TSIG(2)

NAME
ns_sign, ns_sign_tcp, ns_sign_tcp_init, ns_verify, ns_verify_tcp, ns_verify_tcp_init, ns_find_tsig - TSIG system

SYNOPSIS
int
ns_sign(u_char *msg, int *msglen, int msgsize, int error, void *k, const u_char *querysig, int querysiglen, u_char *sig, int *siglen, time_t in_timesigned);
int
ns_sign_tcp(u_char *msg, int *msglen, int msgsize, int error, ns_tcp_tsig_state *state, int done);
int
ns_sign_tcp_init(void *k, const u_char *querysig, int querysiglen, ns_tcp_tsig_state *state);
int
ns_verify(u_char *msg, int *msglen, void *k, const u_char *querysig, int querysiglen, u_char *sig, int *siglen, time_t in_timesigned, int nostrip);
int
ns_verify_tcp(u_char *msg, int *msglen, ns_tcp_tsig_state *state, int required);
int
ns_verify_tcp_init(void *k, const u_char *querysig, int querysiglen, ns_tcp_tsig_state *state);
u_char *
ns_find_tsig(u_char *msg, u_char *eom);

DESCRIPTION
The TSIG routines are used to implement transaction/request security of DNS messages.

ns_sign() and ns_verify() are the basic routines. ns_sign_tcp() and ns_verify_tcp() are used to sign/verify TCP messages that may be split into multiple packets, such as zone transfers, and ns_sign_tcp_init(), ns_verify_tcp_init() initialize the state structure necessary for TCP operations. ns_find_tsig() locates the TSIG record in a message, if one is present.

ns_sign()
msg the incoming DNS message, which will be modified
msglen
    the length of the DNS message, on input and output
msgsize
    the size of the buffer containing the DNS message on input
error
    the value to be placed in the TSIG error field
key the (DST_KEY *) to sign the data
querysig
    for a response, the signature contained in the query
querysiglen
    the length of the query signature
sig a buffer to be filled with the generated signature
siglen
    the length of the signature buffer on input, the signature length on output

ns_sign_tcp()
msg the incoming DNS message, which will be modified
msglen
    the length of the DNS message, on input and output
msgsize
    the size of the buffer containing the DNS message on input
error
    the value to be placed in the TSIG error field
state
    the state of the operation
done
    non-zero value signifies that this is the last packet

ns_sign_tcp_init()
k   the (DST_KEY *) to sign the data
querysig
    for a response, the signature contained in the query
querysiglen
    the length of the query signature
state
    the state of the operation, which this initializes

ns_verify()
msg the incoming DNS message, which will be modified
msglen
    the length of the DNS message, on input and output
key the (DST_KEY *) to sign the data
querysig
    for a response, the signature contained in the query
querysiglen
    the length of the query signature
sig a buffer to be filled with the signature contained
siglen
    the length of the signature buffer on input, the signature length on output
nostrip
    non-zero value means that the TSIG is left intact

ns_verify_tcp()
msg the incoming DNS message, which will be modified
msglen
    the length of the DNS message, on input and output
state
    the state of the operation
required
    non-zero value signifies that a TSIG record must be present at this step

ns_verify_tcp_init()
k   the (DST_KEY *) to verify the data
querysig
    for a response, the signature contained in the query
querysiglen
    the length of the query signature
state
    the state of the operation, which this initializes

ns_find_tsig()
msg the incoming DNS message
msglen
    the length of the DNS message

RETURN VALUES
ns_find_tsig() returns a pointer to the TSIG record if one is found, and NULL otherwise.

All other routines return 0 on success, modifying arguments when necessary.

ns_sign() and ns_sign_tcp() return the following errors:
(-1)
    bad input data
(-ns_r_badkey)
    The key was invalid, or the signing failed
NS_TSIG_ERROR_NO_SPACE
    the message buffer is too small.

ns_verify() and ns_verify_tcp() return the following errors:
(-1)
    bad input data
NS_TSIG_ERROR_FORMERR
    The message is malformed
NS_TSIG_ERROR_NO_TSIG
    The message does not contain a TSIG record
NS_TSIG_ERROR_ID_MISMATCH
    The TSIG original ID field does not match the message ID
(-ns_r_badkey)
    Verification failed due to an invalid key
(-ns_r_badsig)
    Verification failed due to an invalid signature
(-ns_r_badtime)
    Verification failed due to an invalid timestamp
ns_r_badkey
    Verification succeeded but the message had an error of BADKEY
ns_r_badsig
    Verification succeeded but the message had an error of BADSIG
ns_r_badtime
    Verification succeeded but the message had an error of BADTIME

SEE ALSO
resolver(3).

AUTHORS
Brian Wellington, TISLabs at Network Associates