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package clients
import (
"context"
"regexp"
"sync"
"time"
"github.com/mimecast/dtail/internal/clients/remote"
"github.com/mimecast/dtail/internal/discovery"
"github.com/mimecast/dtail/internal/io/logger"
"github.com/mimecast/dtail/internal/omode"
"github.com/mimecast/dtail/internal/ssh/client"
gossh "golang.org/x/crypto/ssh"
)
// This is the main client data structure.
type baseClient struct {
Args
// To display client side stats
stats *stats
// List of remote servers to connect to.
servers []string
// We have one connection per remote server.
connections []*remote.Connection
// SSH auth methods to use to connect to the remote servers.
sshAuthMethods []gossh.AuthMethod
// To deal with SSH host keys
hostKeyCallback client.HostKeyCallback
// Throttle how fast we initiate SSH connections concurrently
throttleCh chan struct{}
// Retry connection upon failure?
retry bool
// Connection maker helper.
maker maker
}
func (c *baseClient) init(maker maker) {
logger.Info("Initiating base client")
c.maker = maker
c.sshAuthMethods, c.hostKeyCallback = client.InitSSHAuthMethods(c.Args.SSHAuthMethods, c.Args.SSHHostKeyCallback, c.Args.TrustAllHosts, c.throttleCh, c.Args.PrivateKeyPathFile)
discoveryService := discovery.New(c.Discovery, c.ServersStr, discovery.Shuffle)
for _, server := range discoveryService.ServerList() {
c.connections = append(c.connections, c.makeConnection(server, c.sshAuthMethods, c.hostKeyCallback))
}
if _, err := regexp.Compile(c.Regex); err != nil {
logger.FatalExit(c.Regex, "Can't test compile regex", err)
}
c.stats = newTailStats(len(c.connections))
}
func (c *baseClient) Start(ctx context.Context) (status int) {
// Periodically check for unknown hosts, and ask the user whether to trust them or not.
go c.hostKeyCallback.PromptAddHosts(ctx)
// Periodically print out connection stats to the client.
go c.stats.periodicLogStats(ctx, c.throttleCh)
// Keep count of active connections
active := make(chan struct{}, len(c.connections))
var mutex sync.Mutex
for i, conn := range c.connections {
go func(i int, conn *remote.Connection) {
connStatus := c.start(ctx, active, i, conn)
// Update global status.
mutex.Lock()
defer mutex.Unlock()
if connStatus > status {
status = connStatus
}
}(i, conn)
}
c.waitUntilDone(ctx, active)
return
}
func (c *baseClient) start(ctx context.Context, active chan struct{}, i int, conn *remote.Connection) (status int) {
// Increment connection count
active <- struct{}{}
// Derement connection count
defer func() { <-active }()
for {
connCtx, cancel := conn.Handler.WithCancel(ctx)
defer cancel()
conn.Start(connCtx, cancel, c.throttleCh, c.stats.connectionsEstCh)
// Retrieve status code from handler (dtail client will exit with that status)
status = conn.Handler.Status()
if !c.retry {
return
}
time.Sleep(time.Second * 2)
logger.Debug(conn.Server, "Reconnecting")
conn = c.makeConnection(conn.Server, c.sshAuthMethods, c.hostKeyCallback)
c.connections[i] = conn
}
}
func (c *baseClient) makeConnection(server string, sshAuthMethods []gossh.AuthMethod, hostKeyCallback client.HostKeyCallback) *remote.Connection {
conn := remote.NewConnection(server, c.UserName, sshAuthMethods, hostKeyCallback)
conn.Handler = c.maker.makeHandler(server)
conn.Commands = c.maker.makeCommands()
return conn
}
func (c *baseClient) waitUntilDone(ctx context.Context, active chan struct{}) {
defer logger.Info("Terminated connection")
// We want to have at least one active connection
<-active
// Put it back on the channel
active <- struct{}{}
if c.Mode == omode.TailClient && c.retry {
<-ctx.Done()
}
for {
numActive := len(active)
if numActive == 0 {
return
}
logger.Debug("Active connections", numActive)
time.Sleep(time.Second)
}
}
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