SCTP多宿主 [英] SCTP Multihoming

问题描述

我已经开发这个简单的客户 - 服务器应用与C，其中客户端被刚刚发送随机数据到服务器和服务器只监听客户端发送的内容。我使用的协议是SCTP和我感兴趣的是如何实现多宿主的功能吧。

I've been developing this simple client - server application with C where the client is just sending random data to the server and the server just listens to what the client sends. The protocol I'm using is SCTP and I'm interested on how to implement the multihoming feature to it.

我一直在寻找通过关于SCTP和多宿主互联网，一直没能找到有关如何指导SCTP使用多个地址进行通信的例子。我只设法找到了什么命令试图设置SCTP时多宿主，它应该是相当简单的，应该使用。

I've been searching through the internet about SCTP and multihoming and haven't been able to find any examples about how to instruct SCTP to use multiple addresses for communication. I've only managed to find what commands one should use when trying to setup SCTP with multihoming and it should be quite straightforward.

我创建了一个客户端和都使用我的计算机上的两个WLAN接口作为连接点的服务器。两个适配器被连接到相同的AP。服务器是从这些接口的客户端监听数据和客户端通过其发送数据。的问题是，当我断开主WLAN适配器的客户端将数据发送到，传输刚停止时它应该退回到辅助连接。我跟踪使用Wireshark和第一INIT和INIT_ACK分组分组报告，无论是客户端和服务器使用的WLAN适配器作为他们的通信链路。

I've created a client and a server which both use my computers two WLAN interfaces as their connection points. Both adapters are connected to the same AP. The server is listening for data from the client from these interfaces and the client sends data through them. The problem is that when I disconnect the primary WLAN adapter the client is sending data to, the transmission just halts when it should fallback to the secondary connection. I've traced the packets with Wireshark and the first INIT and INIT_ACK packets report that both the client and the server are using the WLAN adapters as their communication links.

当我重新连接主WLAN连接传输一小会儿后，继续和突发包的巨大的负荷哪个是不正确的服务器。该包应在辅助连接传送完毕。在很多网站上有人说，SCTP连接自动地之间，但在我情况下没有发生切换。所以，做你们有原因的传输不会退回到辅助连接任何线索，当主链路断开，即使在客户端和服务器知道对方的地址，包括辅助地​​址？

When I reconnect the primary WLAN connection the transmission continues after a little while and bursts a huge load of packets to the server which isn't right. The packets should have been transmitted over the secondary connection. On many sites it is said that SCTP switches between connections automagically but in my case that's not happening. So do you guys have any clues why the transmission doesn't fallback to the secondary connection when the primary link is down even though the client and the server knows each others addresses including the secondary address?

关于服务器：

服务器创建一个SOCK_SEQPACKET型插座，并结合与INADDR_ANY发现的所有接口。 getladdrs报告该服务器为界，3地址（包括127.0.0.1）。之后，该服务器监听到插座并等待客户端发送数据。服务器则sctp_recvmsg通话读取数据。

The server creates a SOCK_SEQPACKET type socket and binds all interfaces found with INADDR_ANY. getladdrs reports that the server is bounded to 3 addresses (including 127.0.0.1). After that the server listens to the socket and waits the client to send data. Server reads the data with sctp_recvmsg call.

关于客户端：

客户端还创建了一个SEQPACKET插座，并连接到一个命令行参数指定一个IP地址。在这种情况下getladdrs也返回像服务器的情况下3个地址。之后，客户端刚开始直到用户中断与Ctrl-C键的发送数据发送到服务器与一个第二延迟到服务器

The client creates also a SEQPACKET socket and connects to an IP-address specified by a commandline argument. getladdrs in this case returns also 3 addresses like in the servers case. After that the client just starts to send data to the server with one second delay to the server until the user interrupts the send with Ctrl-C.

下面是一些源$ C ​​$ C：

Here's some source code:

服务器：

#define BUFFER_SIZE (1 << 16)
#define PORT 10000   

int sock, ret, flags;
int i;
int addr_count = 0;
char buffer[BUFFER_SIZE];
socklen_t from_len;

struct sockaddr_in addr;
struct sockaddr_in *laddr[10];
struct sockaddr_in *paddrs[10];
struct sctp_sndrcvinfo sinfo;
struct sctp_event_subscribe event;  
struct sctp_prim prim_addr; 
struct sctp_paddrparams heartbeat;
struct sigaction sig_handler;

void handle_signal(int signum);

int main(void)
{
    if((sock = socket(AF_INET, SOCK_SEQPACKET, IPPROTO_SCTP)) < 0)
        perror("socket");

    memset(&addr, 0, sizeof(struct sockaddr_in));
    memset((void*)&event, 1, sizeof(struct sctp_event_subscribe));

    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    addr.sin_port = htons(PORT);

    from_len = (socklen_t)sizeof(struct sockaddr_in);

    sig_handler.sa_handler = handle_signal;
    sig_handler.sa_flags = 0;

    if(sigaction(SIGINT, &sig_handler, NULL) == -1)
        perror("sigaction");

    if(setsockopt(sock, IPPROTO_SCTP, SCTP_EVENTS, &event, sizeof(struct sctp_event_subscribe)) < 0)
        perror("setsockopt");

    if(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(int))< 0)
        perror("setsockopt");

    if(bind(sock, (struct sockaddr*)&addr, sizeof(struct sockaddr)) < 0)
        perror("bind");

    if(listen(sock, 2) < 0)
        perror("listen");

    addr_count = sctp_getladdrs(sock, 0, (struct sockaddr**)laddr);
    printf("Addresses binded: %d\n", addr_count);

    for(i = 0; i < addr_count; i++)
         printf("Address %d: %s:%d\n", i +1, inet_ntoa((*laddr)[i].sin_addr), (*laddr)[i].sin_port);

    sctp_freeladdrs((struct sockaddr*)*laddr);

    while(1)
    {
        flags = 0;

        ret = sctp_recvmsg(sock, buffer, BUFFER_SIZE, (struct sockaddr*)&addr, &from_len, NULL, &flags);

        if(flags & MSG_NOTIFICATION)
        printf("Notification received from %s:%u\n",  inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));

        printf("%d bytes received from %s:%u\n", ret, inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));      
    }

    if(close(sock) < 0)
        perror("close");
}   

void handle_signal(int signum)
{
    switch(signum)
    {
        case SIGINT:
            if(close(sock) != 0)
                perror("close");
            exit(0);
            break;  
        default: exit(0);
            break;
    }
}

和客户端：

#define PORT 10000
#define MSG_SIZE 1000
#define NUMBER_OF_MESSAGES 1000
#define PPID 1234

int sock;
struct sockaddr_in *paddrs[10];
struct sockaddr_in *laddrs[10];

void handle_signal(int signum);

int main(int argc, char **argv)
{
    int i;
    int counter = 1;
    int ret;
    int addr_count;
    char address[16];
    char buffer[MSG_SIZE];
    sctp_assoc_t id;
    struct sockaddr_in addr;
    struct sctp_status status;
    struct sctp_initmsg initmsg;
    struct sctp_event_subscribe events;
    struct sigaction sig_handler;

    memset((void*)&buffer,  'j', MSG_SIZE);
    memset((void*)&initmsg, 0, sizeof(initmsg));
    memset((void*)&addr,    0, sizeof(struct sockaddr_in));
    memset((void*)&events, 1, sizeof(struct sctp_event_subscribe));

    if(argc != 2 || (inet_addr(argv[1]) == -1))
    {
        puts("Usage: client [IP ADDRESS in form xxx.xxx.xxx.xxx] ");        
        return 0;
    }

    strncpy(address, argv[1], 15);
    address[15] = 0;

    addr.sin_family = AF_INET;
    inet_aton(address, &(addr.sin_addr));
    addr.sin_port = htons(PORT);

    initmsg.sinit_num_ostreams = 2;
    initmsg.sinit_max_instreams = 2;
    initmsg.sinit_max_attempts = 5;

    sig_handler.sa_handler = handle_signal;
    sig_handler.sa_flags = 0;

    if(sigaction(SIGINT, &sig_handler, NULL) == -1)
        perror("sigaction");

    if((sock = socket(AF_INET, SOCK_SEQPACKET, IPPROTO_SCTP)) < 0)
        perror("socket");

    if((setsockopt(sock, SOL_SCTP, SCTP_INITMSG, &initmsg, sizeof(initmsg))) != 0)
        perror("setsockopt");

    if((setsockopt(sock, SOL_SCTP, SCTP_EVENTS, (const void *)&events, sizeof(events))) != 0)
        perror("setsockopt");

    if(sendto(sock, buffer, MSG_SIZE, 0, (struct sockaddr*)&addr, sizeof(struct sockaddr)) == -1)
        perror("sendto");

    addr_count = sctp_getpaddrs(sock, 0, (struct sockaddr**)paddrs);
    printf("\nPeer addresses: %d\n", addr_count);

    for(i = 0; i < addr_count; i++)
    printf("Address %d: %s:%d\n", i +1, inet_ntoa((*paddrs)[i].sin_addr), (*paddrs)[i].sin_port);

    sctp_freepaddrs((struct sockaddr*)*paddrs);

    addr_count = sctp_getladdrs(sock, 0, (struct sockaddr**)laddrs);
    printf("\nLocal addresses: %d\n", addr_count);

    for(i = 0; i < addr_count; i++)
    printf("Address %d: %s:%d\n", i +1, inet_ntoa((*laddrs)[i].sin_addr), (*laddrs)[i].sin_port);

    sctp_freeladdrs((struct sockaddr*)*laddrs);

    i = sizeof(status);
    if((ret = getsockopt(sock, SOL_SCTP, SCTP_STATUS, &status, (socklen_t *)&i)) != 0)
        perror("getsockopt");

    printf("\nSCTP Status:\n--------\n");
    printf("assoc id  = %d\n", status.sstat_assoc_id);
    printf("state     = %d\n", status.sstat_state);
    printf("instrms   = %d\n", status.sstat_instrms);
    printf("outstrms  = %d\n--------\n\n", status.sstat_outstrms);

    for(i = 0; i < NUMBER_OF_MESSAGES; i++)
    {
        counter++;
        printf("Sending data chunk #%d...", counter);
        if((ret = sendto(sock, buffer, MSG_SIZE, 0, (struct sockaddr*)&addr, sizeof(struct sockaddr))) == -1)
            perror("sendto");

        printf("Sent %d bytes to peer\n",ret);

        sleep(1);
    }

    if(close(sock) != 0)
        perror("close");
}


void handle_signal(int signum)
{

    switch(signum)
    {
        case SIGINT:
            if(close(sock) != 0)
                perror("close");
            exit(0);
            break;  
        default: exit(0);
            break;
    }

}

所以，做你们有什么线索，我在做什么错了？

So do you guys have any clues what I'm doing wrong?

推荐答案

好吧，我终于解决了多宿主问题。这里就是我所做的。

Ok I resolved the multihoming problem finally. Here's what I did.

我心跳值调整为5000毫秒sctp_paddrparams结构。位于结构的标志变量在SPP_HB_ENABLE模式，因为否则SCTP忽略尝试设置用setsockopt值时心跳值（）。

I adjusted the heartbeat value to 5000 ms with sctp_paddrparams struct. The flags variable located in the struct has to in SPP_HB_ENABLE mode because otherwise SCTP ignores the heartbeat value when trying to set the value with setsockopt().

这就是为什么SCTP没有经常因为我想送心跳的原因。究其原因，为什么我没有注意到标志变量，是过时的参考指南SCTP我在读，其中指出，存在不存在的标志结构体变量里面！较新的参考透露，有。所以心跳问题解决了！

That was the reason why SCTP didn't send heartbeats as often as I wanted. The reason, why I didn't notice the flag variable, was the obsolete reference guide to SCTP I was reading, which stated that there didn't exist a flags variable inside the struct! Newer reference revealed that there was. So heartbeat problem solved!

的另一件事是修改rto_max值，例如2000毫秒左右。降低值告诉SCTP以更快改变路径。默认值是60毫秒000这是太高（1分钟它开始改变路径之前）。 rto_max值可以用SCTP_RTOINFO结构进行调整。

Another thing was to modify the rto_max value to, for example, 2000 ms or so. Lowering the value tells SCTP to change the path much sooner. The default value was 60 000 ms which was too high (1 minute before it starts to change the path). rto_max value can be adjusted with sctp_rtoinfo struct.

有了这两项修改的多宿主开始工作。哦，和另一件事。客户必须在STREAM模式中，当服务器处于SEQPACKET模式。客户端发送数据到服务器（），其中addr结构设置为NULL正常的send（）命令和服务器读取数据则sctp_recvmsg

With these two modifications the multihoming started to work. Oh and a another thing. Client has to be in STREAM mode when the Server is in SEQPACKET mode. Client sends data to server with normal send() command and Server read data with sctp_recvmsg() where addr struct is set to NULL.

我希望这个信息可以帮助其他人与SCTP的多宿主挣扎。干杯家伙你的意见，那是一个很大的帮助我！下面是一些code为例所以这也许是第一个多宿主简单净举例来说，如果你问我（没有找到比多数据流实例的所有示例）

I hope that this information helps other guys struggling with the multihoming of SCTP. Cheers guys for your opinions, those were a big help for me! Here is some code example so this maybe the first multihoming simple example in the net if you ask me (didnt find any examples than multistreaming examples)

服务器：

#include <sys/types.h>
#include <sys/socket.h>
#include <signal.h>
#include <netinet/in.h>
#include <netinet/sctp.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <stdlib.h>
#include <pthread.h>

#define BUFFER_SIZE (1 << 16)
#define PORT 10000   

int sock, ret, flags;
int i, reuse = 1;
int addr_count = 0;
char buffer[BUFFER_SIZE];
socklen_t from_len;

struct sockaddr_in addr;
struct sockaddr_in *laddr[10];
struct sockaddr_in *paddrs[10];
struct sctp_sndrcvinfo sinfo;
struct sctp_event_subscribe event;  
struct sctp_prim prim_addr; 
struct sctp_paddrparams heartbeat;
struct sigaction sig_handler;
struct sctp_rtoinfo rtoinfo;

void handle_signal(int signum);

int main(void)
{
    if((sock = socket(AF_INET, SOCK_SEQPACKET, IPPROTO_SCTP)) < 0)
        perror("socket");

    memset(&addr,       0, sizeof(struct sockaddr_in));
    memset(&event,      1, sizeof(struct sctp_event_subscribe));
    memset(&heartbeat,  0, sizeof(struct sctp_paddrparams));
    memset(&rtoinfo,    0, sizeof(struct sctp_rtoinfo));

    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    addr.sin_port = htons(PORT);

    from_len = (socklen_t)sizeof(struct sockaddr_in);

    sig_handler.sa_handler = handle_signal;
    sig_handler.sa_flags = 0;

    heartbeat.spp_flags = SPP_HB_ENABLE;
    heartbeat.spp_hbinterval = 5000;
    heartbeat.spp_pathmaxrxt = 1;

    rtoinfo.srto_max = 2000;

    /*Set Heartbeats*/
    if(setsockopt(sock, SOL_SCTP, SCTP_PEER_ADDR_PARAMS , &heartbeat, sizeof(heartbeat)) != 0)
        perror("setsockopt");

    /*Set rto_max*/
    if(setsockopt(sock, SOL_SCTP, SCTP_RTOINFO , &rtoinfo, sizeof(rtoinfo)) != 0)
        perror("setsockopt");

    /*Set Signal Handler*/
    if(sigaction(SIGINT, &sig_handler, NULL) == -1)
        perror("sigaction");

    /*Set Events */
    if(setsockopt(sock, IPPROTO_SCTP, SCTP_EVENTS, &event, sizeof(struct sctp_event_subscribe)) < 0)
        perror("setsockopt");

    /*Set the Reuse of Address*/
    if(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(int))< 0)
        perror("setsockopt");

    /*Bind the Addresses*/
    if(bind(sock, (struct sockaddr*)&addr, sizeof(struct sockaddr)) < 0)
        perror("bind");

    if(listen(sock, 2) < 0)
        perror("listen");

    /*Get Heartbeat Value*/
    i = (sizeof heartbeat);
    getsockopt(sock, SOL_SCTP, SCTP_PEER_ADDR_PARAMS, &heartbeat, (socklen_t*)&i);
    printf("Heartbeat interval %d\n", heartbeat.spp_hbinterval);

    /*Print Locally Binded Addresses*/
    addr_count = sctp_getladdrs(sock, 0, (struct sockaddr**)laddr);
    printf("Addresses binded: %d\n", addr_count);
    for(i = 0; i < addr_count; i++)
         printf("Address %d: %s:%d\n", i +1, inet_ntoa((*laddr)[i].sin_addr), (*laddr)[i].sin_port);
    sctp_freeladdrs((struct sockaddr*)*laddr);

    while(1)
    {
        flags = 0;

        ret = sctp_recvmsg(sock, buffer, BUFFER_SIZE, NULL, 0, NULL, &flags);

        if(flags & MSG_NOTIFICATION)
        printf("Notification received from %s:%u\n",  inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));

        printf("%d bytes received from %s:%u\n", ret, inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));      
    }

    if(close(sock) < 0)
        perror("close");
}   

void handle_signal(int signum)
{
    switch(signum)
    {
        case SIGINT:
            if(close(sock) != 0)
                perror("close");
            exit(0);
            break;  
        default: exit(0);
            break;
    }
}

客户：

#include <sys/types.h>
#include <sys/socket.h>
#include <signal.h>
#include <netinet/in.h>
#include <netinet/sctp.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>

#define PORT 11000
#define MSG_SIZE 1000
#define NUMBER_OF_MESSAGES 1000

int sock;
struct sockaddr_in *paddrs[5];
struct sockaddr_in *laddrs[5];

void handle_signal(int signum);

int main(int argc, char **argv)
{
    int i;
    int counter = 0;
    int asconf = 1;
    int ret;
    int addr_count;
    char address[16];
    char buffer[MSG_SIZE];
    sctp_assoc_t id;
    struct sockaddr_in addr;
    struct sctp_status status;
    struct sctp_initmsg initmsg;
    struct sctp_event_subscribe events;
    struct sigaction sig_handler;
    struct sctp_paddrparams heartbeat;
    struct sctp_rtoinfo rtoinfo;

    memset(&buffer,     'j', MSG_SIZE);
    memset(&initmsg,    0,   sizeof(struct sctp_initmsg));
    memset(&addr,       0,   sizeof(struct sockaddr_in));
    memset(&events,     1,   sizeof(struct sctp_event_subscribe));
    memset(&status,     0,   sizeof(struct sctp_status));
    memset(&heartbeat,  0,   sizeof(struct sctp_paddrparams));
    memset(&rtoinfo,    0, sizeof(struct sctp_rtoinfo))

    if(argc != 2 || (inet_addr(argv[1]) == -1))
    {
        puts("Usage: client [IP ADDRESS in form xxx.xxx.xxx.xxx] ");        
        return 0;
    }

    strncpy(address, argv[1], 15);
    address[15] = 0;

    addr.sin_family = AF_INET;
    inet_aton(address, &(addr.sin_addr));
    addr.sin_port = htons(PORT);

    initmsg.sinit_num_ostreams = 2;
    initmsg.sinit_max_instreams = 2;
    initmsg.sinit_max_attempts = 1;

    heartbeat.spp_flags = SPP_HB_ENABLE;
    heartbeat.spp_hbinterval = 5000;
    heartbeat.spp_pathmaxrxt = 1;

    rtoinfo.srto_max = 2000;

    sig_handler.sa_handler = handle_signal;
    sig_handler.sa_flags = 0;

    /*Handle SIGINT in handle_signal Function*/
    if(sigaction(SIGINT, &sig_handler, NULL) == -1)
        perror("sigaction");

    /*Create the Socket*/
    if((ret = (sock = socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP))) < 0)
        perror("socket");

    /*Configure Heartbeats*/
    if((ret = setsockopt(sock, SOL_SCTP, SCTP_PEER_ADDR_PARAMS , &heartbeat, sizeof(heartbeat))) != 0)
        perror("setsockopt");

    /*Set rto_max*/
    if((ret = setsockopt(sock, SOL_SCTP, SCTP_RTOINFO , &rtoinfo, sizeof(rtoinfo))) != 0)
        perror("setsockopt");

    /*Set SCTP Init Message*/
    if((ret = setsockopt(sock, SOL_SCTP, SCTP_INITMSG, &initmsg, sizeof(initmsg))) != 0)
        perror("setsockopt");

    /*Enable SCTP Events*/
    if((ret = setsockopt(sock, SOL_SCTP, SCTP_EVENTS, (void *)&events, sizeof(events))) != 0)
        perror("setsockopt");

    /*Get And Print Heartbeat Interval*/
    i = (sizeof heartbeat);
    getsockopt(sock, SOL_SCTP, SCTP_PEER_ADDR_PARAMS, &heartbeat, (socklen_t*)&i);

    printf("Heartbeat interval %d\n", heartbeat.spp_hbinterval);

    /*Connect to Host*/
    if(((ret = connect(sock, (struct sockaddr*)&addr, sizeof(struct sockaddr)))) < 0)
    {
        perror("connect");
        close(sock);
        exit(0);
    }

    /*Get Peer Addresses*/
    addr_count = sctp_getpaddrs(sock, 0, (struct sockaddr**)paddrs);
    printf("\nPeer addresses: %d\n", addr_count);

    /*Print Out Addresses*/
    for(i = 0; i < addr_count; i++)
        printf("Address %d: %s:%d\n", i +1, inet_ntoa((*paddrs)[i].sin_addr), (*paddrs)[i].sin_port);

    sctp_freepaddrs((struct sockaddr*)*paddrs);

    /*Start to Send Data*/
    for(i = 0; i < NUMBER_OF_MESSAGES; i++)
    {
        counter++;
        printf("Sending data chunk #%d...", counter);

        if((ret = send(sock, buffer, MSG_SIZE, 0)) == -1)
            perror("write");

        printf("Sent %d bytes to peer\n",ret);

        sleep(1);
    }

    if(close(sock) != 0)
        perror("close");
}


void handle_signal(int signum)
{
    switch(signum)
    {
        case SIGINT:
            if(close(sock) != 0)
                perror("close");
            exit(0);
            break;  
        default: exit(0);
            break;
    }
}

这篇关于SCTP多宿主的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！