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package handler
import (
"context"
"fmt"
"net/http"
"time"
"git.sigsum.org/sigsum-go/pkg/log"
"git.sigsum.org/sigsum-go/pkg/types"
)
type Config interface {
Prefix() string
LogID() string
Deadline() time.Duration
}
// Handler implements the http.Handler interface
type Handler struct {
Config
Fun func(context.Context, Config, http.ResponseWriter, *http.Request) (int, error)
Endpoint types.Endpoint
Method string
}
// Path returns a path that should be configured for this handler
func (h Handler) Path() string {
if len(h.Prefix()) == 0 {
return h.Endpoint.Path("", "sigsum", "v0")
}
return h.Endpoint.Path("", h.Prefix(), "sigsum", "v0")
}
// ServeHTTP is part of the http.Handler interface
func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
start := time.Now()
code := 0
defer func() {
end := time.Now().Sub(start).Seconds()
sc := fmt.Sprintf("%d", code)
rspcnt.Inc(h.LogID(), string(h.Endpoint), sc)
latency.Observe(end, h.LogID(), string(h.Endpoint), sc)
}()
reqcnt.Inc(h.LogID(), string(h.Endpoint))
code = h.verifyMethod(w, r)
if code != 0 {
return
}
h.handle(w, r)
}
// verifyMethod checks that an appropriate HTTP method is used and
// returns 0 if so, or an HTTP status code if not. Error handling is
// based on RFC 7231, see Sections 6.5.5 (Status 405) and 6.5.1
// (Status 400).
func (h Handler) verifyMethod(w http.ResponseWriter, r *http.Request) int {
checkHTTPMethod := func(m string) bool {
return m == http.MethodGet || m == http.MethodPost
}
if h.Method == r.Method {
return 0
}
code := http.StatusBadRequest
if ok := checkHTTPMethod(r.Method); ok {
w.Header().Set("Allow", h.Method)
code = http.StatusMethodNotAllowed
}
http.Error(w, fmt.Sprintf("error=%s", http.StatusText(code)), code)
return code
}
// handle handles an HTTP request for which the HTTP method is already verified
func (h Handler) handle(w http.ResponseWriter, r *http.Request) {
deadline := time.Now().Add(h.Deadline())
ctx, cancel := context.WithDeadline(r.Context(), deadline)
defer cancel()
code, err := h.Fun(ctx, h.Config, w, r)
if err != nil {
log.Debug("%s/%s: %v", h.Prefix(), h.Endpoint, err)
http.Error(w, fmt.Sprintf("error=%s", err.Error()), code)
} else if code != 200 {
w.WriteHeader(code)
}
}
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