POS_VIA,
POS_CONTACT,
POS_CONTENT,
- POS_MEDIA,
- POS_OWNER_IP4,
- POS_CONNECTION_IP4,
- POS_OWNER_IP6,
- POS_CONNECTION_IP6,
- POS_SDP_HEADER,
+};
+
+struct sip_header {
+ const char *name;
+ const char *cname;
+ const char *search;
+ unsigned int len;
+ unsigned int clen;
+ unsigned int slen;
+ int (*match_len)(const struct nf_conn *ct,
+ const char *dptr, const char *limit,
+ int *shift);
+};
+
+#define __SIP_HDR(__name, __cname, __search, __match) \
+{ \
+ .name = (__name), \
+ .len = sizeof(__name) - 1, \
+ .cname = (__cname), \
+ .clen = (__cname) ? sizeof(__cname) - 1 : 0, \
+ .search = (__search), \
+ .slen = (__search) ? sizeof(__search) - 1 : 0, \
+ .match_len = (__match), \
+}
+
+#define SDP_HDR(__name, __search, __match) \
+ __SIP_HDR(__name, NULL, __search, __match)
+
+enum sdp_header_types {
+ SDP_HDR_UNSPEC,
+ SDP_HDR_VERSION,
+ SDP_HDR_OWNER_IP4,
+ SDP_HDR_CONNECTION_IP4,
+ SDP_HDR_OWNER_IP6,
+ SDP_HDR_CONNECTION_IP6,
+ SDP_HDR_MEDIA,
};
extern unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
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_sdp_header(const struct nf_conn *ct, const char *dptr,
+ unsigned int dataoff, unsigned int datalen,
+ enum sdp_header_types type,
+ enum sdp_header_types term,
+ unsigned int *matchoff, unsigned int *matchlen);
+
#endif /* __KERNEL__ */
#endif /* __NF_CONNTRACK_SIP_H__ */
return NF_ACCEPT;
}
-static unsigned int mangle_sip_packet(struct sk_buff *skb,
- const char **dptr, unsigned int *datalen,
- char *buffer, int bufflen,
- enum sip_header_pos pos)
+static int mangle_content_len(struct sk_buff *skb,
+ const char **dptr, unsigned int *datalen)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
- unsigned int matchlen, matchoff;
+ unsigned int matchoff, matchlen;
+ char buffer[sizeof("65536")];
+ int buflen, c_len;
+ /* Get actual SDP length */
+ if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
+ SDP_HDR_VERSION, SDP_HDR_UNSPEC,
+ &matchoff, &matchlen) <= 0)
+ return 0;
+ c_len = *datalen - matchoff + strlen("v=");
+
+ /* Now, update SDP length */
if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen,
- pos) <= 0)
+ POS_CONTENT) <= 0)
return 0;
+ buflen = sprintf(buffer, "%u", c_len);
return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
- buffer, bufflen);
+ buffer, buflen);
}
-static int mangle_content_len(struct sk_buff *skb,
- const char **dptr, unsigned int *datalen)
+static unsigned mangle_sdp_packet(struct sk_buff *skb,
+ const char **dptr, unsigned int *datalen,
+ enum sdp_header_types type,
+ char *buffer, int buflen)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
- unsigned int matchoff, matchlen;
- char buffer[sizeof("65536")];
- int bufflen;
+ unsigned int matchlen, matchoff;
- /* Get actual SDP length */
- if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff,
- &matchlen, POS_SDP_HEADER) > 0) {
-
- /* since ct_sip_get_info() give us a pointer passing 'v='
- we need to add 2 bytes in this count. */
- int c_len = *datalen - matchoff + 2;
-
- /* Now, update SDP length */
- if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff,
- &matchlen, POS_CONTENT) > 0) {
-
- bufflen = sprintf(buffer, "%u", c_len);
- return mangle_packet(skb, dptr, datalen,
- matchoff, matchlen,
- buffer, bufflen);
- }
- }
- return 0;
+ if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, type, SDP_HDR_UNSPEC,
+ &matchoff, &matchlen) <= 0)
+ return 0;
+ return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
+ buffer, buflen);
}
static unsigned int mangle_sdp(struct sk_buff *skb,
/* Mangle owner and contact info. */
bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip));
- if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen,
- POS_OWNER_IP4))
+ if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_OWNER_IP4,
+ buffer, bufflen))
return 0;
- if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen,
- POS_CONNECTION_IP4))
+ if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_CONNECTION_IP4,
+ buffer, bufflen))
return 0;
/* Mangle media port. */
bufflen = sprintf(buffer, "%u", port);
- if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen,
- POS_MEDIA))
+ if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_MEDIA,
+ buffer, bufflen))
return 0;
return mangle_content_len(skb, dptr, datalen);
.ln_strlen = sizeof(":") - 1,
.match_len = skp_digits_len
},
- [POS_MEDIA] = { /* SDP media info */
- .case_sensitive = 1,
- .lname = "\nm=",
- .lnlen = sizeof("\nm=") - 1,
- .sname = "\rm=",
- .snlen = sizeof("\rm=") - 1,
- .ln_str = "audio ",
- .ln_strlen = sizeof("audio ") - 1,
- .match_len = digits_len
- },
- [POS_OWNER_IP4] = { /* SDP owner address*/
- .case_sensitive = 1,
- .lname = "\no=",
- .lnlen = sizeof("\no=") - 1,
- .sname = "\ro=",
- .snlen = sizeof("\ro=") - 1,
- .ln_str = "IN IP4 ",
- .ln_strlen = sizeof("IN IP4 ") - 1,
- .match_len = epaddr_len
- },
- [POS_CONNECTION_IP4] = {/* SDP connection info */
- .case_sensitive = 1,
- .lname = "\nc=",
- .lnlen = sizeof("\nc=") - 1,
- .sname = "\rc=",
- .snlen = sizeof("\rc=") - 1,
- .ln_str = "IN IP4 ",
- .ln_strlen = sizeof("IN IP4 ") - 1,
- .match_len = epaddr_len
- },
- [POS_OWNER_IP6] = { /* SDP owner address*/
- .case_sensitive = 1,
- .lname = "\no=",
- .lnlen = sizeof("\no=") - 1,
- .sname = "\ro=",
- .snlen = sizeof("\ro=") - 1,
- .ln_str = "IN IP6 ",
- .ln_strlen = sizeof("IN IP6 ") - 1,
- .match_len = epaddr_len
- },
- [POS_CONNECTION_IP6] = {/* SDP connection info */
- .case_sensitive = 1,
- .lname = "\nc=",
- .lnlen = sizeof("\nc=") - 1,
- .sname = "\rc=",
- .snlen = sizeof("\rc=") - 1,
- .ln_str = "IN IP6 ",
- .ln_strlen = sizeof("IN IP6 ") - 1,
- .match_len = epaddr_len
- },
- [POS_SDP_HEADER] = { /* SDP version header */
- .case_sensitive = 1,
- .lname = "\nv=",
- .lnlen = sizeof("\nv=") - 1,
- .sname = "\rv=",
- .snlen = sizeof("\rv=") - 1,
- .ln_str = "=",
- .ln_strlen = sizeof("=") - 1,
- .match_len = digits_len
- }
};
/* get line length until first CR or LF seen. */
}
EXPORT_SYMBOL_GPL(ct_sip_get_info);
+/* SDP header parsing: a SDP session description contains an ordered set of
+ * headers, starting with a section containing general session parameters,
+ * optionally followed by multiple media descriptions.
+ *
+ * SDP headers always start at the beginning of a line. According to RFC 2327:
+ * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should
+ * be tolerant and also accept records terminated with a single newline
+ * character". We handle both cases.
+ */
+static const struct sip_header ct_sdp_hdrs[] = {
+ [SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len),
+ [SDP_HDR_OWNER_IP4] = SDP_HDR("o=", "IN IP4 ", epaddr_len),
+ [SDP_HDR_CONNECTION_IP4] = SDP_HDR("c=", "IN IP4 ", epaddr_len),
+ [SDP_HDR_OWNER_IP6] = SDP_HDR("o=", "IN IP6 ", epaddr_len),
+ [SDP_HDR_CONNECTION_IP6] = SDP_HDR("c=", "IN IP6 ", epaddr_len),
+ [SDP_HDR_MEDIA] = SDP_HDR("m=", "audio ", digits_len),
+};
+
+/* Linear string search within SDP header values */
+static const char *ct_sdp_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')
+ break;
+ if (strncmp(dptr, needle, len) == 0)
+ return dptr;
+ }
+ return NULL;
+}
+
+/* Locate a SDP header (optionally a substring within the header value),
+ * optionally stopping at the first occurence of the term header, parse
+ * it and return the offset and length of the data we're interested in.
+ */
+int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
+ unsigned int dataoff, unsigned int datalen,
+ enum sdp_header_types type,
+ enum sdp_header_types term,
+ unsigned int *matchoff, unsigned int *matchlen)
+{
+ const struct sip_header *hdr = &ct_sdp_hdrs[type];
+ const struct sip_header *thdr = &ct_sdp_hdrs[term];
+ 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;
+ }
+
+ if (term != SDP_HDR_UNSPEC &&
+ limit - dptr >= thdr->len &&
+ strnicmp(dptr, thdr->name, thdr->len) == 0)
+ break;
+ else if (limit - dptr >= hdr->len &&
+ strnicmp(dptr, hdr->name, hdr->len) == 0)
+ dptr += hdr->len;
+ else
+ continue;
+
+ *matchoff = dptr - start;
+ if (hdr->search) {
+ dptr = ct_sdp_header_search(dptr, limit, hdr->search,
+ hdr->slen);
+ if (!dptr)
+ return -1;
+ dptr += hdr->slen;
+ }
+
+ *matchlen = hdr->match_len(ct, dptr, limit, &shift);
+ if (!*matchlen)
+ return -1;
+ *matchoff = dptr - start + shift;
+ return 1;
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header);
+
static int set_expected_rtp(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
union nf_inet_addr *addr, __be16 port)
int ret = NF_ACCEPT;
unsigned int matchoff, matchlen;
u_int16_t port;
- enum sip_header_pos pos;
+ enum sdp_header_types type;
typeof(nf_nat_sip_hook) nf_nat_sip;
/* No Data ? */
goto out;
}
/* Get address and port from SDP packet. */
- pos = family == AF_INET ? POS_CONNECTION_IP4 : POS_CONNECTION_IP6;
- if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen, pos) > 0) {
+ type = family == AF_INET ? SDP_HDR_CONNECTION_IP4 :
+ SDP_HDR_CONNECTION_IP6;
+ if (ct_sip_get_sdp_header(ct, dptr, 0, datalen, type, SDP_HDR_UNSPEC,
+ &matchoff, &matchlen) > 0) {
/* We'll drop only if there are parse problems. */
if (!parse_addr(ct, dptr + matchoff, NULL, &addr,
ret = NF_DROP;
goto out;
}
- if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen,
- POS_MEDIA) > 0) {
+ if (ct_sip_get_sdp_header(ct, dptr, 0, datalen,
+ SDP_HDR_MEDIA, SDP_HDR_UNSPEC,
+ &matchoff, &matchlen) > 0) {
port = simple_strtoul(dptr + matchoff, NULL, 10);
if (port < 1024) {
git://bbs.cooldavid.org / net-next-2.6.git / commitdiff