initial implementation - canonical request

src/aws.zig

@@ -227,7 +227,7 @@ pub fn Request(comptime action: anytype) type {
             // look at the return type
             var isJson: bool = undefined;
             for (response.headers) |h| {
-                if (std.mem.eql(u8, "Content-Type", h.name)) {
+                if (std.ascii.eqlIgnoreCase("Content-Type", h.name)) {
                     if (std.mem.startsWith(u8, h.value, "application/json")) {
                         isJson = true;
                     } else if (std.mem.startsWith(u8, h.value, "application/x-amz-json-1.0")) {

src/aws_http.zig

@@ -120,7 +120,6 @@ pub const AwsHttp = struct {
         // End CreateRequest. This should return a struct with a deinit function that can do
         // destroys, etc
 
-        // TODO: Add headers
         try zfetch.init(); // This only does anything on Windows. Not sure how performant it is to do this on every request
         defer zfetch.deinit();
         var headers = zfetch.Headers.init(self.allocator);
@@ -128,41 +127,54 @@ pub const AwsHttp = struct {
         for (request.headers) |header|
             try headers.appendValue(header.name, header.value);
         try addHeaders(self.allocator, &headers, endpoint.host, request.body, request.content_type, request.headers);
+        log.debug("All Request Headers:", .{});
+        for (headers.list.items) |h|
+            log.debug("\t{s}: {s}", .{ h.name, h.value });
 
         if (signing_config) |opts| try signing.signRequest(self.allocator, request, opts);
 
-        // TODO: make req
-
         // TODO: Construct URL with endpoint and request info
-        var req = try zfetch.Request.init(self.allocator, "https://www.lerch.org", null);
+        var req = try zfetch.Request.init(self.allocator, "https://httpbin.org/post", null);
+        defer req.deinit();
 
-        // TODO: http method as requested
-        // TODO: payload
-        try req.do(.GET, headers, null);
+        const method = std.meta.stringToEnum(zfetch.Method, request.method).?;
+        try req.do(method, headers, if (request.body.len == 0) null else request.body);
 
         // TODO: Timeout - is this now above us?
         log.debug("request_complete. Response code {d}: {s}", .{ req.status.code, req.status.reason });
-        log.debug("headers:", .{});
+        log.debug("Response headers:", .{});
         var resp_headers = try std.ArrayList(Header).initCapacity(self.allocator, req.headers.list.items.len);
+        defer resp_headers.deinit();
+        var content_length: usize = 0;
         for (req.headers.list.items) |h| {
             log.debug("    {s}: {s}", .{ h.name, h.value });
-            resp_headers.appendAssumeCapacity(.{ .name = h.name, .value = h.value });
+            resp_headers.appendAssumeCapacity(.{
+                .name = try (self.allocator.dupe(u8, h.name)),
+                .value = try (self.allocator.dupe(u8, h.value)),
+            });
+            if (content_length == 0 and std.ascii.eqlIgnoreCase("content-length", h.name))
+                content_length = std.fmt.parseInt(usize, h.value, 10) catch 0;
         }
         const reader = req.reader();
         // TODO: Get content length and use that to allocate the buffer
+        // Content length can be missing, and why would we trust it anyway
         var buf: [65535]u8 = undefined;
+        var resp_payload = try std.ArrayList(u8).initCapacity(self.allocator, content_length);
+        defer resp_payload.deinit();
+
         while (true) {
             const read = try reader.read(&buf);
+            try resp_payload.appendSlice(buf[0..read]);
             if (read == 0) break;
         }
-        log.debug("raw response body:\n{s}", .{buf});
+        log.debug("raw response body:\n{s}", .{resp_payload.items});
 
         // Headers would need to be allocated/copied into HttpResult similar
         // to RequestContext, so we'll leave this as a later excercise
         // if it becomes necessary
         const rc = HttpResult{
             .response_code = req.status.code,
-            .body = "change me", // TODO: work this all out
+            .body = resp_payload.toOwnedSlice(),
             .headers = resp_headers.toOwnedSlice(),
             .allocator = self.allocator,
         };

src/aws_signing.zig

@@ -52,7 +52,7 @@ pub const Config = struct {
     // In the CRT, this is only used if the body has been precalculated. We don't have
     // this use case, and we'll ignore
     //     .signed_body_value = c.aws_byte_cursor_from_c_str(""),
-    signed_body_header: enum { sha256, none } = .sha256, // https://github.com/awslabs/aws-c-auth/blob/ace1311f8ef6ea890b26dd376031bed2721648eb/include/aws/auth/signing_config.h#L131
+    signed_body_header: SignatureType = .sha256, // https://github.com/awslabs/aws-c-auth/blob/ace1311f8ef6ea890b26dd376031bed2721648eb/include/aws/auth/signing_config.h#L131
 
     // This is more complex in the CRT. We'll just take the creds. Someone
     // else can use a provider and get them in advance
@@ -61,8 +61,11 @@ pub const Config = struct {
     // string, equal to the value specified here.  If this value is zero or if header signing is being used then
     // this parameter has no effect.
     expiration_in_seconds: u64 = 0,
+
+    flags: ConfigFlags = .{},
 };
 
+pub const SignatureType = enum { sha256, none };
 pub const SigningError = error{
     NotImplemented,
 };
@@ -75,6 +78,510 @@ pub fn signRequest(allocator: std.mem.Allocator, http_request: base.Request, con
 }
 
 fn validateConfig(config: Config) SigningError!void {
-    _ = config;
-    return SigningError.NotImplemented;
+    if (config.signature_type != .headers or
+        config.signed_body_header != .sha256 or
+        config.expiration_in_seconds != 0 or
+        config.algorithm != .v4 or
+        !config.flags.omit_session_token or
+        !config.flags.should_normalize_uri_path or
+        !config.flags.use_double_uri_encode)
+        return SigningError.NotImplemented;
+}
+
+fn createCanonicalRequest(allocator: std.mem.Allocator, request: base.Request, config: Config) ![]const u8 {
+    // CanonicalRequest =
+    // HTTPRequestMethod + '\n' +
+    // CanonicalURI + '\n' +
+    // CanonicalQueryString + '\n' +
+    // CanonicalHeaders + '\n' +
+    // SignedHeaders + '\n' +
+    // HexEncode(Hash(RequestPayload))
+    const fmt =
+        \\{s}
+        \\{s}
+        \\{s}
+        \\{s}
+        \\{s}
+        \\{s}
+    ;
+
+    // TODO: This is all better as a writer - less allocations/copying
+    const canonical_method = canonicalRequestMethod(request.method);
+    const canonical_url = try canonicalUri(allocator, request.path, config.flags.use_double_uri_encode);
+    defer allocator.free(canonical_url);
+    const canonical_query = try canonicalQueryString(allocator, request.path);
+    defer allocator.free(canonical_query);
+    const canonical_headers = try canonicalHeaders(allocator, request.headers);
+    defer allocator.free(canonical_headers.str);
+    defer allocator.free(canonical_headers.signed_headers);
+    const payload_hash = try hashPayload(allocator, request.body, config.signed_body_header);
+    defer allocator.free(payload_hash);
+    return try std.fmt.allocPrint(allocator, fmt, .{
+        canonical_method,
+        canonical_url,
+        canonical_query,
+        canonical_headers.str,
+        canonical_headers.signed_headers,
+        payload_hash,
+    });
+}
+
+fn canonicalRequestMethod(method: []const u8) ![]const u8 {
+    return method; // We assume it's good
+}
+
+fn canonicalUri(allocator: std.mem.Allocator, path: []const u8, double_encode: bool) ![]const u8 {
+    // Add the canonical URI parameter, followed by a newline character. The
+    // canonical URI is the URI-encoded version of the absolute path component
+    // of the URI, which is everything in the URI from the HTTP host to the
+    // question mark character ("?") that begins the query string parameters (if any).
+    //
+    // Normalize URI paths according to RFC 3986. Remove redundant and relative
+    // path components. Each path segment must be URI-encoded twice
+    // (except for Amazon S3 which only gets URI-encoded once).
+    //
+    // Note: In exception to this, you do not normalize URI paths for requests
+    // to Amazon S3. For example, if you have a bucket with an object
+    // named my-object//example//photo.user, use that path. Normalizing
+    // the path to my-object/example/photo.user will cause the request to
+    // fail. For more information, see Task 1: Create a Canonical Request in
+    // the Amazon Simple Storage Service API Reference.
+    //
+    // If the absolute path is empty, use a forward slash (/)
+    //
+    // For now, we will "Remove redundant and relative path components". This
+    // doesn't apply to S3 anyway, and we'll make it the callers's problem
+    if (!double_encode)
+        return error.S3NotImplemented;
+    if (path.len == 0 or path[0] == '?' or path[0] == '#')
+        return try allocator.dupe(u8, "/");
+    const encoded_once = try encodeUri(allocator, path);
+    if (!double_encode)
+        return encoded_once[0 .. std.mem.lastIndexOf(u8, encoded_once, "?") orelse encoded_once.len];
+    defer allocator.free(encoded_once);
+    const encoded_twice = try encodeUri(allocator, encoded_once);
+    return encoded_twice[0 .. std.mem.lastIndexOf(u8, encoded_twice, "?") orelse encoded_twice.len];
+}
+
+fn encodeParamPart(allocator: std.mem.Allocator, path: []const u8) ![]const u8 {
+    const unreserved_marks = "-_.!~*'()";
+    var encoded = try std.ArrayList(u8).initCapacity(allocator, path.len);
+    defer encoded.deinit();
+    for (path) |c| {
+        var should_encode = true;
+        for (unreserved_marks) |r|
+            if (r == c) {
+                should_encode = false;
+                break;
+            };
+        if (should_encode and std.ascii.isAlNum(c))
+            should_encode = false;
+
+        if (!should_encode) {
+            try encoded.append(c);
+            continue;
+        }
+        // Whatever remains, encode it
+        try encoded.append('%');
+        const hex = try std.fmt.allocPrint(allocator, "{s}", .{std.fmt.fmtSliceHexUpper(&[_]u8{c})});
+        defer allocator.free(hex);
+        try encoded.appendSlice(hex);
+    }
+    return encoded.toOwnedSlice();
+}
+fn encodeUri(allocator: std.mem.Allocator, path: []const u8) ![]const u8 {
+    const reserved_characters = ";,/?:@&=+$#";
+    const unreserved_marks = "-_.!~*'()";
+    var encoded = try std.ArrayList(u8).initCapacity(allocator, path.len);
+    defer encoded.deinit();
+    for (path) |c| {
+        var should_encode = true;
+        for (reserved_characters) |r|
+            if (r == c) {
+                should_encode = false;
+                break;
+            };
+        if (should_encode) {
+            for (unreserved_marks) |r|
+                if (r == c) {
+                    should_encode = false;
+                    break;
+                };
+        }
+        if (should_encode and std.ascii.isAlNum(c))
+            should_encode = false;
+
+        if (!should_encode) {
+            try encoded.append(c);
+            continue;
+        }
+        // Whatever remains, encode it
+        try encoded.append('%');
+        const hex = try std.fmt.allocPrint(allocator, "{s}", .{std.fmt.fmtSliceHexUpper(&[_]u8{c})});
+        defer allocator.free(hex);
+        try encoded.appendSlice(hex);
+    }
+    return encoded.toOwnedSlice();
+}
+
+fn canonicalQueryString(allocator: std.mem.Allocator, path: []const u8) ![]const u8 {
+    //     To construct the canonical query string, complete the following steps:
+    //
+    //     Sort the parameter names by character code point in ascending order.
+    //     Parameters with duplicate names should be sorted by value. For example,
+    //     a parameter name that begins with the uppercase letter F precedes a
+    //     parameter name that begins with a lowercase letter b.
+    //
+    //     URI-encode each parameter name and value according to the following rules:
+    //
+    //         Do not URI-encode any of the unreserved characters that RFC 3986
+    //         defines: A-Z, a-z, 0-9, hyphen ( - ), underscore ( _ ), period ( . ), and tilde ( ~ ).
+    //
+    //         Percent-encode all other characters with %XY, where X and Y are
+    //         hexadecimal characters (0-9 and uppercase A-F). For example, the
+    //         space character must be encoded as %20 (not using '+', as some
+    //         encoding schemes do) and extended UTF-8 characters must be in the
+    //         form %XY%ZA%BC.
+    //
+    //         Double-encode any equals ( = ) characters in parameter values.
+    //
+    //     Build the canonical query string by starting with the first parameter
+    //     name in the sorted list.
+    //
+    //     For each parameter, append the URI-encoded parameter name, followed by
+    //     the equals sign character (=), followed by the URI-encoded parameter
+    //     value. Use an empty string for parameters that have no value.
+    //
+    //     Append the ampersand character (&) after each parameter value, except
+    //     for the last value in the list.
+    //
+    // One option for the query API is to put all request parameters in the query
+    // string. For example, you can do this for Amazon S3 to create a presigned
+    // URL. In that case, the canonical query string must include not only
+    // parameters for the request, but also the parameters used as part of the
+    // signing process—the hashing algorithm, credential scope, date, and signed
+    // headers parameters.
+    //
+    // The following example shows a query string that includes authentication
+    // information. The example is formatted with line breaks for readability, but
+    // the canonical query string must be one continuous line of text in your code.
+    const first_question = std.mem.indexOf(u8, path, "?");
+    if (first_question == null)
+        return try allocator.dupe(u8, "");
+
+    // We have a query string
+    const query = path[first_question.? + 1 ..];
+
+    // Split this by component
+    var portions = std.mem.split(u8, query, "&");
+    var sort_me = std.ArrayList([]const u8).init(allocator);
+    defer sort_me.deinit();
+    while (portions.next()) |item|
+        try sort_me.append(item);
+    std.sort.sort([]const u8, sort_me.items, {}, lessThanBinary);
+
+    var normalized = try std.ArrayList(u8).initCapacity(allocator, path.len);
+    defer normalized.deinit();
+    var first = true;
+    for (sort_me.items) |i| {
+        if (!first) try normalized.append('&');
+        first = false;
+        var first_equals = std.mem.indexOf(u8, i, "=");
+        if (first_equals == null) {
+            // Rare. This is "foo="
+            const normed_item = try encodeUri(allocator, i);
+            defer allocator.free(normed_item);
+            try normalized.appendSlice(i); // This should be encoded
+            try normalized.append('=');
+            continue;
+        }
+
+        // normal key=value stuff
+        const key = try encodeParamPart(allocator, i[0..first_equals.?]);
+        defer allocator.free(key);
+
+        const value = try encodeParamPart(allocator, i[first_equals.? + 1 ..]);
+        defer allocator.free(value);
+        // Double-encode any = in the value. But not anything else?
+        const weird_equals_in_value_thing = try replace(allocator, value, "%3D", "%253D");
+        defer allocator.free(weird_equals_in_value_thing);
+        try normalized.appendSlice(key);
+        try normalized.append('=');
+        try normalized.appendSlice(weird_equals_in_value_thing);
+    }
+
+    return normalized.toOwnedSlice();
+}
+
+fn replace(allocator: std.mem.Allocator, haystack: []const u8, needle: []const u8, replacement_value: []const u8) ![]const u8 {
+    var buffer = try allocator.alloc(u8, std.mem.replacementSize(u8, haystack, needle, replacement_value));
+    _ = std.mem.replace(u8, haystack, needle, replacement_value, buffer);
+    return buffer;
+}
+
+fn lessThanBinary(context: void, lhs: []const u8, rhs: []const u8) bool {
+    _ = context;
+    return std.mem.lessThan(u8, lhs, rhs);
+}
+const CanonicalHeaders = struct {
+    str: []const u8,
+    signed_headers: []const u8,
+};
+fn canonicalHeaders(allocator: std.mem.Allocator, headers: []base.Header) !CanonicalHeaders {
+    //
+    // Doc example. Original:
+    //
+    // Host:iam.amazonaws.com\n
+    // Content-Type:application/x-www-form-urlencoded; charset=utf-8\n
+    // My-header1:    a   b   c  \n
+    // X-Amz-Date:20150830T123600Z\n
+    // My-Header2:    "a   b   c"  \n
+    //
+    // Canonical form:
+    // content-type:application/x-www-form-urlencoded; charset=utf-8\n
+    // host:iam.amazonaws.com\n
+    // my-header1:a b c\n
+    // my-header2:"a b c"\n
+    // x-amz-date:20150830T123600Z\n
+    var dest = try allocator.alloc(base.Header, headers.len);
+    defer {
+        for (dest) |h| {
+            allocator.free(h.name);
+            allocator.free(h.value);
+        }
+        allocator.free(dest);
+    }
+    var total_len: usize = 0;
+    var total_name_len: usize = 0;
+    for (headers) |h, i| {
+        total_len += (h.name.len + h.value.len + 2);
+        total_name_len += (h.name.len + 1);
+        const value = try canonicalHeaderValue(allocator, h.value);
+        defer allocator.free(value);
+        dest[i] = .{
+            .name = try std.ascii.allocLowerString(allocator, h.name),
+            .value = try std.fmt.allocPrint(allocator, "{s}", .{value}),
+        };
+    }
+
+    std.sort.sort(base.Header, dest, {}, lessThan);
+
+    var dest_str = try std.ArrayList(u8).initCapacity(allocator, total_len);
+    defer dest_str.deinit();
+    var signed_headers = try std.ArrayList(u8).initCapacity(allocator, total_name_len);
+    defer signed_headers.deinit();
+    var first = true;
+    for (dest) |h| {
+        dest_str.appendSliceAssumeCapacity(h.name);
+        dest_str.appendAssumeCapacity(':');
+        dest_str.appendSliceAssumeCapacity(h.value);
+        dest_str.appendAssumeCapacity('\n');
+
+        if (!first) signed_headers.appendAssumeCapacity(';');
+        first = false;
+        signed_headers.appendSliceAssumeCapacity(h.name);
+    }
+    return CanonicalHeaders{
+        .str = dest_str.toOwnedSlice(),
+        .signed_headers = signed_headers.toOwnedSlice(),
+    };
+}
+
+fn canonicalHeaderValue(allocator: std.mem.Allocator, value: []const u8) ![]const u8 {
+    var started = false;
+    var in_quote = false;
+    var start: usize = 0;
+    const rc = try allocator.alloc(u8, value.len);
+    var rc_inx: usize = 0;
+    for (value) |c, i| {
+        if (!started and !std.ascii.isSpace(c)) {
+            started = true;
+            start = i;
+        }
+        if (started) {
+            if (!in_quote and i > 0 and std.ascii.isSpace(c) and std.ascii.isSpace(value[i - 1]))
+                continue;
+            // if (c == '"') in_quote = !in_quote;
+            rc[rc_inx] = c;
+            rc_inx += 1;
+        }
+    }
+    // Trim end
+    while (std.ascii.isSpace(rc[rc_inx - 1]))
+        rc_inx -= 1;
+    return rc[0..rc_inx];
+}
+fn lessThan(context: void, lhs: base.Header, rhs: base.Header) bool {
+    _ = context;
+    return std.ascii.lessThanIgnoreCase(lhs.name, rhs.name);
+}
+
+fn hashPayload(allocator: std.mem.Allocator, payload: []const u8, sig_type: SignatureType) ![]const u8 {
+    if (sig_type != .sha256)
+        return error.NotImplemented;
+    const to_hash = blk: {
+        if (payload.len > 0) {
+            break :blk payload;
+        }
+        break :blk "";
+    };
+    var out: [std.crypto.hash.sha2.Sha256.digest_length]u8 = undefined;
+    std.crypto.hash.sha2.Sha256.hash(to_hash, &out, .{});
+    return try std.fmt.allocPrint(allocator, "{s}", .{std.fmt.fmtSliceHexLower(&out)});
+}
+// SignedHeaders + '\n' +
+// HexEncode(Hash(RequestPayload))
+test "canonical method" {
+    const actual = try canonicalRequestMethod("GET");
+    try std.testing.expectEqualStrings("GET", actual);
+}
+
+test "canonical uri" {
+    const allocator = std.testing.allocator;
+    const path = "/documents and settings/?foo=bar";
+    const expected = "/documents%2520and%2520settings/";
+    const actual = try canonicalUri(allocator, path, true);
+    defer allocator.free(actual);
+    try std.testing.expectEqualStrings(expected, actual);
+
+    const slash = try canonicalUri(allocator, "", true);
+    defer allocator.free(slash);
+    try std.testing.expectEqualStrings("/", slash);
+}
+test "canonical query" {
+    const allocator = std.testing.allocator;
+    const path = "blahblahblah?foo=bar&zed=dead&qux&equals=x=y&Action=ListUsers&Version=2010-05-08";
+
+    // {
+    //     // TODO: Remove block
+    //     std.testing.log_level = .debug;
+    //     _ = try std.io.getStdErr().write("\n");
+    // }
+    const expected = "Action=ListUsers&Version=2010-05-08&equals=x%253Dy&foo=bar&qux=&zed=dead";
+    const actual = try canonicalQueryString(allocator, path);
+    defer allocator.free(actual);
+    try std.testing.expectEqualStrings(expected, actual);
+}
+test "canonical headers" {
+    const allocator = std.testing.allocator;
+    var headers = try std.ArrayList(base.Header).initCapacity(allocator, 5);
+    defer headers.deinit();
+    try headers.append(.{ .name = "Host", .value = "iam.amazonaws.com" });
+    try headers.append(.{ .name = "Content-Type", .value = "application/x-www-form-urlencoded; charset=utf-8" });
+    try headers.append(.{ .name = "My-header1", .value = "  a  b  c  " });
+    try headers.append(.{ .name = "X-Amz-Date", .value = "20150830T123600Z" });
+    try headers.append(.{ .name = "My-header2", .value = "  \"a  b  c\"  " });
+    const expected =
+        \\content-type:application/x-www-form-urlencoded; charset=utf-8
+        \\host:iam.amazonaws.com
+        \\my-header1:a b c
+        \\my-header2:"a b c"
+        \\x-amz-date:20150830T123600Z
+        \\
+    ;
+    // {
+    //     // TODO: Remove block
+    //     std.testing.log_level = .debug;
+    //     _ = try std.io.getStdErr().write("\n");
+    // }
+    const actual = try canonicalHeaders(allocator, headers.items);
+    defer allocator.free(actual.str);
+    defer allocator.free(actual.signed_headers);
+    try std.testing.expectEqualStrings(expected, actual.str);
+    try std.testing.expectEqualStrings("content-type;host;my-header1;my-header2;x-amz-date", actual.signed_headers);
+}
+
+test "canonical request" {
+    const allocator = std.testing.allocator;
+    var headers = try std.ArrayList(base.Header).initCapacity(allocator, 5);
+    defer headers.deinit();
+    try headers.append(.{ .name = "Content-Type", .value = "application/x-www-form-urlencoded" });
+    try headers.append(.{ .name = "Content-Length", .value = "43" });
+    try headers.append(.{ .name = "User-Agent", .value = "zig-aws 1.0, Powered by the AWS Common Runtime." });
+    try headers.append(.{ .name = "Host", .value = "sts.us-west-2.amazonaws.com" });
+    try headers.append(.{ .name = "Accept", .value = "application/json" });
+    const req = base.Request{
+        .path = "/",
+        .query = "",
+        .body = "Action=GetCallerIdentity&Version=2011-06-15",
+        .method = "POST",
+        .content_type = "application/json",
+        .headers = headers.items,
+    };
+    {
+        // TODO: Remove block
+        std.testing.log_level = .debug;
+        _ = try std.io.getStdErr().write("\n");
+    }
+    const request = try createCanonicalRequest(allocator, req, .{
+        .region = "us-west-2", // us-east-1
+        .service = "sts", // service
+        .credentials = .{
+            .access_key = "AKIDEXAMPLE",
+            .secret_key = "wJalrXUtnFEMI/K7MDENG+bPxRfiCYEXAMPLEKEY",
+            .session_token = null,
+        },
+        .signing_time = 1642187728, // Should be 2015-08-30T12:36:00Z. Does zig stdlib have date parsing?
+    });
+    defer allocator.free(request);
+    std.log.debug("canonical request:\n{s}", .{request});
+    try std.testing.expect(request.len > 0); // TODO: improvify this
+
+}
+test "can sign" {
+    // [debug] (aws): call: prefix sts, sigv4 sts, version 2011-06-15, action GetCallerIdentity
+    // [debug] (aws): proto: AwsProtocol.query
+    // [debug] (awshttp): host: sts.us-west-2.amazonaws.com, scheme: https, port: 443
+    // [debug] (awshttp): Calling endpoint https://sts.us-west-2.amazonaws.com
+    // [debug] (awshttp): Path: /
+    // [debug] (awshttp): Query:
+    // [debug] (awshttp): Method: POST
+    // [debug] (awshttp): body length: 43
+    // [debug] (awshttp): Body
+    // ====
+    // Action=GetCallerIdentity&Version=2011-06-15
+    // ====
+    // [debug] (awshttp): All Request Headers:
+    // [debug] (awshttp):      Accept: application/json
+    // [debug] (awshttp):      Host: sts.us-west-2.amazonaws.com
+    // [debug] (awshttp):      User-Agent: zig-aws 1.0, Powered by the AWS Common Runtime.
+    // [debug] (awshttp):      Content-Type: application/x-www-form-urlencoded
+    // [debug] (awshttp):      Content-Length: 43
+
+    const allocator = std.testing.allocator;
+    var headers = try std.ArrayList(base.Header).initCapacity(allocator, 5);
+    defer headers.deinit();
+    try headers.append(.{ .name = "Content-Type", .value = "application/x-www-form-urlencoded" });
+    try headers.append(.{ .name = "Content-Length", .value = "43" });
+    try headers.append(.{ .name = "User-Agent", .value = "zig-aws 1.0, Powered by the AWS Common Runtime." });
+    try headers.append(.{ .name = "Host", .value = "sts.us-west-2.amazonaws.com" });
+    try headers.append(.{ .name = "Accept", .value = "application/json" });
+    const req = base.Request{
+        .path = "/",
+        .query = "",
+        .body = "Action=GetCallerIdentity&Version=2011-06-15",
+        .method = "POST",
+        .content_type = "application/json",
+        .headers = headers.items,
+    };
+    {
+        // TODO: Remove block
+        std.testing.log_level = .debug;
+        _ = try std.io.getStdErr().write("\n");
+    }
+
+    // we could look at sigv4 signing tests at:
+    // https://github.com/awslabs/aws-c-auth/blob/ace1311f8ef6ea890b26dd376031bed2721648eb/tests/sigv4_signing_tests.c#L1478
+    //
+    // for valid signatures. TODO: Get literally anything working first
+    try signRequest(allocator, req, .{
+        .region = "us-west-2", // us-east-1
+        .service = "sts", // service
+        .credentials = .{
+            .access_key = "AKIDEXAMPLE",
+            .secret_key = "wJalrXUtnFEMI/K7MDENG+bPxRfiCYEXAMPLEKEY",
+            .session_token = null,
+        },
+        .signing_time = 1642187728, // Should be 2015-08-30T12:36:00Z. Does zig stdlib have date parsing?
+    });
 }

src/date.zig

@@ -0,0 +1,79 @@
+// From https://gist.github.com/WoodyAtHome/3ef50b17f0fa2860ac52b97af12f8d15
+// Translated from German. We don't need any local time for this use case, and conversion
+// really requires the TZ DB.
+
+const std = @import("std");
+
+pub const DateTime = struct { day: u8, month: u8, year: u16, hour: u8, minute: u8, second: u8 };
+
+pub fn timestamp2DateTime(timestamp: i64) DateTime {
+
+    // aus https://de.wikipedia.org/wiki/Unixzeit
+    const unixtime = @intCast(u64, timestamp);
+    const SECONDS_PER_DAY = 86400; //*  24* 60 * 60 */
+    const DAYS_PER_YEAR = 365; //* Normal year (no leap year) */
+    const DAYS_IN_4_YEARS = 1461; //*   4*365 +   1 */
+    const DAYS_IN_100_YEARS = 36524; //* 100*365 +  25 - 1 */
+    const DAYS_IN_400_YEARS = 146097; //* 400*365 + 100 - 4 + 1 */
+    const DAY_NUMBER_ADJUSTED_1970_01_01 = 719468; //* Day number relates to March 1st */
+
+    var dayN: u64 = DAY_NUMBER_ADJUSTED_1970_01_01 + unixtime / SECONDS_PER_DAY;
+    var seconds_since_midnight: u64 = unixtime % SECONDS_PER_DAY;
+    var temp: u64 = 0;
+
+    // Leap year rules for Gregorian Calendars
+    // Any year divisible by 100 is not a leap year unless also divisible by 400
+    temp = 4 * (dayN + DAYS_IN_100_YEARS + 1) / DAYS_IN_400_YEARS - 1;
+    var year = @intCast(u16, 100 * temp);
+    dayN -= DAYS_IN_100_YEARS * temp + temp / 4;
+
+    // For Julian calendars, each year divisible by 4 is a leap year
+    temp = 4 * (dayN + DAYS_PER_YEAR + 1) / DAYS_IN_4_YEARS - 1;
+    year += @intCast(u16, temp);
+    dayN -= DAYS_PER_YEAR * temp + temp / 4;
+
+    // TagN calculates the days of the year in relation to March 1
+    var month = @intCast(u8, (5 * dayN + 2) / 153);
+    var day = @intCast(u8, dayN - (@intCast(u64, month) * 153 + 2) / 5 + 1);
+    //  153 = 31+30+31+30+31 Days for the 5 months from March through July
+    //  153 = 31+30+31+30+31 Days for the 5 months from August through December
+    //        31+28          Days for January and February (see below)
+    //  +2: Rounding adjustment
+    //  +1: The first day in March is March 1st (not March 0)
+
+    month += 3; // Convert from the day that starts on March 1st, to a human year */
+    if (month > 12) { // months 13 and 14 become 1 (January) und 2 (February) of the next year
+        month -= 12;
+        year += 1;
+    }
+
+    var hours = @intCast(u8, seconds_since_midnight / 3600);
+    var minutes = @intCast(u8, seconds_since_midnight % 3600 / 60);
+    var seconds = @intCast(u8, seconds_since_midnight % 60);
+
+    return DateTime{ .day = day, .month = month, .year = year, .hour = hours, .minute = minutes, .second = seconds };
+}
+
+pub fn printDateTime(dt: DateTime) void {
+    std.log.debug("{:0>4}-{:0>2}-{:0>2}T{:0>2}:{:0>2}:{:0<2}Z", .{
+        dt.year,
+        dt.month,
+        dt.day,
+        dt.hour,
+        dt.minute,
+        dt.second,
+    });
+}
+
+pub fn printNowUtc() void {
+    printDateTime(timestamp2DateTime(std.time.timestamp()));
+}
+
+test "GMT and localtime" {
+    std.testing.log_level = .debug;
+    std.log.debug("\n", .{});
+    printDateTime(timestamp2DateTime(std.time.timestamp()));
+    try std.testing.expectEqual(DateTime{ .year = 2020, .month = 8, .day = 28, .hour = 9, .minute = 32, .second = 27 }, timestamp2DateTime(1598607147));
+
+    try std.testing.expectEqual(DateTime{ .year = 2020, .month = 11, .day = 1, .hour = 5, .minute = 6, .second = 7 }, timestamp2DateTime(1604207167));
+}