#include "os.h"#include <libsec.h> /* rfc2104 */static DigestState*hmac_x(uchar *p, ulong len, uchar *key, ulong klen, uchar *digest, DigestState *s,	DigestState*(*x)(uchar*, ulong, uchar*, DigestState*), int xlen){	int i;	uchar pad[65], innerdigest[256]; 	if(xlen > sizeof(innerdigest))		return nil; 	if(klen>64)		return nil; 	/* first time through */	if(s == nil || s->seeded == 0){		for(i=0; i<64; i++)			pad[i] = 0x36;		pad[64] = 0;		for(i=0; i<klen; i++)			pad[i] ^= key[i];		s = (*x)(pad, 64, nil, s);		if(s == nil)			return nil;	} 	s = (*x)(p, len, nil, s);	if(digest == nil)		return s; 	/* last time through */	for(i=0; i<64; i++)		pad[i] = 0x5c;	pad[64] = 0;	for(i=0; i<klen; i++)		pad[i] ^= key[i];	(*x)(nil, 0, innerdigest, s);	s = (*x)(pad, 64, nil, nil);	(*x)(innerdigest, xlen, digest, s);	return nil;} DigestState*hmac_sha1(uchar *p, ulong len, uchar *key, ulong klen, uchar *digest, DigestState *s){	return hmac_x(p, len, key, klen, digest, s, sha1, SHA1dlen);} DigestState*hmac_md5(uchar *p, ulong len, uchar *key, ulong klen, uchar *digest, DigestState *s){	return hmac_x(p, len, key, klen, digest, s, md5, MD5dlen);}