go-nostr/utils.go

package nostr

import (
	"net/url"
	"strings"
	"sync"

	"github.com/dgraph-io/ristretto/z"
	"golang.org/x/exp/constraints"
)

const MAX_LOCKS = 50

var namedMutexPool = make([]sync.Mutex, MAX_LOCKS)

func namedLock(name string) (unlock func()) {
	idx := z.MemHashString(name) % MAX_LOCKS
	namedMutexPool[idx].Lock()
	return namedMutexPool[idx].Unlock
}

func similar[E constraints.Ordered](as, bs []E) bool {
	if len(as) != len(bs) {
		return false
	}

	for _, a := range as {
		for _, b := range bs {
			if b == a {
				goto next
			}
		}
		// didn't find a B that corresponded to the current A
		return false

	next:
		continue
	}

	return true
}

// Escaping strings for JSON encoding according to RFC8259.
// Also encloses result in quotation marks "".
func escapeString(dst []byte, s string) []byte {
	dst = append(dst, '"')
	for i := 0; i < len(s); i++ {
		c := s[i]
		switch {
		case c == '"':
			// quotation mark
			dst = append(dst, []byte{'\\', '"'}...)
		case c == '\\':
			// reverse solidus
			dst = append(dst, []byte{'\\', '\\'}...)
		case c >= 0x20:
			// default, rest below are control chars
			dst = append(dst, c)
		case c == 0x08:
			dst = append(dst, []byte{'\\', 'b'}...)
		case c < 0x09:
			dst = append(dst, []byte{'\\', 'u', '0', '0', '0', '0' + c}...)
		case c == 0x09:
			dst = append(dst, []byte{'\\', 't'}...)
		case c == 0x0a:
			dst = append(dst, []byte{'\\', 'n'}...)
		case c == 0x0c:
			dst = append(dst, []byte{'\\', 'f'}...)
		case c == 0x0d:
			dst = append(dst, []byte{'\\', 'r'}...)
		case c < 0x10:
			dst = append(dst, []byte{'\\', 'u', '0', '0', '0', 0x57 + c}...)
		case c < 0x1a:
			dst = append(dst, []byte{'\\', 'u', '0', '0', '1', 0x20 + c}...)
		case c < 0x20:
			dst = append(dst, []byte{'\\', 'u', '0', '0', '1', 0x47 + c}...)
		}
	}
	dst = append(dst, '"')
	return dst
}

func IsValidRelayURL(u string) bool {
	parsed, err := url.Parse(u)
	if err != nil {
		return false
	}
	if parsed.Scheme != "wss" && parsed.Scheme != "ws" {
		return false
	}
	if len(strings.Split(parsed.Host, ".")) < 2 {
		return false
	}
	return true
}