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Simple Static File Server in Reason/OCaml
let recv = (client, maxlen) => {
let bytes = Bytes.create(maxlen);
let len = Unix.recv(client, bytes, 0, maxlen, []);
Bytes.sub_string(bytes, 0, len)
};
let parse_top = top => {
let parts = Str.split(Str.regexp("[ \t]+"), top);
switch (parts) {
| [method, path, ...others] => Some((method, path))
| _ => None
}
};
module StringMap = Map.Make(String);
let parse_headers = headers => {
List.fold_left(
(map, line) => {
let parts = Str.split(Str.regexp(":"), line);
switch parts {
| [] | [_] => map
| [name, ...rest] => StringMap.add(name, String.concat(":", rest), map)
}
},
StringMap.empty,
headers
)
};
let parse_request = text => {
let items = Str.split(Str.regexp("\r?\n"), text);
switch items {
| [] => failwith("Invalid request")
| [top, ...headers] =>
switch (parse_top(top)) {
| None => failwith("Invalid top: " ++ top)
| Some((method, path)) =>
let header_map = parse_headers(headers);
(method, path, header_map)
}
}
};
module Response = {
type response =
| Ok(string, string) /* mime, text */
| Bad(int, string); /* code, text */
};
open Response;
let format_response = response => {
let (top, body) = switch (response) {
| Ok(mime, body) => {
("HTTP/1.1 200 Ok\nContent-type: " ++ mime, body)
}
| Bad(code, body) => {
("HTTP/1.1 " ++ string_of_int(code) ++ " Error\nContent-type: text/plain", body)
}
};
top ++ "\nServer: Ocaml-Cross-Mobile\nContent-length: " ++ string_of_int(String.length(body)) ++ "\n\n" ++ body
};
let listen = (port, handler) => {
let sock = Unix.socket(Unix.PF_INET, Unix.SOCK_STREAM, 0);
Unix.setsockopt(sock, Unix.SO_REUSEADDR, true);
Unix.bind(sock, Unix.ADDR_INET(Unix.inet_addr_any, port));
print_endline("Listening! Open http://localhost:" ++ string_of_int(port));
while (true) {
Unix.listen(sock, 1000);
let (client, source) = Unix.accept(sock);
let request = recv(client, 1024);
let response = try {
let (method, path, header_map) = parse_request(request);
print_endline("Request for: " ++ path);
handler(method, path, header_map);
} {
| _ => Bad(500, "Server error")
};
let response = format_response(response);
let total = String.length(response);
let left = ref(String.length(response));
while (left^ > 0) {
left := left^ - Unix.send(client, response, total - left^, left^, []);
};
Unix.shutdown(client, Unix.SHUTDOWN_ALL);
}
};
let readall = (fd) => {
let rec loop = () => switch (Pervasives.input_line(fd)) {
| exception End_of_file => []
| line => [line, ...loop()]
};
loop();
};
let exists = path => try {Unix.stat(path) |> ignore; true} {
| Not_found => false
};
let readFile = path => {
let fd = Unix.openfile(path, [Unix.O_RDONLY], 0o640);
let text = String.concat("\n", readall(Unix.in_channel_of_descr(fd)));
Unix.close(fd);
text
};
let mime_for_name = ext => switch (String.lowercase(ext)) {
| "txt" => "text/plain"
| "html" => "text/html"
| "json" => "text/json"
| "js" => "application/javascript"
| "jpg" | "jpeg" => "image/jpeg"
| "png" => "image/png"
| "pdf" => "image/pdf"
| "ico" => "image/ico"
| "gif" => "image/gif"
| _ => "application/binary"
};
let ext = path => {
let parts = Str.split(Str.regexp("\\."), path);
List.nth(parts, List.length(parts) - 1)
};
let isFile = path => switch (Unix.stat(path)) {
| exception Unix.Unix_error(Unix.ENOENT, _, _) => false
| {Unix.st_kind: Unix.S_REG} => true
| _ => false
};
open BasicServer.Response;
let serveStatic = (full_path, path) => {
switch (Unix.stat(full_path)) {
| exception Unix.Unix_error(Unix.ENOENT, _, _) => Bad(404, "File not found: " ++ path)
| stat =>
switch (stat.Unix.st_kind) {
| Unix.S_REG => Ok(mime_for_name(ext(path)), readFile(full_path))
| Unix.S_DIR => {
let index = Filename.concat(full_path, "index.html");
if (isFile(index)) {
Ok("text/html", readFile(index))
} else {
Ok("text/plain", "Directory")
}
}
| _ => Bad(404, "Unexpected file type: " ++ path)
};
}
};
let handler = (base, method, path, headers) => {
switch (method) {
| "GET" => {
let full_path = Filename.concat(base, "." ++ path);
serveStatic(full_path, path)
}
| _ => Bad(401, "Method not allowed: " ++ method)
}
};
let main = () => {
switch (Sys.argv) {
| [|_|] => BasicServer.listen(3451, handler("./"))
| [|_, path|] => BasicServer.listen(3451, handler(path))
| _ => print_endline("Usage: serve [path: default current]")
}
};
main();
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