GnuTLS: Don't skip really long certificate fields

Closes #5271

2 files changed, 15 insertions, 19 deletions

diff --git a/docs/KNOWN_BUGS b/docs/KNOWN_BUGS
index 1cbc76514..93cb36902 100644
--- a/docs/KNOWN_BUGS
+++ b/docs/KNOWN_BUGS
@@ -25,7 +25,6 @@ problems may have been fixed or changed somewhat since this was written!
  2. TLS
  2.1 CURLINFO_SSL_VERIFYRESULT has limited support
  2.2 DER in keychain
- 2.3 GnuTLS backend skips really long certificate fields
  2.4 DarwinSSL won't import PKCS#12 client certificates without a password
  2.5 Client cert handling with Issuer DN differs between backends
  2.6 CURL_GLOBAL_SSL
@@ -209,12 +208,6 @@ problems may have been fixed or changed somewhat since this was written!
  Curl doesn't recognize certificates in DER format in keychain, but it works
  with PEM.  https://curl.haxx.se/bug/view.cgi?id=1065
 
-2.3 GnuTLS backend skips really long certificate fields
-
- libcurl calls gnutls_x509_crt_get_dn() with a fixed buffer size and if the
- field is too long in the cert, it'll just return an error and the field will
- be displayed blank.
-
 2.4 DarwinSSL won't import PKCS#12 client certificates without a password
 
  libcurl calls SecPKCS12Import with the PKCS#12 client certificate, but that
diff --git a/lib/vtls/gtls.c b/lib/vtls/gtls.c
index 01dbf850a..4ed3ea5cf 100644
--- a/lib/vtls/gtls.c
+++ b/lib/vtls/gtls.c
@@ -802,7 +802,8 @@ gtls_connect_step3(struct connectdata *conn,
   unsigned int verify_status = 0;
   gnutls_x509_crt_t x509_cert, x509_issuer;
   gnutls_datum_t issuerp;
-  char certbuf[256] = ""; /* big enough? */
+  gnutls_datum_t certfields;
+  char certname[65] = ""; /* limited to 64 chars by ASN.1 */
   size_t size;
   time_t certclock;
   const char *ptr;
@@ -1036,11 +1037,11 @@ gtls_connect_step3(struct connectdata *conn,
           SSL_SET_OPTION(issuercert)?SSL_SET_OPTION(issuercert):"none");
   }
 
-  size = sizeof(certbuf);
+  size = sizeof(certname);
   rc = gnutls_x509_crt_get_dn_by_oid(x509_cert, GNUTLS_OID_X520_COMMON_NAME,
                                      0, /* the first and only one */
                                      FALSE,
-                                     certbuf,
+                                     certname,
                                      &size);
   if(rc) {
     infof(data, "error fetching CN from cert:%s\n",
@@ -1101,16 +1102,16 @@ gtls_connect_step3(struct connectdata *conn,
 
     if(SSL_CONN_CONFIG(verifyhost)) {
       failf(data, "SSL: certificate subject name (%s) does not match "
-            "target host name '%s'", certbuf, dispname);
+            "target host name '%s'", certname, dispname);
       gnutls_x509_crt_deinit(x509_cert);
       return CURLE_PEER_FAILED_VERIFICATION;
     }
     else
       infof(data, "\t common name: %s (does not match '%s')\n",
-            certbuf, dispname);
+            certname, dispname);
   }
   else
-    infof(data, "\t common name: %s (matched)\n", certbuf);
+    infof(data, "\t common name: %s (matched)\n", certname);
 
   /* Check for time-based validity */
   certclock = gnutls_x509_crt_get_expiration_time(x509_cert);
@@ -1195,9 +1196,10 @@ gtls_connect_step3(struct connectdata *conn,
         gnutls_x509_crt_get_version(x509_cert));
 
 
-  size = sizeof(certbuf);
-  gnutls_x509_crt_get_dn(x509_cert, certbuf, &size);
-  infof(data, "\t subject: %s\n", certbuf);
+  rc = gnutls_x509_crt_get_dn2(x509_cert, &certfields);
+  if(rc != 0)
+    return CURLE_OUT_OF_MEMORY;
+  infof(data, "\t subject: %s\n", certfields.data);
 
   certclock = gnutls_x509_crt_get_activation_time(x509_cert);
   showtime(data, "start date", certclock);
@@ -1205,9 +1207,10 @@ gtls_connect_step3(struct connectdata *conn,
   certclock = gnutls_x509_crt_get_expiration_time(x509_cert);
   showtime(data, "expire date", certclock);
 
-  size = sizeof(certbuf);
-  gnutls_x509_crt_get_issuer_dn(x509_cert, certbuf, &size);
-  infof(data, "\t issuer: %s\n", certbuf);
+  rc = gnutls_x509_crt_get_issuer_dn2(x509_cert, &certfields);
+  if(rc != 0)
+    return CURLE_OUT_OF_MEMORY;
+  infof(data, "\t issuer: %s\n", certfields.data);
 #endif
 
   gnutls_x509_crt_deinit(x509_cert);