09 "ˆl–äY>”Je¶¥8 ¸Û7ú˜´oÁ ƒm÷ÙÀ¿i # Features -- what curl can do ## curl tool - config file support - multiple URLs in a single command line - range "globbing" support: [0-13], {one,two,three} - multiple file upload on a single command line - redirect stderr - parallel transfers ## libcurl - URL RFC 3986 syntax - custom maximum download time - custom lowest download speed acceptable - custom output result after completion - guesses protocol from hostname unless specified - supports .netrc - progress bar with time statistics while downloading - standard proxy environment variables support - have run on 101 operating systems and 28 CPU architectures - selectable network interface for outgoing traffic - IPv6 support on Unix and Windows - happy eyeballs dual-stack IPv4 + IPv6 connects - persistent connections - SOCKS 4 + 5 support, with or without local name resolving - *pre-proxy* support, for *proxy chaining* - supports username and password in proxy environment variables - operations through HTTP proxy "tunnel" (using CONNECT) - replaceable memory functions (malloc, free, realloc, etc) - asynchronous name resolving - both a push and a pull style interface - international domain names (IDN) - transfer rate limiting - stable API and ABI - TCP keep alive - TCP Fast Open - DNS cache (that can be shared between transfers) - non-blocking single-threaded parallel transfers - Unix domain sockets to server or proxy - DNS-over-HTTPS - uses non-blocking name resolves - selectable name resolver backend ## URL API - parses RFC 3986 URLs - generates URLs from individual components - manages "redirects" ## Header API - easy access to HTTP response headers, from all contexts - named headers - iterate over headers ## TLS - selectable TLS backend(s) - TLS False Start - TLS version control - TLS session resumption - key pinning - mutual authentication - Use dedicated CA cert bundle - Use OS-provided CA store - separate TLS options for HTTPS proxy ## HTTP - HTTP/0.9 responses are optionally accepted - HTTP/1.0 - HTTP/1.1 - HTTP/2, including multiplexing and server push - GET - PUT - HEAD - POST - multipart formpost (RFC 1867-style) - authentication: Basic, Digest, NTLM (9) and Negotiate (SPNEGO) to server and proxy - resume transfers - follow redirects - maximum amount of redirects to follow - custom HTTP request - cookie get/send fully parsed - reads/writes the Netscape cookie file format - custom headers (replace/remove internally generated headers) - custom user-agent string - custom referrer string - range - proxy authentication - time conditions - via HTTP proxy, HTTPS proxy or SOCKS proxy - HTTP/2 or HTTP/1.1 to HTTPS proxy - retrieve file modification date - Content-Encoding support for deflate, gzip, brotli and zstd - "Transfer-Encoding: chunked" support in uploads - HSTS - alt-svc - ETags - HTTP/1.1 trailers, both sending and getting ## HTTPS - HTTP/3 - using client certificates - verify server certificate - via HTTP proxy, HTTPS proxy or SOCKS proxy - select desired encryption - select usage of a specific TLS version - ECH ## FTP - download - authentication - Kerberos 5 - active/passive using PORT, EPRT, PASV or EPSV - single file size information (compare to HTTP HEAD) - 'type=' URL support - directory listing - directory listing names-only - upload - upload append - upload via http-proxy as HTTP PUT - download resume - upload resume - custom ftp commands (before and/or after the transfer) - simple "range" support - via HTTP proxy, HTTPS proxy or SOCKS proxy - all operations can be tunneled through proxy - customizable to retrieve file modification date - no directory depth limit ## FTPS - implicit `ftps://` support that use SSL on both connections - explicit "AUTH TLS" and "AUTH SSL" usage to "upgrade" plain `ftp://` connection to use SSL for both or one of the connections ## SSH (both SCP and SFTP) - selectable SSH backend - known hosts support - public key fingerprinting - both password a