Support key fetching using HTTP.

A simple test case is:

  gpg2 --fetch-key http://werner.eifelkommune.de/mykey.asc

dirmngr/ChangeLog

@@ -1,3 +1,11 @@
+2011-02-09  Werner Koch  <wk@g10code.com>
+
+	* ks-action.c (ks_action_fetch): Support http URLs.
+	* ks-engine-http.c: New.
+
+	* ks-engine-finger.c (ks_finger_get): Rename to ks_finger_fetch.
+	Change caller.
+
 2011-02-08  Werner Koch  <wk@g10code.com>
 
 	* server.c (cmd_ks_fetch): New.

dirmngr/Makefile.am

@@ -51,7 +51,7 @@ dirmngr_SOURCES = dirmngr.c dirmngr.h server.c crlcache.c crlfetch.c	\
 	cdb.h cdblib.c ldap.c misc.c dirmngr-err.h w32-ldap-help.h \
 	ocsp.c ocsp.h validate.c validate.h ldap-wrapper.h $(ldap_url) \
 	ks-action.c ks-action.h ks-engine.h \
-        ks-engine-hkp.c ks-engine-finger.c
+        ks-engine-hkp.c ks-engine-http.c ks-engine-finger.c
 
 if USE_LDAPWRAPPER
 dirmngr_SOURCES += ldap-wrapper.c

dirmngr/ks-action.c

@@ -167,7 +167,12 @@ ks_action_fetch (ctrl_t ctrl, const char *url, estream_t outfp)
 
   if (parsed_uri->is_http)
     {
-      err = gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+      err = ks_http_fetch (ctrl, url, &infp);
+      if (!err)
+        {
+          err = copy_stream (infp, outfp);
+          es_fclose (infp);
+        }
     }
   else if (!parsed_uri->opaque)
     {
@@ -175,12 +180,10 @@ ks_action_fetch (ctrl_t ctrl, const char *url, estream_t outfp)
     }
   else if (!strcmp (parsed_uri->scheme, "finger"))
     {
-      err = ks_finger_get (ctrl, parsed_uri, &infp);
+      err = ks_finger_fetch (ctrl, parsed_uri, &infp);
       if (!err)
         {
           err = copy_stream (infp, outfp);
-          /* Reading from the finger serrver should not fail, thus
-             return this error.  */
           es_fclose (infp);
         }
     }

dirmngr/ks-engine-finger.c

@@ -1,4 +1,4 @@
-/* ks-engine-finger.c - HKP keyserver engine
+/* ks-engine-finger.c - Finger OpenPGP key access
  * Copyright (C) 2011 Free Software Foundation, Inc.
  *
  * This file is part of GnuPG.
@@ -33,7 +33,7 @@
 /* Get the key from URI which is expected to specify a finger scheme.
    On success R_FP has an open stream to read the data.  */
 gpg_error_t
-ks_finger_get (ctrl_t ctrl, parsed_uri_t uri, estream_t *r_fp)
+ks_finger_fetch (ctrl_t ctrl, parsed_uri_t uri, estream_t *r_fp)
 {
   gpg_error_t err;
   estream_t fp;

dirmngr/ks-engine-http.c

@@ -0,0 +1,141 @@
+/* ks-engine-http.c - HTTP OpenPGP key access
+ * Copyright (C) 2011 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "dirmngr.h"
+#include "misc.h"
+#include "ks-engine.h"
+
+/* How many redirections do we allow.  */
+#define MAX_REDIRECTS 2
+
+
+/* Get the key from URL which is expected to specify a http style
+   scheme.  On success R_FP has an open stream to read the data.  */
+gpg_error_t
+ks_http_fetch (ctrl_t ctrl, const char *url, estream_t *r_fp)
+{
+  gpg_error_t err;
+  http_t http = NULL;
+  int redirects_left = MAX_REDIRECTS;
+  estream_t fp = NULL;
+  char *request_buffer = NULL;
+
+  *r_fp = NULL;
+ once_more:
+  err = http_open (&http,
+                   HTTP_REQ_GET,
+                   url,
+                   /* fixme: AUTH */ NULL,
+                   0,
+                   /* fixme: proxy*/ NULL,
+                   NULL, NULL,
+                   /*FIXME curl->srvtag*/NULL);
+  if (!err)
+    {
+      fp = http_get_write_ptr (http);
+      /* Avoid caches to get the most recent copy of the key.  We set
+         both the Pragma and Cache-Control versions of the header, so
+         we're good with both HTTP 1.0 and 1.1.  */
+      es_fputs ("Pragma: no-cache\r\n"
+                "Cache-Control: no-cache\r\n", fp);
+      http_start_data (http);
+      if (es_ferror (fp))
+        err = gpg_error_from_syserror ();
+    }
+  if (err)
+    {
+      /* Fixme: After a redirection we show the old host name.  */
+      log_error (_("error connecting to `%s': %s\n"),
+                 url, gpg_strerror (err));
+      goto leave;
+    }
+
+  /* Wait for the response.  */
+  dirmngr_tick (ctrl);
+  err = http_wait_response (http);
+  if (err)
+    {
+      log_error (_("error reading HTTP response for `%s': %s\n"),
+                 url, gpg_strerror (err));
+      goto leave;
+    }
+
+  switch (http_get_status_code (http))
+    {
+    case 200:
+      err = 0;
+      break; /* Success.  */
+
+    case 301:
+    case 302:
+      {
+        const char *s = http_get_header (http, "Location");
+
+        log_info (_("URL `%s' redirected to `%s' (%u)\n"),
+                  url, s?s:"[none]", http_get_status_code (http));
+        if (s && *s && redirects_left-- )
+          {
+            xfree (request_buffer);
+            request_buffer = xtrystrdup (s);
+            if (request_buffer)
+              {
+                url = request_buffer;
+                http_close (http, 0);
+                http = NULL;
+                goto once_more;
+              }
+            err = gpg_error_from_syserror ();
+          }
+        else
+          err = gpg_error (GPG_ERR_NO_DATA);
+        log_error (_("too many redirections\n"));
+      }
+      goto leave;
+
+    default:
+      log_error (_("error accessing `%s': http status %u\n"),
+                 url, http_get_status_code (http));
+      err = gpg_error (GPG_ERR_NO_DATA);
+      goto leave;
+    }
+
+  fp = http_get_read_ptr (http);
+  if (!fp)
+    {
+      err = gpg_error (GPG_ERR_BUG);
+      goto leave;
+    }
+
+  /* Return the read stream and close the HTTP context.  */
+  *r_fp = fp;
+  http_close (http, 1);
+  http = NULL;
+
+ leave:
+  http_close (http, 0);
+  xfree (request_buffer);
+  return err;
+}

dirmngr/ks-engine.h

@@ -31,8 +31,12 @@ gpg_error_t ks_hkp_get (ctrl_t ctrl, parsed_uri_t uri,
 gpg_error_t ks_hkp_put (ctrl_t ctrl, parsed_uri_t uri,
                         const void *data, size_t datalen);
 
+/*-- ks-engine-http.c --*/
+gpg_error_t ks_http_fetch (ctrl_t ctrl, const char *url, estream_t *r_fp);
+
+
 /*-- ks-engine-finger.c --*/
-gpg_error_t ks_finger_get (ctrl_t ctrl, parsed_uri_t uri, estream_t *r_fp);
+gpg_error_t ks_finger_fetch (ctrl_t ctrl, parsed_uri_t uri, estream_t *r_fp);