netrc: don't ignore the login name specified with "--user"

- for "--netrc", don't ignore the login/password specified with "--user",
  only ignore the login/password in the URL.
  This restores the netrc behaviour of curl 7.61.1 and earlier.
- fix the documentation of CURL_NETRC_REQUIRED
- improve the detection of login/password changes when reading .netrc
- don't read .netrc if both login and password are already set

Fixes #3213
Closes #3224

1 files changed, 9 insertions, 2 deletions

diff --git a/lib/netrc.c b/lib/netrc.c
index 1724b35b0..aba355b76 100644
--- a/lib/netrc.c
+++ b/lib/netrc.c
@@ -53,6 +53,8 @@ enum host_lookup_state {
 int Curl_parsenetrc(const char *host,
                     char **loginp,
                     char **passwordp,
+                    bool *login_changed,
+                    bool *password_changed,
                     char *netrcfile)
 {
   FILE *file;
@@ -164,7 +166,7 @@ int Curl_parsenetrc(const char *host,
             if(specific_login) {
               state_our_login = strcasecompare(login, tok);
             }
-            else {
+            else if(!login || strcmp(login, tok)) {
               if(login_alloc) {
                 free(login);
                 login_alloc = FALSE;
@@ -179,7 +181,8 @@ int Curl_parsenetrc(const char *host,
             state_login = 0;
           }
           else if(state_password) {
-            if(state_our_login || !specific_login) {
+            if((state_our_login || !specific_login)
+                && (!password || strcmp(password, tok))) {
               if(password_alloc) {
                 free(password);
                 password_alloc = FALSE;
@@ -211,15 +214,19 @@ int Curl_parsenetrc(const char *host,
 
     out:
     if(!retcode) {
+      *login_changed = FALSE;
+      *password_changed = FALSE;
       if(login_alloc) {
         if(*loginp)
           free(*loginp);
         *loginp = login;
+        *login_changed = TRUE;
       }
       if(password_alloc) {
         if(*passwordp)
           free(*passwordp);
         *passwordp = password;
+        *password_changed = TRUE;
       }
     }
     else {