1. Modify the code for nano_get_url by adding the appropriate headers where necessary and performing redirects if needed in order to fetch any webpage
Solution to exercise in exercise_1 directory.
erl
1> nano_get_url:get_url().
Redirected to: http://www.google.com/webhp
{"200",
[{"date","Tue, 19 May 2020 12:56:02 GMT"},
{"expires","-1"},
{"cache-control","private, max-age=0"},
{"content-type","text/html; charset=ISO-8859-1"},
{"p3p",
"CP=\"This is not a P3P policy! See g.co/p3phelp for more info.\""},
{"server","gws"},
{"x-xss-protection","0"},
{"x-frame-options","SAMEORIGIN"},
{"set-cookie",
"1P_JAR=2020-05-19-12; expires=Thu, 18-Jun-2020 12:56:02 GMT; path=/; domain=.google.com; Secure"},
{"set-cookie",
"NID=204=0DCMqJF2Ile8j7aDSW3HPuCPI7mGgttfvnahCPE_bl4ViwbvXd6wa6e-pw4dC_4hmlkaaRZSn6to3int8t8WKylCs9IsZYGoBo63tloqAGx5Llldh1MRs66OHqFzY_DUsg9BWfbBiLwqckyYatgYO3hMji8QkaWwgcKlsOcKUek; expires=Wed, 18-Nov-2020 12:56:02 GMT; path=/; domain=.google.com; HttpOnly"},
{"accept-ranges","none"},
{"vary","Accept-Encoding"}],
<<"<!doctype html><html itemscope=\"\" itemtype=\"http://schema.org/WebPage\" lang=\"en\"><head><meta content=\"Se"...>>}
2>
2. Enter the cdoe for a simple TCP server on page 267. Modify the code to receive a {Mod, Func, Args} tuple instead of a string. Compute Reply = apply(Mod, Func, Args) and send the value back to the socket. Write equivalent client code that encodes the Mod, Func, and Args in a form understood by the server.
Solution to the exercise in the exercise_2 directory.
In one erl shell run the server:
erl
1> nano_server:start().
Server received binary = <<131,104,3,100,0,6,101,114,108,97,110,103,100,0,13,
108,105,115,116,95,116,111,95,116,117,112,108,101,
108,0,0,0,1,107,0,1,5,106>>
Server (unpacking) {erlang,list_to_tuple,[[5]]}
Server replying = {5}
Server socket closed
And in another run the client:
erl
1> nano_client:send(erlang, list_to_tuple, [[5]]).
Client received binary = <<131,104,1,97,5>>
Client result = {5}
3. Repeat the previous exercise using UDP.
Solution to the exercise in the exercise_3 directory.
In one erl shell run the server:
erl
1> nano_server:start().
Server received binary = <<131,104,3,100,0,6,101,114,108,97,110,103,100,0,13,
108,105,115,116,95,116,111,95,116,117,112,108,101,
108,0,0,0,1,107,0,2,1,23,106>>
Server (unpacking) {erlang,list_to_tuple,[[1,23]]}
Server replying = {1,23}
And in another run the client:
erl
1> nano_client:send(erlang, list_to_tuple, [[1,23]]).
Client received binary = <<131,104,2,97,1,97,23>>
Client result = {1,23}
{1,23}
4. Add a layer of cryptography by encoding the binary before sending it to the outgoing socket and decoding it after it is received on the incoming socket.
Solution to the exercise in the exercise_4 directory.
In one erl shell run the server:
erl
1> nano_server:start().
Server received binary = <<131,104,3,100,0,6,101,114,108,97,110,103,100,0,13,
108,105,115,116,95,116,111,95,116,117,112,108,101,
108,0,0,0,1,107,0,1,5,106>>
Server (unpacking) {erlang,list_to_tuple,[[5]]}
Server replying = {5}
Server socket closed
And in another run the client:
erl
1> nano_client:send(erlang, list_to_tuple, [[5]]).
Client received binary = <<131,104,1,97,5>>
Client result = {5}
5. Make a simple "email-like" system. use Eralng terms as messages and store them in $HOME/mbox.
Solution to the exercise in the exercise_4 directory. I chose to keep this as simple as possible and not require any authentication for checking email messages. Any user can read the messages of any other user on the servers.
In one erl shell run the server:
erl
Erlang/OTP 19 [erts-8.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]
Eshell V8.2 (abort with ^G)
1> nano_server:start().
Server (unpacking) {"Stratus3D",{send_msg,"Hey there!"}}
Writing "~/mbox/Stratus3D/576460656748859828-message.txt"
Server replying = ok
Server socket closed
Server (unpacking) {"Stratus3D",{send_msg,"hello?"}}
Writing "~/mbox/Stratus3D/576460656748859828-message.txt"
Server replying = ok
Server socket closed
Server received binary = <<131,104,2,107,0,6,116,114,101,118,111,114,100,0,12,
103,101,116,95,97,108,108,95,109,115,103,115>>
Server (unpacking) {"Stratus3D",get_all_msgs}
{"576460739590151126-message.txt",<<"Hey there!">>},
{"576460739789060103-message.txt",<<"hello?">>},
Server socket closed
Server received binary = <<131,104,2,107,0,6,116,114,101,118,111,114,104,2,100,
0,8,115,101,110,100,95,109,115,103,107,0,6,104,101,
108,108,111,63>>
And in another run the client:
erl
1> nano_client:send_msg("Stratus3D", "localhost", "Hey there!").
Client received binary = <<131,100,0,2,111,107>>
Client result = ok
ok
1> nano_client:send_msg("Stratus3D", "localhost", "hello?").
Client received binary = <<131,100,0,2,111,107>>
Client result = ok
ok
2> nano_client:receive_msgs("Stratus3D", "localhost").
Client result = [{"576460739590151126-message.txt",<<"Hey there!">>},
{"576460739789060103-message.txt",<<"hello?">>}]