static int mangle_content_len(struct sk_buff *skb, unsigned int dataoff, const char **dptr, unsigned int *datalen) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 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_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH, &matchoff, &matchlen) <= 0) return 0; buflen = sprintf(buffer, "%u", c_len); return mangle_packet(skb, dataoff, dptr, datalen, matchoff, matchlen, buffer, buflen); }
static unsigned mangle_sdp_packet(struct sk_buff *skb, const char **dptr, unsigned int dataoff, unsigned int *datalen, enum sdp_header_types type, enum sdp_header_types term, char *buffer, int buflen) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); unsigned int matchlen, matchoff; if (ct_sip_get_sdp_header(ct, *dptr, dataoff, *datalen, type, term, &matchoff, &matchlen) <= 0) return 0; return mangle_packet(skb, dptr, datalen, matchoff, matchlen, buffer, buflen); }