curl/docs/FEATURES.md
Viktor Szakats f81f351b9a
tidy-up: OS names
Use these words and casing more consistently across text, comments and
one curl tool output:
AIX, ALPN, ANSI, BSD, Cygwin, Darwin, FreeBSD, GitHub, HP-UX, Linux,
macOS, MS-DOS, MSYS, MinGW, NTLM, POSIX, Solaris, UNIX, Unix, Unicode,
WINE, WebDAV, Win32, winbind, WinIDN, Windows, Windows CE, Winsock.

Mostly OS names and a few more.

Also a couple of other minor text fixups.

Closes #14360
2024-08-04 19:17:45 +02:00

6.0 KiB

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 late 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 and public key auth

SFTP

  • both password and public key auth
  • with custom commands sent before/after the transfer
  • directory listing

TFTP

  • download
  • upload

TELNET

  • connection negotiation
  • custom telnet options
  • stdin/stdout I/O

LDAP

  • full LDAP URL support

DICT

  • extended DICT URL support

FILE

  • URL support
  • upload
  • resume

SMB

  • SMBv1 over TCP and SSL
  • download
  • upload
  • authentication with NTLMv1

SMTP

  • authentication: Plain, Login, CRAM-MD5, Digest-MD5, NTLM, Kerberos 5 and External
  • send emails
  • mail from support
  • mail size support
  • mail auth support for trusted server-to-server relaying
  • multiple recipients
  • via http-proxy

SMTPS

  • implicit smtps:// support
  • explicit "STARTTLS" usage to "upgrade" plain smtp:// connections to use SSL
  • via http-proxy

POP3

  • authentication: Clear Text, APOP and SASL
  • SASL based authentication: Plain, Login, CRAM-MD5, Digest-MD5, NTLM, Kerberos 5 and External
  • list emails
  • retrieve emails
  • enhanced command support for: CAPA, DELE, TOP, STAT, UIDL and NOOP via custom requests
  • via http-proxy

POP3S

  • implicit pop3s:// support
  • explicit STLS usage to "upgrade" plain pop3:// connections to use SSL
  • via http-proxy

IMAP

  • authentication: Clear Text and SASL
  • SASL based authentication: Plain, Login, CRAM-MD5, Digest-MD5, NTLM, Kerberos 5 and External
  • list the folders of a mailbox
  • select a mailbox with support for verifying the UIDVALIDITY
  • fetch emails with support for specifying the UID and SECTION
  • upload emails via the append command
  • enhanced command support for: EXAMINE, CREATE, DELETE, RENAME, STATUS, STORE, COPY and UID via custom requests
  • via http-proxy

IMAPS

  • implicit imaps:// support
  • explicit "STARTTLS" usage to "upgrade" plain imap:// connections to use SSL
  • via http-proxy

MQTT

  • Subscribe to and publish topics using URL scheme mqtt://broker/topic