[NETFILTER]: nf_conntrack_sip: parse SIP headers properly
Introduce new function for SIP header parsing that properly deals with
continuation lines and whitespace in headers and use it.
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
commit ad68c0360489e4b074598ccdaff30d0651198fb2
tree f0b21dcbff630b2d4dfdac64d45ac649b224aac8
parent 5c32e869153429dda7acaa55eb609138af7f6f01
author Patrick McHardy <kaber@xxxxxxxxx> Thu, 28 Feb 2008 12:08:22 +0100
committer Patrick McHardy <kaber@xxxxxxxxx> Thu, 28 Feb 2008 12:08:22 +0100
include/linux/netfilter/nf_conntrack_sip.h | 30 ++-
net/ipv4/netfilter/nf_nat_sip.c | 18 +-
net/netfilter/nf_conntrack_sip.c | 271 +++++++++++++---------------
3 files changed, 151 insertions(+), 168 deletions(-)
diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h
index 9b96e17..fac85c6 100644
--- a/include/linux/netfilter/nf_conntrack_sip.h
+++ b/include/linux/netfilter/nf_conntrack_sip.h
@@ -11,14 +11,6 @@ enum sip_expectation_classes {
};
#define SIP_EXPECT_MAX (__SIP_EXPECT_MAX - 1)
-enum sip_header_pos {
- POS_FROM,
- POS_TO,
- POS_VIA,
- POS_CONTACT,
- POS_CONTENT,
-};
-
struct sip_header {
const char *name;
const char *cname;
@@ -42,9 +34,20 @@ struct sip_header {
.match_len = (__match), \
}
+#define SIP_HDR(__name, __cname, __search, __match) \
+ __SIP_HDR(__name, __cname, __search, __match)
+
#define SDP_HDR(__name, __search, __match) \
__SIP_HDR(__name, NULL, __search, __match)
+enum sip_header_types {
+ SIP_HDR_FROM,
+ SIP_HDR_TO,
+ SIP_HDR_CONTACT,
+ SIP_HDR_VIA,
+ SIP_HDR_CONTENT_LENGTH,
+};
+
enum sdp_header_types {
SDP_HDR_UNSPEC,
SDP_HDR_VERSION,
@@ -66,13 +69,10 @@ extern unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
extern int ct_sip_parse_request(const struct nf_conn *ct,
const char *dptr, unsigned int datalen,
unsigned int *matchoff, unsigned int *matchlen);
-extern int ct_sip_get_info(const struct nf_conn *ct, const char *dptr,
- size_t dlen, unsigned int *matchoff,
- unsigned int *matchlen, enum sip_header_pos pos);
-extern int ct_sip_lnlen(const char *line, const char *limit);
-extern const char *ct_sip_search(const char *needle, const char *haystack,
- size_t needle_len, size_t haystack_len,
- int case_sensitive);
+extern int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
+ unsigned int dataoff, unsigned int datalen,
+ enum sip_header_types type,
+ unsigned int *matchoff, unsigned int *matchlen);
extern int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
unsigned int dataoff, unsigned int datalen,
diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index 60151b5..c13e438 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -108,14 +108,14 @@ static int map_addr(struct sk_buff *skb,
static int map_sip_addr(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
- enum sip_header_pos pos, struct addr_map *map)
+ enum sip_header_types type, struct addr_map *map)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
unsigned int matchlen, matchoff;
- if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen,
- pos) <= 0)
+ if (ct_sip_get_header(ct, *dptr, 0, *datalen, type,
+ &matchoff, &matchlen) <= 0)
return 1;
return map_addr(skb, dptr, datalen, matchoff, matchlen, map);
}
@@ -141,10 +141,10 @@ static unsigned int ip_nat_sip(struct sk_buff *skb,
return NF_DROP;
}
- if (!map_sip_addr(skb, dptr, datalen, POS_FROM, &map) ||
- !map_sip_addr(skb, dptr, datalen, POS_TO, &map) ||
- !map_sip_addr(skb, dptr, datalen, POS_VIA, &map) ||
- !map_sip_addr(skb, dptr, datalen, POS_CONTACT, &map))
+ if (!map_sip_addr(skb, dptr, datalen, SIP_HDR_FROM, &map) ||
+ !map_sip_addr(skb, dptr, datalen, SIP_HDR_TO, &map) ||
+ !map_sip_addr(skb, dptr, datalen, SIP_HDR_VIA, &map) ||
+ !map_sip_addr(skb, dptr, datalen, SIP_HDR_CONTACT, &map))
return NF_DROP;
return NF_ACCEPT;
}
@@ -166,8 +166,8 @@ static int mangle_content_len(struct sk_buff *skb,
c_len = *datalen - matchoff + strlen("v=");
/* Now, update SDP length */
- if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen,
- POS_CONTENT) <= 0)
+ if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH,
+ &matchoff, &matchlen) <= 0)
return 0;
buflen = sprintf(buffer, "%u", c_len);
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index d79a6fc..cf35a73 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -47,109 +47,6 @@ unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
struct nf_conntrack_expect *exp) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sdp_hook);
-static int digits_len(const struct nf_conn *, const char *, const char *, int *);
-static int epaddr_len(const struct nf_conn *, const char *, const char *, int *);
-static int skp_digits_len(const struct nf_conn *, const char *, const char *, int *);
-static int skp_epaddr_len(const struct nf_conn *, const char *, const char *, int *);
-
-struct sip_header_nfo {
- const char *lname;
- const char *sname;
- const char *ln_str;
- size_t lnlen;
- size_t snlen;
- size_t ln_strlen;
- int case_sensitive;
- int (*match_len)(const struct nf_conn *, const char *,
- const char *, int *);
-};
-
-static const struct sip_header_nfo ct_sip_hdrs[] = {
- [POS_FROM] = { /* SIP From header */
- .lname = "From:",
- .lnlen = sizeof("From:") - 1,
- .sname = "\r\nf:",
- .snlen = sizeof("\r\nf:") - 1,
- .ln_str = "sip:",
- .ln_strlen = sizeof("sip:") - 1,
- .match_len = skp_epaddr_len,
- },
- [POS_TO] = { /* SIP To header */
- .lname = "To:",
- .lnlen = sizeof("To:") - 1,
- .sname = "\r\nt:",
- .snlen = sizeof("\r\nt:") - 1,
- .ln_str = "sip:",
- .ln_strlen = sizeof("sip:") - 1,
- .match_len = skp_epaddr_len
- },
- [POS_VIA] = { /* SIP Via header */
- .lname = "Via:",
- .lnlen = sizeof("Via:") - 1,
- .sname = "\r\nv:",
- .snlen = sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
- .ln_str = "UDP ",
- .ln_strlen = sizeof("UDP ") - 1,
- .match_len = epaddr_len,
- },
- [POS_CONTACT] = { /* SIP Contact header */
- .lname = "Contact:",
- .lnlen = sizeof("Contact:") - 1,
- .sname = "\r\nm:",
- .snlen = sizeof("\r\nm:") - 1,
- .ln_str = "sip:",
- .ln_strlen = sizeof("sip:") - 1,
- .match_len = skp_epaddr_len
- },
- [POS_CONTENT] = { /* SIP Content length header */
- .lname = "Content-Length:",
- .lnlen = sizeof("Content-Length:") - 1,
- .sname = "\r\nl:",
- .snlen = sizeof("\r\nl:") - 1,
- .ln_str = ":",
- .ln_strlen = sizeof(":") - 1,
- .match_len = skp_digits_len
- },
-};
-
-/* get line length until first CR or LF seen. */
-int ct_sip_lnlen(const char *line, const char *limit)
-{
- const char *k = line;
-
- while ((line < limit) && (*line == '\r' || *line == '\n'))
- line++;
-
- while (line < limit) {
- if (*line == '\r' || *line == '\n')
- break;
- line++;
- }
- return line - k;
-}
-EXPORT_SYMBOL_GPL(ct_sip_lnlen);
-
-/* Linear string search, case sensitive. */
-const char *ct_sip_search(const char *needle, const char *haystack,
- size_t needle_len, size_t haystack_len,
- int case_sensitive)
-{
- const char *limit = haystack + (haystack_len - needle_len);
-
- while (haystack < limit) {
- if (case_sensitive) {
- if (strncmp(haystack, needle, needle_len) == 0)
- return haystack;
- } else {
- if (strnicmp(haystack, needle, needle_len) == 0)
- return haystack;
- }
- haystack++;
- }
- return NULL;
-}
-EXPORT_SYMBOL_GPL(ct_sip_search);
-
static int string_len(const struct nf_conn *ct, const char *dptr,
const char *limit, int *shift)
{
@@ -173,16 +70,6 @@ static int digits_len(const struct nf_conn *ct, const char *dptr,
return len;
}
-/* get digits length, skipping blank spaces. */
-static int skp_digits_len(const struct nf_conn *ct, const char *dptr,
- const char *limit, int *shift)
-{
- for (; dptr < limit && *dptr == ' '; dptr++)
- (*shift)++;
-
- return digits_len(ct, dptr, limit, shift);
-}
-
static int parse_addr(const struct nf_conn *ct, const char *cp,
const char **endp, union nf_inet_addr *addr,
const char *limit)
@@ -303,50 +190,146 @@ int ct_sip_parse_request(const struct nf_conn *ct,
}
EXPORT_SYMBOL_GPL(ct_sip_parse_request);
-/* Returns 0 if not found, -1 error parsing. */
-int ct_sip_get_info(const struct nf_conn *ct,
- const char *dptr, size_t dlen,
- unsigned int *matchoff,
- unsigned int *matchlen,
- enum sip_header_pos pos)
+/* SIP header parsing: SIP headers are located at the beginning of a line, but
+ * may span several lines, in which case the continuation lines begin with a
+ * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or
+ * CRLF, RFC 3261 allows only CRLF, we support both.
+ *
+ * Headers are followed by (optionally) whitespace, a colon, again (optionally)
+ * whitespace and the values. Whitespace in this context means any amount of
+ * tabs, spaces and continuation lines, which are treated as a single whitespace
+ * character.
+ */
+static const struct sip_header ct_sip_hdrs[] = {
+ [SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
+ [SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
+ [SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
+ [SIP_HDR_VIA] = SIP_HDR("Via", "v", "UDP ", epaddr_len),
+ [SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len),
+};
+
+static const char *sip_follow_continuation(const char *dptr, const char *limit)
{
- const struct sip_header_nfo *hnfo = &ct_sip_hdrs[pos];
- const char *limit, *aux, *k = dptr;
- int shift = 0;
+ /* Walk past newline */
+ if (++dptr >= limit)
+ return NULL;
+
+ /* Skip '\n' in CR LF */
+ if (*(dptr - 1) == '\r' && *dptr == '\n') {
+ if (++dptr >= limit)
+ return NULL;
+ }
- limit = dptr + (dlen - hnfo->lnlen);
+ /* Continuation line? */
+ if (*dptr != ' ' && *dptr != '\t')
+ return NULL;
- while (dptr < limit) {
- if ((strncmp(dptr, hnfo->lname, hnfo->lnlen) != 0) &&
- (hnfo->sname == NULL ||
- strncmp(dptr, hnfo->sname, hnfo->snlen) != 0)) {
- dptr++;
+ /* skip leading whitespace */
+ for (; dptr < limit; dptr++) {
+ if (*dptr != ' ' && *dptr != '\t')
+ break;
+ }
+ return dptr;
+}
+
+static const char *sip_skip_whitespace(const char *dptr, const char *limit)
+{
+ for (; dptr < limit; dptr++) {
+ if (*dptr == ' ')
+ continue;
+ if (*dptr != '\r' && *dptr != '\n')
+ break;
+ dptr = sip_follow_continuation(dptr, limit);
+ if (dptr == NULL)
+ return NULL;
+ }
+ return dptr;
+}
+
+/* Search within a SIP header value, dealing with continuation lines */
+static const char *ct_sip_header_search(const char *dptr, const char *limit,
+ const char *needle, unsigned int len)
+{
+ for (limit -= len; dptr < limit; dptr++) {
+ if (*dptr == '\r' || *dptr == '\n') {
+ dptr = sip_follow_continuation(dptr, limit);
+ if (dptr == NULL)
+ break;
continue;
}
- aux = ct_sip_search(hnfo->ln_str, dptr, hnfo->ln_strlen,
- ct_sip_lnlen(dptr, limit),
- hnfo->case_sensitive);
- if (!aux) {
- pr_debug("'%s' not found in '%s'.\n", hnfo->ln_str,
- hnfo->lname);
- return -1;
+
+ if (strnicmp(dptr, needle, len) == 0)
+ return dptr;
+ }
+ return NULL;
+}
+
+int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
+ unsigned int dataoff, unsigned int datalen,
+ enum sip_header_types type,
+ unsigned int *matchoff, unsigned int *matchlen)
+{
+ const struct sip_header *hdr = &ct_sip_hdrs[type];
+ const char *start = dptr, *limit = dptr + datalen;
+ int shift = 0;
+
+ for (dptr += dataoff; dptr < limit; dptr++) {
+ /* Find beginning of line */
+ if (*dptr != '\r' && *dptr != '\n')
+ continue;
+ if (++dptr >= limit)
+ break;
+ if (*(dptr - 1) == '\r' && *dptr == '\n') {
+ if (++dptr >= limit)
+ break;
}
- aux += hnfo->ln_strlen;
- *matchlen = hnfo->match_len(ct, aux, limit, &shift);
- if (!*matchlen)
- return -1;
+ /* Skip continuation lines */
+ if (*dptr == ' ' || *dptr == '\t')
+ continue;
+
+ /* Find header. Compact headers must be followed by a
+ * non-alphabetic character to avoid mismatches. */
+ if (limit - dptr >= hdr->len &&
+ strnicmp(dptr, hdr->name, hdr->len) == 0)
+ dptr += hdr->len;
+ else if (hdr->cname && limit - dptr >= hdr->clen + 1 &&
+ strnicmp(dptr, hdr->cname, hdr->clen) == 0 &&
+ !isalpha(*(dptr + hdr->clen + 1)))
+ dptr += hdr->clen;
+ else
+ continue;
+
+ /* Find and skip colon */
+ dptr = sip_skip_whitespace(dptr, limit);
+ if (dptr == NULL)
+ break;
+ if (*dptr != ':' || ++dptr >= limit)
+ break;
+
+ /* Skip whitespace after colon */
+ dptr = sip_skip_whitespace(dptr, limit);
+ if (dptr == NULL)
+ break;
- *matchoff = (aux - k) + shift;
+ *matchoff = dptr - start;
+ if (hdr->search) {
+ dptr = ct_sip_header_search(dptr, limit, hdr->search,
+ hdr->slen);
+ if (!dptr)
+ return -1;
+ dptr += hdr->slen;
+ }
- pr_debug("%s match succeeded! - len: %u\n", hnfo->lname,
- *matchlen);
+ *matchlen = hdr->match_len(ct, dptr, limit, &shift);
+ if (!*matchlen)
+ return -1;
+ *matchoff = dptr - start + shift;
return 1;
}
- pr_debug("%s header not found.\n", hnfo->lname);
return 0;
}
-EXPORT_SYMBOL_GPL(ct_sip_get_info);
+EXPORT_SYMBOL_GPL(ct_sip_get_header);
/* SDP header parsing: a SDP session description contains an ordered set of
* headers, starting with a section containing general session parameters,
-
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