CRF Custom File Client

-- File Transfers over CRFv3.1

-- Packet structure:
-- [1] : Ident string
-- [2] : Action
-- [3] : Target
-- [4] : Data Parameter
-- [5] : Binary Flag

if not LANClient then
    error("LAN Client API not loaded.")
end

function readFile(server, file, binary)
    LANClient.send(server, textutils.serialize({"FileTransfer", "read", file, binary}))
    while true do
    local sender, data = LANClient.receive(5)
        if not sender then
            return false, "Server timed out"
        elseif sender == server then
            data = textutils.unserialize(data)
            if type(data) == "table" then
                if data[1] == "FileTransfer" then
                    if data[2] == "Error" then
                        return false, data[3]
                    elseif data[2] == "data" then
                        return true, data[3]
                    else
                        return false, "Unknown response"
                    end
                end
            end
        end
    end
end

function listFiles(server, dir)
    LANClient.send(server, textutils.serialize({"FileTransfer", "list", file}))
    local sender, data = LANClient.receive(5, server)
    if not sender then
        return false, "Server timed out"
    else
        data = textutils.unserialize(data)
        if type(data) == "table" then
            if data[1] == "FileTransfer" then
                if data[2] == "Error" then
                    return false, data[3]
                elseif data[2] == "list" then
                    return true, data[3]
                else
                    return false, "Unknown response"
                end
            end
        end
    end
end

function writeFile(server, file, data, binary)
    LANClient.send(server, textutils.serialize({"FileTransfer", "write", file, binary}))
    local sender, data = LANClient.receive(5, server)
    if not sender then
        return false, "Server timed out"
    else
        data = textutils.unserialize(data)
        if type(data) == "table" then
            if data[1] == "FileTransfer" then
                if data[2] == "Error" then
                    return false, data[3]
                elseif data[2] == "Okay" then
                    return true
                else
                    return false, "Unknown response"
                end
            end
        end
    end
end

function deleteFile(server, file)
    return false, "This action is prohibited on your system"
end

function mkDir(server, dir)
    LANClient.send(server, textutils.serialize({"FileTransfer", "mkdir", dir}))
    local sender, data = LANClient.receive(5, server)
    if not sender then
        return false, "Server timed out"
    else
        data = textutils.unserialize(data)
        if type(data) == "table" then
            if data[1] == "FileTransfer" then
                if data[2] == "Error" then
                    return false, data[3]
                elseif data[2] == "Okay" then
                    return true
                else
                    return false, "Unknown response"
                end
            end
        end
    end
end

if shell then
    local file = fs.open(shell.getRunningProgram(), "r")
    if file then
        local l = file.readLine()
        file.close()
        if string.match(l, "File Transfers") then
            local args = {...}
            if #args == 0 then
                print("FTP -- File transfer interface and API")
                print(string.rep("-", term.getSize()))
                print("Usage: ftp [action] [server] [target] [params]")
                print("Actions:")
                print("read (\"ftp read [server] [remoteFile] [localFile]\"): Get a file.")
                print("write (\"ftp write [server] [localFile] [remoteFile]\"): Send a file.")
                print("mkdir (\"ftp mkdir [server] [remoteDir]\"): Make a directory.")
                print("delete (\"ftp delete [server] [remoteFile]\"): Delete a file.")
                print("list (\"ftp list [server] [remoteDir]\"): Get a directory listing.")
            elseif #args == 4 then
                if args[1] == "read" then
                    local stat, data = readFile(tonumber(args[2]), args[3], false)
                    if stat then
                        local f = fs.open(args[4], "w")
                        f.write(data)
                        f.close()
                        print("Data written to "..args[4])
                    else
                        print("Could not get file: "..data)
                    end
                elseif args[1] == "write" then
                    local f = fs.open(args[3], "r")
                    data = f.readAll()
                    f.close()
                    local stat, err = writeFile(tonumber(args[2]), args[4], data, false)
                    if stat then
                        print("File successfully transferred.")
                    else
                        print("Could not transfer file: "..err)
                    end
                end
            elseif #args == 3 then
                if args[1] == "mkdir" then
                    local stat, err = mkDir(tonumber(args[2]), args[3])
                    if stat then
                        print("Directory successfully created.")
                    else
                        print("Could not make directory: "..err)
                    end
                elseif args[1] == "delete" then
                    local stat, err = deleteFile(tonumber(args[2]), args[3])
                    if stat then
                        print("File successfully deleted.")
                    else
                        print("Could not delete file: "..err)
                    end
                elseif args[1] == "list" then
                    local stat, list = listFiles(tonumber(args[2]), args[3])
                    if stat then
                        textutils.tabulate(list)
                    else
                        print("Could not get directory listing: "..err)
                    end
                end
            end
        end
    end
end