Lua socket error on connection

Question

I'm trying to make a http get, using Lua Socket:

local client = socket.connect('warm-harbor-2019.herokuapp.com',80)
if client then
    client:send("GET /get_tweets HTTP/1.0\r\n\r\n")
      s, status, partial = client:receive(1024)
    end
end

I expect s to be a tweet, since the get that I'm making returns one. But I'm getting:

http/1.1 404 object not found

catwell · Accepted Answer · 2014-05-19 20:52:26Z

5

Here is a runnable version of your code example (that exhibit the problem you described):

local socket = require "socket"
local client = socket.connect('warm-harbor-2019.herokuapp.com',80)
if client then
    client:send("GET /get_tweets HTTP/1.0\r\n\r\n")
    local s, status, partial = client:receive(1024)
    print(s)
end

If you read the error page returned, you can see that its title is Heroku | No such app.

The reason for that is that the Heroku router only works when a Host header is provided. The easiest way to do it is to use the actual HTTP module of LuaSocket instead of TCP directly:

local http = require "socket.http"
local s, status, headers = http.request("http://warm-harbor-2019.herokuapp.com/get_tweets")
print(s)

If you cannot use socket.http you can pass the Host header manually:

local socket = require "socket"
local client = socket.connect('warm-harbor-2019.herokuapp.com',80)
client:send("GET /get_tweets HTTP/1.0\r\nHost: warm-harbor-2019.herokuapp.com\r\n\r\n")
local s, status, partial = client:receive(1024)
print(s, status, partial)

With my version of LuaSocket, s will be nil, status will be "closed" and partial will contain the full HTTP response (with headers etc).

edited May 19, 2014 at 20:52

answered May 18, 2014 at 18:27

catwell

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3 Comments

Matheus Lima Over a year ago

Looks solid, but my require 'socket.http' is not working, only require 'socket'. Do I need to add a file to the project? Right now, i just have one lua file.

catwell Over a year ago

This is probably because you use an old version of LuaSocket. If you require "socket" (without assigning it to a local variable) does socket.http exist? If so replace http.request by socket.http.request.

Matheus Lima Over a year ago

Ok, I'm using NCLua. I did what you told, in a separated file, and it worked fine. But for some reason 'socket' is working, but 'socket.http' is not. Is there a way to do it with 'socket' ?

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