SSL_alert_type_string(3) OpenSSL SSL_alert_type_string(3)NAME
SSL_alert_type_string, SSL_alert_type_string_long,
SSL_alert_desc_string, SSL_alert_desc_string_long - get
textual description of alert information
SYNOPSIS
#include <openssl/ssl.h>
char *SSL_alert_type_string(int value);
char *SSL_alert_type_string_long(int value);
char *SSL_alert_desc_string(int value);
char *SSL_alert_desc_string_long(int value);
DESCRIPTIONSSL_alert_type_string() returns a one letter string
indicating the type of the alert specified by value.
SSL_alert_type_string_long() returns a string indicating
the type of the alert specified by value.
SSL_alert_desc_string() returns a two letter string as a
short form describing the reason of the alert specified by
value.
SSL_alert_desc_string_long() returns a string describing
the reason of the alert specified by value.
NOTES
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 discretion.
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.
RETURN VALUES
The following strings can occur for
SSL_alert_type_string() or SSL_alert_type_string_long():
""""'/'arning""""
""""'/'atal""""
""""'/'nknown""""
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() or SSL_alert_desc_string_long():
""""CNlose notify""""
The connection shall be closed. This is a warning
alert.
""""UMnexpected message""""
An inappropriate message was received. This alert is
always fatal and should never be observed in
communication between proper implementations.
""""BMad record mac""""
This alert is returned if a record is received with an
incorrect MAC. This message is always fatal.
""""DFecompression failure""""
The decompression function received improper input
(e.g. data that would expand to excessive length).
This message is always fatal.
""""HFandshake 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.
""""NCo certificate""""
A client, that was asked to send a certificate, does
not send a certificate (SSLv3 only).
""""BCad certificate""""
A certificate was corrupt, contained signatures that
did not verify correctly, etc
""""UCnsupported certificate""""
A certificate was of an unsupported type.
""""CRertificate revoked""""
A certificate was revoked by its signer.
""""CEertificate expired""""
A certificate has expired or is not currently valid.
""""CUertificate unknown""""
Some other (unspecified) issue arose in processing the
certificate, rendering it unacceptable.
""""IPllegal parameter""""
A field in the handshake was out of range or
inconsistent with other fields. This is always fatal.
""""DCecryption 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.
""""ROecord 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.
""""CAnknown 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
always fatal.
""""ADccess denied""""
A valid certificate was received, but when access
control was applied, the sender decided not to proceed
with negotiation. This message is always fatal.
""""DEecode 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 fatal.
""""CYecrypt error""""
A handshake cryptographic operation failed, including
being unable to correctly verify a signature, decrypt
a key exchange, or validate a finished message.
""""ERxport 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.
""""PVrotocol 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.
""""ISnsufficient 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.
""""IEnternal 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.
""""USser 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 a warning.
""""NRo 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.
""""UKnknown""""
This indicates that no description is available for
this alert type. Probably value does not contain a
correct alert message.
SEE ALSOssl(3), SSL_CTX_set_info_callback(3)13/Sep/2001 0.9.6j SSL_alert_type_string(3)
