Re: How to set a flow label in IPv6 TCP server

[LDB]

kengo sakai wrote:
> Hi,
> 
> I am tring to set a flow label in IPv6 TCP message which TCP server send.
> I could set a flow label in IPv6 TCP message which TCP client send.
> Does anyone know how to set a flow label in IPv6 TCP server?
> 
> There seems to be no documentation available about IPv6 flow lable in Linux.
> 
> Attached you can find my simple TCP server program, which does not compile.
> Of course I don't expect you to debug my code,
> but I suppose it may be helpful.
> 
> Regards,
> Kengo
> 
> // tcpserver6.c
> #include <sys/types.h>
> #include <sys/socket.h>
> #include <netdb.h>
> #include <string.h>
> #include <unistd.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <errno.h>
> 
> #define BACKLOG 5
> #define PORT "12345"
> 
> int tcp_listen(const char* service) {
>     int err;
>     struct addrinfo hints;
>     struct addrinfo* res = NULL;
>     struct addrinfo* ai;
>     int sockfd;
> 
>     memset(&hints, 0, sizeof(hints));
>     hints.ai_family = AF_INET6;
>     hints.ai_socktype = SOCK_STREAM;
>     hints.ai_flags = AI_PASSIVE;
> 
>     err = getaddrinfo(NULL, service, &hints, &res);
>     if (err != 0) {
>         printf("getaddrinfo(): %s\n", gai_strerror(err));
>         return -1;
>     }
> 
>     ai = res;
>     sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
>     if (sockfd < 0)
>         return -1;
> 
>     if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)
>         return -1;
> 
>     if (listen(sockfd, BACKLOG) < 0)
>         return -1;
> 
>     freeaddrinfo(res);
>     return sockfd;
> }
> 
> int main() {
>     int sockfd;
> 
>     sockfd = tcp_listen(PORT);
>     if (sockfd < 0) {
>         perror("server");
>         exit(1);
>     }
> 
>     printf("wait...\n");
> 
>     while (1) {
>         int cs;
>         struct sockaddr_storage sa;
>         socklen_t len = sizeof(sa);
>         cs = accept(sockfd, (struct sockaddr*) &sa, &len);
>         if (cs < 0) {
>             if (errno == EINTR)
>                 continue;
>             perror("accept");
>             exit(1);
>         }
> 
>         printf("accepted.\n");
> 
>         char ch;
> 
>         (void)set_flow_label(cs, &sa);
>         read(cs, &ch, 1);
>         write(cs, &ch, 1); // I expect that the flowlabel is set to the packet.
> 
>         close(cs);
>     }
>     return 0;
> }
> // tcpserver6.c end
> 
> // flowlabel.c
> #include <sys/socket.h>
> #include <linux/in.h>
> #include <linux/in6.h>
> #include <string.h>
> #include <stdio.h>
> #include <errno.h>
> 
> int set_flow_label(int sock, struct sockaddr_in6 *addr)
> {
>     char freq_buf[sizeof(struct in6_flowlabel_req)];
>     struct in6_flowlabel_req *freq = (struct in6_flowlabel_req *)freq_buf;
>     int freq_len = sizeof(*freq);
>     int on = 1;
> 
>     if (setsockopt(sock, IPPROTO_IPV6, IPV6_FLOWINFO_SEND,
>                &on, sizeof(on)) == -1) {
>         printf("setsockopt: %s\n", strerror(errno));
>         return 1;
>     }
> 
>     memset(freq, 0, sizeof(*freq));
>     freq->flr_label = 0;
>     freq->flr_action = IPV6_FL_A_GET;
>     freq->flr_flags = IPV6_FL_F_CREATE;
>     freq->flr_share = IPV6_FL_S_EXCL;
>     memcpy(&freq->flr_dst, &addr->sin6_addr, 16);
>     if (setsockopt(sock, IPPROTO_IPV6, IPV6_FLOWLABEL_MGR, freq, freq_len)
>             == -1) {
>         printf("setsockopt: %s\n", strerror(errno));
>         return 1;
>     }
>     return 0;
> }
> // flowlabel.c end
> --
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> 
> 

It compiled just fine, without edits, for me.

LDB
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