[vlc-devel] [PATCH] Add support for AMT multicast tunneling over non-multicast enabled networks

Thomas Guillem thomas at gllm.fr
Mon Aug 5 11:25:31 CEST 2019


Hello, 

On Fri, Aug 2, 2019, at 22:11, Natalie Landsberg wrote:
> Updated based on VLC developer comments.
> 
> Changes:
>   1. in amt_send_mem_upd(), memcpy was used to copy structs. Changed to 
> copy each individual piece, like uint8_t, uin16_t, etc.
>   2. similar to above, changed in amt_rcv_mem_query()
>   3. for both amt_rcv_mem_query() and amt_send_mem_upd(), made sure to 
> set each part to little endian before sending.

Great.

But I just encountered a crash when closing VLC while AMT was opening. cf. the comments regarding net_Close/net_Open.

I also have other comments.

> ---
>  modules/access/Makefile.am |    4 +
>  modules/access/amt.c       | 1489 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 1493 insertions(+)
>  create mode 100644 modules/access/amt.c
> 
> diff --git a/modules/access/Makefile.am b/modules/access/Makefile.am
> index 1b85e8dd18..c3a82f6333 100644
> --- a/modules/access/Makefile.am
> +++ b/modules/access/Makefile.am
> @@ -379,6 +379,10 @@ libudp_plugin_la_SOURCES = access/udp.c
>  libudp_plugin_la_LIBADD = $(SOCKET_LIBS)
>  access_LTLIBRARIES += libudp_plugin.la
>  
> +libamt_plugin_la_SOURCES = access/amt.c access/amt.h
> +libamt_plugin_la_LIBADD = $(SOCKET_LIBS)
> +access_LTLIBRARIES += libamt_plugin.la
> +
>  libunc_plugin_la_SOURCES = access/unc.c access/smb_common.h
>  libunc_plugin_la_LIBADD = -lmpr -lnetapi32
>  if HAVE_WIN32
> diff --git a/modules/access/amt.c b/modules/access/amt.c
> new file mode 100644
> index 0000000000..a96a2066f7
> --- /dev/null
> +++ b/modules/access/amt.c
> @@ -0,0 +1,1489 @@
> +/**
> + * @file amt.c
> + * @brief Automatic Multicast Tunneling Protocol (AMT) file for VLC 
> media player
> + * Allows multicast streaming when not in a multicast-enabled network
> + * Currently IPv4 is supported, but IPv6 is not yet.
> + *
> + * Copyright (C) 2018 VLC authors and VideoLAN
> + * Copyright (c) Juniper Networks, Inc., 2018. All rights reserved.
> + *
> + * Authors: Christophe Massiot <massiot at via.ecp.fr>           - 
> original UDP code
> + *          Tristan Leteurtre <tooney at via.ecp.fr>             - 
> original UDP code
> + *          Laurent Aimar <fenrir at via.ecp.fr>                 - 
> original UDP code
> + *          Jean-Paul Saman <jpsaman #_at_# m2x dot nl>       - 
> original UDP code
> + *          Remi Denis-Courmont                               - 
> original UDP code
> + *          Natalie Landsberg <natalie.landsberg97 at gmail.com> - AMT 
> support
> + *          Wayne Brassem <wbrassem at rogers.com>               - Added 
> FQDN support
> + *
> + * This code is licensed to you under the GNU Lesser General Public 
> License
> + * version 2.1 or later. You may not use this code except in 
> compliance with
> + * the GNU Lesser General Public License.
> + * This code is not an official Juniper product.
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public License
> + * as published by the Free Software Foundation; either version 2.1
> + * of the License, or (at your option) any later version.
> + *
> + * This library 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 Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
> 02110-1301  USA
> + 
> ****************************************************************************/
> +#ifdef HAVE_CONFIG_H
> +# include "config.h"
> +#endif
> +
> +#include <errno.h>
> +#include <ctype.h>
> +#include <assert.h>
> +#ifdef HAVE_ARPA_INET_H
> +# include <arpa/inet.h>
> +#endif
> +
> +#ifdef HAVE_SYS_SELECT_H
> +# include <sys/select.h>
> +#endif
> +
> +#ifdef HAVE_SYS_SOCKET_H
> +# include <sys/socket.h>
> +#endif
> +
> +#include <vlc_common.h>
> +#include <vlc_demux.h>
> +#include <vlc_plugin.h>
> +#include <vlc_access.h>
> +#include <vlc_network.h>
> +#include <vlc_block.h>
> +#include <vlc_interrupt.h>
> +#include <vlc_url.h>
> +
> +#ifdef HAVE_POLL
> + #include <poll.h>
> +#endif
> +#ifdef HAVE_SYS_UIO_H
> + #include <sys/uio.h>
> +#endif
> +
> +#define BUFFER_TEXT N_("Receive buffer")
> +#define BUFFER_LONGTEXT N_("AMT receive buffer size (bytes)" )
> +#define TIMEOUT_TEXT N_("Native multicast timeout (sec)")
> +#define AMT_TIMEOUT_TEXT N_("AMT timeout (sec)")
> +#define AMT_RELAY_ADDRESS N_("AMT relay (IP address or FQDN)")
> +#define AMT_RELAY_ADDR_LONG N_("AMT relay anycast address, or specify 
> the relay you want by address or fully qualified domain name")
> +#define AMT_DEFAULT_RELAY N_("amt-relay.m2icast.net")
> +
> +/*****************************************************************************
> + * Various Lengths of Msgs or Hdrs
> + 
> *****************************************************************************/
> +#define MAC_LEN 6                /* length of generated MAC in bytes */
> +#define NONCE_LEN 4              /* length of nonce in bytes */
> +
> +#define MSG_TYPE_LEN 1           /* length of msg type */
> +#define RELAY_QUERY_MSG_LEN 48   /* total length of relay query */
> +#define RELAY_ADV_MSG_LEN 12     /* length of relay advertisement 
> message */
> +#define IGMP_QUERY_LEN 24        /* length of encapsulated IGMP query 
> message */
> +#define IGMP_REPORT_LEN 20
> +#define AMT_HDR_LEN 2            /* length of AMT header on a packet */
> +#define IP_HDR_LEN 20            /* length of standard IP header */
> +#define IP_HDR_IGMP_LEN 24       /* length of IP header with an IGMP 
> report */
> +#define UDP_HDR_LEN 8            /* length of standard UDP header */
> +#define AMT_REQUEST_MSG_LEN 9
> +#define AMT_DISCO_MSG_LEN 8
> +
> +/*****************************************************************************
> + * Different AMT Message Types
> + 
> *****************************************************************************/
> +#define AMT_RELAY_DISCO 1       /* relay discovery */
> +#define AMT_RELAY_ADV 2         /* relay advertisement */
> +#define AMT_REQUEST 3           /* request */
> +#define AMT_MEM_QUERY 4         /* membership query */
> +#define AMT_MEM_UPD 5           /* membership update */
> +#define AMT_MULT_DATA 6         /* multicast data */
> +#define AMT_TEARDOWN 7          /* teardown (not currently supported) 
> */
> +
> +/*****************************************************************************
> + * Different IGMP Message Types
> + 
> *****************************************************************************/
> +#define AMT_IGMPV3_MEMBERSHIP_QUERY_TYPEID 0x11
> +#define AMT_IGMPV3_MEMBERSHIP_REPORT_TYPEID 0x22
> +/* IGMPv2, interoperability  */
> +#define AMT_IGMPV1_MEMBERSHIP_REPORT_TYPEID 0x12
> +#define AMT_IGMPV2_MEMBERSHIP_REPORT_TYPEID 0x16
> +#define AMT_IGMPV2_MEMBERSHIP_LEAVE_TYPEID 0x17
> +
> +#define AMT_IGMP_INCLUDE 0x01
> +#define AMT_IGMP_EXCLUDE 0x02
> +#define AMT_IGMP_INCLUDE_CHANGE 0x03
> +#define AMT_IGMP_EXCLUDE_CHANGE 0x04
> +#define AMT_IGMP_ALLOW 0x05
> +#define AMT_IGMP_BLOCK 0x06
> +
> +#define MCAST_ANYCAST  "0.0.0.0"
> +#define MCAST_ALLHOSTS "224.0.0.22"
> +#define LOCAL_LOOPBACK "127.0.0.1"
> +#define AMT_PORT 2268
> +
> +#define MAX_IPV4_UDP (65535u - (20 + 8))
> +
> +/* IPv4 Header Format */
> +typedef struct _amt_ip {
> +    uint8_t  ver_ihl;
> +    uint8_t  tos;
> +    uint16_t tot_len;
> +    uint16_t id;
> +    uint16_t frag_off;
> +    uint8_t  ttl;
> +    uint8_t  protocol;
> +    uint16_t check;
> +    uint32_t srcAddr;
> +    uint32_t destAddr;
> +} amt_ip_t;
> +
> +/* IPv4 Header Format with options field */
> +typedef struct _amt_ip_alert {
> +    uint8_t  ver_ihl;
> +    uint8_t  tos;
> +    uint16_t tot_len;
> +    uint16_t id;
> +    uint16_t frag_off;
> +    uint8_t  ttl;
> +    uint8_t  protocol;
> +    uint16_t check;
> +    uint32_t srcAddr;
> +    uint32_t destAddr;
> +    uint32_t options;
> +} amt_ip_alert_t;
> +
> +/* IGMPv3 Group Record Format (RFC3376) */
> +typedef struct _amt_igmpv3_groupRecord {
> +    uint8_t  type;
> +    uint8_t  auxDatalen;
> +    uint16_t nSrc;
> +    uint32_t ssm;
> +    uint32_t srcIP[1];
> +} amt_igmpv3_groupRecord_t;
> +
> +/* IGMPv3 Membership Report Format (RFC3376) */
> +typedef struct _amt_igmpv3_membership_report {
> +    uint8_t  type;
> +    uint8_t  resv;
> +    uint16_t checksum;
> +    uint16_t resv2;
> +    uint16_t nGroupRecord;
> +    amt_igmpv3_groupRecord_t grp[1];
> +} amt_igmpv3_membership_report_t;
> +
> +/* IGMPv3 Membership Query Format (RFC3376) */
> +typedef struct _amt_igmpv3_membership_query {
> +    uint8_t  type;
> +    uint8_t  max_resp_code;  /* in 100ms, Max Resp Time = (mant | 
> 0x10) << (exp + 3) */
> +    uint32_t checksum;
> +    uint32_t ssmIP;
> +    uint8_t  s_qrv;
> +    uint8_t  qqic;           /* in second, query Time = (mant | 0x10) 
> << (exp + 3) */
> +    uint16_t nSrc;
> +    uint32_t srcIP[1];
> +} amt_igmpv3_membership_query_t;
> +
> +/* ATM Membership Update Format (RFC7450) */
> +typedef struct _amt_membership_update_msg {
> +    amt_ip_alert_t ipHead;
> +    amt_igmpv3_membership_report_t memReport;
> +} amt_membership_update_msg_t;
> +
> +/* AMT Functions */
> +static int amt_sockets_init( stream_t *p_access );
> +static void amt_send_relay_discovery_msg( stream_t *p_access, char 
> *relay_ip );
> +static void amt_send_relay_request( stream_t *p_access, char *relay_ip 
> );
> +static int amt_joinSSM_group( stream_t *p_access );
> +static int amt_joinASM_group( stream_t *p_access );
> +static int amt_leaveASM_group( stream_t *p_access );
> +static int amt_leaveSSM_group( stream_t *p_access );
> +static bool amt_rcv_relay_adv( stream_t *p_access );
> +static bool amt_rcv_relay_mem_query( stream_t *p_access );
> +static void amt_send_mem_update( stream_t *p_access, char *relay_ip, 
> bool leave );
> +static bool open_amt_tunnel( stream_t *p_access );
> +static void *amt_mem_upd( void *data );
> +
> +/* Struct to hold AMT state */
> +typedef struct _access_sys_t
> +{
> +    char *mcastGroup;
> +    char *mcastSrc;
> +    char *relay;
> +    char *relayDisco;

Why not using  char serverinfo[INET_ADDRSTRLEN] here ?

That way, you got one less strdup/free/malloc-check to do.

> +    block_t *overflow_block;
> +
> +    vlc_thread_t updateThread;
> +    vlc_tick_t queryTime;
> +
> +    /* Mulicast group and source */
> +    struct sockaddr_in mcastGroupAddr;
> +    struct sockaddr_in mcastSrcAddr;
> +
> +    /* AMT relay imformation */
> +    struct sockaddr_in relayDiscoAddr;
> +    struct sockaddr_in relayAddr;
> +    struct sockaddr_in stLocalAddr;
> +    struct sockaddr_in stSvrAddr;
> +
> +    /* AMT Relay Membership Query data (RFC7450) */
> +    struct relay_mem_query_msg_t {
> +        uint32_t ulRcvedNonce;
> +        uint8_t  type;
> +        uint8_t  uchaMAC[MAC_LEN];
> +        uint8_t  uchaIGMP[IGMP_QUERY_LEN];
> +    } relay_mem_query_msg;
> +
> +    /* AMT Relay Advertisement data (RFC7450) */
> +    struct relay_adv_msg_t {
> +        uint32_t ulRcvNonce;
> +        uint32_t ipAddr;
> +        uint8_t  type;
> +    } relay_adv_msg;
> +
> +    amt_ip_t relay_ip_hdr;
> +    amt_igmpv3_membership_query_t relay_igmp_query;
> +    ssize_t mtu;
> +
> +    uint32_t glob_ulNonce;
> +    uint32_t ulRelayNonce;
> +
> +    int fd;
> +    int sAMT;
> +    int sQuery;
> +    int timeout;
> +    int amtTimeout;
> +
> +    bool tryAMT;
> +    bool threadReady;
> +} access_sys_t;
> +
> +/* Standard open/close functions */
> +static int  Open (vlc_object_t *);
> +static void Close (vlc_object_t *);
> +
> +/* Utility functions */
> +static uint16_t get_checksum(void* vdata, size_t length);
> +static void make_report( amt_igmpv3_membership_report_t *mr );
> +static void make_ip_header( amt_ip_alert_t *ipHead );
> +
> +vlc_module_begin ()
> +    set_shortname( N_("AMT" ) )
> +    set_description( N_("AMT input") )
> +    set_category( CAT_INPUT )
> +    set_subcategory( SUBCAT_INPUT_ACCESS )
> +
> +    add_integer( "amt-timeout", 5, AMT_TIMEOUT_TEXT, NULL, true )
> +    add_integer( "amt-native-timeout", 3, TIMEOUT_TEXT, NULL, true )
> +    add_string( "amt-relay", AMT_DEFAULT_RELAY, AMT_RELAY_ADDRESS, 
> AMT_RELAY_ADDR_LONG, true )
> +
> +    set_capability( "access", 0 )
> +    add_shortcut( "amt" )
> +
> +    set_callbacks( Open, Close )
> +vlc_module_end ()
> +
> +/*****************************************************************************
> + * Local prototypes
> + 
> *****************************************************************************/
> +static block_t *BlockUDP( stream_t *, bool * );
> +static int Control( stream_t *, int, va_list );
> +
> +/*****************************************************************************
> + * Open: Open a connection to the multicast feed
> + 
> *****************************************************************************/
> +static int Open( vlc_object_t *p_this )
> +{
> +    stream_t            *p_access = (stream_t*) p_this;
> +    access_sys_t        *sys = NULL;
> +    struct addrinfo      hints, *serverinfo = NULL;
> +    struct sockaddr_in  *server_addr;
> +    char                *psz_name = NULL, *saveptr, *psz_strtok_r, 
> ip_buffer[INET_ADDRSTRLEN];
> +    int                  i_bind_port = 1234, i_server_port = 0, 
> VLC_ret = VLC_SUCCESS, res;
> +    vlc_url_t            url;
> +
> +    if( p_access->b_preparsing )
> +        return VLC_EGENERIC;
> +
> +    /* Allocate the structure for holding AMT info and zeroize it */
> +    sys = vlc_obj_calloc( p_this, 1, sizeof( *sys ) );
> +    if( unlikely( sys == NULL ) )
> +        return VLC_ENOMEM;
> +
> +    /* The standard MPEG-2 transport is 188 bytes.  7 packets fit into 
> a standard 1500 byte Ethernet frame */
> +    sys->mtu = 7 * 188;
> +
> +    /* Protective packet overflow buffer designed to accommodate 
> maximum IPv4 UDP payload minus the anticapated MTU */
> +    sys->overflow_block = block_Alloc(MAX_IPV4_UDP - sys->mtu);
> +    if( unlikely( sys->overflow_block == NULL ) )
> +        return VLC_ENOMEM;
> +
> +    p_access->p_sys = sys;
> +
> +    /* Set up p_access */
> +    ACCESS_SET_CALLBACKS( NULL, BlockUDP, Control, NULL );
> +
> +    if( !p_access->psz_location )
> +        return VLC_EGENERIC;
> +
> +    psz_name = strdup( p_access->psz_location );
> +    if ( unlikely( psz_name == NULL ) )
> +        return VLC_ENOMEM;
> +
> +    /* Parse psz_name syntax :
> +     * [serveraddr[:serverport]][@[bindaddr]:[bindport]] */
> +    if( vlc_UrlParse( &url, p_access->psz_url ) != 0 )
> +    {
> +        msg_Err( p_access, "Invalid URL: %s", p_access->psz_url );
> +        VLC_ret = VLC_EGENERIC;
> +        goto cleanup;
> +    }
> +
> +    /* Determining the multicast source and group depends on the URL 
> provided */
> +    /*                                                                 
>        */
> +    /* The address(es) in the URL can be in the form of IP address or 
> FQDN    */
> +    /* By calling vlc_getaaddrinfo() you get it in IP form either way  
>        */
> +    /*                                                                 
>        */
> +    /* Case 1: amt://<source-ip-address>@<multicast-group-ip-address>  
>        */
> +    /*                                                                 
>        */
> +    /*         sys->mcastSrc = <source-ip-address>                     
>        */
> +    /*         sys->mcastSrcAddr = inet_pton( sys->mcastSrc )          
>        */
> +    /*                                                                 
>        */
> +    /*         sys->mcastGroup = <multicast-group-ip-address>          
>        */
> +    /*         sys->mcastGroupAddr = inet_pton( sys->mcastGroup )      
>        */
> +    /*                                                                 
>        */
> +    /* Case 2: amt://<multicast-group-ip-address>                      
>        */
> +    /*                                                                 
>        */
> +    /*         sys->mcastSrc = MCAST_ANYCAST = "0.0.0.0"               
>        */
> +    /*         sys->mcastSrcAddr = inet_pton( sys->mcastSrc ) = 0      
>        */
> +    /*                                                                 
>        */
> +    /*         sys->mcastGroup = <multicast-group-ip-address>          
>        */
> +    /*         sys->mcastGroupAddr = inet_pton( sys->mcastGroup )      
>        */
> +    /*                                                                 
>        */
> +
> +    /* If UDP port provided then assign port to stream */
> +    if( url.i_port > 0 )
> +        i_bind_port = url.i_port;
> +
> +    msg_Dbg( p_access, "Opening multicast: %s:%d local=%s:%d", 
> url.psz_host, i_server_port, url.psz_path, i_bind_port );
> +
> +    /* Initialize hints prior to call to vlc_getaddrinfo with either 
> IP address or FQDN */
> +    memset( &hints, 0, sizeof( hints ));
> +    hints.ai_family = AF_INET;  /* Setting to AF_UNSPEC accepts both 
> IPv4 and IPv6 */
> +    hints.ai_socktype = SOCK_DGRAM;
> +
> +    /* Retrieve list of multicast addresses matching the multicast 
> group identifier */
> +    res = vlc_getaddrinfo( url.psz_host, AMT_PORT, &hints, &serverinfo 
> );
> +
> +    /* If an error returned print reason and exit */
> +    if( res )
> +    {
> +        msg_Err( p_access, "Could not find multicast group %s, reason: 
> %s", url.psz_host, gai_strerror(res) );
> +        VLC_ret = VLC_EGENERIC;
> +        goto cleanup;
> +    }
> +
> +    /* Convert binary socket address to string */
> +    server_addr = (struct sockaddr_in *) serverinfo->ai_addr;
> +    inet_ntop(AF_INET, &(server_addr->sin_addr), ip_buffer, 
> INET_ADDRSTRLEN);

error, not checked here.

> +
> +    /* Store the binary socket representation of multicast group 
> address */
> +    sys->mcastGroupAddr = *server_addr;
> +
> +    /* Release the allocated memory */
> +    freeaddrinfo( serverinfo );
> +    serverinfo = NULL;
> +
> +    /* Store string representation */
> +    sys->mcastGroup = strdup( ip_buffer );
> +    if( unlikely( sys->mcastGroup == NULL ) )
> +    {
> +        VLC_ret = VLC_ENOMEM;
> +        goto cleanup;
> +    }
> +
> +    msg_Dbg( p_access, "Setting multicast group address to %s", 
> sys->mcastGroup);
> +
> +    /* Extract the source from the URL, or the multicast group when no 
> source is provided */
> +    if ( !( psz_strtok_r = strtok_r( psz_name, "@", &saveptr ) ) )
> +    {
> +        msg_Err( p_access, "Could not parse location %s", psz_name);
> +        VLC_ret = VLC_EGENERIC;
> +        goto cleanup;
> +    }
> +
> +    /* Store the string representation */
> +    sys->mcastSrc = strdup( psz_strtok_r );
> +    if( unlikely( sys->mcastSrc == NULL ) )
> +    {
> +        VLC_ret = VLC_ENOMEM;
> +        goto cleanup;
> +    }
> +
> +    /* If strings are equal then no multicast source has been 
> specified, so try anycast */
> +    if( strcmp( url.psz_host, sys->mcastSrc ) == 0 )
> +    {
> +        free( sys->mcastSrc );
> +        sys->mcastSrc = strdup(MCAST_ANYCAST);
> +        sys->mcastSrcAddr.sin_addr.s_addr = 0;
> +        msg_Dbg( p_access, "No multicast source address specified, 
> trying ASM...");
> +    }
> +
> +    /* retrieve list of source addresses matching the multicast source 
> identifier */
> +    res = vlc_getaddrinfo( sys->mcastSrc, AMT_PORT, &hints, 
> &serverinfo );
> +
> +    /* If an error returned print reason and exit */
> +    if( res )
> +    {
> +        msg_Err( p_access, "Could not find multicast source %s, 
> reason: %s", sys->mcastSrc, gai_strerror(res) );
> +        VLC_ret = VLC_EGENERIC;
> +        goto cleanup;
> +    }
> +
> +    /* Convert binary socket address to string */
> +    server_addr = (struct sockaddr_in *) serverinfo->ai_addr;
> +    inet_ntop(AF_INET, &(server_addr->sin_addr), ip_buffer, 
> INET_ADDRSTRLEN);

error, not checked here

> +
> +    /* Store the binary socket representation of multicast source 
> address */
> +    sys->mcastSrcAddr = *server_addr;
> +
> +    /* free the original source address buffer (IP or FQDN) and assign 
> it just the IP address */
> +    free( sys->mcastSrc );
> +
> +    /* Store string representation */
> +    sys->mcastSrc = strdup( ip_buffer );
> +    if( unlikely( sys->mcastSrc == NULL ) )
> +    {
> +        VLC_ret = VLC_ENOMEM;
> +        goto cleanup;
> +    }
> +
> +    msg_Dbg( p_access, "Setting multicast source address to %s", 
> sys->mcastSrc);
> +
> +    /* Pull the AMT relay address from the settings */
> +    sys->relay = var_InheritString( p_access, "amt-relay" );
> +    if( unlikely( sys->relay == NULL ) )
> +    {
> +        msg_Err( p_access, "No relay anycast or unicast address 
> specified." );
> +        VLC_ret = VLC_EGENERIC;
> +        goto cleanup;
> +    }
> +
> +    msg_Dbg( p_access, "Addresses: mcastGroup: %s mcastSrc: %s relay: 
> %s", \
> +             sys->mcastGroup, sys->mcastSrc, sys->relay);
> +
> +    /* Native multicast file descriptor */
> +    sys->fd = net_OpenDgram( p_access, sys->mcastGroup, i_bind_port,
> +                             sys->mcastSrc, i_server_port, IPPROTO_UDP 
> );
> +    if( sys->fd == -1 )
> +    {
> +        msg_Err( p_access, "cannot open socket" );
> +        VLC_ret = VLC_EGENERIC;
> +        goto cleanup;
> +    }

You should also init other FDs (sAMT, sQuery) to -1 here.

> +
> +    sys->timeout = var_InheritInteger( p_access, "amt-native-timeout");
> +    if( sys->timeout > 0)
> +        sys->timeout *= 1000;
> +
> +    sys->amtTimeout = var_InheritInteger( p_access, "amt-timeout" );
> +    if( sys->amtTimeout > 0)
> +        sys->amtTimeout *= 1000;
> +
> +    sys->tryAMT = false;
> +    sys->threadReady = false;
> +
> +cleanup: /* fall through */
> +
> +    /* release the allocated memory */
> +    free( psz_name );
> +    vlc_UrlClean( &url );
> +    freeaddrinfo( serverinfo );
> +
> +    /* if an error occurred free the memory */
> +    if ( VLC_ret != VLC_SUCCESS )
> +    {
> +        msg_Dbg( p_access, "Open(): Before free( sys-> sys->Addr ) #4" 
> );
> +        free( sys->mcastGroup );
> +        free( sys->mcastSrc );
> +    }
> +
> +    return VLC_ret;
> +}
> +
> +/*****************************************************************************
> + * Close: Cancel thread and free data structures
> + 
> *****************************************************************************/
> +static void Close( vlc_object_t *p_this )
> +{
> +    stream_t     *p_access = (stream_t*)p_this;
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    msg_Dbg( p_access, "Closing AMT plugin" );
> +
> +    /* If using AMT tunneling send leave message and free the relay 
> addresses */
> +    if ( sys->tryAMT )
> +    {
> +        /* Prepare socket options */
> +        if( sys->mcastSrcAddr.sin_addr.s_addr )
> +            amt_leaveSSM_group( p_access );
> +        else
> +            amt_leaveASM_group( p_access );
> +
> +        /* Send IGMP leave message */
> +        amt_send_mem_update( p_access, sys->relayDisco, true );
> +
> +        free( sys->relay );
> +        free( sys->relayDisco );
> +    }
> +
> +    /* If overflow block allocated then free the memory */
> +    if( sys->overflow_block )
> +        block_Release( sys->overflow_block );
> +
> +    /* If membership thread spawned cancel it */
> +    if( sys->threadReady )
> +    {
> +        msg_Dbg( p_access, "Canceling IGMP membership thread" );
> +        sys->threadReady = false;
> +        vlc_cancel( sys->updateThread );
> +        vlc_join( sys->updateThread, NULL );
> +    }
> +
> +    free( sys->mcastGroup );
> +    free( sys->mcastSrc );
> +
> +    net_Close( sys->fd );
> +    net_Close( sys->sAMT );
> +    net_Close( sys->sQuery );

sAMT, and sQuery are not necessarilly valid here since these socket are opened from the pf_block callback.
You should close them only if != -1.

> +
> +    msg_Dbg( p_access, "Exiting AMT plugin" );
> +}
> +
> +/*****************************************************************************
> + * Control: Define stream controls
> + 
> *****************************************************************************/
> +static int Control( stream_t *p_access, int i_query, va_list args )
> +{
> +    switch( i_query )
> +    {
> +        case STREAM_CAN_SEEK:
> +        case STREAM_CAN_FASTSEEK:
> +        case STREAM_CAN_PAUSE:
> +        case STREAM_CAN_CONTROL_PACE:
> +            *va_arg( args, bool * ) = false;
> +            break;
> +
> +        case STREAM_GET_PTS_DELAY:
> +            *va_arg( args, vlc_tick_t * ) =
> +                VLC_TICK_FROM_MS(var_InheritInteger( p_access, 
> "network-caching" ));
> +            break;
> +
> +        default:
> +            return VLC_EGENERIC;
> +    }
> +
> +    return VLC_SUCCESS;
> +}
> +
> +/*****************************************************************************
> + * BlockUDP: Responsible for returning the multicast payload
> + * BlockUDP: Sections of code are based upon BlockUDP code in udp.c
> + *
> + * Default MTU based on number of MPEG-2 transports carried in a 1500 
> byte Ethernet frame
> + * however the code is able to receive maximal IPv4 UDP frames and 
> then adjusts the MTU
> + 
> *****************************************************************************/
> +static block_t *BlockUDP(stream_t *p_access, bool *restrict eof)
> +{
> +    access_sys_t *sys = p_access->p_sys;
> +    ssize_t len = 0, shift = 0, tunnel = IP_HDR_LEN + UDP_HDR_LEN + 
> AMT_HDR_LEN;
> +
> +    /* Allocate anticipated MTU buffer for holding the UDP packet 
> suitable for native or AMT tunneled multicast */
> +    block_t *pkt = block_Alloc( sys->mtu + tunnel );
> +    if ( unlikely( pkt == NULL ) )
> +        return NULL;
> +
> +    /* Structure initialized to hold anticipated MTU buffer along with 
> protective overflow buffer */
> +    struct iovec iov[] = {{
> +        .iov_base = pkt->p_buffer,
> +        .iov_len = sys->mtu + tunnel,
> +    },{
> +        .iov_base = sys->overflow_block->p_buffer,
> +        .iov_len = sys->overflow_block->i_buffer,
> +    }};
> +
> +    /* References the two element array above to be passed into 
> recvmsg */
> +    struct msghdr msg = {
> +        .msg_iov = iov,
> +        .msg_iovlen = 2,
> +    };
> +
> +    struct pollfd ufd[1];
> +
> +    if( sys->tryAMT )
> +        ufd[0].fd = sys->sAMT; /* AMT tunneling file descriptor */
> +    else
> +        ufd[0].fd = sys->fd;   /* Native multicast file descriptor */
> +    ufd[0].events = POLLIN;
> +
> +    switch (vlc_poll_i11e(ufd, 1, sys->timeout))
> +    {
> +        case 0:
> +            if( !sys->tryAMT )
> +            {
> +                msg_Err(p_access, "Native multicast receive time-out");
> +                if( !open_amt_tunnel( p_access ) )
> +                    goto error;
> +                break;
> +            }
> +            else
> +            {
> +                *eof = true;
> +            }
> +            /* fall through */
> +        case -1:
> +            goto error;
> +    }
> +
> +    /* If using AMT tunneling perform basic checks and point to 
> beginning of the payload */
> +    if( sys->tryAMT )
> +    {
> +        len = recvmsg( sys->sAMT, &msg, 0 );
> +
> +        /* Check for the integrity of the received AMT packet */
> +        if( len < 0 || *(pkt->p_buffer) != AMT_MULT_DATA )
> +            goto error;
> +
> +        /* Set the offet to the first byte of the payload */
> +        shift += tunnel;
> +
> +        /* If the length received is less than the AMT tunnel header 
> then it's truncated */
> +        if( len < tunnel )
> +        {
> +            msg_Err(p_access, "%zd bytes packet truncated (MTU was 
> %zd)", len, sys->mtu);
> +            pkt->i_flags |= BLOCK_FLAG_CORRUPTED;
> +        }
> +
> +        /* Otherwise subtract the length of the AMT encapsulation from 
> the packet received */
> +        else
> +        {
> +            len -= tunnel;
> +        }
> +    }
> +
> +    /* Otherwise pull native multicast */
> +    else
> +    {
> +        len = recvmsg(sys->fd, &msg, 0);
> +    }
> +
> +    /* If the payload length is greater than the MTU then the overflow 
> buffer was utilized */
> +    if ( unlikely( len > sys->mtu ) )
> +    {
> +        msg_Warn(p_access, "%zd bytes packet received (MTU was %zd), 
> adjusting mtu", len, sys->mtu);
> +
> +        block_t *gather_block = sys->overflow_block;
> +
> +        /* Allocate a new overflow buffer based on the received 
> payload length */
> +        sys->overflow_block = block_Alloc(MAX_IPV4_UDP - len);
> +
> +        /* Set number of bytes consumed in the overflow block */
> +        gather_block->i_buffer = len - sys->mtu;
> +
> +        /* Chain the anticipated packet and overflow buffers, copy 
> into a single buffer and free the chain */
> +        pkt->p_next = gather_block;
> +        pkt = block_ChainGather( pkt );
> +
> +        /* Adjust the anticipated MTU to match the payload received */
> +        sys->mtu = len;
> +    }
> +
> +    /* Set the offset to payload start */
> +    pkt->p_buffer += shift;
> +    pkt->i_buffer -= shift;
> +
> +    return pkt;
> +
> +error:
> +    block_Release( pkt );
> +    return NULL;
> +}
> +
> +/*****************************************************************************
> + * open_amt_tunnel: Create an AMT tunnel to the AMT relay
> + 
> *****************************************************************************/
> +static bool open_amt_tunnel( stream_t *p_access )
> +{
> +    struct addrinfo hints, *serverinfo, *server;
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    memset( &hints, 0, sizeof( hints ));
> +    hints.ai_family = AF_INET;  /* Setting to AF_UNSPEC accepts both 
> IPv4 and IPv6 */
> +    hints.ai_socktype = SOCK_DGRAM;
> +
> +    msg_Dbg( p_access, "Attempting AMT to %s...", sys->relay);
> +    sys->tryAMT = true;
> +
> +    /* Retrieve list of addresses matching the AMT relay */
> +    int res = vlc_getaddrinfo( sys->relay, AMT_PORT, &hints, 
> &serverinfo );

"On failure, *res is undefined. On success, it must be freed with"
You are cleaning an undefined variable (serverinfo) in the error path. It is the same for all 3 vlc_getaddrinfo() usages.

> +
> +    /* If an error returned print reason and exit */
> +    if( res )
> +    {
> +        msg_Err( p_access, "Could not find relay %s, reason: %s", 
> sys->relay, gai_strerror(res) );
> +        goto error;
> +    }
> +
> +    /* Iterate through the list of sockets to find one that works */
> +    for (server = serverinfo; server != NULL; server = server->ai_next)
> +    {
> +        struct sockaddr_in *server_addr = (struct sockaddr_in *) 
> server->ai_addr;
> +        char relay_ip[INET_ADDRSTRLEN];
> +
> +        /* Convert to binary representation */
> +        inet_ntop(AF_INET, &(server_addr->sin_addr), relay_ip, 
> INET_ADDRSTRLEN);

error not checked here.

> +
> +        /* Store string representation */
> +        sys->relayDisco = strdup( relay_ip );
> +        if( unlikely( sys->relayDisco == NULL ) )
> +        {
> +            goto error;
> +        }
> +
> +        msg_Dbg( p_access, "Trying AMT Server: %s", sys->relayDisco);
> +
> +        /* Store the binary representation */
> +        sys->relayDiscoAddr.sin_addr = server_addr->sin_addr;
> +
> +        /* If can't open socket try any others in list */
> +        if( amt_sockets_init( p_access ) != 0 )
> +            msg_Err( p_access, "Error initializing socket to %s", 
> relay_ip );
> +
> +        /* Otherwise negotiate with AMT relay and confirm you can pull 
> a UDP packet  */
> +        else
> +        {
> +            amt_send_relay_discovery_msg( p_access, relay_ip );
> +            msg_Dbg( p_access, "Sent relay AMT discovery message to 
> %s", relay_ip );
> +
> +            if( !amt_rcv_relay_adv( p_access ) )
> +            {
> +                msg_Err( p_access, "Error receiving AMT relay 
> advertisement msg from %s, skipping", relay_ip );
> +                goto error;

Should you clean what was done in amt_sockets_init() from here ?

> +            }
> +            msg_Dbg( p_access, "Received AMT relay advertisement from 
> %s", relay_ip );
> +
> +            amt_send_relay_request( p_access, relay_ip );
> +            msg_Dbg( p_access, "Sent AMT relay request message to %s", 
> relay_ip );
> +
> +            if( !amt_rcv_relay_mem_query( p_access ) )
> +            {
> +                msg_Err( p_access, "Could not receive AMT relay 
> membership query from %s, reason: %s", relay_ip, vlc_strerror(errno));
> +                goto error;
> +            }
> +            msg_Dbg( p_access, "Received AMT relay membership query 
> from %s", relay_ip );
> +
> +            /* If single source multicast send SSM join */
> +            if( sys->mcastSrcAddr.sin_addr.s_addr )
> +            {
> +                if( amt_joinSSM_group( p_access ) != 0 )
> +                {
> +                    msg_Err( p_access, "Error joining SSM %s", 
> vlc_strerror(errno) );
> +                    goto error;
> +                }
> +                msg_Dbg( p_access, "Joined SSM src: %s group: %s", 
> sys->mcastSrc, sys->mcastGroup );
> +            }
> +
> +            /* If any source multicast send ASM join */
> +            else {
> +                if( amt_joinASM_group( p_access ) != 0 )
> +                {
> +                    msg_Err( p_access, "Error joining ASM %s", 
> vlc_strerror(errno) );
> +                    goto error;
> +                }
> +                msg_Dbg( p_access, "Joined ASM group: %s", 
> sys->mcastGroup );
> +            }
> +
> +            bool eof=false;
> +            block_t *pkt;
> +
> +            /* Confirm that you can pull a UDP packet from the socket 
> */
> +            if ( !(pkt = BlockUDP( p_access, &eof )) )
> +                msg_Err( p_access, "Unable to receive UDP packet from 
> AMT relay %s for multicast group %s", relay_ip, sys->mcastGroup );
> +            else
> +            {
> +                block_Release( pkt );
> +                msg_Dbg( p_access, "Got UDP packet from multicast 
> group %s via AMT relay %s, continuing...", sys->mcastGroup, relay_ip );
> +                break;   /* found an active server sending UDP 
> packets, so exit loop */
> +           }
> +        }
> +    }
> +
> +    /* if server is NULL then no AMT relay is responding */
> +    if (server == NULL)
> +    {
> +        msg_Err( p_access, "No AMT servers responding" );
> +        goto error;
> +    }
> +
> +    sys->queryTime = vlc_tick_now() / CLOCK_FREQ;
> +
> +    /* release the allocated memory */
> +    freeaddrinfo( serverinfo );
> +    return true;
> +
> +error:
> +    /* release the allocated memory */
> +    freeaddrinfo( serverinfo );
> +    sys->threadReady = false;
> +    return false;
> +}
> +
> +/**
> + * Calculate checksum
> + */
> +static uint16_t get_checksum(void* vdata, size_t length) {
> +    // Cast the data pointer to one that can be indexed.
> +    char* data=(char*)vdata;
> +
> +    // Initialise the accumulator.
> +    uint32_t acc=0xffff;
> +
> +    // Handle complete 16-bit blocks.
> +    for (size_t i=0;i+1<length;i+=2) {
> +        uint16_t word;
> +        memcpy(&word,data+i,2);
> +        acc+=ntohs(word);
> +        if (acc>0xffff) {
> +            acc-=0xffff;
> +        }
> +    }
> +
> +    // Handle any partial block at the end of the data.
> +    if (length&1) {
> +        uint16_t word=0;
> +        memcpy(&word,data+length-1,1);
> +        acc+=ntohs(word);
> +        if (acc>0xffff) {
> +            acc-=0xffff;
> +        }
> +    }
> +
> +    // Return the checksum in network byte order.
> +    return htons(~acc);
> +}
> +
> +/**
> + * Make IGMP Membership report
> + * */
> +static void make_report( amt_igmpv3_membership_report_t *mr )
> +{
> +    mr->type = AMT_IGMPV3_MEMBERSHIP_REPORT_TYPEID;
> +    mr->resv = 0;
> +    mr->checksum = 0;
> +    mr->resv2 = 0;
> +    mr->nGroupRecord = hton16(1);
> +}
> +
> +/**
> + * Make IP header
> + * */
> +static void make_ip_header( amt_ip_alert_t *p_ipHead )
> +{
> +    p_ipHead->ver_ihl = 0x46;
> +    p_ipHead->tos = 0xc0;
> +    p_ipHead->tot_len = hton16(IP_HDR_IGMP_LEN + IGMP_REPORT_LEN);
> +    p_ipHead->id = 0x00;
> +    p_ipHead->frag_off = 0x0000;
> +    p_ipHead->ttl = 0x01;
> +    p_ipHead->protocol = 0x02;
> +    p_ipHead->check = 0;
> +    p_ipHead->srcAddr = INADDR_ANY;
> +    p_ipHead->options = 0x0000;
> +}
> +
> +/** Create relay discovery socket, query socket, UDP socket and
> + * fills in relay anycast address for discovery
> + * return 0 if successful, -1 if not
> + */
> +static int amt_sockets_init( stream_t *p_access )
> +{
> +    struct sockaddr_in rcvAddr;
> +    access_sys_t *sys = p_access->p_sys;
> +    memset( &rcvAddr, 0, sizeof(struct sockaddr_in) );
> +    int enable = 0, res = 0;
> +
> +    /* Relay anycast address for discovery */
> +    sys->relayDiscoAddr.sin_family = AF_INET;
> +    sys->relayDiscoAddr.sin_port = htons( AMT_PORT );
> +
> +    /* create UDP socket */
> +    sys->sAMT = vlc_socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP, true );
> +    if( sys->sAMT == -1 )
> +    {
> +        msg_Err( p_access, "Failed to create UDP socket" );
> +        goto error;
> +    }
> +
> +    res = setsockopt(sys->sAMT, IPPROTO_IP, IP_PKTINFO, &enable, 
> sizeof(enable));
> +    if(res < 0)
> +    {
> +        msg_Err( p_access, "Couldn't set socket options for 
> IPPROTO_IP, IP_PKTINFO\n %s", vlc_strerror(errno));
> +        goto error;
> +    }
> +
> +    res = setsockopt(sys->sAMT, SOL_SOCKET, SO_REUSEADDR, &enable, 
> sizeof(enable));
> +    if(res < 0)
> +    {
> +        msg_Err( p_access, "Couldn't make socket reusable");
> +        goto error;
> +    }
> +
> +    rcvAddr.sin_family      = AF_INET;
> +    rcvAddr.sin_port        = htons( 0 );
> +    rcvAddr.sin_addr.s_addr = INADDR_ANY;
> +
> +    if( bind(sys->sAMT, (struct sockaddr *)&rcvAddr, sizeof(rcvAddr) ) 
> != 0 )
> +    {
> +        msg_Err( p_access, "Failed to bind UDP socket error: %s", 
> vlc_strerror(errno) );
> +        goto error;
> +    }
> +
> +    sys->sQuery = vlc_socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP, true );
> +    if( sys->sQuery == -1 )
> +    {
> +        msg_Err( p_access, "Failed to create query socket" );
> +        goto error;
> +    }
> +
> +    /* bind socket to local address */
> +    sys->stLocalAddr.sin_family      = AF_INET;
> +    sys->stLocalAddr.sin_port        = htons( 0 );
> +    sys->stLocalAddr.sin_addr.s_addr = INADDR_ANY;
> +
> +    if( bind(sys->sQuery, (struct sockaddr *)&sys->stLocalAddr, 
> sizeof(struct sockaddr) ) != 0 )
> +    {
> +        msg_Err( p_access, "Failed to bind query socket" );
> +        goto error;
> +    }
> +
> +    sys->stSvrAddr.sin_family        = AF_INET;
> +    sys->stSvrAddr.sin_port          = htons( 9124 );
> +    res = inet_pton( AF_INET, LOCAL_LOOPBACK, &sys->stSvrAddr.sin_addr 
> );
> +    if( res == 0 )
> +    {
> +        msg_Err( p_access, "Could not convert loopback address" );
> +        goto error;
> +    }
> +
> +    return 0;
> +
> +error:
> +    net_Close( sys->sAMT );
> +    net_Close( sys->sQuery );

You should  close these socket only if != -1.
You should also set them again to -1 to avoid double close from the Close callback.


> +    return -1;
> +}
> +
> +/**
> + * Send a relay discovery message, before 3-way handshake
> + * */
> +static void amt_send_relay_discovery_msg( stream_t *p_access, char 
> *relay_ip )
> +{
> +    char          chaSendBuffer[AMT_DISCO_MSG_LEN];
> +    unsigned int  ulNonce;
> +    int           nRet;
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    /* initialize variables */
> +    memset( chaSendBuffer, 0, sizeof(chaSendBuffer) );
> +    ulNonce = 0;
> +    nRet = 0;
> +
> +    /*
> +     * create AMT discovery message format
> +     * +---------------------------------------------------+
> +     * | Msg Type(1Byte)| Reserved (3 byte)| nonce (4byte) |
> +     * +---------------------------------------------------+
> +     */
> +
> +    chaSendBuffer[0] = AMT_RELAY_DISCO;
> +    chaSendBuffer[1] = 0;
> +    chaSendBuffer[2] = 0;
> +    chaSendBuffer[3] = 0;
> +
> +    /* create nonce and copy into send buffer */
> +    srand( (unsigned int)time(NULL) );
> +    ulNonce = htonl( rand() );
> +    memcpy( &chaSendBuffer[4], &ulNonce, sizeof(ulNonce) );
> +    sys->glob_ulNonce = ulNonce;
> +
> +    /* send it */
> +    nRet = sendto( sys->sAMT, chaSendBuffer, sizeof(chaSendBuffer), 0,\
> +            (struct sockaddr *)&sys->relayDiscoAddr, sizeof(struct 
> sockaddr) );
> +
> +    if( nRet < 0)
> +        msg_Err( p_access, "Sendto failed to %s with error %d.", 
> relay_ip, errno);
> +}
> +
> +/**
> + * Send relay request message, stage 2 of handshake
> + * */
> +static void amt_send_relay_request( stream_t *p_access, char *relay_ip 
> )
> +{
> +    char         chaSendBuffer[AMT_REQUEST_MSG_LEN];
> +    uint32_t     ulNonce;
> +    int          nRet;
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    memset( chaSendBuffer, 0, sizeof(chaSendBuffer) );
> +
> +    ulNonce = 0;
> +    nRet = 0;
> +
> +    /*
> +     * create AMT request message format
> +     * 
> +-----------------------------------------------------------------+
> +     * | Msg Type(1Byte)| Reserved(1byte)|P flag(1byte)|Reserved (2 
> byte)|
> +     * 
> +-----------------------------------------------------------------+
> +     * |             nonce (4byte)                                     
>   |
> +     * 
> +-----------------------------------------------------------------+
> +     *
> +     * The P flag is set to indicate which group membership protocol 
> the
> +     * gateway wishes the relay to use in the Membership Query 
> response:
> +
> +     * Value Meaning
> +
> +     *  0    The relay MUST respond with a Membership Query message 
> that
> +     *       contains an IPv4 packet carrying an IGMPv3 General Query
> +     *       message.
> +     *  1    The relay MUST respond with a Membership Query message 
> that
> +     *       contains an IPv6 packet carrying an MLDv2 General Query
> +     *       message.
> +     *
> +     */
> +
> +    chaSendBuffer[0] = AMT_REQUEST;
> +    chaSendBuffer[1] = 0;
> +    chaSendBuffer[2] = 0;
> +    chaSendBuffer[3] = 0;
> +
> +    ulNonce = sys->glob_ulNonce;
> +    memcpy( &chaSendBuffer[4], &ulNonce, sizeof(ulNonce) );
> +
> +    nRet = send( sys->sAMT, chaSendBuffer, sizeof(chaSendBuffer), 0 );
> +
> +    if( nRet < 0 )
> +        msg_Err(p_access, "Error sending relay request to %s error: 
> %s", relay_ip, vlc_strerror(errno) );
> +}
> +
> +/*
> +* create AMT request message format
> +* 
> +----------------------------------------------------------------------------------+
> +* | Msg Type(1 byte)| Reserved (1 byte)| MAC (6 byte)| nonce (4 byte) 
> | IGMP packet  |
> +* 
> +----------------------------------------------------------------------------------+
> +*/
> +static void amt_send_mem_update( stream_t *p_access, char *relay_ip, 
> bool leave)
> +{
> +    int           sendBufSize = IP_HDR_IGMP_LEN + MAC_LEN + NONCE_LEN 
> + AMT_HDR_LEN;
> +    char          pSendBuffer[ sendBufSize + IGMP_REPORT_LEN ];
> +    uint32_t      ulNonce = 0;
> +    size_t        shift = 0;
> +    access_sys_t *sys = p_access->p_sys;
> +    amt_membership_update_msg_t memUpdateMsg;
> +    
> +    memset( &memUpdateMsg, 0, sizeof(memUpdateMsg) );
> +    memset( pSendBuffer, 0, sizeof(pSendBuffer) );
> +
> +    pSendBuffer[0] = AMT_MEM_UPD;
> +    shift += 2;
> +
> +    /* copy relay MAC response */
> +    memcpy( &pSendBuffer[shift], sys->relay_mem_query_msg.uchaMAC, 
> MAC_LEN );
> +    shift += MAC_LEN;
> +
> +    /* copy nonce */
> +    ulNonce = ntohl(sys->glob_ulNonce);
> +    memcpy( &pSendBuffer[shift], &ulNonce, NONCE_LEN );
> +    shift += NONCE_LEN;
> +
> +    /* make IP header for IGMP packet */
> +    make_ip_header( &memUpdateMsg.ipHead );
> +
> +    struct sockaddr_in temp;
> +    inet_pton( AF_INET, MCAST_ALLHOSTS, &(temp.sin_addr) );

Error not checked here.

> +    memUpdateMsg.ipHead.destAddr = temp.sin_addr.s_addr;
> +    memUpdateMsg.ipHead.check = get_checksum( &memUpdateMsg.ipHead, 
> IP_HDR_IGMP_LEN );
> +
> +    amt_igmpv3_groupRecord_t groupRcd;
> +    groupRcd.auxDatalen = 0;
> +    groupRcd.ssm = sys->mcastGroupAddr.sin_addr.s_addr;
> +
> +    if( sys->mcastSrcAddr.sin_addr.s_addr )
> +    {
> +        groupRcd.type = leave ? AMT_IGMP_BLOCK:AMT_IGMP_INCLUDE;
> +        groupRcd.nSrc = hton16(1);
> +        groupRcd.srcIP[0] = sys->mcastSrcAddr.sin_addr.s_addr;
> +    } else {
> +        groupRcd.type = leave ? 
> AMT_IGMP_INCLUDE_CHANGE:AMT_IGMP_EXCLUDE_CHANGE;
> +        groupRcd.nSrc = 0;
> +    }
> +
> +    /* make IGMP membership report */
> +    make_report( &memUpdateMsg.memReport );
> +    memcpy(&memUpdateMsg.memReport.grp[0], &groupRcd, 
> (int)sizeof(groupRcd) );
> +    memUpdateMsg.memReport.checksum = get_checksum( 
> &memUpdateMsg.memReport, IGMP_REPORT_LEN );
> +    
> +    // copy ip header piece by piece
> +    pSendBuffer[shift] = memUpdateMsg.ipHead.ver_ihl;
> +    shift += 1;
> +    pSendBuffer[shift] = memUpdateMsg.ipHead.tos;
> +    shift += 1;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.ipHead.tot_len);
> +    shift += 2;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.ipHead.id);
> +    shift += 2;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.ipHead.frag_off);
> +    shift += 2;
> +    pSendBuffer[shift] = memUpdateMsg.ipHead.ttl;
> +    shift += 1;
> +    pSendBuffer[shift] = memUpdateMsg.ipHead.protocol;
> +    shift += 1;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.ipHead.check);
> +    shift += 2;
> +    SetDWLE(&pSendBuffer[shift], memUpdateMsg.ipHead.srcAddr);
> +    shift += 4;
> +    SetDWLE(&pSendBuffer[shift], memUpdateMsg.ipHead.destAddr);
> +    shift += 4;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.ipHead.options);
> +    shift += 4;
> +
> +    //copy IGMP report piece by piece
> +    pSendBuffer[shift] = memUpdateMsg.memReport.type & 0xff;
> +    shift += 1;
> +    pSendBuffer[shift] = memUpdateMsg.memReport.resv & 0xff;
> +    shift += 1;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.memReport.checksum);
> +    shift += 2;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.memReport.resv2);
> +    shift += 2;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.memReport.nGroupRecord);
> +    shift += 2;
> +    pSendBuffer[shift] = memUpdateMsg.memReport.grp[0].type & 0xff;
> +    shift += 1;
> +    pSendBuffer[shift] = memUpdateMsg.memReport.grp[0].auxDatalen & 
> 0xff;
> +    shift += 1;
> +    SetWLE(&pSendBuffer[shift], memUpdateMsg.memReport.grp[0].nSrc);
> +    shift += 2;
> +    SetDWLE(&pSendBuffer[shift], memUpdateMsg.memReport.grp[0].ssm);
> +    shift += 4;
> +    SetDWLE(&pSendBuffer[shift], 
> memUpdateMsg.memReport.grp[0].srcIP[0]);
> +    shift += 4;
> +    assert( (int)sizeof(pSendBuffer) <= ( sendBufSize + 
> IGMP_REPORT_LEN ) );
> +
> +    send( sys->sAMT, pSendBuffer, sizeof(pSendBuffer), 0 );
> +    msg_Dbg( p_access, "AMT relay membership report sent to %s", 
> relay_ip );
> +}
> +
> +/**
> + * Receive relay advertisement message
> + *
> + *
> + *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + *  |  V=0  |Type=2 |                   Reserved                    |
> + *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + *  |                        Discovery Nonce                        |
> + *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + *  |                                                               |
> + *  ~                  Relay Address (IPv4 or IPv6)                 ~
> + *  |                                                               |
> + *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + * */
> +static bool amt_rcv_relay_adv( stream_t *p_access )
> +{
> +    char pkt[RELAY_ADV_MSG_LEN];
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    memset( pkt, 0, RELAY_ADV_MSG_LEN );
> +
> +    struct pollfd ufd[1];
> +
> +    ufd[0].fd = sys->sAMT;
> +    ufd[0].events = POLLIN;
> +
> +    switch( vlc_poll_i11e(ufd, 1, sys->timeout) )
> +    {
> +        case 0:
> +            msg_Err(p_access, "AMT relay advertisement receive 
> time-out");
> +            /* fall through */
> +        case -1:
> +            return false;
> +    }
> +
> +    struct sockaddr temp;
> +    uint32_t temp_size = sizeof( struct sockaddr );
> +    ssize_t len = recvfrom( sys->sAMT, &pkt, RELAY_ADV_MSG_LEN, 0, 
> &temp, &temp_size );
> +
> +    if (len < 0 || len != RELAY_ADV_MSG_LEN)
> +    {
> +        msg_Err(p_access, "Received message length is not correct");
> +        return false;
> +    }
> +
> +    sys->relay_adv_msg.type = pkt[0];
> +    if( sys->relay_adv_msg.type != AMT_RELAY_ADV )
> +    {
> +        msg_Err( p_access, "Received message not an AMT relay 
> advertisement, ignoring. ");
> +        return false;
> +    }
> +
> +    memcpy( &sys->relay_adv_msg.ulRcvNonce, &pkt[NONCE_LEN], NONCE_LEN 
> );
> +    if( sys->glob_ulNonce != sys->relay_adv_msg.ulRcvNonce )
> +    {
> +        msg_Err( p_access, "Discovery nonces differ! currNonce:%x 
> rcvd%x", sys->glob_ulNonce, ntohl(sys->relay_adv_msg.ulRcvNonce) );
> +        return false;
> +    }
> +
> +    memcpy( &sys->relay_adv_msg.ipAddr, &pkt[8], 4 );
> +
> +    memset( &sys->relayAddr, 0, sizeof(sys->relayAddr) );
> +    sys->relayAddr.sin_family       = AF_INET;
> +    sys->relayAddr.sin_addr.s_addr  = sys->relay_adv_msg.ipAddr;
> +    sys->relayAddr.sin_port         = htons( AMT_PORT );
> +
> +    int nRet = connect( sys->sAMT, (struct sockaddr *)&sys->relayAddr, 
> sizeof(sys->relayAddr) );
> +    if( nRet < 0 )
> +    {
> +        msg_Err( p_access, "Error connecting AMT UDP socket: %s", 
> vlc_strerror(errno) );
> +        return false;
> +    }
> +
> +    return true;
> +}
> +
> +/**
> + * Receive relay membership query message
> + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> +   |  V=0  |Type=4 | Reserved  |L|G|         Response MAC          |
> +   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
> +   |                                                               |
> +   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> +   |                         Request Nonce                         |
> +   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> +   |                                                               |
> +   |               Encapsulated General Query Message              |
> +   ~                 IPv4:IGMPv3(Membership Query)                 ~
> +   |                  IPv6:MLDv2(Listener Query)                   |
> +   |                                                               |
> +   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> +   |     Gateway Port Number       |                               |
> +   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
> +   |                                                               |
> +   +                                                               +
> +   |                Gateway IP Address (IPv4 or IPv6)              |
> +   +                                                               +
> +   |                                                               |
> +   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> +   |                               |
> +   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> + */
> +static bool amt_rcv_relay_mem_query( stream_t *p_access )
> +{
> +    char pkt[RELAY_QUERY_MSG_LEN];
> +    memset( pkt, 0, RELAY_QUERY_MSG_LEN );
> +    struct pollfd ufd[1];
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    ufd[0].fd = sys->sAMT;
> +    ufd[0].events = POLLIN;
> +
> +    switch( vlc_poll_i11e(ufd, 1, sys->timeout) )
> +    {
> +        case 0:
> +            msg_Err(p_access, "AMT relay membership query receive 
> time-out");
> +            /* fall through */
> +        case -1:
> +            return false;
> +    }
> +
> +    ssize_t len = recv( sys->sAMT, &pkt, RELAY_QUERY_MSG_LEN, 0 );
> +
> +    if (len < 0 || len != RELAY_QUERY_MSG_LEN)
> +    {
> +        msg_Err(p_access, "Received message length is not correct");
> +        return false;
> +    }
> +
> +    sys->relay_mem_query_msg.type = pkt[0];
> +    /* pkt[1] is reserved  */
> +    memcpy( &sys->relay_mem_query_msg.uchaMAC[0], &pkt[AMT_HDR_LEN], 
> MAC_LEN );
> +    memcpy( &sys->relay_mem_query_msg.ulRcvedNonce, &pkt[AMT_HDR_LEN + 
> MAC_LEN], NONCE_LEN );
> +    if( sys->relay_mem_query_msg.ulRcvedNonce != sys->glob_ulNonce )
> +    {
> +        msg_Warn( p_access, "Nonces are different rcvd: %x glob: %x", 
> sys->relay_mem_query_msg.ulRcvedNonce, sys->glob_ulNonce );
> +        return false;
> +    }
> +
> +    sys->glob_ulNonce = ntohl(sys->relay_mem_query_msg.ulRcvedNonce);

Why not using GetDWBE(&pkt[AMT_HDR_LEN + MAC_LEN]) here like it is done just after with GetWLE ?
PS: BE, for Big-endian, the network byte order.

Same for other places where ntohl() is used.


> +
> +    size_t shift = AMT_HDR_LEN + MAC_LEN + NONCE_LEN;
> +    uint16_t temp16;
> +    uint32_t temp32;
> +
> +    sys->relay_ip_hdr.ver_ihl = pkt[shift];
> +    shift += 1; assert( shift < RELAY_QUERY_MSG_LEN);
> +    sys->relay_ip_hdr.tos = pkt[shift];
> +    shift += 1; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy(&temp16, &pkt[shift], sizeof(temp16));
> +    sys->relay_ip_hdr.tot_len = GetWLE(&temp16);
> +    shift += 2; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy(&temp16, &pkt[shift], sizeof(temp16));
> +    sys->relay_ip_hdr.id = GetWLE(&temp16);
> +    shift += 2; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy(&temp16, &pkt[shift], sizeof(temp16));
> +    sys->relay_ip_hdr.frag_off = GetWLE(&temp16);
> +    shift += 2; assert( shift < RELAY_QUERY_MSG_LEN);
> +    sys->relay_ip_hdr.ttl = pkt[shift];
> +    shift += 1; assert( shift < RELAY_QUERY_MSG_LEN);
> +    sys->relay_ip_hdr.protocol = pkt[shift];
> +    shift += 1; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy(&temp16, &pkt[shift], sizeof(temp16));
> +    sys->relay_ip_hdr.check = GetWLE(&temp16);
> +    shift += 2; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy(&temp32, &pkt[shift], sizeof(temp32));
> +    sys->relay_ip_hdr.srcAddr = GetDWLE(&temp32);
> +    shift += 4; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy(&temp32, &pkt[shift], sizeof(temp32));
> +    sys->relay_ip_hdr.destAddr = GetDWLE(&temp32);
> +    shift += 4; assert( shift < RELAY_QUERY_MSG_LEN);
> +
> +    //shift += IP_HDR_IGMP_LEN;

Useless comment here.

> +    sys->relay_igmp_query.type = pkt[shift];
> +    shift++; assert( shift < RELAY_QUERY_MSG_LEN);
> +    sys->relay_igmp_query.max_resp_code = pkt[shift];
> +    shift++; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy( &temp16, &pkt[shift], sizeof(temp16) );
> +    sys->relay_igmp_query.checksum = GetWLE(&temp16);
> +    shift += 2; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy( &temp32, &pkt[shift], sizeof(temp32) );
> +    sys->relay_igmp_query.ssmIP = GetDWLE(&temp32);
> +    shift += 4; assert( shift < RELAY_QUERY_MSG_LEN);
> +    sys->relay_igmp_query.s_qrv = pkt[shift];
> +    shift++; assert( shift < RELAY_QUERY_MSG_LEN);
> +    if( pkt[shift] == 0 )
> +        sys->relay_igmp_query.qqic = 125;
> +    else
> +        sys->relay_igmp_query.qqic = pkt[shift];
> +
> +    shift++; assert( shift < RELAY_QUERY_MSG_LEN);
> +    memcpy( &temp16, &pkt[shift], sizeof(temp16) );
> +    sys->relay_igmp_query.nSrc = GetWLE(&temp16);
> +
> +    // If there are more than 0 sources, 
> +    // the IGMP query is not a general query and should be dropped.
> +    if( sys->relay_igmp_query.nSrc != 0 )
> +    {
> +        msg_Warn( p_access, "Number of IGMP sources is not zero; not a 
> general query." );
> +        return false;
> +    }
> +
> +    /* if a membership thread exists cancel it */
> +    if( sys->threadReady )
> +    {
> +        msg_Dbg( p_access, "Canceling existing AMT relay membership 
> update thread");
> +
> +        sys->threadReady = false;
> +        vlc_cancel( sys->updateThread );
> +        vlc_join( sys->updateThread, NULL );
> +    }
> +
> +    msg_Dbg( p_access, "Spawning AMT relay membership update thread");
> +
> +    if( vlc_clone( &sys->updateThread, amt_mem_upd, p_access, 
> VLC_THREAD_PRIORITY_LOW) )
> +    {
> +        msg_Err( p_access, "Could not create AMT relay membership 
> update thread" );
> +        return false;
> +    }
> +
> +    /* set theadReady to true, thread will send periodic membership 
> updates until false */
> +    sys->threadReady = true;
> +    return true;
> +}
> +
> +/**
> + * Join SSM group based on input addresses, or use the defaults
> + * */
> +static int amt_joinSSM_group( stream_t *p_access )
> +{
> +    struct ip_mreq_source imr;
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    imr.imr_multiaddr.s_addr = sys->mcastGroupAddr.sin_addr.s_addr;
> +    imr.imr_sourceaddr.s_addr = sys->mcastSrcAddr.sin_addr.s_addr;
> +    imr.imr_interface.s_addr = INADDR_ANY;
> +
> +    return setsockopt( sys->sAMT, IPPROTO_IP, 
> IP_ADD_SOURCE_MEMBERSHIP, (char *)&imr, sizeof(imr) );
> +}
> +
> +static int amt_joinASM_group( stream_t *p_access )
> +{
> +    struct ip_mreq imr;
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    imr.imr_multiaddr.s_addr = sys->mcastGroupAddr.sin_addr.s_addr;
> +    imr.imr_interface.s_addr = INADDR_ANY;
> +
> +    return setsockopt( sys->sAMT, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char 
> *)&imr, sizeof(imr) );
> +}
> +
> +/**
> + * Leave SSM group that was joined earlier.
> + * */
> +static int amt_leaveSSM_group( stream_t *p_access )
> +{
> +    struct ip_mreq_source imr;
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    imr.imr_multiaddr.s_addr = sys->mcastGroupAddr.sin_addr.s_addr;
> +    imr.imr_sourceaddr.s_addr = sys->mcastSrcAddr.sin_addr.s_addr;
> +    imr.imr_interface.s_addr = INADDR_ANY;
> +
> +    return setsockopt( sys->sAMT, IPPROTO_IP, 
> IP_DROP_SOURCE_MEMBERSHIP, (char *)&imr, sizeof(imr) );
> +}
> +
> +/**
> + * Leave ASM group that was joined earlier.
> + * */
> +static int amt_leaveASM_group( stream_t *p_access )
> +{
> +    struct ip_mreq imr;
> +    access_sys_t *sys = p_access->p_sys;
> +
> +    imr.imr_multiaddr.s_addr = sys->mcastGroupAddr.sin_addr.s_addr;
> +    imr.imr_interface.s_addr = INADDR_ANY;
> +
> +    return setsockopt( sys->sAMT, IPPROTO_IP, IP_DROP_MEMBERSHIP, 
> (char *)&imr, sizeof(imr) );
> +}
> +
> +/* A thread is spawned since IGMP membership updates need to issued 
> periodically in order to continue to receive multicast */
> +/* Simple timers are not suitable for this requirement since the 
> parent is otherwise occupied in receiving UDP packet flow */
> +static void *amt_mem_upd( void *data )
> +{
> +    stream_t     *p_access = (stream_t*) data;
> +    access_sys_t *sys = p_access->p_sys;
> + 
> +    msg_Dbg( p_access, "AMT relay membership update thread started" );
> + 
> +    /* thread sends periodic AMT membership updates until Close() 
> which terminates thread */
> +    while ( true  )
> +    {
> +        amt_send_mem_update( p_access, sys->relayDisco, false );
> +        vlc_tick_sleep( (vlc_tick_t)sys->relay_igmp_query.qqic * 
> CLOCK_FREQ );

You could use the VLC_TICK_FROM_SEC() macro here.

> +    }
> + 
> +    return NULL;
> +}
> -- 
> 2.20.1 (Apple Git-117)
> 
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