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-rw-r--r--libssh/pcap.c291
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diff --git a/libssh/pcap.c b/libssh/pcap.c
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+/*
+ * This file is part of the SSH Library
+ *
+ * Copyright (c) 2009 by Aris Adamantiadis
+ *
+ * The SSH Library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at your
+ * option) any later version.
+ *
+ * The SSH Library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the SSH Library; see the file COPYING. If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/* pcap.c */
+/** \defgroup ssh_pcap SSH-pcap
+ * \brief libssh pcap file generation
+ *
+ * \addtogroup ssh_pcap
+ * @{ */
+
+#include <stdio.h>
+#include <sys/time.h>
+
+#include "config.h"
+#include "libssh/libssh.h"
+#include "libssh/pcap.h"
+#include "libssh/session.h"
+#include "libssh/buffer.h"
+
+#ifdef WITH_PCAP
+/* The header of a pcap file is the following. We are not going to make it
+ * very complicated.
+ * Just for information.
+ */
+struct pcap_hdr_s {
+ u_int32_t magic_number; /* magic number */
+ u_int16_t version_major; /* major version number */
+ u_int16_t version_minor; /* minor version number */
+ int32_t thiszone; /* GMT to local correction */
+ u_int32_t sigfigs; /* accuracy of timestamps */
+ u_int32_t snaplen; /* max length of captured packets, in octets */
+ u_int32_t network; /* data link type */
+};
+
+#define PCAP_MAGIC 0xa1b2c3d4
+#define PCAP_VERSION_MAJOR 2
+#define PCAP_VERSION_MINOR 4
+
+#define DLT_RAW 12 /* raw IP */
+
+/* TCP flags */
+#define TH_FIN 0x01
+#define TH_SYN 0x02
+#define TH_RST 0x04
+#define TH_PUSH 0x08
+#define TH_ACK 0x10
+#define TH_URG 0x20
+
+/* The header of a pcap packet.
+ * Just for information.
+ */
+struct pcaprec_hdr_s {
+ u_int32_t ts_sec; /* timestamp seconds */
+ u_int32_t ts_usec; /* timestamp microseconds */
+ u_int32_t incl_len; /* number of octets of packet saved in file */
+ u_int32_t orig_len; /* actual length of packet */
+};
+
+/** @private
+ * @brief a pcap context expresses the state of a pcap dump
+ * in a SSH session only. Multiple pcap contexts may be used into
+ * a single pcap file.
+ */
+
+struct ssh_pcap_context_struct {
+ ssh_session session;
+ ssh_pcap_file file;
+ /* All of these informations are useful to generate
+ * the dummy IP and TCP packets
+ */
+ u_int32_t ipsource;
+ u_int32_t ipdest;
+ u_int16_t portsource;
+ u_int16_t portdest;
+ u_int32_t outsequence;
+ u_int32_t insequence;
+};
+
+/** @private
+ * @brief a pcap file expresses the state of a pcap file which may
+ * contain several streams.
+ */
+struct ssh_pcap_file_struct {
+ FILE *output;
+};
+
+/**
+ * @brief create a new ssh_pcap_file object
+ */
+ssh_pcap_file ssh_pcap_file_new(){
+ return malloc(sizeof(struct ssh_pcap_file_struct));
+}
+
+/** @internal
+ * @brief writes a packet on file
+ */
+static int ssh_pcap_file_write(ssh_pcap_file pcap, ssh_buffer packet){
+ int err;
+ uint32_t len;
+ if(pcap == NULL || pcap->output==NULL)
+ return SSH_ERROR;
+ len=buffer_get_len(packet);
+ err=fwrite(buffer_get(packet),len,1,pcap->output);
+ if(err<0)
+ return SSH_ERROR;
+ else
+ return SSH_OK;
+}
+
+/** @internal
+ * @brief prepends a packet with the pcap header and writes packet
+ * on file
+ */
+int ssh_pcap_file_write_packet(ssh_pcap_file pcap, ssh_buffer packet, u_int32_t original_len){
+ ssh_buffer header=buffer_new();
+ struct timeval now;
+ int err;
+ if(header == NULL)
+ return SSH_ERROR;
+ gettimeofday(&now,NULL);
+ buffer_add_u32(header,htonl(now.tv_sec));
+ buffer_add_u32(header,htonl(now.tv_usec));
+ buffer_add_u32(header,htonl(buffer_get_len(packet)));
+ buffer_add_u32(header,htonl(original_len));
+ buffer_add_buffer(header,packet);
+ err=ssh_pcap_file_write(pcap,header);
+ buffer_free(header);
+ return err;
+}
+
+/**
+ * @brief opens a new pcap file and create header
+ */
+int ssh_pcap_file_open(ssh_pcap_file pcap, const char *filename){
+ ssh_buffer header;
+ int err;
+ if(pcap == NULL)
+ return SSH_ERROR;
+ if(pcap->output){
+ fclose(pcap->output);
+ pcap->output=NULL;
+ }
+ pcap->output=fopen(filename,"wb");
+ if(pcap->output==NULL)
+ return SSH_ERROR;
+ header=buffer_new();
+ if(header==NULL)
+ return SSH_ERROR;
+ buffer_add_u32(header,htonl(PCAP_MAGIC));
+ buffer_add_u16(header,htons(PCAP_VERSION_MAJOR));
+ buffer_add_u16(header,htons(PCAP_VERSION_MINOR));
+ /* currently hardcode GMT to 0 */
+ buffer_add_u32(header,htonl(0));
+ /* accuracy */
+ buffer_add_u32(header,htonl(0));
+ /* size of the biggest packet */
+ buffer_add_u32(header,htonl(MAX_PACKET_LEN));
+ /* we will write sort-of IP */
+ buffer_add_u32(header,htonl(DLT_RAW));
+ err=ssh_pcap_file_write(pcap,header);
+ buffer_free(header);
+ return err;
+}
+
+int ssh_pcap_file_close(ssh_pcap_file pcap){
+ int err;
+ if(pcap ==NULL || pcap->output==NULL)
+ return SSH_ERROR;
+ err=fclose(pcap->output);
+ pcap->output=NULL;
+ if(err != 0)
+ return SSH_ERROR;
+ else
+ return SSH_OK;
+}
+
+void ssh_pcap_free(ssh_pcap_file pcap){
+ ssh_pcap_file_close(pcap);
+ SAFE_FREE(pcap);
+}
+
+
+/** @internal
+ * @brief allocates a new ssh_pcap_context object
+ */
+
+ssh_pcap_context ssh_pcap_context_new(ssh_session session){
+ ssh_pcap_context ctx=malloc(sizeof(struct ssh_pcap_context_struct));
+ if(ctx==NULL){
+ ssh_set_error_oom(session);
+ return NULL;
+ }
+ ZERO_STRUCTP(ctx);
+ ctx->session=session;
+ return ctx;
+}
+
+void ssh_pcap_context_set_file(ssh_pcap_context ctx, ssh_pcap_file pcap){
+ ctx->file=pcap;
+}
+
+int ssh_pcap_context_write(ssh_pcap_context ctx,enum ssh_pcap_direction direction
+ , void *data, u_int32_t len, u_int32_t origlen){
+ ssh_buffer ip=buffer_new();
+ int err;
+ if(ip==NULL){
+ ssh_set_error_oom(ctx->session);
+ return SSH_ERROR;
+ }
+ /* build an IP packet */
+ /* V4, 20 bytes */
+ buffer_add_u8(ip,4 << 4 | 5);
+ /* tos */
+ buffer_add_u8(ip,0);
+ /* total len */
+ buffer_add_u16(ip,htons(origlen + 40));
+ /* id */
+ buffer_add_u16(ip,htons(1));
+ /* fragment offset */
+ buffer_add_u16(ip,htons(0));
+ /* TTL */
+ buffer_add_u8(ip,64);
+ /* protocol TCP=6 */
+ buffer_add_u8(ip,6);
+ /* checksum */
+ buffer_add_u16(ip,0);
+ if(direction==SSH_PCAP_DIR_OUT){
+ buffer_add_u32(ip,ctx->ipsource);
+ buffer_add_u32(ip,ctx->ipdest);
+ } else {
+ buffer_add_u32(ip,ctx->ipdest);
+ buffer_add_u32(ip,ctx->ipsource);
+ }
+ /* TCP */
+ if(direction==SSH_PCAP_DIR_OUT){
+ buffer_add_u16(ip,ntohs(ctx->portsource));
+ buffer_add_u16(ip,ntohs(ctx->portdest));
+ } else {
+ buffer_add_u16(ip,ntohs(ctx->portdest));
+ buffer_add_u16(ip,ntohs(ctx->portsource));
+ }
+ /* sequence number */
+ if(direction==SSH_PCAP_DIR_OUT){
+ buffer_add_u32(ip,ntohl(ctx->outsequence));
+ } else {
+ buffer_add_u32(ip,ntohl(ctx->insequence));
+ }
+ /* ack number */
+ if(direction==SSH_PCAP_DIR_OUT){
+ buffer_add_u32(ip,ntohl(ctx->insequence));
+ } else {
+ buffer_add_u32(ip,ntohl(ctx->outsequence));
+ }
+ /* header len */
+ buffer_add_u8(ip,5 << 4);
+ /* flags */
+ buffer_add_u8(ip,TH_PUSH | TH_ACK);
+ /* window */
+ buffer_add_u16(ip,htons(65535));
+ /* checksum */
+ buffer_add_u16(ip,htons(0));
+ /* urgent data ptr */
+ buffer_add_u16(ip,0);
+ /* actual data */
+ buffer_add_data(ip,data,len);
+ err=ssh_pcap_file_write_packet(ctx->file,ip,origlen + 40);
+ buffer_free(ip);
+ return err;
+}
+
+#endif /* WITH_PCAP */
+/** @} */
+/* vim: set ts=2 sw=2 et cindent: */