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Some miscellaneous marshalling helpers.

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I'm about to use these in a new piece of code, but they may come in
helpful elsewhere as well. match_ssh_id in particular wraps an idiom
that's quite common in the rest of the codebase.
This commit is contained in:
Simon Tatham 2015-04-27 20:48:29 +01:00
parent 2968563180
commit 1e453d1f97
2 changed files with 51 additions and 0 deletions
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34
misc.c
View File

@ -9,6 +9,7 @@
#include <ctype.h>
#include <assert.h>
#include "putty.h"
#include "misc.h"
/*
* Parse a string block size specification. This is approximately a
@ -1035,3 +1036,36 @@ int smemeq(const void *av, const void *bv, size_t len)
* we want to return 1, so then we can just shift down. */
return (0x100 - val) >> 8;
}
int match_ssh_id(int stringlen, const void *string, const char *id)
{
int idlen = strlen(id);
return (idlen == stringlen && !memcmp(string, id, idlen));
}
void *get_ssh_string(int *datalen, const void **data, int *stringlen)
{
void *ret;
int len;
if (*datalen < 4)
return NULL;
len = GET_32BIT_MSB_FIRST((const unsigned char *)*data);
if (*datalen < len+4)
return NULL;
ret = (void *)((const char *)*data + 4);
*datalen -= len + 4;
*data = (const char *)*data + len + 4;
*stringlen = len;
return ret;
}
int get_ssh_uint32(int *datalen, const void **data, unsigned *ret)
{
if (*datalen < 4)
return FALSE;
*ret = GET_32BIT_MSB_FIRST((const unsigned char *)*data);
*datalen -= 4;
*data = (const char *)*data + 4;
return TRUE;
}

17
misc.h
View File

@ -78,6 +78,23 @@ void smemclr(void *b, size_t len);
* by the 'eq' in the name. */
int smemeq(const void *av, const void *bv, size_t len);
/* Extracts an SSH-marshalled string from the start of *data. If
* successful (*datalen is not too small), advances data/datalen past
* the string and returns a pointer to the string itself and its
* length in *stringlen. Otherwise does nothing and returns NULL.
*
* Like strchr, this function can discard const from its parameter.
* Treat it as if it was a family of two functions, one returning a
* non-const string given a non-const pointer, and one taking and
* returning const. */
void *get_ssh_string(int *datalen, const void **data, int *stringlen);
/* Extracts an SSH uint32, similarly. Returns TRUE on success, and
* leaves the extracted value in *ret. */
int get_ssh_uint32(int *datalen, const void **data, unsigned *ret);
/* Given a not-necessarily-zero-terminated string in (length,data)
* form, check if it equals an ordinary C zero-terminated string. */
int match_ssh_id(int stringlen, const void *string, const char *id);
/*
* Debugging functions.
*