docs/libcurl: add TLS backend info for all TLS options

All man pages that are listed to be for TLS now must also specify
exactly what TLS backends the option works for, or use All if they all
work.

cd2nroff makes sure this is done and that the listed backends exist.

Closes #13168

docs/CURLDOWN.md

@@ -72,6 +72,8 @@ Each curldown starts with a header with meta-data:
     See-also:
       - CURLOPT_HEADEROPT (3)
       - CURLOPT_HTTPAUTH (3)
+    TLS-backend:
+      - [name]
     ---
 
 All curldown files *must* have all the headers present and at least one
@@ -80,7 +82,21 @@ All curldown files *must* have all the headers present and at least one
 If the man page is for section 3 (library related). The `Protocol` list must
 contain at least one protocol, which can be `*` if the option is virtually for
 everything. If `*` is used, it must be the only listed protocol. Recognized
-protocols are either URL schemes (in uppercase) or `TLS`.
+protocols are either URL schemes (in uppercase), `TLS` or `TCP`.
+
+If the `Protocol` list contains `TLS`, then there must also be a `TLS-backend`
+list, specifying `*` or a list of what TLS backends that work with this
+option. The available TLS backends are:
+
+- `BearSSL`
+- `GnuTLS`
+- `mbedTLS`
+- `OpenSSL` (also covers BoringSSL, libressl, quictls, AWS-LC and AmiSSL)
+- `rustls`
+- `Schannel`
+- `Secure Transport`
+- `wolfSSL`
+- `All`: all TLS backends
 
 Following the header in the file, is the manual page using markdown-like
 syntax:

docs/libcurl/curl_ws_recv.md

@@ -11,7 +11,7 @@ See-also:
   - curl_ws_send (3)
   - libcurl-ws (3)
 Protocol:
-  - Ws
+  - WS
 ---
 
 # NAME

docs/libcurl/opts/CURLINFO_CAINFO.md

@@ -10,6 +10,8 @@ See-also:
   - curl_easy_setopt (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLINFO_CAPATH.md

@@ -10,6 +10,11 @@ See-also:
   - curl_easy_setopt (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - mbedTLS
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLINFO_CERTINFO.md

@@ -10,6 +10,11 @@ See-also:
   - curl_easy_setopt (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - Schannel
+  - Secure Transport
 ---
 
 # NAME

docs/libcurl/opts/CURLINFO_PROXY_SSL_VERIFYRESULT.md

@@ -10,6 +10,9 @@ See-also:
   - curl_easy_setopt (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLINFO_SSL_ENGINES.md

@@ -10,6 +10,8 @@ See-also:
   - curl_easy_setopt (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLINFO_SSL_VERIFYRESULT.md

@@ -10,6 +10,9 @@ See-also:
   - curl_easy_setopt (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLINFO_TLS_SESSION.md

@@ -10,6 +10,9 @@ See-also:
   - curl_easy_setopt (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLINFO_TLS_SSL_PTR.md

@@ -10,6 +10,14 @@ See-also:
   - curl_easy_setopt (3)
 Protocol:
   - TLS
+TLS-backend:
+  - BearSSL
+  - GnuTLS
+  - mbedTLS
+  - OpenSSL
+  - Schannel
+  - Secure Transport
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_CAINFO.md

@@ -13,6 +13,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_CAINFO_BLOB.md

@@ -11,6 +11,14 @@ See-also:
   - CURLOPT_CAPATH (3)
   - CURLOPT_SSL_VERIFYHOST (3)
   - CURLOPT_SSL_VERIFYPEER (3)
+TLS-backend:
+  - BearSSL
+  - OpenSSL
+  - mbedTLS
+  - rustls
+  - wolfSSL
+  - Secure Transport
+  - Schannel
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_CAPATH.md

@@ -11,6 +11,11 @@ See-also:
   - CURLOPT_STDERR (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - mbedTLS
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_CA_CACHE_TIMEOUT.md

@@ -12,6 +12,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_CERTINFO.md

@@ -12,6 +12,11 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - Schannel
+  - Secure Transport
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_CRLFILE.md

@@ -10,6 +10,10 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - GnuTLS
+  - mbedTLS
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_DOH_SSL_VERIFYHOST.md

@@ -12,6 +12,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_DOH_SSL_VERIFYPEER.md

@@ -14,6 +14,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_DOH_SSL_VERIFYSTATUS.md

@@ -10,6 +10,9 @@ See-also:
   - CURLOPT_SSL_VERIFYSTATUS (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_EGDSOCKET.md

@@ -8,6 +8,8 @@ See-also:
   - CURLOPT_RANDOM_FILE (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_ISSUERCERT.md

@@ -10,6 +10,9 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_ISSUERCERT_BLOB.md

@@ -11,6 +11,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_KEYPASSWD.md

@@ -9,6 +9,11 @@ See-also:
   - CURLOPT_SSLKEY (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - mbedTLS
+  - Schannel
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PINNEDPUBLICKEY.md

@@ -11,6 +11,13 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - wolfSSL
+  - mbedTLS
+  - Secure Transport
+  - Schannel
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_CAINFO.md

@@ -16,6 +16,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_CAINFO_BLOB.md

@@ -16,6 +16,11 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - rustls
+  - Secure Transport
+  - Schannel
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_CAPATH.md

@@ -12,6 +12,10 @@ See-also:
   - CURLOPT_STDERR (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - mbedTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_CRLFILE.md

@@ -11,6 +11,10 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - GnuTLS
+  - mbedTLS
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_ISSUERCERT.md

@@ -12,6 +12,9 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME
@@ -76,7 +79,7 @@ int main(void)
 
 # AVAILABILITY
 
-Added in 7.71.0. This option is supported by the OpenSSL backends.
+Added in 7.71.0. This option is supported by the OpenSSL and GnuTLS backends.
 
 # RETURN VALUE
 

docs/libcurl/opts/CURLOPT_PROXY_ISSUERCERT_BLOB.md

@@ -12,6 +12,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_KEYPASSWD.md

@@ -11,6 +11,11 @@ See-also:
   - CURLOPT_SSLKEY (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - mbedTLS
+  - Schannel
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_PINNEDPUBLICKEY.md

@@ -12,6 +12,11 @@ See-also:
   - CURLOPT_PROXY_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - mbedTLS
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSLCERT.md

@@ -10,6 +10,13 @@ See-also:
   - CURLOPT_SSLCERT (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - mbedTLS
+  - Schannel
+  - Secure Transport
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSLCERTTYPE.md

@@ -10,6 +10,13 @@ See-also:
   - CURLOPT_SSLCERTTYPE (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - mbedTLS
+  - Schannel
+  - Secure Transport
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSLCERT_BLOB.md

@@ -11,6 +11,10 @@ See-also:
   - CURLOPT_SSLCERT_BLOB (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - Schannel
+  - Secure Transport
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSLKEY.md

@@ -12,6 +12,11 @@ See-also:
   - CURLOPT_SSLKEYTYPE (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - mbedTLS
+  - Schannel
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSLKEYTYPE.md

@@ -10,6 +10,10 @@ See-also:
   - CURLOPT_SSLKEYTYPE (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - BearSSL
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSLKEY_BLOB.md

@@ -10,6 +10,8 @@ See-also:
   - CURLOPT_SSLKEY_BLOB (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSLVERSION.md

@@ -11,6 +11,8 @@ See-also:
   - CURLOPT_USE_SSL (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSL_CIPHER_LIST.md

@@ -12,6 +12,13 @@ See-also:
   - CURLOPT_TLS13_CIPHERS (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - BearSSL
+  - Schannel
+  - Secure Transport
+  - wolfSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSL_OPTIONS.md

@@ -11,6 +11,8 @@ See-also:
   - CURLOPT_SSL_CIPHER_LIST (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSL_VERIFYHOST.md

@@ -11,6 +11,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_SSL_VERIFYPEER.md

@@ -10,6 +10,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_TLS13_CIPHERS.md

@@ -12,6 +12,10 @@ See-also:
   - CURLOPT_TLS13_CIPHERS (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - rustls
+  - Schannel
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_TLSAUTH_PASSWORD.md

@@ -11,6 +11,9 @@ See-also:
   - CURLOPT_TLSAUTH_USERNAME (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_TLSAUTH_TYPE.md

@@ -11,6 +11,9 @@ See-also:
   - CURLOPT_TLSAUTH_USERNAME (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_PROXY_TLSAUTH_USERNAME.md

@@ -11,6 +11,9 @@ See-also:
   - CURLOPT_TLSAUTH_TYPE (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_RANDOM_FILE.md

@@ -8,6 +8,8 @@ See-also:
   - CURLOPT_EGDSOCKET (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSH_AUTH_TYPES.md

@@ -9,7 +9,7 @@ See-also:
   - CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 (3)
   - CURLOPT_SSH_PUBLIC_KEYFILE (3)
 Protocol:
-  - SFP
+  - SFTP
   - SCP
 ---
 

docs/libcurl/opts/CURLOPT_SSH_KEYDATA.md

@@ -8,7 +8,8 @@ See-also:
   - CURLOPT_SSH_KEYDATA (3)
   - CURLOPT_SSH_KNOWNHOSTS (3)
 Protocol:
-  - TLS
+  - SFTP
+  - SCP
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLCERT.md

@@ -10,6 +10,13 @@ See-also:
   - CURLOPT_SSLKEY (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - mbedTLS
+  - Schannel
+  - Secure Transport
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLCERTTYPE.md

@@ -9,6 +9,13 @@ See-also:
   - CURLOPT_SSLKEY (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
+  - mbedTLS
+  - Schannel
+  - Secure Transport
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLCERT_BLOB.md

@@ -10,6 +10,11 @@ See-also:
   - CURLOPT_SSLKEY (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - Secure Transport
+  - Schannel
+  - mbedTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLENGINE.md

@@ -10,6 +10,8 @@ See-also:
   - CURLOPT_SSLKEY (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLENGINE_DEFAULT.md

@@ -9,6 +9,8 @@ See-also:
   - CURLOPT_SSLENGINE (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLKEY.md

@@ -10,6 +10,11 @@ See-also:
   - CURLOPT_SSLKEY_BLOB (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - mbedTLS
+  - Schannel
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLKEYTYPE.md

@@ -10,6 +10,10 @@ See-also:
   - CURLOPT_SSLKEY (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - BearSSL
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLKEY_BLOB.md

@@ -9,6 +9,8 @@ See-also:
   - CURLOPT_SSLKEYTYPE (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSLVERSION.md

@@ -11,6 +11,8 @@ See-also:
   - CURLOPT_USE_SSL (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_CIPHER_LIST.md

@@ -12,6 +12,13 @@ See-also:
   - CURLOPT_USE_SSL (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - BearSSL
+  - Schannel
+  - Secure Transport
+  - wolfSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_CTX_DATA.md

@@ -9,6 +9,11 @@ See-also:
   - CURLOPT_SSL_CTX_FUNCTION (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - wolfSSL
+  - mbedTLS
+  - BearSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_CTX_FUNCTION.md

@@ -10,6 +10,11 @@ See-also:
   - CURLOPT_CAINFO (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - wolfSSL
+  - mbedTLS
+  - BearSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_EC_CURVES.md

@@ -10,6 +10,9 @@ See-also:
   - CURLOPT_TLS13_CIPHERS (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - wolfSSL
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_ENABLE_ALPN.md

@@ -9,6 +9,8 @@ See-also:
   - CURLOPT_SSL_OPTIONS (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_ENABLE_NPN.md

@@ -9,6 +9,8 @@ See-also:
   - CURLOPT_SSL_OPTIONS (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_FALSESTART.md

@@ -8,6 +8,8 @@ See-also:
   - CURLOPT_TCP_FASTOPEN (3)
 Protocol:
   - TLS
+TLS-backend:
+  - Secure Transport
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_OPTIONS.md

@@ -10,6 +10,8 @@ See-also:
   - CURLOPT_SSL_CIPHER_LIST (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_SESSIONID_CACHE.md

@@ -11,6 +11,8 @@ See-also:
   - CURLOPT_SSLVERSION (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_VERIFYHOST.md

@@ -10,6 +10,8 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_VERIFYPEER.md

@@ -13,6 +13,8 @@ See-also:
   - CURLOPT_SSL_VERIFYHOST (3)
 Protocol:
   - TLS
+TLS-backend:
+  - All
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_SSL_VERIFYSTATUS.md

@@ -10,6 +10,9 @@ See-also:
   - CURLOPT_SSL_VERIFYPEER (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_TLS13_CIPHERS.md

@@ -13,6 +13,10 @@ See-also:
   - CURLOPT_USE_SSL (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - rustls
+  - Schannel
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_TLSAUTH_PASSWORD.md

@@ -10,6 +10,9 @@ See-also:
   - CURLOPT_TLSAUTH_USERNAME (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_TLSAUTH_TYPE.md

@@ -9,6 +9,9 @@ See-also:
   - CURLOPT_TLSAUTH_USERNAME (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

docs/libcurl/opts/CURLOPT_TLSAUTH_USERNAME.md

@@ -9,6 +9,9 @@ See-also:
   - CURLOPT_TLSAUTH_TYPE (3)
 Protocol:
   - TLS
+TLS-backend:
+  - OpenSSL
+  - GnuTLS
 ---
 
 # NAME

scripts/cd2nroff

@@ -96,17 +96,64 @@ sub outseealso {
     return @o;
 }
 
+my %knownprotos = (
+    'DICT' => 1,
+    'FILE' => 1,
+    'FTP' => 1,
+    'FTPS' => 1,
+    'GOPHER' => 1,
+    'GOPHERS' => 1,
+    'HTTP' => 1,
+    'HTTPS' => 1,
+    'IMAP' => 1,
+    'IMAPS' => 1,
+    'LDAP' => 1,
+    'LDAPS' => 1,
+    'MQTT' => 1,
+    'POP3' => 1,
+    'POP3S' => 1,
+    'RTMP' => 1,
+    'RTMPS' => 1,
+    'RTSP' => 1,
+    'SCP' => 1,
+    'SFTP' => 1,
+    'SMB' => 1,
+    'SMBS' => 1,
+    'SMTP' => 1,
+    'SMTPS' => 1,
+    'TELNET' => 1,
+    'TFTP' => 1,
+    'WS' => 1,
+    'WSS' => 1,
+    'TLS' => 1,
+    'TCP' => 1,
+    '*' => 1
+    );
+
+my %knowntls = (
+    'BearSSL' => 1,
+    'GnuTLS' => 1,
+    'mbedTLS' => 1,
+    'OpenSSL' => 1,
+    'rustls' => 1,
+    'Schannel' => 1,
+    'Secure Transport' => 1,
+    'wolfSSL' => 1,
+    'All' => 1,
+    );
+
 sub single {
     my @seealso;
     my @proto;
+    my @tls;
     my $d;
     my ($f)=@_;
     my $copyright;
     my $errors = 0;
     my $fh;
     my $line;
-    my $salist;
-    my $protolist;
+    my $list;
+    my $tlslist;
     my $section;
     my $source;
     my $spdx;
@@ -143,7 +190,7 @@ sub single {
             $source=$1;
         }
         elsif(/^See-also: +(.*)/i) {
-            $salist = 0;
+            $list = 1; # 1 for see-also
             push @seealso, $1;
         }
         elsif(/^See-also: */i) {
@@ -151,21 +198,25 @@ sub single {
                 print STDERR "$f:$line:1:ERROR: bad See-Also, needs list\n";
                 return 2;
             }
-            $salist = 1;
-            $protolist = 0;
+            $list = 1; # 1 for see-also
         }
         elsif(/^Protocol:/i) {
-            $salist = 0;
-            $protolist = 1;
+            $list = 2; # 2 for protocol
+        }
+        elsif(/^TLS-backend:/i) {
+            $list = 3; # 3 for TLS backend
         }
         elsif(/^ +- (.*)/i) {
             # the only lists we support are see-also and protocol
-            if($salist) {
+            if($list == 1) {
                 push @seealso, $1;
             }
-            elsif($protolist) {
+            elsif($list == 2) {
                 push @proto, $1;
             }
+            elsif($list == 3) {
+                push @tls, $1;
+            }
             else {
                 print STDERR "$f:$line:1:ERROR: list item without owner?\n";
                 return 2;
@@ -201,9 +252,34 @@ sub single {
                 print STDERR "$f:$line:1:ERROR: no 'SPDX-License-Identifier:' field present\n";
                 return 2;
             }
-            if(!$proto[0] && ($section == 3)) {
-                printf STDERR "$f:$line:1:ERROR: missing Protocol:\n";
-                exit 2;
+            if($section == 3) {
+                if(!$proto[0]) {
+                    printf STDERR "$f:$line:1:ERROR: missing Protocol:\n";
+                    exit 2;
+                }
+                my $tls = 0;
+                for my $p (@proto) {
+                    if($p eq "TLS") {
+                        $tls = 1;
+                    }
+                    if(!$knownprotos{$p}) {
+                        printf STDERR "$f:$line:1:ERROR: invalid protocol used: $p:\n";
+                        exit 2;
+                    }
+                }
+                # This is for TLS, require TLS-backend:
+                if($tls) {
+                    if(!$tls[0]) {
+                        printf STDERR "$f:$line:1:ERROR: missing TLS-backend:\n";
+                        exit 2;
+                    }
+                    for my $t (@tls) {
+                        if(!$knowntls{$t}) {
+                            printf STDERR "$f:$line:1:ERROR: invalid TLS backend: $t:\n";
+                            exit 2;
+                        }
+                    }
+                }
             }
             last;
         }