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// Commons for HTTP handling
package rpc
import (
"bufio"
"bytes"
"fmt"
"net"
"net/http"
"runtime/debug"
"time"
"github.com/tendermint/tendermint/alert"
"github.com/tendermint/tendermint/binary"
. "github.com/tendermint/tendermint/common"
)
func StartHTTPServer(listenAddr string, handler http.Handler) {
log.Info(Fmt("Starting RPC HTTP server on %v", listenAddr))
go func() {
listener, err := net.Listen("tcp", listenAddr)
if err != nil {
Exit(Fmt("Failed to listen to %v", listenAddr))
}
res := http.Serve(
listener,
RecoverAndLogHandler(handler),
)
log.Crit("RPC HTTP server stopped", "result", res)
}()
}
func WriteRPCResponse(w http.ResponseWriter, res RPCResponse) {
buf, n, err := new(bytes.Buffer), new(int64), new(error)
binary.WriteJSON(res, buf, n, err)
if *err != nil {
log.Warn("Failed to write RPC response", "error", err)
}
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(200)
w.Write(buf.Bytes())
}
//-----------------------------------------------------------------------------
// Wraps an HTTP handler, adding error logging.
// If the inner function panics, the outer function recovers, logs, sends an
// HTTP 500 error response.
func RecoverAndLogHandler(handler http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Wrap the ResponseWriter to remember the status
rww := &ResponseWriterWrapper{-1, w}
begin := time.Now()
// Common headers
origin := r.Header.Get("Origin")
rww.Header().Set("Access-Control-Allow-Origin", origin)
rww.Header().Set("Access-Control-Allow-Credentials", "true")
rww.Header().Set("Access-Control-Expose-Headers", "X-Server-Time")
rww.Header().Set("X-Server-Time", fmt.Sprintf("%v", begin.Unix()))
defer func() {
// Send a 500 error if a panic happens during a handler.
// Without this, Chrome & Firefox were retrying aborted ajax requests,
// at least to my localhost.
if e := recover(); e != nil {
// If RPCResponse
if res, ok := e.(RPCResponse); ok {
WriteRPCResponse(rww, res)
} else {
// For the rest,
log.Error("Panic in RPC HTTP handler", "error", e, "stack", string(debug.Stack()))
rww.WriteHeader(http.StatusInternalServerError)
WriteRPCResponse(rww, NewRPCResponse(nil, Fmt("Internal Server Error: %v", e)))
}
}
// Finally, log.
durationMS := time.Since(begin).Nanoseconds() / 1000000
if rww.Status == -1 {
rww.Status = 200
}
log.Debug("Served RPC HTTP response",
"method", r.Method, "url", r.URL,
"status", rww.Status, "duration", durationMS,
"remoteAddr", r.RemoteAddr,
)
}()
handler.ServeHTTP(rww, r)
})
}
// Remember the status for logging
type ResponseWriterWrapper struct {
Status int
http.ResponseWriter
}
func (w *ResponseWriterWrapper) WriteHeader(status int) {
w.Status = status
w.ResponseWriter.WriteHeader(status)
}
// implements http.Hijacker
func (w *ResponseWriterWrapper) Hijack() (net.Conn, *bufio.ReadWriter, error) {
return w.ResponseWriter.(http.Hijacker).Hijack()
}
// Stick it as a deferred statement in gouroutines to prevent the program from crashing.
func Recover(daemonName string) {
if e := recover(); e != nil {
stack := string(debug.Stack())
errorString := fmt.Sprintf("[%s] %s\n%s", daemonName, e, stack)
alert.Alert(errorString)
}
}