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/* $Id: wire.c 7258 2005-06-06 03:14:45Z eagle $
**
** Wire format article utilities.
**
** Originally written by Alex Kiernan (alex.kiernan@thus.net)
**
** These routines manipulate wire format articles; in particular, they should
** be safe in the presence of embedded NULs. They assume wire format
** conventions (\r\n as a line ending, in particular) and will not work with
** articles in native format.
**
** The functions in this file take const char * pointers and return char *
** pointers so that they can work on both const char * and char * article
** bodies without changing the const sense. This unfortunately means that
** the routines in this file will produce warnings about const being cast
** away. To avoid those, one would need to duplicate all the code in this
** file or use C++.
*/
#include "config.h"
#include "clibrary.h"
#include <assert.h>
#include "inn/wire.h"
#include "libinn.h"
/*
** Given a pointer to the start of an article, locate the first octet of the
** body (which may be the octet beyond the end of the buffer if your article
** is bodiless).
*/
char *
wire_findbody(const char *article, size_t length)
{
char *p;
const char *end;
/* Handle the degenerate case of an article with no headers. */
if (length > 5 && article[0] == '\r' && article[1] == '\n')
return (char *) article + 2;
/* Jump from \r to \r and give up if we're too close to the end. */
end = article + length;
for (p = (char *) article; (p + 4) <= end; ++p) {
p = memchr(p, '\r', end - p - 3);
if (p == NULL)
break;
if (memcmp(p, "\r\n\r\n", 4) == 0) {
p += 4;
return p;
}
}
return NULL;
}
/*
** Given a pointer into an article and a pointer to the last octet of the
** article, find the next line ending and return a pointer to the first
** character after that line ending. If no line ending is found in the
** article or if it is at the end of the article, return NULL.
*/
char *
wire_nextline(const char *article, const char *end)
{
char *p;
for (p = (char *) article; (p + 2) <= end; ++p) {
p = memchr(p, '\r', end - p - 2);
if (p == NULL)
break;
if (p[1] == '\n') {
p += 2;
return p;
}
}
return NULL;
}
/*
** Returns true if line is the beginning of a valid header for header, also
** taking the length of the header name as a third argument. Assumes that
** there is at least length + 2 bytes of data at line, and that the header
** name doesn't contain nul.
*/
static bool
isheader(const char *line, const char *header, size_t length)
{
if (line[length] != ':' || !ISWHITE(line[length + 1]))
return false;
return strncasecmp(line, header, length) == 0;
}
/*
** Skip over folding whitespace, as defined by RFC 2822. Takes a pointer to
** where to start skipping and a pointer to the end of the data, and will not
** return a pointer past the end pointer. If skipping folding whitespace
** takes us past the end of data, return NULL.
*/
static char *
skip_fws(char *text, const char *end)
{
char *p;
for (p = text; p <= end; p++) {
if (p < end + 1 && p[0] == '\r' && p[1] == '\n' && ISWHITE(p[2]))
p += 2;
if (!ISWHITE(*p))
return p;
}
return NULL;
}
/*
** Given a pointer to the start of the article, the article length, and the
** header to look for, find the first occurance of that header in the
** article. Skip over headers with no content, but allow for headers that
** are folded before the first text in the header. If no matching headers
** with content other than spaces and tabs are found, return NULL.
*/
char *
wire_findheader(const char *article, size_t length, const char *header)
{
char *p;
const char *end;
ptrdiff_t headerlen;
headerlen = strlen(header);
end = article + length - 1;
/* There has to be enough space left in the article for at least the
header, the colon, whitespace, and one non-whitespace character, hence
3, minus 1 since the character pointed to by end is part of the
article. */
p = (char *) article;
while (p != NULL && end - p > headerlen + 2) {
if (p[0] == '\r' && p[1] == '\n')
return NULL;
else if (isheader(p, header, headerlen)) {
p = skip_fws(p + headerlen + 2, end);
if (p == NULL)
return NULL;
if (p >= end || p[0] != '\r' || p[1] != '\n')
return p;
}
p = wire_nextline(p, end);
}
return NULL;
}
/*
** Given a pointer to a header and a pointer to the last octet of the
** article, find the end of the header (a pointer to the final \n of the
** header value). If the header contents don't end in \r\n, return NULL.
*/
char *
wire_endheader(const char *header, const char *end)
{
char *p;
p = wire_nextline(header, end);
while (p != NULL) {
if (!ISWHITE(*p))
return p - 1;
p = wire_nextline(p, end);
}
if (end - header >= 1 && *end == '\n' && *(end - 1) == '\r')
return (char *) end;
return NULL;
}
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