Clean up HTTP server implementation

[unknownbrackets]

Felt like doing a bit of NIH.

Here's an example (working with PPSSPP, not necessarily optimal or spec compliant):

        net::Init();
        auto http = new http::Server(new threading::SameThreadExecutor());
        http->RegisterHandler("/test.cso", [](const http::Request &request) {
            s64 sz = File::GetFileSize(SERVE_FILENAME);

            std::string range;
            if (request.Method() == http::RequestHeader::HEAD) {
                request.WriteHttpResponseHeader(200, sz, "application/octet-stream", "Accept-Ranges: bytes\r\n");
            } else if (request.GetHeader("range", &range)) {
                s64 begin = 0, last = 0;
                if (sscanf(range.c_str(), "bytes=%lld-%lld", &begin, &last) != 2) {
                    request.WriteHttpResponseHeader(400, -1, "text/plain");
                    request.Out()->Push("Could not understand range request.");
                    return;
                }

                if (begin < 0 || begin > last || last >= sz) {
                    request.WriteHttpResponseHeader(416, -1, "text/plain");
                    request.Out()->Push("Range goes outside of file.");
                    return;
                }

                FILE *fp = File::OpenCFile(SERVE_FILENAME, "rb");
                if (!fp || fseek(fp, begin, SEEK_SET) != 0) {
                    request.WriteHttpResponseHeader(500, -1, "text/plain");
                    request.Out()->Push("File access failed.");
                    if (fp) {
                        fclose(fp);
                    }
                    return;
                }

                s64 len = last - begin + 1;
                char contentRange[1024];
                sprintf(contentRange, "Content-Range: bytes %lld-%lld/%lld\r\n", begin, last, sz);
                request.WriteHttpResponseHeader(206, len, "application/octet-stream", contentRange);

                char *buf = new char[16 * 1024];
                for (s64 pos = 0; pos < len; pos += 16 * 1024) {
                    s64 chunklen = std::min(len - pos, (s64)16 * 1024);
                    fread(buf, chunklen, 1, fp);
                    request.Out()->Push(buf, chunklen);
                }
                fclose(fp);
                delete [] buf;
                request.Out()->Flush();
            } else {
                request.WriteHttpResponseHeader(418, -1, "text/plain");
                request.Out()->Push("This server only supports range requests.");
            }
        });
        http->Run(8023);

-[Unknown]

[hrydgard]

Very nice.

Nothing wrong with a little NIH now and then :)