SSL_alert_type_string, SSL_alert_type_string_long, SSL_alert_desc_string,
SSL_alert_desc_string_long - get textual description of alert information
const char *SSL_alert_type_string(int value);
const char *SSL_alert_type_string_long(int value);
const char *SSL_alert_desc_string(int value);
const char *SSL_alert_desc_string_long(int value);
returns a one letter string indicating the type
of the alert specified by value
returns a string indicating the type of the
alert specified by value
returns a two letter string as a short form
describing the reason of the alert specified by value
returns a string describing the reason of
the alert specified by value
When one side of an SSL/TLS communication wants to inform the peer about a
special situation, it sends an alert. The alert is sent as a special message
and does not influence the normal data stream (unless its contents results in
the communication being canceled).
A warning alert is sent, when a non-fatal error condition occurs. The
"close notify" alert is sent as a warning alert. Other examples for
non-fatal errors are certificate errors ("certificate expired",
"unsupported certificate"), for which a warning alert may be sent.
(The sending party may however decide to send a fatal error.) The receiving
side may cancel the connection on reception of a warning alert on it
Several alert messages must be sent as fatal alert messages as specified by the
TLS RFC. A fatal alert always leads to a connection abort.
The following strings can occur for SSL_alert_type_string()
- This indicates that no support is available for this alert type. Probably
value does not contain a correct alert message.
The following strings can occur for SSL_alert_desc_string()
- "CN"/"close notify"
- The connection shall be closed. This is a warning alert.
- "UM"/"unexpected message"
- An inappropriate message was received. This alert is always fatal and
should never be observed in communication between proper
- "BM"/"bad record mac"
- This alert is returned if a record is received with an incorrect MAC. This
message is always fatal.
- "DF"/"decompression failure"
- The decompression function received improper input (e.g. data that would
expand to excessive length). This message is always fatal.
- "HF"/"handshake failure"
- Reception of a handshake_failure alert message indicates that the sender
was unable to negotiate an acceptable set of security parameters given the
options available. This is a fatal error.
- "NC"/"no certificate"
- A client, that was asked to send a certificate, does not send a
certificate (SSLv3 only).
- "BC"/"bad certificate"
- A certificate was corrupt, contained signatures that did not verify
- "UC"/"unsupported certificate"
- A certificate was of an unsupported type.
- "CR"/"certificate revoked"
- A certificate was revoked by its signer.
- "CE"/"certificate expired"
- A certificate has expired or is not currently valid.
- "CU"/"certificate unknown"
- Some other (unspecified) issue arose in processing the certificate,
rendering it unacceptable.
- "IP"/"illegal parameter"
- A field in the handshake was out of range or inconsistent with other
fields. This is always fatal.
- "DC"/"decryption failed"
- A TLSCiphertext decrypted in an invalid way: either it wasn't an even
multiple of the block length or its padding values, when checked, weren't
correct. This message is always fatal.
- "RO"/"record overflow"
- A TLSCiphertext record was received which had a length more than 2^14+2048
bytes, or a record decrypted to a TLSCompressed record with more than
2^14+1024 bytes. This message is always fatal.
- "CA"/"unknown CA"
- A valid certificate chain or partial chain was received, but the
certificate was not accepted because the CA certificate could not be
located or couldn't be matched with a known, trusted CA. This message is
- "AD"/"access denied"
- A valid certificate was received, but when access control was applied, the
sender decided not to proceed with negotiation. This message is always
- "DE"/"decode error"
- A message could not be decoded because some field was out of the specified
range or the length of the message was incorrect. This message is always
- "CY"/"decrypt error"
- A handshake cryptographic operation failed, including being unable to
correctly verify a signature, decrypt a key exchange, or validate a
- "ER"/"export restriction"
- A negotiation not in compliance with export restrictions was detected; for
example, attempting to transfer a 1024 bit ephemeral RSA key for the
RSA_EXPORT handshake method. This message is always fatal.
- "PV"/"protocol version"
- The protocol version the client has attempted to negotiate is recognized,
but not supported. (For example, old protocol versions might be avoided
for security reasons). This message is always fatal.
- "IS"/"insufficient security"
- Returned instead of handshake_failure when a negotiation has failed
specifically because the server requires ciphers more secure than those
supported by the client. This message is always fatal.
- "IE"/"internal error"
- An internal error unrelated to the peer or the correctness of the protocol
makes it impossible to continue (such as a memory allocation failure).
This message is always fatal.
- "US"/"user canceled"
- This handshake is being canceled for some reason unrelated to a protocol
failure. If the user cancels an operation after the handshake is complete,
just closing the connection by sending a close_notify is more appropriate.
This alert should be followed by a close_notify. This message is generally
- "NR"/"no renegotiation"
- Sent by the client in response to a hello request or by the server in
response to a client hello after initial handshaking. Either of these
would normally lead to renegotiation; when that is not appropriate, the
recipient should respond with this alert; at that point, the original
requester can decide whether to proceed with the connection. One case
where this would be appropriate would be where a server has spawned a
process to satisfy a request; the process might receive security
parameters (key length, authentication, etc.) at startup and it might be
difficult to communicate changes to these parameters after that point.
This message is always a warning.
- "UP"/"unknown PSK identity"
- Sent by the server to indicate that it does not recognize a PSK identity
or an SRP identity.
- This indicates that no description is available for this alert type.
Probably value does not contain a correct alert message.