http-proxy: only attempt FTP over HTTP proxy

... all other non-HTTP protocol schemes are now defaulting to "tunnel
trough" mode if a HTTP proxy is specified. In reality there are no HTTP
proxies out there that allow those other schemes.

Assisted-by: Ray Satiro, Michael Kaufmann

Closes #1505

6 files changed, 14 insertions, 313 deletions

diff --git a/lib/ftp.c b/lib/ftp.c
index f929c3407..1e3aa8d7c 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -180,8 +180,8 @@ const struct Curl_handler Curl_handler_ftp = {
   ZERO_NULL,                       /* readwrite */
   PORT_FTP,                        /* defport */
   CURLPROTO_FTP,                   /* protocol */
-  PROTOPT_DUAL | PROTOPT_CLOSEACTION | PROTOPT_NEEDSPWD
-  | PROTOPT_NOURLQUERY /* flags */
+  PROTOPT_DUAL | PROTOPT_CLOSEACTION | PROTOPT_NEEDSPWD |
+  PROTOPT_NOURLQUERY | PROTOPT_PROXY_AS_HTTP /* flags */
 };
 
 
@@ -212,59 +212,6 @@ const struct Curl_handler Curl_handler_ftps = {
 };
 #endif
 
-#ifndef CURL_DISABLE_HTTP
-/*
- * HTTP-proxyed FTP protocol handler.
- */
-
-static const struct Curl_handler Curl_handler_ftp_proxy = {
-  "FTP",                                /* scheme */
-  Curl_http_setup_conn,                 /* setup_connection */
-  Curl_http,                            /* do_it */
-  Curl_http_done,                       /* done */
-  ZERO_NULL,                            /* do_more */
-  ZERO_NULL,                            /* connect_it */
-  ZERO_NULL,                            /* connecting */
-  ZERO_NULL,                            /* doing */
-  ZERO_NULL,                            /* proto_getsock */
-  ZERO_NULL,                            /* doing_getsock */
-  ZERO_NULL,                            /* domore_getsock */
-  ZERO_NULL,                            /* perform_getsock */
-  ZERO_NULL,                            /* disconnect */
-  ZERO_NULL,                            /* readwrite */
-  PORT_FTP,                             /* defport */
-  CURLPROTO_HTTP,                       /* protocol */
-  PROTOPT_NONE                          /* flags */
-};
-
-
-#ifdef USE_SSL
-/*
- * HTTP-proxyed FTPS protocol handler.
- */
-
-static const struct Curl_handler Curl_handler_ftps_proxy = {
-  "FTPS",                               /* scheme */
-  Curl_http_setup_conn,                 /* setup_connection */
-  Curl_http,                            /* do_it */
-  Curl_http_done,                       /* done */
-  ZERO_NULL,                            /* do_more */
-  ZERO_NULL,                            /* connect_it */
-  ZERO_NULL,                            /* connecting */
-  ZERO_NULL,                            /* doing */
-  ZERO_NULL,                            /* proto_getsock */
-  ZERO_NULL,                            /* doing_getsock */
-  ZERO_NULL,                            /* domore_getsock */
-  ZERO_NULL,                            /* perform_getsock */
-  ZERO_NULL,                            /* disconnect */
-  ZERO_NULL,                            /* readwrite */
-  PORT_FTPS,                            /* defport */
-  CURLPROTO_HTTP,                       /* protocol */
-  PROTOPT_NONE                          /* flags */
-};
-#endif
-#endif
-
 static void close_secondarysocket(struct connectdata *conn)
 {
   if(CURL_SOCKET_BAD != conn->sock[SECONDARYSOCKET]) {
@@ -4462,28 +4409,6 @@ static CURLcode ftp_setup_connection(struct connectdata *conn)
   char command;
   struct FTP *ftp;
 
-  if(conn->bits.httpproxy && !data->set.tunnel_thru_httpproxy) {
-    /* Unless we have asked to tunnel ftp operations through the proxy, we
-       switch and use HTTP operations only */
-#ifndef CURL_DISABLE_HTTP
-    if(conn->handler == &Curl_handler_ftp)
-      conn->handler = &Curl_handler_ftp_proxy;
-    else {
-#ifdef USE_SSL
-      conn->handler = &Curl_handler_ftps_proxy;
-#else
-      failf(data, "FTPS not supported!");
-      return CURLE_UNSUPPORTED_PROTOCOL;
-#endif
-    }
-    /* set it up as a HTTP connection instead */
-    return conn->handler->setup_connection(conn);
-#else
-    failf(data, "FTP over http proxy requires HTTP support built-in!");
-    return CURLE_UNSUPPORTED_PROTOCOL;
-#endif
-  }
-
   conn->data->req.protop = ftp = malloc(sizeof(struct FTP));
   if(NULL == ftp)
     return CURLE_OUT_OF_MEMORY;
diff --git a/lib/imap.c b/lib/imap.c
index b528f77d9..18b1760fc 100644
--- a/lib/imap.c
+++ b/lib/imap.c
@@ -160,58 +160,6 @@ const struct Curl_handler Curl_handler_imaps = {
 };
 #endif
 
-#ifndef CURL_DISABLE_HTTP
-/*
- * HTTP-proxyed IMAP protocol handler.
- */
-
-static const struct Curl_handler Curl_handler_imap_proxy = {
-  "IMAP",                               /* scheme */
-  Curl_http_setup_conn,                 /* setup_connection */
-  Curl_http,                            /* do_it */
-  Curl_http_done,                       /* done */
-  ZERO_NULL,                            /* do_more */
-  ZERO_NULL,                            /* connect_it */
-  ZERO_NULL,                            /* connecting */
-  ZERO_NULL,                            /* doing */
-  ZERO_NULL,                            /* proto_getsock */
-  ZERO_NULL,                            /* doing_getsock */
-  ZERO_NULL,                            /* domore_getsock */
-  ZERO_NULL,                            /* perform_getsock */
-  ZERO_NULL,                            /* disconnect */
-  ZERO_NULL,                            /* readwrite */
-  PORT_IMAP,                            /* defport */
-  CURLPROTO_HTTP,                       /* protocol */
-  PROTOPT_NONE                          /* flags */
-};
-
-#ifdef USE_SSL
-/*
- * HTTP-proxyed IMAPS protocol handler.
- */
-
-static const struct Curl_handler Curl_handler_imaps_proxy = {
-  "IMAPS",                              /* scheme */
-  Curl_http_setup_conn,                 /* setup_connection */
-  Curl_http,                            /* do_it */
-  Curl_http_done,                       /* done */
-  ZERO_NULL,                            /* do_more */
-  ZERO_NULL,                            /* connect_it */
-  ZERO_NULL,                            /* connecting */
-  ZERO_NULL,                            /* doing */
-  ZERO_NULL,                            /* proto_getsock */
-  ZERO_NULL,                            /* doing_getsock */
-  ZERO_NULL,                            /* domore_getsock */
-  ZERO_NULL,                            /* perform_getsock */
-  ZERO_NULL,                            /* disconnect */
-  ZERO_NULL,                            /* readwrite */
-  PORT_IMAPS,                           /* defport */
-  CURLPROTO_HTTP,                       /* protocol */
-  PROTOPT_NONE                          /* flags */
-};
-#endif
-#endif
-
 /* SASL parameters for the imap protocol */
 static const struct SASLproto saslimap = {
   "imap",                     /* The service name */
@@ -1715,31 +1663,6 @@ static CURLcode imap_setup_connection(struct connectdata *conn)
 
   /* Clear the TLS upgraded flag */
   conn->tls_upgraded = FALSE;
-
-  /* Set up the proxy if necessary */
-  if(conn->bits.httpproxy && !data->set.tunnel_thru_httpproxy) {
-    /* Unless we have asked to tunnel IMAP operations through the proxy, we
-       switch and use HTTP operations only */
-#ifndef CURL_DISABLE_HTTP
-    if(conn->handler == &Curl_handler_imap)
-      conn->handler = &Curl_handler_imap_proxy;
-    else {
-#ifdef USE_SSL
-      conn->handler = &Curl_handler_imaps_proxy;
-#else
-      failf(data, "IMAPS not supported!");
-      return CURLE_UNSUPPORTED_PROTOCOL;
-#endif
-    }
-
-    /* set it up as an HTTP connection instead */
-    return conn->handler->setup_connection(conn);
-#else
-    failf(data, "IMAP over http proxy requires HTTP support built-in!");
-    return CURLE_UNSUPPORTED_PROTOCOL;
-#endif
-  }
-
   data->state.path++;   /* don't include the initial slash */
 
   return CURLE_OK;
diff --git a/lib/pop3.c b/lib/pop3.c
index 3feb3be83..4aff6031c 100644
--- a/lib/pop3.c
+++ b/lib/pop3.c
@@ -158,58 +158,6 @@ const struct Curl_handler Curl_handler_pop3s = {
 };
 #endif
 
-#ifndef CURL_DISABLE_HTTP
-/*
- * HTTP-proxyed POP3 protocol handler.
- */
-
-static const struct Curl_handler Curl_handler_pop3_proxy = {
-  "POP3",                               /* scheme */
-  Curl_http_setup_conn,                 /* setup_connection */
-  Curl_http,                            /* do_it */
-  Curl_http_done,                       /* done */
-  ZERO_NULL,                            /* do_more */
-  ZERO_NULL,                            /* connect_it */
-  ZERO_NULL,                            /* connecting */
-  ZERO_NULL,                            /* doing */
-  ZERO_NULL,                            /* proto_getsock */
-  ZERO_NULL,                            /* doing_getsock */
-  ZERO_NULL,                            /* domore_getsock */
-  ZERO_NULL,                            /* perform_getsock */
-  ZERO_NULL,                            /* disconnect */
-  ZERO_NULL,                            /* readwrite */
-  PORT_POP3,                            /* defport */
-  CURLPROTO_HTTP,                       /* protocol */
-  PROTOPT_NONE                          /* flags */
-};
-
-#ifdef USE_SSL
-/*
- * HTTP-proxyed POP3S protocol handler.
- */
-
-static const struct Curl_handler Curl_handler_pop3s_proxy = {
-  "POP3S",                              /* scheme */
-  Curl_http_setup_conn,                 /* setup_connection */
-  Curl_http,                            /* do_it */
-  Curl_http_done,                       /* done */
-  ZERO_NULL,                            /* do_more */
-  ZERO_NULL,                            /* connect_it */
-  ZERO_NULL,                            /* connecting */
-  ZERO_NULL,                            /* doing */
-  ZERO_NULL,                            /* proto_getsock */
-  ZERO_NULL,                            /* doing_getsock */
-  ZERO_NULL,                            /* domore_getsock */
-  ZERO_NULL,                            /* perform_getsock */
-  ZERO_NULL,                            /* disconnect */
-  ZERO_NULL,                            /* readwrite */
-  PORT_POP3S,                           /* defport */
-  CURLPROTO_HTTP,                       /* protocol */
-  PROTOPT_NONE                          /* flags */
-};
-#endif
-#endif
-
 /* SASL parameters for the pop3 protocol */
 static const struct SASLproto saslpop3 = {
   "pop",                      /* The service name */
@@ -1355,31 +1303,6 @@ static CURLcode pop3_setup_connection(struct connectdata *conn)
 
   /* Clear the TLS upgraded flag */
   conn->tls_upgraded = FALSE;
-
-  /* Set up the proxy if necessary */
-  if(conn->bits.httpproxy && !data->set.tunnel_thru_httpproxy) {
-    /* Unless we have asked to tunnel POP3 operations through the proxy, we
-       switch and use HTTP operations only */
-#ifndef CURL_DISABLE_HTTP
-    if(conn->handler == &Curl_handler_pop3)
-      conn->handler = &Curl_handler_pop3_proxy;
-    else {
-#ifdef USE_SSL
-      conn->handler = &Curl_handler_pop3s_proxy;
-#else
-      failf(data, "POP3S not supported!");
-      return CURLE_UNSUPPORTED_PROTOCOL;
-#endif
-    }
-
-    /* set it up as an HTTP connection instead */
-    return conn->handler->setup_connection(conn);
-#else
-    failf(data, "POP3 over http proxy requires HTTP support built-in!");
-    return CURLE_UNSUPPORTED_PROTOCOL;
-#endif
-  }
-
   data->state.path++;   /* don't include the initial slash */
 
   return CURLE_OK;
diff --git a/lib/smtp.c b/lib/smtp.c
index fe064cb2f..e609ec9d9 100644
--- a/lib/smtp.c
+++ b/lib/smtp.c
@@ -157,58 +157,6 @@ const struct Curl_handler Curl_handler_smtps = {
 };
 #endif
 
-#ifndef CURL_DISABLE_HTTP
-/*
- * HTTP-proxyed SMTP protocol handler.
- */
-
-static const struct Curl_handler Curl_handler_smtp_proxy = {
-  "SMTP",                               /* scheme */
-  Curl_http_setup_conn,                 /* setup_connection */
-  Curl_http,                            /* do_it */
-  Curl_http_done,                       /* done */
-  ZERO_NULL,                            /* do_more */
-  ZERO_NULL,                            /* connect_it */
-  ZERO_NULL,                            /* connecting */
-  ZERO_NULL,                            /* doing */
-  ZERO_NULL,                            /* proto_getsock */
-  ZERO_NULL,                            /* doing_getsock */
-  ZERO_NULL,                            /* domore_getsock */
-  ZERO_NULL,                            /* perform_getsock */
-  ZERO_NULL,                            /* disconnect */
-  ZERO_NULL,                            /* readwrite */
-  PORT_SMTP,                            /* defport */
-  CURLPROTO_HTTP,                       /* protocol */
-  PROTOPT_NONE                          /* flags */
-};
-
-#ifdef USE_SSL
-/*
- * HTTP-proxyed SMTPS protocol handler.
- */
-
-static const struct Curl_handler Curl_handler_smtps_proxy = {
-  "SMTPS",                              /* scheme */
-  Curl_http_setup_conn,                 /* setup_connection */
-  Curl_http,                            /* do_it */
-  Curl_http_done,                       /* done */
-  ZERO_NULL,                            /* do_more */
-  ZERO_NULL,                            /* connect_it */
-  ZERO_NULL,                            /* connecting */
-  ZERO_NULL,                            /* doing */
-  ZERO_NULL,                            /* proto_getsock */
-  ZERO_NULL,                            /* doing_getsock */
-  ZERO_NULL,                            /* domore_getsock */
-  ZERO_NULL,                            /* perform_getsock */
-  ZERO_NULL,                            /* disconnect */
-  ZERO_NULL,                            /* readwrite */
-  PORT_SMTPS,                           /* defport */
-  CURLPROTO_HTTP,                       /* protocol */
-  PROTOPT_NONE                          /* flags */
-};
-#endif
-#endif
-
 /* SASL parameters for the smtp protocol */
 static const struct SASLproto saslsmtp = {
   "smtp",                     /* The service name */
@@ -1451,30 +1399,6 @@ static CURLcode smtp_setup_connection(struct connectdata *conn)
   /* Clear the TLS upgraded flag */
   conn->tls_upgraded = FALSE;
 
-  /* Set up the proxy if necessary */
-  if(conn->bits.httpproxy && !data->set.tunnel_thru_httpproxy) {
-    /* Unless we have asked to tunnel SMTP operations through the proxy, we
-       switch and use HTTP operations only */
-#ifndef CURL_DISABLE_HTTP
-    if(conn->handler == &Curl_handler_smtp)
-      conn->handler = &Curl_handler_smtp_proxy;
-    else {
-#ifdef USE_SSL
-      conn->handler = &Curl_handler_smtps_proxy;
-#else
-      failf(data, "SMTPS not supported!");
-      return CURLE_UNSUPPORTED_PROTOCOL;
-#endif
-    }
-    /* set it up as a HTTP connection instead */
-    return conn->handler->setup_connection(conn);
-
-#else
-    failf(data, "SMTP over http proxy requires HTTP support built-in!");
-    return CURLE_UNSUPPORTED_PROTOCOL;
-#endif
-  }
-
   /* Initialise the SMTP layer */
   result = smtp_init(conn);
   if(result)
diff --git a/lib/url.c b/lib/url.c
index 51e50a80b..20fdbbbb9 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -5348,12 +5348,15 @@ static CURLcode create_conn_helper_init_proxy(struct connectdata *conn)
       result = CURLE_UNSUPPORTED_PROTOCOL;
       goto out;
 #else
-      /* force this connection's protocol to become HTTP if not already
-         compatible - if it isn't tunneling through */
-      if(!(conn->handler->protocol & PROTO_FAMILY_HTTP) &&
-         !conn->bits.tunnel_proxy)
-        conn->handler = &Curl_handler_http;
-
+      /* force this connection's protocol to become HTTP if compatible */
+      if(!(conn->handler->protocol & PROTO_FAMILY_HTTP)) {
+        if((conn->handler->flags & PROTOPT_PROXY_AS_HTTP) &&
+           !conn->bits.tunnel_proxy)
+          conn->handler = &Curl_handler_http;
+        else
+          /* if not converting to HTTP over the proxy, enforce tunneling */
+          conn->bits.tunnel_proxy = TRUE;
+      }
       conn->bits.httpproxy = TRUE;
 #endif
     }
diff --git a/lib/urldata.h b/lib/urldata.h
index 681fef1fb..23423e11b 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -855,6 +855,9 @@ struct Curl_handler {
 #define PROTOPT_STREAM (1<<9) /* a protocol with individual logical streams */
 #define PROTOPT_URLOPTIONS (1<<10) /* allow options part in the userinfo field
                                       of the URL */
+#define PROTOPT_PROXY_AS_HTTP (1<<11) /* allow this non-HTTP scheme over a
+                                         HTTP proxy as HTTP proxies may know
+                                         this protocol and act as a gateway */
 
 /* return the count of bytes sent, or -1 on error */
 typedef ssize_t (Curl_send)(struct connectdata *conn, /* connection data */