try to add test

docs/cmdline-opts/Makefile.inc

@@ -160,6 +160,7 @@ DPAGES = \
   max-redirs.md \
   max-time.md \
   metalink.md \
+  mptcp.md \
   negotiate.md \
   netrc-file.md \
   netrc-optional.md \

docs/cmdline-opts/mptcp.md

@@ -0,0 +1,32 @@
+---
+c: Copyright (C) Dorian Craps, <dorian.craps@student.vinci.be>
+SPDX-License-Identifier: curl
+Long: mptcp
+Added: 8.6.1 
+Help: Enable Multipath TCP (MPTCP)
+Category: connection
+Multi: boolean
+See-also:
+
+Example:
+  - --mptcp $URL
+---
+
+# `--mptcp`
+
+Enables the use of Multipath TCP (MPTCP) for connections. MPTCP is an extension to the standard TCP that allows multiple TCP streams over different network paths between the same source and destination. This can enhance bandwidth and improve reliability by using multiple paths simultaneously.
+
+MPTCP is beneficial in networks where multiple paths exist between clients and servers, such as mobile networks where a device may switch between Wi-Fi and cellular data or in wired networks with multiple ISPs.
+
+## Usage
+
+To use MPTCP for your connections, add the `--mptcp` option when using `curl`:
+
+## Requirements
+
+- Your operating system must support MPTCP, and it must be enabled.
+- The server you are connecting to must also support MPTCP.
+
+## Availability
+
+The `--mptcp` option is available starting from `curl` version 8.6.1.

docs/libcurl/curl_easy_setopt.md

@@ -423,6 +423,10 @@ Path to a Unix domain socket. See CURLOPT_UNIX_SOCKET_PATH(3)
 
 Path to an abstract Unix domain socket. See CURLOPT_ABSTRACT_UNIX_SOCKET(3)
 
+## CURLOPT_MPTCP
+
+Enable Multipath TCP (MPTCP). See CURLOPT_MPTCP(3)
+
 # NAMES and PASSWORDS OPTIONS (Authentication)
 
 ## CURLOPT_NETRC

docs/libcurl/opts/CURLOPT_MPTCP.md

@@ -0,0 +1,70 @@
+---
+c: Copyright (C) Dorian Craps, <dorian.craps@student.vinci.be>
+SPDX-License-Identifier: curl
+Title: CURLOPT_MPTCP
+Section: 3
+Source: libcurl
+See-also:
+---
+
+# NAME
+
+CURLOPT_MPTCP - enable Multipath TCP
+
+# SYNOPSIS
+
+~~~c
+
+#include <curl/curl.h>
+
+CURLcode curl_easy_setopt(CURL *handle, CURLOPT_MPTCP, long enable);
+~~~
+
+# DESCRIPTION
+
+Pass a long as parameter set to 1L to enable or 0 to disable.
+
+Multipath TCP (MPTCP) is an extension of TCP that allows multiple paths 
+to be used simultaneously by a single TCP connection, enhancing redundancy, 
+bandwidth, and potentially reducing latency. 
+It works by presenting a standard TCP interface to applications while 
+managing multiple underlying TCP connections.
+
+Enabling MPTCP can improve the performance and reliability of network requests, 
+particularly in environments where multiple network paths (e.g., WiFi and 
+cellular) are available.
+
+Note: MPTCP support depends on the underlying operating system and network 
+infrastructure. Not all networks support MPTCP, and its effectiveness will 
+vary based on the network configuration and conditions.
+
+# DEFAULT
+
+0
+
+# PROTOCOLS
+
+All
+
+# EXAMPLE
+
+~~~c
+
+int main(void)
+{
+  CURL *curl = curl_easy_init();
+  if(curl) {
+    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
+    curl_easy_setopt(curl, CURLOPT_MPTCP, 1L);
+    curl_easy_perform(curl);
+  }
+}
+~~~
+
+# AVAILABILITY
+
+Support for MPTCP in libcurl requires Linux 5.6 or later. The feature's availability in libcurl can also depend on the version of libcurl. Added in 8.6.1.
+
+# RETURN VALUE
+
+Returns CURLE_OK if MPTCP is successfully enabled for the connection, otherwise returns an error code specific to the reason it could not be enabled, which might include lack of operating system support or libcurl not being built with MPTCP support.

docs/libcurl/symbols-in-versions

@@ -708,6 +708,7 @@ CURLOPT_MAXREDIRS               7.5
 CURLOPT_MIME_OPTIONS            7.81.0
 CURLOPT_MIMEPOST                7.56.0
 CURLOPT_MUTE                    7.1           7.8         7.15.5
+CURLOPT_MPTCP                   8.6.1
 CURLOPT_NETRC                   7.1
 CURLOPT_NETRC_FILE              7.11.0
 CURLOPT_NEW_DIRECTORY_PERMS     7.16.4

docs/options-in-versions

@@ -125,6 +125,7 @@
 --max-redirs                         7.5
 --max-time (-m)                      4.0
 --metalink                           7.27.0
+--mptcp                              8.6.1
 --negotiate                          7.10.6
 --netrc (-n)                         4.6
 --netrc-file                         7.21.5

include/curl/curl.h

@@ -2206,6 +2206,9 @@ typedef enum {
   /* millisecond version */
   CURLOPT(CURLOPT_SERVER_RESPONSE_TIMEOUT_MS, CURLOPTTYPE_LONG, 324),
 
+  /* Set MPTCP */
+  CURLOPT(CURLOPT_MPTCP, CURLOPTTYPE_LONG, 325),
+
   CURLOPT_LASTENTRY /* the last unused */
 } CURLoption;
 

lib/cf-socket.c

@@ -244,6 +244,10 @@ void Curl_sock_assign_addr(struct Curl_sockaddr_ex *dest,
     dest->socktype = SOCK_STREAM;
     dest->protocol = IPPROTO_IP;
     break;
+  case TRNSPRT_MPTCP:
+    dest->socktype = SOCK_STREAM;
+    dest->protocol = IPPROTO_MPTCP;
+    break;
   default: /* UDP and QUIC */
     dest->socktype = SOCK_DGRAM;
     dest->protocol = IPPROTO_UDP;
@@ -1601,7 +1605,12 @@ CURLcode Curl_cf_tcp_create(struct Curl_cfilter **pcf,
   if(!ctx) {
     result = CURLE_OUT_OF_MEMORY;
     goto out;
+  }  
+#ifdef __linux__
+  if (data->set.mptcp)  {
+     transport = TRNSPRT_MPTCP;
   }
+#endif
   cf_socket_ctx_init(ctx, ai, transport);
 
   result = Curl_cf_create(&cf, &Curl_cft_tcp, ctx);

lib/cf-socket.h

@@ -28,6 +28,10 @@
 #include "nonblock.h" /* for curlx_nonblock(), formerly Curl_nonblock() */
 #include "sockaddr.h"
 
+#ifndef IPPROTO_MPTCP
+#define IPPROTO_MPTCP 262
+#endif
+
 struct Curl_addrinfo;
 struct Curl_cfilter;
 struct Curl_easy;

lib/easyoptions.c

@@ -178,6 +178,7 @@ struct curl_easyoption Curl_easyopts[] = {
   {"MAX_SEND_SPEED_LARGE", CURLOPT_MAX_SEND_SPEED_LARGE, CURLOT_OFF_T, 0},
   {"MIMEPOST", CURLOPT_MIMEPOST, CURLOT_OBJECT, 0},
   {"MIME_OPTIONS", CURLOPT_MIME_OPTIONS, CURLOT_LONG, 0},
+  {"MPTCP", CURLOPT_MPTCP, CURLOT_LONG, 0},
   {"NETRC", CURLOPT_NETRC, CURLOT_VALUES, 0},
   {"NETRC_FILE", CURLOPT_NETRC_FILE, CURLOT_STRING, 0},
   {"NEW_DIRECTORY_PERMS", CURLOPT_NEW_DIRECTORY_PERMS, CURLOT_LONG, 0},
@@ -375,6 +376,6 @@ struct curl_easyoption Curl_easyopts[] = {
  */
 int Curl_easyopts_check(void)
 {
-  return ((CURLOPT_LASTENTRY%10000) != (324 + 1));
+  return ((CURLOPT_LASTENTRY%10000) != (325 + 1));
 }
 #endif

lib/setopt.c

@@ -2931,6 +2931,9 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
     result = CURLE_NOT_BUILT_IN;
 #endif
     break;
+  case  CURLOPT_MPTCP:
+    data->set.mptcp = TRUE;
+    break;  
   case CURLOPT_SSL_ENABLE_NPN:
     break;
   case CURLOPT_SSL_ENABLE_ALPN:

lib/urldata.h

@@ -788,6 +788,7 @@ struct ldapconninfo;
 #define TRNSPRT_UDP 4
 #define TRNSPRT_QUIC 5
 #define TRNSPRT_UNIX 6
+#define TRNSPRT_MPTCP 7
 
 /*
  * The connectdata struct contains all fields and variables that should be
@@ -1811,6 +1812,7 @@ struct UserDefined {
 #ifdef USE_WEBSOCKETS
   BIT(ws_raw_mode);
 #endif
+  bool mptcp; /* enable MPTCP support */
 };
 
 #ifndef CURL_DISABLE_MIME

src/tool_cfgable.c

@@ -45,6 +45,7 @@ void config_init(struct OperationConfig *config)
   config->http09_allowed = FALSE;
   config->ftp_skip_ip = TRUE;
   config->file_clobber_mode = CLOBBER_DEFAULT;
+  config->mptcp = FALSE;
   curlx_dyn_init(&config->postdata, MAX_FILE2MEMORY);
 }
 

src/tool_cfgable.h

@@ -298,6 +298,7 @@ struct OperationConfig {
   struct State state;             /* for create_transfer() */
   bool rm_partial;                /* on error, remove partially written output
                                      files */
+  bool mptcp;
 };
 
 struct GlobalConfig {

src/tool_getparam.c

@@ -199,6 +199,7 @@ typedef enum {
   C_MAX_REDIRS,
   C_MAX_TIME,
   C_METALINK,
+  C_MPTCP,
   C_NEGOTIATE,
   C_NETRC,
   C_NETRC_FILE,
@@ -480,6 +481,7 @@ static const struct LongShort aliases[]= {
   {"max-redirs",                 ARG_STRG, ' ', C_MAX_REDIRS},
   {"max-time",                   ARG_STRG, 'm', C_MAX_TIME},
   {"metalink",                   ARG_BOOL, ' ', C_METALINK},
+  {"mptcp",                      ARG_BOOL, ' ', C_MPTCP},
   {"negotiate",                  ARG_BOOL, ' ', C_NEGOTIATE},
   {"netrc",                      ARG_BOOL, 'n', C_NETRC},
   {"netrc-file",                 ARG_FILE, ' ', C_NETRC_FILE},
@@ -2742,6 +2744,9 @@ ParameterError getparameter(const char *flag, /* f or -long-flag */
         }
       }
       break;
+    case C_MPTCP: /* --mptcp */
+      config->mptcp = TRUE;
+      break;
     default: /* unknown flag */
       err = PARAM_OPTION_UNKNOWN;
       break;

src/tool_listhelp.c

@@ -378,6 +378,9 @@ const struct helptxt helptext[] = {
   {"    --metalink",
    "Process given URLs as metalink XML file",
    CURLHELP_MISC},
+  {"    --mptcp",
+   "Enable Multipath TCP (MPTCP)",
+   CURLHELP_CONNECTION},
   {"    --negotiate",
    "Use HTTP Negotiate (SPNEGO) authentication",
    CURLHELP_AUTH | CURLHELP_HTTP},

src/tool_operate.c

@@ -1291,6 +1291,9 @@ static CURLcode single_transfer(struct GlobalConfig *global,
         if(config->tcp_fastopen)
           my_setopt(curl, CURLOPT_TCP_FASTOPEN, 1L);
 
+        if(config->mptcp)
+          my_setopt(curl, CURLOPT_MPTCP, 1L);        
+
         /* where to store */
         my_setopt(curl, CURLOPT_WRITEDATA, per);
         my_setopt(curl, CURLOPT_INTERLEAVEDATA, per);

tests/data/Makefile.inc

@@ -261,4 +261,4 @@ test3024 test3025 test3026 test3027 test3028 test3029 test3030 \
 \
 test3100 test3101 test3102 test3103 \
 test3200 \
-test3201 test3202
+test3201 test3202 test3203

tests/data/test3203

@@ -0,0 +1,49 @@
+<testcase>
+<info>
+<keywords>
+MPTCP
+Multipath TCP
+mptcp
+</keywords>
+</info>
+
+<!-- Server-side configuration -->
+<reply>
+<data nocheck="yes">
+HTTP/1.1 200 OK
+Server: swsclose
+Content-Type: text/plain
+
+Ceci est une réponse de test MPTCP.
+</data>
+</reply>
+
+<!-- Client-side commands -->
+<client>
+<server>
+mptcp
+</server>
+<precheck>
+sh -c '[ "$(cat /proc/sys/net/mptcp/enabled 2>/dev/null)" = "1" ]'
+</precheck>
+<name>
+MPTCP GET Request
+</name>
+<command>
+--mptcp http://%HOSTIP:%HTTPPORT/%TESTNUMBER
+</command>
+</client>
+
+  <!-- Verification -->
+<verify>
+<protocol>
+GET /%TESTNUMBER HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+User-Agent: curl/%VERSION
+Accept: */*
+</protocol>
+<errorcode>
+      0
+</errorcode>
+</verify>
+</testcase>

tests/http-server.pl

@@ -56,6 +56,7 @@ BEGIN
 my $keepalive_secs;  # number of seconds to keep idle connections
 my $srcdir;
 my $gopher = 0;
+my $mptcp = 0;
 
 my $flags  = "";
 my $path   = '.';
@@ -115,6 +116,9 @@ BEGIN
     elsif($ARGV[0] eq '--gopher') {
         $gopher = 1;
     }
+    elsif($ARGV[0] eq '--mptcp') {
+        $mptcp = 1;
+    }
     elsif($ARGV[0] eq '--port') {
         if($ARGV[1] =~ /^(\d+)$/) {
             $port = $1;
@@ -177,6 +181,7 @@ BEGIN
     "--logdir \"$logdir\" ".
     "--portfile \"$portfile\" ";
 $flags .= "--gopher " if($gopher);
+$flags .= "--mptcp " if($mptcp);
 $flags .= "--connect $connect " if($connect);
 $flags .= "--keepalive $keepalive_secs " if($keepalive_secs);
 if($ipvnum eq 'unix') {

tests/runner.pm

@@ -590,7 +590,7 @@ sub singletest_startservers {
 
     # timestamp required servers verification start
     $$testtimings{"timesrvrini"} = Time::HiRes::time();
-
+    
     my $why;
     my $error;
     if (!$listonly) {

tests/runtests.pl

@@ -463,6 +463,9 @@ sub parseprotocols {
     # 'http-proxy' is used in test cases to do CONNECT through
     push @protocols, 'http-proxy';
 
+    # 'mptcp' is used in test cases to do MPTCP
+    push @protocols, 'mptcp';
+
     # 'none' is used in test cases to mean no server
     push @protocols, 'none';
 }