fix some gcc warnings (#73) * tweak string size fix gcc8 warnings ``` svr-agentfwd.c: In function 'bindagent': svr-agentfwd.c:254:53: warning: '%s' directive output may be truncated writing up to 107 bytes into a region of size between 0 and 107 [-Wformat-truncation=] snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/%s", path, sockfile); ^~ ~~~~~~~~ svr-agentfwd.c:254:2: note: 'snprintf' output between 2 and 216 bytes into a destination of size 108 snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/%s", path, sockfile); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ``` * cleanup signed/unsigned comparison fix gcc8 warnings ``` scp.c: In function 'do_local_cmd': scp.c:132:17: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] for (i = 0; i < a->num; i++) ^ scpmisc.c: In function 'addargs': scpmisc.c:161:25: warning: comparison of integer expressions of different signedness: 'int' and 'u_int' {aka 'unsigned int'} [-Wsign-compare] } else if (args->num+2 >= nalloc) ^~ scpmisc.c: In function 'replacearg': scpmisc.c:183:12: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] if (which >= args->num) ^~ scpmisc.c: In function 'freeargs': scpmisc.c:196:17: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] for (i = 0; i < args->num; i++) ^ ``` see https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/misc.h.diff?r1=1.16&r2=1.17

#ifndef DROPBEAR_DROPBEAR_ECC_H
#define DROPBEAR_DROPBEAR_ECC_H

#include "includes.h"

#include "buffer.h"

#if DROPBEAR_ECC

struct dropbear_ecc_curve {
	int ltc_size; /* to match the byte sizes in ltc_ecc_sets[] */
	const ltc_ecc_set_type *dp; /* curve domain parameters */
	const struct ltc_hash_descriptor *hash_desc;
	const char *name;
};

extern struct dropbear_ecc_curve ecc_curve_nistp256;
extern struct dropbear_ecc_curve ecc_curve_nistp384;
extern struct dropbear_ecc_curve ecc_curve_nistp521;
extern struct dropbear_ecc_curve *dropbear_ecc_curves[];

void dropbear_ecc_fill_dp(void);
struct dropbear_ecc_curve* curve_for_dp(const ltc_ecc_set_type *dp);

/* "pubkey" refers to a point, but LTC uses ecc_key structure for both public
   and private keys */
void buf_put_ecc_raw_pubkey_string(buffer *buf, ecc_key *key);
ecc_key * buf_get_ecc_raw_pubkey(buffer *buf, const struct dropbear_ecc_curve *curve);
int buf_get_ecc_privkey_string(buffer *buf, ecc_key *key);

mp_int * dropbear_ecc_shared_secret(ecc_key *pub_key, const ecc_key *priv_key);

#endif

#endif /* DROPBEAR_DROPBEAR_ECC_H */