Databases
StackOverflow2013
Postsdbo
POHow to copy the struct variables into buffer in c socket program?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to copy the struct variables into buffer in c socket program?
    primarykey
    data
    text
    <p>In the client side,I need to receive the packets from the network and write it into a file which will be sent to the server for further process. </p> <p>There was problem in receiving and processing the packets because i used to send just a buffer not 'saddr' and its 'size' in write() api. </p> <p>Hence i used structure to declare all the members such as buffer, saddr, saddr_size. This is my data_capture code:</p> <pre><code>int logfile; struct sockaddr_in source, dest; struct fields{ //edited void* b; struct sockaddr *s; socklen_t *ssize; }data; int main() { int saddr_size, data_size; struct fields data; struct sockaddr saddr; gopromiscous(); unsigned char *buffer = (unsigned char *) malloc(1024); logfile = open("sniff_data.bin", O_CREAT | O_WRONLY | O_APPEND, 0777); if (logfile == -1) { printf("Unable to create sniff_data file."); } printf("\n Client Receiving the Packets...\n"); int sock_raw = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); setsockopt(sock_raw, SOL_SOCKET, SO_BINDTODEVICE, "eth0", strlen("eth0") + 1); if (sock_raw &lt; 0) { perror("Socket Error"); return 1; } int count = 10; while (count &gt;= 0) { count--; saddr_size = sizeof saddr; //Receive a packet data_size = recvfrom(sock_raw, buffer, 1024, 0, &amp;saddr, (socklen_t*) &amp;saddr_size); // i have created struct to buffer,saddr and saddr_size above if (data_size &lt; 0) { printf("Recvfrom error , failed to get packets\n"); return 1; } //i need to copy the values of buffer, saddr and sddr_size into a variable and //then use that variable in write api strcpy(data.b,buffer); //edited data.s=&amp;saddr; data.ssize=(socklen_t*)&amp;saddr_size; int cont = write(logfile, &amp;data, data_size); } printf("\n Done\n"); close(logfile); close(sock_raw); return 0; } int gopromiscous() { int fd; struct ifreq eth; fd = socket(AF_INET, SOCK_PACKET, htons(0x800)); strcpy(eth.ifr_name, "eth0"); ioctl(fd, SIOCGIFFLAGS, &amp;eth); eth.ifr_flags |= IFF_PROMISC; ioctl(fd, SIOCSIFFLAGS, &amp;eth); printf("\n Entered Promiscuous Mode Successfully\n"); } </code></pre> <p>I used strcpy to copy the values of buffer,sadddr,saddr_size to a variable which can be used in write api. I mean to say i want to copy the whole structure into a buffer and then use it in write().</p> <p>data process code is :</p> <pre><code> void ProcessPacket(unsigned char* , int); void print_ip_header(unsigned char* , int); void print_tcp_packet(unsigned char * , int ); void print_udp_packet(unsigned char * , int ); void print_icmp_packet(unsigned char* , int ); void PrintData (unsigned char* , int); FILE *logfile; int infile; struct sockaddr_in source,dest; int tcp=0,udp=0,icmp=0,others=0,igmp=0,total=0,i,j; int main() { int saddr_size , data_size; struct sockaddr saddr; struct fields{ void* b; struct sockaddr *s; socklen_t *ssize; }data2; unsigned char *buffer3 = (unsigned char *) malloc(1024); char *fname = "/home/shishira/Desktop/packet_capture/info_agent_report_processed.txt"; infile=open("info_agent_report.txt",O_RDONLY); logfile=fopen(fname,"w"); printf("\n Starting..\n"); saddr_size = sizeof saddr; //Now process the packet int totl=1; do { printf("iteration %d of processing at taskagent\n",totl++); data_size=read(infile,&amp;data2,3024); //the value which was read by struct variables should be copied to buffer3 . strcpy(buffer3,data2.b); saddr=*(data2.s); (socklen_t*)saddr_size=*(data2.ssize); ProcessPacket(buffer3 , data_size); } while(data_size&gt;0); fclose(logfile); close(infile); printf("\n"); printf(" Finished\n\n"); return 0; } </code></pre> <p>when i compile this data_process code i get error in the line (socklen_t*)saddr_size=*(data2.ssize); warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] error: lvalue required as left operand of assignment</p> <p>I had previously posted this question but i dint get the solution . Hence have posted it again by uploading entire modified code. Please somebody help me.</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USBeginner
    1. USBeginner
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow to copy the struct variables into buffer in c socket program?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI agree with Parthiban..Your problem is not just writing to log file. In fact, it is simple when you correct your other errors in your code.
      singulars
      1. POHow to copy the struct variables into buffer in c socket program?
      1. USRaju Kundhe
    2. CO`(socklen_t*) &saddr_size);` this will fail misarably on systems where `int` is not the same size as `socklen_t`.
      singulars
      1. POHow to copy the struct variables into buffer in c socket program?
      1. USalk
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload