HTTP Commands (httpc)

Overview

The httpc command-line tool is a curl-like HTTP client that operates over the reliable UDP protocol. It supports GET and POST requests with headers, inline data, file uploads, and verbose output.

General Usage

httpc command [arguments]

All requests are sent through the reliable UDP protocol implementation, providing TCP-like reliability over UDP.

Commands

help

Displays usage information.

httpc help
httpc help get
httpc help post

httpc is a curl-like application but supports HTTP protocol only.
Usage:
    httpc command [arguments]
The commands are:
    get     executes a HTTP GET request and prints the response.
    post    executes a HTTP POST request and prints the response.
    help    prints this screen.

Use "httpc help [command]" for more information about a command.

GET Command

Executes an HTTP GET request for a given URL.

Syntax

httpc get [-v] [-h key:value] URL

Parameters

-v

flag

Verbose mode. Prints the detailed response including protocol, status, and headers.

-h

string

Associates headers to the HTTP request with the format key:value. Can be used multiple times.

URL

string

required

The target URL for the GET request. Must include protocol, host, and path.

Examples

httpc get http://httpbin.org/get

Response Format

Normal Mode
Verbose Mode (-v)

Shows only the response body:

{
  "args": {},
  "headers": {
    "Host": "httpbin.org"
  },
  "url": "http://httpbin.org/get"
}

Shows status, headers, and body:

HTTPFC/1.0 200 OK
Content-Type: application/json
Content-Length: 312

{
  "args": {},
  "headers": {
    "Host": "httpbin.org"
  },
  "url": "http://httpbin.org/get"
}

Help Text

httpc help get

usage: httpc get [-v] [-h key:value] URL

Get executes a HTTP GET request for a given URL.

    -v	Prints the detail of the response such as protocol, status, and headers.
    -h key:value	Associates headers to HTTP Request with the format 'key:value'.

POST Command

Executes an HTTP POST request for a given URL with inline data or file content.

Syntax

httpc post [-v] [-h key:value] [-d inline-data] [-f file] [-o output] URL

Parameters

-v

flag

Verbose mode. Prints the detailed response including protocol, status, and headers.

-h

string

Associates headers to the HTTP request with the format key:value. Can be used multiple times.

-d

string

Associates inline data to the body of the HTTP POST request.

-f

string

Associates the content of a file to the body of the HTTP POST request.

-o

string

Writes the response output to the specified file instead of stdout.

URL

string

required

The target URL for the POST request.

Either -d or -f can be used, but not both simultaneously.

Examples

httpc post -h Content-Type:application/json \
  -d '{"Assignment": 1}' \
  http://httpbin.org/post

Request Format

The POST command automatically constructs a proper HTTP request:

POST /post HTTPFC/1.0
Content-Type: application/json
Content-Length: 20

{"Assignment": 1}

Help Text

httpc help post

usage: httpc post [-v] [-h key:value] [-d inline-data] [-f file] URL

Post executes a HTTP POST request for a given URL with inline data or from file.

    -v	Prints the detail of the response such as protocol, status, and headers.
    -h key:value	 Associates headers to HTTP Request with the format 'key:value'.
    -d string	 Associates an inline data to the body HTTP POST request.
    -f file	Associates the content of a file to the body HTTP POST request

Either [-d] or [-f] can be used but not both.

Common Flags

-v (Verbose)

Purpose: Display full response detailsBehavior:

Shows HTTP version and status code
Displays all response headers
Shows response body

Example:

httpc get -v http://httpbin.org/get

Output:

HTTPFC/1.0 200 OK
Content-Type: application/json
Content-Length: 256

{"response": "data"}

-h (Headers)

Purpose: Add custom HTTP headers to the requestFormat: -h key:valueUsage:

Can be specified multiple times
No spaces around the colon
Common headers: Content-Type, Authorization, Accept, User-Agent

Examples:

# Single header
httpc get -h Accept:application/json http://example.com

# Multiple headers
httpc post \
  -h Content-Type:application/json \
  -h Authorization:Bearer-token \
  -d '{"data":"value"}' \
  http://example.com/api

-d (Inline Data)

Purpose: Send inline data in POST request bodyPOST only: This flag is only valid for POST requestsUsage:

Mutually exclusive with -f
Automatically sets Content-Length header
String data is sent as-is

Examples:

# JSON data
httpc post -d '{"name":"John"}' http://example.com/api

# Form data
httpc post -d 'name=John&[email protected]' http://example.com/form

# With explicit content type
httpc post \
  -h Content-Type:application/json \
  -d '{"user":{"name":"John"}}' \
  http://example.com/api

-f (File Data)

Purpose: Send file contents in POST request bodyPOST only: This flag is only valid for POST requestsUsage:

Mutually exclusive with -d
Reads entire file into request body
File path is relative to current directory

Examples:

# Send JSON file
httpc post -f request.json http://example.com/api

# Send with headers
httpc post \
  -h Content-Type:application/json \
  -f data.json \
  http://example.com/api

# Verbose with file
httpc post -v -f payload.txt http://example.com/upload

-o (Output File)

Purpose: Write response to a file instead of stdoutUsage:

Works with both GET and POST
Creates or overwrites the specified file
File path is relative to current directory

Examples:

# Save GET response
httpc get -o response.json http://api.example.com/data

# Save POST response
httpc post -d '{"query":"test"}' -o result.txt http://example.com/api

# Verbose mode with file output
httpc get -v -o output.html http://example.com/page

URL Format

URLs must follow this format:

http://host:port/path

protocol

string

required

Must be http://

host

string

required

Hostname or IP address

port

number

required

Port number (no default)

path

string

Request path (defaults to /)

URL Examples

# With port
http://localhost:8080/api/data

# With IP address
http://192.168.1.100:8000/index.html

# With query parameters
http://example.com:8080/search?q=test&limit=10

HTTP Protocol

The client uses a custom HTTP/1.0-like protocol:

The protocol identifier is HTTPFC/1.0 instead of standard HTTP/1.0

Request Format

GET /path HTTPFC/1.0
Header1: value1
Header2: value2

POST /path HTTPFC/1.0
Header1: value1
Content-Length: 15

{"data":"test"}

Connection Process

Three-way handshake

The client establishes a reliable connection using SYN, SYN-ACK, ACK packets.

Request transmission

The HTTP request is chunked and sent using the Selective Repeat protocol.

Response reception

The client receives response packets, sends ACKs/NACKs, and assembles the complete response.

Connection closure

The connection is closed after the response is fully received.

Error Messages

Malformed URL

malformed URL

Cause: Invalid URL format or missing componentsSolution: Ensure URL follows the format http://host:port/path

Wrong command

Wrong command

Cause: Command doesn’t start with httpcSolution: Start command with httpc followed by get, post, or help

Connection Error

Exceptions during socket operationsPossible causes:

Server not reachable
Network timeout
Port unavailable

Solution: Verify server is running and network connectivity

Integration Example

Using the httpc client programmatically:

import client.Httpc;
import util.Response;

public class Example {
    public static void main(String[] args) {
        Httpc client = new Httpc();
        
        try {
            // Execute GET request
            String cmd = "httpc get -v http://httpbin.org:80/get";
            Response response = client.getResponse(cmd);
            
            System.out.println("Status: " + response.getStatus());
            System.out.println("Code: " + response.getCode());
            
            if (response.getInFile()) {
                // Response was written to file
                System.out.println("Output written to: " + response.getFile());
            } else {
                // Print response body
                System.out.println(response.getBody());
            }
            
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

ReliableClientProtocol

Underlying reliable UDP protocol

Packet Format

Packet structure used for transmission

Getting Started

Architecture

Components

Guides

API Reference

Overview

General Usage

Commands

help

GET Command

Syntax

Parameters

Examples

Response Format

Help Text

POST Command

Syntax

Parameters

Examples

Request Format

Help Text

Common Flags

URL Format

URL Examples

HTTP Protocol

Request Format

Connection Process

Error Messages

Integration Example

See Also

ReliableClientProtocol

Packet Format

Build docs developers (and LLMs) love

Getting Started

Architecture

Components

Guides

API Reference

​Overview

​General Usage

​Commands

​help

​GET Command

​Syntax

​Parameters

​Examples

​Response Format

​Help Text

​POST Command

​Syntax

​Parameters

​Examples

​Request Format

​Help Text

​Common Flags

​URL Format

​URL Examples

​HTTP Protocol

​Request Format

​Connection Process

​Error Messages

​Integration Example

​See Also

ReliableClientProtocol

Packet Format

Build docs developers (and LLMs) love

Overview

General Usage

Commands

help

GET Command

Syntax

Parameters

Examples

Response Format

Help Text

POST Command

Syntax

Parameters

Examples

Request Format

Help Text

Common Flags

URL Format

URL Examples

HTTP Protocol

Request Format

Connection Process

Error Messages

Integration Example

See Also