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Factor out code to read mailboxes, and make read more robust

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New tel_read_header(), tel_read_body().  Use them in rea(),
show_first_tel(), copy_and_expire().

rea() now stops when it encounters a corrupt telegram, and logs the
problem.  Before, error detection was incomplete, and errors were not
logged.  Corrupt mailboxes could make it crash.

show_first_tel() and copy_and_expire() can now cope with telegrams of
arbitrary length, like rea(), and sanity-check the header fields they
don't actually use.
This commit is contained in:
Markus Armbruster 2009-02-08 11:13:25 +01:00
parent 6f1e669bea
commit 4238323d63
5 changed files with 114 additions and 76 deletions
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55
src/lib/common/mailbox.c
View file

@ -36,6 +36,7 @@
#include <stdio.h>
#include "optlist.h"
#include "tel.h"
#include "prototypes.h"
char *
mailbox(char *buf, natid cn)
@ -43,3 +44,57 @@ mailbox(char *buf, natid cn)
sprintf(buf, "%s/tel%d", teldir, cn);
return buf;
}
/*
* Read telegram header from FP into TEL.
* MBOX is the file name, it is used for logging errors.
* Return 1 on success, 0 on EOF, -1 on error.
*/
int
tel_read_header(FILE *fp, char *mbox, struct telstr *tel)
{
size_t n;
n = fread(tel, 1, sizeof(*tel), fp);
if (n == 0 && feof(fp))
return 0;
if (n != sizeof(*tel)
|| tel->tel_type > TEL_LAST || tel->tel_from > MAXNOC) {
logerror("Mailbox %s corrupt: bad header", mbox);
return -1;
}
return 1;
}
/*
* Read telegram body from FP.
* MBOX is the file name, it is used for logging errors.
* TEL is the header.
* Unless SINK is null, it is called like SINK(CHUNK, SZ, ARG) to
* consume the body, chunk by chunk. The chunks are UTF-8, and
* CHUNK[SZ} is 0. Reading fails when SINK() returns a negative
* value.
* Return 0 on success, -1 on failure.
*/
int
tel_read_body(FILE *fp, char *mbox, struct telstr *tel,
int (*sink)(char *, size_t, void *),
void *arg)
{
char buf[4096];
size_t left, sz;
left = tel->tel_length;
while (left) {
sz = MIN(left, sizeof(buf) - 1);
if (fread(buf, 1, sz, fp) != sz) {
logerror("Mailbox %s corrupt: can't read body", mbox);
return -1;
}
buf[sz] = 0;
if (sink && sink(buf, sz, arg) < 0)
return -1;
left -= sz;
}
return 0;
}