X509_verify_cert - discover and verify X509 certificte chain
#include <openssl/x509.h>
int X509_verify_cert(X509_STORE_CTX *ctx);
The X509_verify_cert()
function attempts to discover and validate a
certificate chain based on parameters in ctx. A complete description of
the process is contained in the verify manual page.
If a complete chain can be built and validated this function returns 1, otherwise it return zero, in exceptional circumstances it can also return a negative code.
If the function fails additional error information can be obtained by examining ctx using, for example X509_STORE_CTX_get_error().
Applications rarely call this function directly but it is used by OpenSSL internally for certificate validation, in both the S/MIME and SSL/TLS code.
A negative return value from X509_verify_cert()
can occur if it is invoked
incorrectly, such as with no certificate set in ctx, or when it is called
twice in succession without reinitialising ctx for the second call.
A negative return value can also happen due to internal resource problems or if
a retry operation is requested during internal lookups (which never happens
with standard lookup methods).
Applications must check for <= 0 return value on error.
This function uses the header x509.h as opposed to most chain verification functiosn which use x509_vfy.h.
X509_verify_cert()
is available in all versions of SSLeay and OpenSSL.