From 14fcd5f3a3a5611a61cb6e9861113b0c16579d84 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Tue, 21 May 2019 09:43:10 +0200
Subject: url: convert the zone id from a IPv6 URL to correct scope id

Reported-by: GitYuanQu on github
Fixes #3902
---
 lib/url.c | 65 +++++++++++++++++++++------------------------------------------
 1 file changed, 22 insertions(+), 43 deletions(-)

diff --git a/lib/url.c b/lib/url.c
index 944754816..c441ae716 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -2002,61 +2002,40 @@ static CURLcode parseurlandfillconn(struct Curl_easy *data,
     hostname = (char *)"";
 
   if(hostname[0] == '[') {
-    /* This looks like an IPv6 address literal.  See if there is an address
+    /* This looks like an IPv6 address literal. See if there is an address
        scope. */
-    char *percent = strchr(++hostname, '%');
+    char *zoneid;
+    size_t hlen;
+    uc = curl_url_get(uh, CURLUPART_ZONEID, &zoneid, 0);
     conn->bits.ipv6_ip = TRUE;
-    if(percent) {
-      unsigned int identifier_offset = 3;
+
+    /* cut off the brackets! */
+    hostname++;
+    hlen = strlen(hostname);
+    hostname[hlen - 1] = 0;
+    if(!uc && zoneid) {
       char *endp;
       unsigned long scope;
-      if(strncmp("%25", percent, 3) != 0) {
-        infof(data,
-              "Please URL encode %% as %%25, see RFC 6874.\n");
-        identifier_offset = 1;
-      }
-      scope = strtoul(percent + identifier_offset, &endp, 10);
-      if(*endp == ']') {
-        /* The address scope was well formed.  Knock it out of the
-           hostname. */
-        memmove(percent, endp, strlen(endp) + 1);
+      scope = strtoul(zoneid, &endp, 10);
+      if(!*endp && (scope < UINT_MAX)) {
+        /* A plain number, use it direcly as a scope id. */
         conn->scope_id = (unsigned int)scope;
       }
+#ifdef HAVE_IF_NAMETOINDEX
       else {
         /* Zone identifier is not numeric */
-#if defined(HAVE_NET_IF_H) && defined(IFNAMSIZ) && defined(HAVE_IF_NAMETOINDEX)
-        char ifname[IFNAMSIZ + 2];
-        char *square_bracket;
         unsigned int scopeidx = 0;
-        strncpy(ifname, percent + identifier_offset, IFNAMSIZ + 2);
-        /* Ensure nullbyte termination */
-        ifname[IFNAMSIZ + 1] = '\0';
-        square_bracket = strchr(ifname, ']');
-        if(square_bracket) {
-          /* Remove ']' */
-          *square_bracket = '\0';
-          scopeidx = if_nametoindex(ifname);
-          if(scopeidx == 0) {
-            infof(data, "Invalid network interface: %s; %s\n", ifname,
-                  strerror(errno));
-          }
-        }
-        if(scopeidx > 0) {
-          char *p = percent + identifier_offset + strlen(ifname);
-
-          /* Remove zone identifier from hostname */
-          memmove(percent, p, strlen(p) + 1);
-          conn->scope_id = scopeidx;
-        }
+        scopeidx = if_nametoindex(zoneid);
+        if(!scopeidx)
+          infof(data, "Invalid zoneid id: %s; %s\n", zoneid,
+                strerror(errno));
         else
-#endif /* HAVE_NET_IF_H && IFNAMSIZ */
-          infof(data, "Invalid IPv6 address format\n");
+          conn->scope_id = scopeidx;
+
       }
+#endif /* HAVE_IF_NAMETOINDEX */
+      free(zoneid);
     }
-    percent = strchr(hostname, ']');
-    if(percent)
-      /* terminate IPv6 numerical at end bracket */
-      *percent = 0;
   }
 
   /* make sure the connect struct gets its own copy of the host name */
-- 
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