diff --git a/lib/curl_krb5.h b/lib/curl_krb5.h
index f0a6fa69b..3f40f9a6c 100644
--- a/lib/curl_krb5.h
+++ b/lib/curl_krb5.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -26,7 +26,7 @@ struct Curl_sec_client_mech {
   const char *name;
   size_t size;
   int (*init)(void *);
-  int (*auth)(void *, struct connectdata *);
+  int (*auth)(void *, struct Curl_easy *data, struct connectdata *);
   void (*end)(void *);
   int (*check_prot)(void *, int);
   int (*overhead)(void *, int, int);
@@ -39,10 +39,10 @@ struct Curl_sec_client_mech {
 #define AUTH_ERROR      2
 
 #ifdef HAVE_GSSAPI
-int Curl_sec_read_msg(struct connectdata *conn, char *,
+int Curl_sec_read_msg(struct Curl_easy *data, struct connectdata *conn, char *,
                       enum protection_level);
 void Curl_sec_end(struct connectdata *);
-CURLcode Curl_sec_login(struct connectdata *);
+CURLcode Curl_sec_login(struct Curl_easy *, struct connectdata *);
 int Curl_sec_request_prot(struct connectdata *conn, const char *level);
 #else
 #define Curl_sec_end(x)
diff --git a/lib/ftp.c b/lib/ftp.c
index c7162e152..ab6685ade 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -561,13 +561,13 @@ static CURLcode ftp_readresp(struct Curl_easy *data,
     /* handle the security-oriented responses 6xx ***/
     switch(code) {
     case 631:
-      code = Curl_sec_read_msg(conn, buf, PROT_SAFE);
+      code = Curl_sec_read_msg(data, conn, buf, PROT_SAFE);
       break;
     case 632:
-      code = Curl_sec_read_msg(conn, buf, PROT_PRIVATE);
+      code = Curl_sec_read_msg(data, conn, buf, PROT_PRIVATE);
       break;
     case 633:
-      code = Curl_sec_read_msg(conn, buf, PROT_CONFIDENTIAL);
+      code = Curl_sec_read_msg(data, conn, buf, PROT_CONFIDENTIAL);
       break;
     default:
       /* normal ftp stuff we pass through! */
@@ -2685,7 +2685,7 @@ static CURLcode ftp_statemachine(struct Curl_easy *data,
            set a valid level */
         Curl_sec_request_prot(conn, data->set.str[STRING_KRB_LEVEL]);
 
-        if(Curl_sec_login(conn))
+        if(Curl_sec_login(data, conn))
           infof(data, "Logging in with password in cleartext!\n");
         else
           infof(data, "Authentication successful\n");
diff --git a/lib/http.h b/lib/http.h
index 9129a406a..28f9341f6 100644
--- a/lib/http.h
+++ b/lib/http.h
@@ -288,9 +288,10 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
 /**
  * Curl_http_output_auth() setups the authentication headers for the
  * host/proxy and the correct authentication
- * method. conn->data->state.authdone is set to TRUE when authentication is
+ * method. data->state.authdone is set to TRUE when authentication is
  * done.
  *
+ * @param data all information about the current transfer
  * @param conn all information about the current connection
  * @param request pointer to the request keyword
  * @param httpreq is the request type
diff --git a/lib/krb5.c b/lib/krb5.c
index 898d74144..eb83566d6 100644
--- a/lib/krb5.c
+++ b/lib/krb5.c
@@ -56,7 +56,8 @@
 #include "curl_memory.h"
 #include "memdebug.h"
 
-static CURLcode ftpsend(struct connectdata *conn, const char *cmd)
+static CURLcode ftpsend(struct Curl_easy *data, struct connectdata *conn,
+                        const char *cmd)
 {
   ssize_t bytes_written;
 #define SBUF_SIZE 1024
@@ -80,7 +81,7 @@ static CURLcode ftpsend(struct connectdata *conn, const char *cmd)
   write_len += 2;
   bytes_written = 0;
 
-  result = Curl_convert_to_network(conn->data, s, write_len);
+  result = Curl_convert_to_network(data, s, write_len);
   /* Curl_convert_to_network calls failf if unsuccessful */
   if(result)
     return result;
@@ -89,7 +90,7 @@ static CURLcode ftpsend(struct connectdata *conn, const char *cmd)
 #ifdef HAVE_GSSAPI
     conn->data_prot = PROT_CMD;
 #endif
-    result = Curl_write(conn->data, conn->sock[FIRSTSOCKET], sptr, write_len,
+    result = Curl_write(data, conn->sock[FIRSTSOCKET], sptr, write_len,
                         &bytes_written);
 #ifdef HAVE_GSSAPI
     DEBUGASSERT(data_sec > PROT_NONE && data_sec < PROT_LAST);
@@ -99,7 +100,7 @@ static CURLcode ftpsend(struct connectdata *conn, const char *cmd)
     if(result)
       break;
 
-    Curl_debug(conn->data, CURLINFO_HEADER_OUT, sptr, (size_t)bytes_written);
+    Curl_debug(data, CURLINFO_HEADER_OUT, sptr, (size_t)bytes_written);
 
     if(bytes_written != (ssize_t)write_len) {
       write_len -= bytes_written;
@@ -202,14 +203,13 @@ krb5_encode(void *app_data, const void *from, int length, int level, void **to)
 }
 
 static int
-krb5_auth(void *app_data, struct connectdata *conn)
+krb5_auth(void *app_data, struct Curl_easy *data, struct connectdata *conn)
 {
   int ret = AUTH_OK;
   char *p;
   const char *host = conn->host.name;
   ssize_t nread;
   curl_socklen_t l = sizeof(conn->local_addr);
-  struct Curl_easy *data = conn->data;
   CURLcode result;
   const char *service = data->set.str[STRING_SERVICE_NAME] ?
                         data->set.str[STRING_SERVICE_NAME] :
@@ -242,7 +242,7 @@ krb5_auth(void *app_data, struct connectdata *conn)
   for(;;) {
     /* this really shouldn't be repeated here, but can't help it */
     if(service == srv_host) {
-      result = ftpsend(conn, "AUTH GSSAPI");
+      result = ftpsend(data, conn, "AUTH GSSAPI");
       if(result)
         return -2;
 
@@ -319,7 +319,7 @@ krb5_auth(void *app_data, struct connectdata *conn)
 
         cmd = aprintf("ADAT %s", p);
         if(cmd)
-          result = ftpsend(conn, cmd);
+          result = ftpsend(data, conn, cmd);
         else
           result = CURLE_OUT_OF_MEMORY;
 
@@ -454,7 +454,7 @@ static int ftp_send_command(struct Curl_easy *data, const char *message, ...)
   mvsnprintf(print_buffer, sizeof(print_buffer), message, args);
   va_end(args);
 
-  if(ftpsend(data->conn, print_buffer)) {
+  if(ftpsend(data, data->conn, print_buffer)) {
     ftp_code = -1;
   }
   else {
@@ -495,7 +495,7 @@ socket_read(curl_socket_t fd, void *to, size_t len)
    CURLcode saying whether an error occurred or CURLE_OK if |len| was
    written. */
 static CURLcode
-socket_write(struct connectdata *conn, curl_socket_t fd, const void *to,
+socket_write(struct Curl_easy *data, curl_socket_t fd, const void *to,
              size_t len)
 {
   const char *to_p = to;
@@ -503,7 +503,7 @@ socket_write(struct connectdata *conn, curl_socket_t fd, const void *to,
   ssize_t written;
 
   while(len > 0) {
-    result = Curl_write_plain(conn->data, fd, to_p, len, &written);
+    result = Curl_write_plain(data, fd, to_p, len, &written);
     if(!result) {
       len -= written;
       to_p += written;
@@ -598,8 +598,8 @@ static ssize_t sec_recv(struct Curl_easy *data, int sockindex,
 
 /* Send |length| bytes from |from| to the |fd| socket taking care of encoding
    and negotiating with the server. |from| can be NULL. */
-static void do_sec_send(struct connectdata *conn, curl_socket_t fd,
-                        const char *from, int length)
+static void do_sec_send(struct Curl_easy *data, struct connectdata *conn,
+                        curl_socket_t fd, const char *from, int length)
 {
   int bytes, htonl_bytes; /* 32-bit integers for htonl */
   char *buffer = NULL;
@@ -623,7 +623,7 @@ static void do_sec_send(struct connectdata *conn, curl_socket_t fd,
     return; /* error */
 
   if(iscmd) {
-    error = Curl_base64_encode(conn->data, buffer, curlx_sitouz(bytes),
+    error = Curl_base64_encode(data, buffer, curlx_sitouz(bytes),
                                &cmd_buffer, &cmd_size);
     if(error) {
       free(buffer);
@@ -633,27 +633,27 @@ static void do_sec_send(struct connectdata *conn, curl_socket_t fd,
       static const char *enc = "ENC ";
       static const char *mic = "MIC ";
       if(prot_level == PROT_PRIVATE)
-        socket_write(conn, fd, enc, 4);
+        socket_write(data, fd, enc, 4);
       else
-        socket_write(conn, fd, mic, 4);
+        socket_write(data, fd, mic, 4);
 
-      socket_write(conn, fd, cmd_buffer, cmd_size);
-      socket_write(conn, fd, "\r\n", 2);
-      infof(conn->data, "Send: %s%s\n", prot_level == PROT_PRIVATE?enc:mic,
+      socket_write(data, fd, cmd_buffer, cmd_size);
+      socket_write(data, fd, "\r\n", 2);
+      infof(data, "Send: %s%s\n", prot_level == PROT_PRIVATE?enc:mic,
             cmd_buffer);
       free(cmd_buffer);
     }
   }
   else {
     htonl_bytes = htonl(bytes);
-    socket_write(conn, fd, &htonl_bytes, sizeof(htonl_bytes));
-    socket_write(conn, fd, buffer, curlx_sitouz(bytes));
+    socket_write(data, fd, &htonl_bytes, sizeof(htonl_bytes));
+    socket_write(data, fd, buffer, curlx_sitouz(bytes));
   }
   free(buffer);
 }
 
-static ssize_t sec_write(struct connectdata *conn, curl_socket_t fd,
-                         const char *buffer, size_t length)
+static ssize_t sec_write(struct Curl_easy *data, struct connectdata *conn,
+                         curl_socket_t fd, const char *buffer, size_t length)
 {
   ssize_t tx = 0, len = conn->buffer_size;
 
@@ -665,7 +665,7 @@ static ssize_t sec_write(struct connectdata *conn, curl_socket_t fd,
     if(length < (size_t)len)
       len = length;
 
-    do_sec_send(conn, fd, buffer, curlx_sztosi(len));
+    do_sec_send(data, conn, fd, buffer, curlx_sztosi(len));
     length -= len;
     buffer += len;
     tx += len;
@@ -680,11 +680,11 @@ static ssize_t sec_send(struct Curl_easy *data, int sockindex,
   struct connectdata *conn = data->conn;
   curl_socket_t fd = conn->sock[sockindex];
   *err = CURLE_OK;
-  return sec_write(conn, fd, buffer, len);
+  return sec_write(data, conn, fd, buffer, len);
 }
 
-int Curl_sec_read_msg(struct connectdata *conn, char *buffer,
-                      enum protection_level level)
+int Curl_sec_read_msg(struct Curl_easy *data, struct connectdata *conn,
+                      char *buffer, enum protection_level level)
 {
   /* decoded_len should be size_t or ssize_t but conn->mech->decode returns an
      int */
@@ -694,6 +694,8 @@ int Curl_sec_read_msg(struct connectdata *conn, char *buffer,
   size_t decoded_sz = 0;
   CURLcode error;
 
+  (void) data;
+
   if(!conn->mech)
     /* not inititalized, return error */
     return -1;
@@ -719,7 +721,7 @@ int Curl_sec_read_msg(struct connectdata *conn, char *buffer,
 
   {
     buf[decoded_len] = '\n';
-    Curl_debug(conn->data, CURLINFO_HEADER_IN, buf, decoded_len + 1);
+    Curl_debug(data, CURLINFO_HEADER_IN, buf, decoded_len + 1);
   }
 
   buf[decoded_len] = '\0';
@@ -747,8 +749,8 @@ static int sec_set_protection_level(struct Curl_easy *data)
   DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
 
   if(!conn->sec_complete) {
-    infof(conn->data, "Trying to change the protection level after the"
-                      " completion of the data exchange.\n");
+    infof(data, "Trying to change the protection level after the"
+                " completion of the data exchange.\n");
     return -1;
   }
 
@@ -765,7 +767,7 @@ static int sec_set_protection_level(struct Curl_easy *data)
       return -1;
 
     if(code/100 != 2) {
-      failf(conn->data, "Failed to set the protection's buffer size.");
+      failf(data, "Failed to set the protection's buffer size.");
       return -1;
     }
     conn->buffer_size = buffer_size;
@@ -786,7 +788,7 @@ static int sec_set_protection_level(struct Curl_easy *data)
     return -1;
 
   if(code/100 != 2) {
-    failf(conn->data, "Failed to set the protection level.");
+    failf(data, "Failed to set the protection level.");
     return -1;
   }
 
@@ -808,10 +810,9 @@ Curl_sec_request_prot(struct connectdata *conn, const char *level)
   return 0;
 }
 
-static CURLcode choose_mech(struct connectdata *conn)
+static CURLcode choose_mech(struct Curl_easy *data, struct connectdata *conn)
 {
   int ret;
-  struct Curl_easy *data = conn->data;
   void *tmp_allocation;
   const struct Curl_sec_client_mech *mech = &Curl_krb5_client_mech;
 
@@ -858,7 +859,7 @@ static CURLcode choose_mech(struct connectdata *conn)
   }
 
   /* Authenticate */
-  ret = mech->auth(conn->app_data, conn);
+  ret = mech->auth(conn->app_data, data, conn);
 
   if(ret != AUTH_CONTINUE) {
     if(ret != AUTH_OK) {
@@ -883,9 +884,9 @@ static CURLcode choose_mech(struct connectdata *conn)
 }
 
 CURLcode
-Curl_sec_login(struct connectdata *conn)
+Curl_sec_login(struct Curl_easy *data, struct connectdata *conn)
 {
-  return choose_mech(conn);
+  return choose_mech(data, conn);
 }
 
 
diff --git a/lib/ldap.c b/lib/ldap.c
index 9808ac132..307ebebaf 100644
--- a/lib/ldap.c
+++ b/lib/ldap.c
@@ -100,7 +100,8 @@ struct ldap_urldesc {
 #undef LDAPURLDesc
 #define LDAPURLDesc struct ldap_urldesc
 
-static int  _ldap_url_parse(const struct connectdata *conn,
+static int  _ldap_url_parse(struct Curl_easy *data,
+                            const struct connectdata *conn,
                             LDAPURLDesc **ludp);
 static void _ldap_free_urldesc(LDAPURLDesc *ludp);
 
@@ -232,7 +233,7 @@ static int ldap_win_bind_auth(LDAP *server, const char *user,
 }
 #endif /* #if defined(USE_WINDOWS_SSPI) */
 
-static int ldap_win_bind(struct connectdata *conn, LDAP *server,
+static int ldap_win_bind(struct Curl_easy *data, LDAP *server,
                          const char *user, const char *passwd)
 {
   int rc = LDAP_INVALID_CREDENTIALS;
@@ -240,7 +241,7 @@ static int ldap_win_bind(struct connectdata *conn, LDAP *server,
   PTCHAR inuser = NULL;
   PTCHAR inpass = NULL;
 
-  if(user && passwd && (conn->data->set.httpauth & CURLAUTH_BASIC)) {
+  if(user && passwd && (data->set.httpauth & CURLAUTH_BASIC)) {
     inuser = curlx_convert_UTF8_to_tchar((char *) user);
     inpass = curlx_convert_UTF8_to_tchar((char *) passwd);
 
@@ -251,7 +252,7 @@ static int ldap_win_bind(struct connectdata *conn, LDAP *server,
   }
 #if defined(USE_WINDOWS_SSPI)
   else {
-    rc = ldap_win_bind_auth(server, user, passwd, conn->data->set.httpauth);
+    rc = ldap_win_bind_auth(server, user, passwd, data->set.httpauth);
   }
 #endif
 
@@ -300,7 +301,7 @@ static CURLcode ldap_do(struct Curl_easy *data, bool *done)
 #ifdef HAVE_LDAP_URL_PARSE
   rc = ldap_url_parse(data->change.url, &ludp);
 #else
-  rc = _ldap_url_parse(conn, &ludp);
+  rc = _ldap_url_parse(data, conn, &ludp);
 #endif
   if(rc != 0) {
     failf(data, "LDAP local: %s", ldap_err2string(rc));
@@ -472,7 +473,7 @@ static CURLcode ldap_do(struct Curl_easy *data, bool *done)
   }
 #ifdef USE_WIN32_LDAP
   ldap_set_option(server, LDAP_OPT_PROTOCOL_VERSION, &ldap_proto);
-  rc = ldap_win_bind(conn, server, user, passwd);
+  rc = ldap_win_bind(data, server, user, passwd);
 #else
   rc = ldap_simple_bind_s(server, user, passwd);
 #endif
@@ -480,7 +481,7 @@ static CURLcode ldap_do(struct Curl_easy *data, bool *done)
     ldap_proto = LDAP_VERSION2;
     ldap_set_option(server, LDAP_OPT_PROTOCOL_VERSION, &ldap_proto);
 #ifdef USE_WIN32_LDAP
-    rc = ldap_win_bind(conn, server, user, passwd);
+    rc = ldap_win_bind(data, server, user, passwd);
 #else
     rc = ldap_simple_bind_s(server, user, passwd);
 #endif
@@ -812,14 +813,15 @@ static bool split_str(char *str, char ***out, size_t *count)
  *
  * <hostname> already known from 'conn->host.name'.
  * <port>     already known from 'conn->remote_port'.
- * extract the rest from 'conn->data->state.path+1'. All fields are optional.
+ * extract the rest from 'data->state.path+1'. All fields are optional.
  * e.g.
  *   ldap://<hostname>:<port>/?<attributes>?<scope>?<filter>
  * yields ludp->lud_dn = "".
  *
  * Defined in RFC4516 section 2.
  */
-static int _ldap_url_parse2(const struct connectdata *conn, LDAPURLDesc *ludp)
+static int _ldap_url_parse2(struct Curl_easy *data,
+                            const struct connectdata *conn, LDAPURLDesc *ludp)
 {
   int rc = LDAP_SUCCESS;
   char *p;
@@ -828,10 +830,10 @@ static int _ldap_url_parse2(const struct connectdata *conn, LDAPURLDesc *ludp)
   char *query = NULL;
   size_t i;
 
-  if(!conn->data ||
-     !conn->data->state.up.path ||
-     conn->data->state.up.path[0] != '/' ||
-     !strncasecompare("LDAP", conn->data->state.up.scheme, 4))
+  if(!data ||
+     !data->state.up.path ||
+     data->state.up.path[0] != '/' ||
+     !strncasecompare("LDAP", data->state.up.scheme, 4))
     return LDAP_INVALID_SYNTAX;
 
   ludp->lud_scope = LDAP_SCOPE_BASE;
@@ -839,13 +841,13 @@ static int _ldap_url_parse2(const struct connectdata *conn, LDAPURLDesc *ludp)
   ludp->lud_host  = conn->host.name;
 
   /* Duplicate the path */
-  p = path = strdup(conn->data->state.up.path + 1);
+  p = path = strdup(data->state.up.path + 1);
   if(!path)
     return LDAP_NO_MEMORY;
 
   /* Duplicate the query if present */
-  if(conn->data->state.up.query) {
-    q = query = strdup(conn->data->state.up.query);
+  if(data->state.up.query) {
+    q = query = strdup(data->state.up.query);
     if(!query) {
       free(path);
       return LDAP_NO_MEMORY;
@@ -861,7 +863,7 @@ static int _ldap_url_parse2(const struct connectdata *conn, LDAPURLDesc *ludp)
     LDAP_TRACE(("DN '%s'\n", dn));
 
     /* Unescape the DN */
-    result = Curl_urldecode(conn->data, dn, 0, &unescaped, NULL, REJECT_ZERO);
+    result = Curl_urldecode(data, dn, 0, &unescaped, NULL, REJECT_ZERO);
     if(result) {
       rc = LDAP_NO_MEMORY;
 
@@ -926,7 +928,7 @@ static int _ldap_url_parse2(const struct connectdata *conn, LDAPURLDesc *ludp)
       LDAP_TRACE(("attr[%zu] '%s'\n", i, attributes[i]));
 
       /* Unescape the attribute */
-      result = Curl_urldecode(conn->data, attributes[i], 0, &unescaped, NULL,
+      result = Curl_urldecode(data, attributes[i], 0, &unescaped, NULL,
                               REJECT_ZERO);
       if(result) {
         free(attributes);
@@ -996,8 +998,7 @@ static int _ldap_url_parse2(const struct connectdata *conn, LDAPURLDesc *ludp)
     LDAP_TRACE(("filter '%s'\n", filter));
 
     /* Unescape the filter */
-    result = Curl_urldecode(conn->data, filter, 0, &unescaped, NULL,
-                            REJECT_ZERO);
+    result = Curl_urldecode(data, filter, 0, &unescaped, NULL, REJECT_ZERO);
     if(result) {
       rc = LDAP_NO_MEMORY;
 
@@ -1035,7 +1036,8 @@ quit:
   return rc;
 }
 
-static int _ldap_url_parse(const struct connectdata *conn,
+static int _ldap_url_parse(struct Curl_easy *data,
+                           const struct connectdata *conn,
                            LDAPURLDesc **ludpp)
 {
   LDAPURLDesc *ludp = calloc(1, sizeof(*ludp));
@@ -1045,7 +1047,7 @@ static int _ldap_url_parse(const struct connectdata *conn,
   if(!ludp)
      return LDAP_NO_MEMORY;
 
-  rc = _ldap_url_parse2(conn, ludp);
+  rc = _ldap_url_parse2(data, conn, ludp);
   if(rc != LDAP_SUCCESS) {
     _ldap_free_urldesc(ludp);
     ludp = NULL;
diff --git a/lib/sendf.c b/lib/sendf.c
index 5075c5439..b3c7fe33d 100644
--- a/lib/sendf.c
+++ b/lib/sendf.c
@@ -142,7 +142,8 @@ bool Curl_recv_has_postponed_data(struct connectdata *conn, int sockindex)
          psnd->recv_size > psnd->recv_processed;
 }
 
-static CURLcode pre_receive_plain(struct connectdata *conn, int num)
+static CURLcode pre_receive_plain(struct Curl_easy *data,
+                                  struct connectdata *conn, int num)
 {
   const curl_socket_t sockfd = conn->sock[num];
   struct postponed_data * const psnd = &(conn->postponed[num]);
@@ -161,7 +162,7 @@ static CURLcode pre_receive_plain(struct connectdata *conn, int num)
       /* Have some incoming data */
       if(!psnd->buffer) {
         /* Use buffer double default size for intermediate buffer */
-        psnd->allocated_size = 2 * conn->data->set.buffer_size;
+        psnd->allocated_size = 2 * data->set.buffer_size;
         psnd->buffer = malloc(psnd->allocated_size);
         if(!psnd->buffer)
           return CURLE_OUT_OF_MEMORY;
@@ -230,7 +231,7 @@ bool Curl_recv_has_postponed_data(struct connectdata *conn, int sockindex)
   (void)sockindex;
   return false;
 }
-#define pre_receive_plain(c,n) CURLE_OK
+#define pre_receive_plain(d,c,n) CURLE_OK
 #define get_pre_recved(c,n,b,l) 0
 #endif /* ! USE_RECV_BEFORE_SEND_WORKAROUND */
 
@@ -347,7 +348,7 @@ ssize_t Curl_send_plain(struct Curl_easy *data, int num,
      To avoid lossage of received data, recv() must be
      performed before every send() if any incoming data is
      available. */
-  if(pre_receive_plain(conn, num)) {
+  if(pre_receive_plain(data, conn, num)) {
     *code = CURLE_OUT_OF_MEMORY;
     return -1;
   }