reaches the end-of-file instead of end-of-line it assigns variable but exits. hence, check if we have anything in INPUT .

Answer 2

Hello @x1n13y84issmd42

Just in case you are still looking for a solution.. I had good results when trying the following:

#!/usr/bin/env bash

read -d } PAYLOAD;

Instead of parsing each line as they come, the "-d }" option makes read store everything that comes through stdin in PAYLOAD until it meets "}".

You can then process $PAYLOAD} with jq for instance