# HG changeset patch
# User Kim Alvefur <zash@zash.se>
# Date 1697297466 -7200
# Node ID 30f91daa40b4b8cd2e35c3ad60e81105d9932f9d
# Parent  ecfd7aece33b81fd06ff4871b6c2e6885c845c82
mod_storage_s3: Beginnings of an experimental S3 storage driver

Tested against MinIO

diff -r ecfd7aece33b -r 30f91daa40b4 mod_storage_s3/mod_storage_s3.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_storage_s3/mod_storage_s3.lua	Sat Oct 14 17:31:06 2023 +0200
@@ -0,0 +1,142 @@
+local http = require "prosody.net.http";
+local array = require "prosody.util.array";
+local async = require "prosody.util.async";
+local hashes = require "prosody.util.hashes";
+local httputil = require "prosody.util.http";
+local it = require "prosody.util.iterators";
+local jid = require "prosody.util.jid";
+local json = require "prosody.util.json";
+local st = require "prosody.util.stanza";
+local xml = require "prosody.util.xml";
+local url = require "socket.url";
+
+local hmac_sha256 = hashes.hmac_sha256;
+local sha256 = hashes.sha256;
+
+local driver = {};
+
+local bucket = module:get_option_string("s3_bucket", "prosody");
+local base_uri = module:get_option_string("s3_base_uri", "http://localhost:9000");
+local region = module:get_option_string("s3_region", "us-east-1");
+
+local access_key = module:get_option_string("s3_access_key");
+local secret_key = module:get_option_string("s3_secret_key");
+
+function driver:open(store, typ)
+	local mt = self[typ or "keyval"]
+	if not mt then
+		return nil, "unsupported-store";
+	end
+	return setmetatable({ store = store; bucket = bucket; type = typ }, mt);
+end
+
+local keyval = { };
+driver.keyval = { __index = keyval; __name = module.name .. " keyval store" };
+
+local aws4_format = "AWS4-HMAC-SHA256 Credential=%s/%s, SignedHeaders=%s, Signature=%s";
+
+local function new_request(method, path, payload)
+	local request = url.parse(base_uri);
+	request.path = path;
+
+	local payload_type = nil;
+	if st.is_stanza(payload) then
+		payload_type = "application/xml";
+		payload = tostring(payload);
+	elseif payload ~= nil then
+		payload_type = "application/json";
+		payload = json.encode(payload);
+	end
+
+	local payload_hash = sha256(payload or "", true);
+
+	local now = os.time();
+	local aws_datetime = os.date("!%Y%m%dT%H%M%SZ", now);
+	local aws_date = os.date("!%Y%m%d", now);
+
+	local headers = {
+		["Accept"] = "*/*";
+		["Authorization"] = nil;
+		["Content-Type"] = payload_type;
+		["Host"] = request.authority;
+		["User-Agent"] = "Prosody XMPP Server";
+		["X-Amz-Content-Sha256"] = payload_hash;
+		["X-Amz-Date"] = aws_datetime;
+	};
+
+	local canonical_uri = url.build({ path = request.path });
+	local canonical_query = "";
+	local canonical_headers = array();
+	local signed_headers = array()
+
+	for header_name, header_value in it.sorted_pairs(headers) do
+		header_name = header_name:lower();
+		canonical_headers:push(header_name .. ":" .. header_value .. "\n");
+		signed_headers:push(header_name);
+	end
+
+	canonical_headers = canonical_headers:concat();
+	signed_headers = signed_headers:concat(";");
+
+	local scope = aws_date .. "/" .. region .. "/s3/aws4_request";
+
+	local canonical_request = method .. "\n"
+		.. canonical_uri .. "\n"
+		.. canonical_query .. "\n"
+		.. canonical_headers .. "\n"
+		.. signed_headers .. "\n"
+		.. payload_hash;
+
+	local signature_payload = "AWS4-HMAC-SHA256" .. "\n" .. aws_datetime .. "\n" .. scope .. "\n" .. sha256(canonical_request, true);
+
+	-- This can be cached?
+	local date_key = hmac_sha256("AWS4" .. secret_key, aws_date);
+	local date_region_key = hmac_sha256(date_key, region);
+	local date_region_service_key = hmac_sha256(date_region_key, "s3");
+	local signing_key = hmac_sha256(date_region_service_key, "aws4_request");
+
+	local signature = hmac_sha256(signing_key, signature_payload, true);
+
+	headers["Authorization"] = string.format(aws4_format, access_key, scope, signed_headers, signature);
+
+	return http.request(url.build(request), { method = method; headers = headers; body = payload });
+end
+
+-- coerce result back into Prosody data type
+local function on_result(response)
+	local content_type = response.headers["content-type"];
+	if content_type == "application/json" then
+		return json.decode(response.body);
+	elseif content_type == "application/xml" then
+		return xml.parse(response.body);
+	elseif content_type == "application/x-www-form-urlencoded" then
+		return httputil.formdecode(response.body);
+	else
+		response.log("warn", "Unknown response data type %s", content_type);
+		return response.body;
+	end
+end
+
+function keyval:_path(key)
+	return url.build_path({
+		is_absolute = true;
+		bucket;
+		jid.escape(module.host);
+		jid.escape(self.store);
+		jid.escape(key or "");
+	})
+end
+
+function keyval:get(user)
+	return async.wait_for(new_request("GET", self:_path(user)):next(on_result));
+end
+
+function keyval:set(user, data)
+	return async.wait_for(new_request("PUT", self:_path(user), data));
+end
+
+function keyval:users()
+	return nil, "not-implemented";
+end
+
+module:provides("storage", driver);