Re: [Qemu-devel] [PATCH 1/4] Use getaddrinfo for migration

[Kevin Wolf <kwolf@redhat.com>]

Am 10.02.2012 07:27, schrieb Amos Kong:
> This allows us to use ipv4/ipv6 for migration addresses.
> Once there, it also uses /etc/services names (it came free).
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> Signed-off-by: Amos Kong <akong@redhat.com>
> ---
>  migration-tcp.c |   60 ++++++++-----------------------
>  net.c           |  108 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  qemu_socket.h   |    3 ++
>  3 files changed, 127 insertions(+), 44 deletions(-)

This patch is making too many changes at once:

1. Move code around
2. Remove duplicated code between client and server
3. Replace parse_host_port() with an open-coded version
4. Modify the open-coded parse_host_port() to use getaddrinfo instead of
inet_aton/gethostbyname (Why can't we just change parse_host_port? Are
there valid reasons to use the old implementation? Which?)

This makes it rather hard to review.

> diff --git a/migration-tcp.c b/migration-tcp.c
> index 35a5781..644bb8f 100644
> --- a/migration-tcp.c
> +++ b/migration-tcp.c
> @@ -81,43 +81,27 @@ static void tcp_wait_for_connect(void *opaque)
>  
>  int tcp_start_outgoing_migration(MigrationState *s, const char *host_port)
>  {
> -    struct sockaddr_in addr;
>      int ret;
> -
> -    ret = parse_host_port(&addr, host_port);
> -    if (ret < 0) {
> -        return ret;
> -    }
> +    int fd;
>  
>      s->get_error = socket_errno;
>      s->write = socket_write;
>      s->close = tcp_close;
>  
> -    s->fd = qemu_socket(PF_INET, SOCK_STREAM, 0);
> -    if (s->fd == -1) {
> -        DPRINTF("Unable to open socket");
> -        return -socket_error();
> -    }
> -
> -    socket_set_nonblock(s->fd);
> -
> -    do {
> -        ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
> -        if (ret == -1) {
> -            ret = -socket_error();
> -        }
> -        if (ret == -EINPROGRESS || ret == -EWOULDBLOCK) {
> -            qemu_set_fd_handler2(s->fd, NULL, NULL, tcp_wait_for_connect, s);
> -            return 0;
> -        }
> -    } while (ret == -EINTR);
> -
> -    if (ret < 0) {
> +    ret = tcp_client_start(host_port, &fd);
> +    s->fd = fd;
> +    if (ret == -EINPROGRESS || ret == -EWOULDBLOCK) {
> +        DPRINTF("connect in progress");
> +        qemu_set_fd_handler2(s->fd, NULL, NULL, tcp_wait_for_connect, s);
> +    } else if (ret < 0) {
>          DPRINTF("connect failed\n");
> -        migrate_fd_error(s);
> +        if (ret != -EINVAL) {
> +            migrate_fd_error(s);
> +        }

This looks odd. It is probably needed to keep the old behaviour where a
failed parse_host_port() wouldn't call migrate_fd_error(). Is this
really required? Maybe I'm missing something, but the caller can't know
which failure case we had and if migrate_fd_error() has been called.

>          return ret;
> +    } else {
> +        migrate_fd_connect(s);
>      }
> -    migrate_fd_connect(s);
>      return 0;
>  }
>  
> @@ -157,28 +141,16 @@ out2:
>  
>  int tcp_start_incoming_migration(const char *host_port)
>  {
> -    struct sockaddr_in addr;
> -    int val;
> +    int ret;
>      int s;
>  
>      DPRINTF("Attempting to start an incoming migration\n");
>  
> -    if (parse_host_port(&addr, host_port) < 0) {
> -        fprintf(stderr, "invalid host/port combination: %s\n", host_port);
> -        return -EINVAL;
> -    }
> -
> -    s = qemu_socket(PF_INET, SOCK_STREAM, 0);
> -    if (s == -1) {
> -        return -socket_error();
> +    ret = tcp_server_start(host_port, &s);
> +    if (ret < 0) {
> +        return ret;
>      }
>  
> -    val = 1;
> -    setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char *)&val, sizeof(val));
> -
> -    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
> -        goto err;
> -    }
>      if (listen(s, 1) == -1) {
>          goto err;
>      }
> diff --git a/net.c b/net.c
> index c34474f..f63014c 100644
> --- a/net.c
> +++ b/net.c
> @@ -99,6 +99,114 @@ static int get_str_sep(char *buf, int buf_size, const char **pp, int sep)
>      return 0;
>  }
>  
> +static int tcp_server_bind(int fd, struct addrinfo *rp)
> +{
> +    int ret;
> +    int val = 1;
> +
> +    /* allow fast reuse */
> +    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (const char *)&val, sizeof(val));
> +
> +    ret = bind(fd, rp->ai_addr, rp->ai_addrlen);
> +
> +    if (ret == -1) {
> +        ret = -socket_error();
> +    }
> +    return ret;
> +
> +}
> +
> +static int tcp_client_connect(int fd, struct addrinfo *rp)
> +{
> +    int ret;
> +
> +    do {
> +        ret = connect(fd, rp->ai_addr, rp->ai_addrlen);
> +        if (ret == -1) {
> +            ret = -socket_error();
> +        }
> +    } while (ret == -EINTR);
> +
> +    return ret;
> +}
> +
> +
> +static int tcp_start_common(const char *str, int *fd, bool server)
> +{
> +    char hostname[512];
> +    const char *service;
> +    const char *name;
> +    struct addrinfo hints;
> +    struct addrinfo *result, *rp;
> +    int s;
> +    int sfd;
> +    int ret = -EINVAL;
> +
> +    *fd = -1;
> +    service = str;
> +    if (get_str_sep(hostname, sizeof(hostname), &service, ':') < 0) {
> +        return -EINVAL;
> +    }

Separating host name and port at the first colon looks wrong for IPv6.

> +    if (server && strlen(hostname) == 0) {
> +        name = NULL;
> +    } else {
> +        name = hostname;
> +    }
> +
> +    /* Obtain address(es) matching host/port */
> +
> +    memset(&hints, 0, sizeof(struct addrinfo));
> +    hints.ai_family = AF_UNSPEC;     /* Allow IPv4 or IPv6 */
> +    hints.ai_socktype = SOCK_STREAM; /* Datagram socket */
> +
> +    if (server) {
> +        hints.ai_flags = AI_PASSIVE;
> +    }
> +
> +    s = getaddrinfo(name, service, &hints, &result);
> +    if (s != 0) {
> +        fprintf(stderr, "qemu: getaddrinfo: %s\n", gai_strerror(s));

error_report?

Kevin