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• Constructing radiotap header and ieee80211 header structures for packet injection

  - by hektor

  I am trying to communicate between two laptop machines using Wifi. The structure of the radiotap header and ieee80211 header I am using is: struct ieee80211_radiotap_header { unsigned char it_version; uint16_t it_len; uint32_t it_present; }; /* Structure for 80211 header */ struct ieee80211_hdr_3addr { uint16_t frame_ctl[2]; uint16_t duration_id; unsigned char addr1[ETH_ALEN]; unsigned char addr2[ETH_ALEN]; unsigned char addr3[ETH_ALEN]; uint16_t seq_ctl; }; struct packet { struct ieee80211_radiotap_header rtap_header; struct ieee80211_hdr_3addr iee802_header; unsigned char payload[30]; }; /* In main program */ struct packet mypacket; struct ieee80211_radiotap_header ratap_header; struct ieee80211_hdr_3addr iee802_header; unsigned char addr1[ETH_ALEN] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF}; /* broadcast address */ unsigned char addr2[ETH_ALEN] = {0x28,0xcf,0xda,0xde,0xd3,0xcc}; /* mac address of network card */ unsigned char addr3[ETH_ALEN] = {0xd8,0xc7,0xc8,0xd7,0x9f,0x21}; /* mac address of access point i am trying to connect to */ /* Radio tap header data */ ratap_header.it_version = 0x00; ratap_header.it_len = 0x07; ratap_header.it_present = (1 << IEEE80211_RADIOTAP_RATE); mypacket.rtap_header = ratap_header; /* ieee80211 header data */ iee802_header.frame_ctl[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_MGT | IEEE80211_FC0_SUBTYPE_BEACON; iee802_header.frame_ctl[1] =IEEE80211_FC1_DIR_NODS; strcpy(iee802_header.addr1,addr1); strcpy(iee802_header.addr2,addr2); strcpy(iee802_header.addr3,addr3); iee802_header.seq_ctl = 0x1086; mypacket.iee802_header=iee802_header; /* Payload */ unsigned char payload[PACKET_LENGTH]="temp"; strcpy(mypacket.payload , payload); I am able to receive the packets when I test the transmission and reception on the same laptop. However I am not able to receive the packet transmitted on a different laptop. Wireshark does not show the packet as well. Can anyone point out the mistake I am making?

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• Does printf have side effects?

  - by martani_net

  I have an array of the following strcuture struct T_info { char capitale[255]; char pays[255]; char commentaire[255]; }; struct T_info *tableau; Then when I populate the array and call printf allone on each element it works fine strcpy(tab[line].capitale, buffer); strcpy(tab[line].pays, buffer); strcpy(tab[line].commentaire, buffer); printf("%s\n", tab[line].capitale); printf("%s\n", tab[line].pays); printf("%s\n", tab[line].commentaire); but if I call, printf("%s, %s, %s", tab[line].capitale, tab[line].pays, tab[line].commentaires) I get wrong resutts, is printf changing its parameters or what is going on?

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• Argc/Argv C Problems

  - by Salman

  Hey all, If I have the following code: main(int argc, char *argv[]){ char serveradd[20]; strcpy(serveradd, argv[1]); int port = atoi(argv[2]); printf("%s %d \n", serveradd, port); The first two arguments to the command line are printed. However, if I do this: char serveradd[20]; strcpy(serveradd, argv[1]); int port = atoi(argv[2]); char versionnum[1]; strcpy(versionnum, argv[3]); printf("%s %d %s \n", serveradd, port, versionnum);` The first argument (serveradd) does not print out to the screen and is not being stored... Why is this happening and how can I fix it? Thanks!

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• Memory error, access violation.

  - by Ordo

  Hello! I'm learning C on my own and as a exercise i have written a program but it does not work. The program is splitted into 3 parts. A header file, a main file for executing the program a file to define the functions. I'm not using all the functions yet but that shouldn't be the problem. Here is my header file, nothing special in it. #ifndef EMPLOYEE_H #define EMPLOYEE_H struct Employee { char first[21]; char last[21]; char title[21]; int salary; }; struct Employee* createEmployee(char*, char*, char*, int); // Creates a struct Employee object on the heap. char* getfirstname (struct Employee*); char* getlastname (struct Employee*); char* gettitle (struct Employee*); int getsalary (struct Employee*); void setfirstname (struct Employee*, char*); void setlastname (struct Employee*, char*); void settitle (struct Employee*, char*); void setsalary (struct Employee*, int); void printEmployee(struct Employee*); #endif In this file i define the functions and how they work: #include "7.1.h" #include <stdio.h> #include <stdlib.h> #include <string.h> struct Employee* createEmployee(char* first, char* last, char* title, int salary) // Creates a struct Employee object on the heap. { struct Employee* p = (struct Employee*) malloc(sizeof(struct Employee)); if (p != NULL) { strcpy(p->first, first); strcpy(p->last, last); strcpy(p->title, title); p->salary, salary; } return p; } char* getfirstname (struct Employee* p) { if (p != NULL) return p ? p->first : ""; } char* getlastname (struct Employee* p) { if (p != NULL) return p ? p->last : ""; } char* gettitle (struct Employee* p) { if (p != NULL) return p ? p->title : ""; } int getsalary (struct Employee* p) { if (p != NULL) return p ? p->salary : 0; } void setfirstname (struct Employee* p, char* first) { if (p != NULL) strcpy(p->first, first); } void setlastname (struct Employee* p, char* last) { if (p != NULL) strcpy(p->last, last); } void settitle (struct Employee* p, char* title) { if (p != NULL) strcpy(p->title, title); } void setsalary (struct Employee* p, char* salary) { if (p != NULL) p->salary, salary; } void printEmployee(struct Employee* p) { if (p != NULL) { printf("%s, %s, %s, %d", p->first, p->last, p->salary, p->salary ); } } And the last file is used to executed the program/functions: #include "7.1.h" #include <stdio.h> #include <stdlib.h> int main () { char decision; struct Employee emp; struct Employee* emps[3]; for ( int i = 0; i < 1; i ++) { printf("Please type in the emplooyes data.\nFirstname:"); scanf("%s", emp.first); printf("Lastname:"); scanf("%s", emp.last); printf("Title:"); scanf("%s", emp.title); printf("Salary:"); scanf("%d", &emp.salary); emps[i] = createEmployee(emp.first, emp.last, emp.title, emp.salary); } printf("Do you want to print out your information? (Y/N):"); scanf("%c", &decision); if (decision == 'y' || decision == 'Y') { printEmployee(emps[1]); } } I don't know what the problem is. I 'm always getting the following error message after typing in first, last, title and salary for the first time. The error is written in german. It means: Unhandled exception at 0x102de42e (msvcr100d.dll) in 7.1.exe: 0xC0000005: Access violation when writing to 0xCCCCCCCC position. I could fix the first problem with the hints given below. Now when i want to print out the employee data using the function:printEmployee(emps[1]);, I get the same kind of error with access violation.

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• sorting set of five string in alphabetical oder throwing warning?

  - by rost rost

  sorting set of five string in alphabetical oder throwing warning ?my code is below please help me to fix it #include<stdio.h> #include<string.h> int main() { char a[5][20],t[20]; int i,j; printf("enter 5 string\n") scanf("%s",a); for(i=1;i<5;i++) { for(j=1;j<5;j++) { if(strcmp(a[j-1],a[j])>0) { strcpy (t,a[j-1]); strcpy (a[j-1],a[j]); strcpy(a[j],t); } } } for(i=1;i<5;i++) printf("%s\n",a[i]); } ~

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• Const unsigned char* to char*

  - by BSchlinker

  So, I have two types at the moment: const unsigned char* unencrypted_data_char; string unencrypted_data; I'm attempting to perform a simple conversion of data from one to the other (string - const unsigned char*) As a result, I have the following: strcpy((unencrypted_data_char),(unencrypted_data.c_str())); However, I'm receiving the error: error C2664: 'strcpy' : cannot convert parameter 1 from 'const unsigned char *' to 'char *' Any advise? I thought using reinterpret_cast would help, but it doesn't seem to make a difference.

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• Const unsigned char* to char8

  - by BSchlinker

  So, I have two types at the moment: const unsigned char* unencrypted_data_char; string unencrypted_data; I'm attempting to perform a simple conversion of data from one to the other (string - const unsigned char*) As a result, I have the following: strcpy((unencrypted_data_char),(unencrypted_data.c_str())); However, I'm receiving the error: error C2664: 'strcpy' : cannot convert parameter 1 from 'const unsigned char *' to 'char *' Any advise? I thought using reinterpret_cast would help, but it doesn't seem to make a difference.

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• C++: incorrect swapping of nodes in linked list

  - by Dragon

  I have 2 simple structures: struct Address { char city[255]; }; typedef Address* AddressPtr; struct Person { char fullName[255]; Address* address; Person* next; }; typedef Person* PersonPtr; The Person structure forms the Linked list where new elements are added to the beginning of the list. What I want to do is to sort them by fullName. At first I tried to swap links, but I lost the beginning of the list and as a result my list was sorted partially. Then I decided to sort list by swapping the values of nodes. But I get strange results. For a list with names: Test3, Test2, Test1, I get Test3, Test3, Test3. Here is my sorting code: void sortByName(PersonPtr& head) { TaskPtr currentNode, nextNode; for(currentNode = head; currentNode->next != NULL; currentNode = currentNode->next) { for(nextNode = currentNode->next; nextNode != NULL; nextNode = nextNode->next) { if(strcmp(currentNode->fullName, nextNode->fullName) > 0) { swapNodes(currentNode, nextNode); } } } } void swapNodes(PersonPtr& node1, PersonPtr& node2) { PersonPtr temp_node = node2; strcpy(node2->fullName, node1->fullName); strcpy(node1->fullName, temp_node->fullName); strcpy(node2->address->city, node1->address->city); strcpy(node1->address->city, temp_node->address->city); } After the sorting completion, nodes values are a little bit strange. UPDATED This is how I swapped links void swapNodes(PersonPtr& node1, PersonPtr& node2) { PersonPtr temp_person; AddressPtr temp_address; temp_person = node2; node2 = node1; node1 = temp_person; temp_address = node2->address; node2->address = node1->address; node1->address = temp_address; }

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• C programming: hashtable insertion/search

  - by Ricardo Campos

  Hello i have a problem with my hash table its implemented like this: #define HT_SIZE 10 typedef struct _list_t_ { char key[20]; char string[20]; char prevValue[20]; struct _list_t_ *next; } list_t; typedef struct _hash_table_t_ { int size; /* the size of the table */ list_t ***table; /* first */ sem_t lock; } hash_table_t; I have a Linked list with 3 pointers because i want a hash table with several partitions (shards), here is my initialization of my Hash table: hash_table_t *create_hash_table(int NUM_SERVER_THREADS, int num_shards){ hash_table_t *new_table; int j,i; if (HT_SIZE<1) return NULL; /* invalid size for table */ /* Attempt to allocate memory for the hashtable structure */ new_table = (hash_table_t*)malloc(sizeof(hash_table_t)*HT_SIZE); /* Attempt to allocate memory for the table itself */ new_table->table = (list_t ***)calloc(1,sizeof(list_t **)); /* Initialize the elements of the table */ for(j=0; j<num_shards; j++){ new_table->table[j] = (list_t **)calloc(1,sizeof(list_t *)); for(i=0; i<HT_SIZE; i++){ new_table->table[j][i] = (list_t *)calloc(1,sizeof(list_t )); } } /* Set the table's size */ new_table->size = HT_SIZE; sem_init(&new_table->lock, 0, 1); return new_table; } Here is my search function to search in the hash table list_t *lookup_string(hash_table_t *hashtable, char *key, int shardId){ list_t *list ; int hashval = hash(key); /* Go to the correct list based on the hash value and see if key is * in the list. If it is, return return a pointer to the list element. * If it isn't, the item isn't in the table, so return NULL. */ sem_wait(&hashtable->lock); for(list = hashtable->table[shardId][hashval]; list != NULL; list =list->next) { if (strcmp(key, list->key) == 0){ sem_post(&hashtable->lock); return list; } } sem_post(&hashtable->lock); return NULL; } And my insert function: char *add_string(hash_table_t *hashtable, char *str,char *key, int shardId){ list_t *new_list; list_t *current_list; unsigned int hashval = hash(key); /*printf("|%d|%d|%s|\n",hashval,shardId,key);*/ /* Lock for concurrency */ sem_wait(&hashtable->lock); /* Attempt to allocate memory for list */ new_list = (list_t*)malloc(sizeof(list_t)); /* Does item already exist? */ sem_post(&hashtable->lock); current_list = lookup_string(hashtable, key,shardId); sem_wait(&hashtable->lock); /* item already exists, don't insert it again. */ if (current_list != NULL){ strcpy(new_list->prevValue,current_list->string); strcpy(new_list->string,str); strcpy(new_list->key,key); new_list->next = hashtable->table[shardId][hashval]; hashtable->table[shardId][hashval] = new_list; sem_post(&hashtable->lock); return new_list->prevValue; } /* Insert into list */ strcpy(new_list->string,str); strcpy(new_list->key,key); new_list->next = hashtable->table[shardId][hashval]; hashtable->table[shardId][hashval] = new_list; /* Unlock */ sem_post(&hashtable->lock); return new_list->prevValue; } My main class runs some of tests by executing the insertion / reading / delete from the elements of the hash table the problem is when i have more than 4 partitions/shards the tests stop at the first reading element saying it returned the wrong value NULL on the search function, when its less than 4 it runs perfectly well and passes all the tests. You can see my main.c in here if you want to give a look: http://hostcode.sourceforge.net/view/1105 My complete Hash table code: http://hostcode.sourceforge.net/view/1103 And other functions where hash table code is executed: .c file http://hostcode.sourceforge.net/view/1104 .h file http://hostcode.sourceforge.net/view/1106 Thank for you time, i appreciate any help you can give to me this is a college important project that I'm trying to solve and I'm stuck here for 2 days.

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• How to copy file using NSIS ?

  - by Xinus

  I want to copy war file to tomcat web-app directory using NSIS setup. I have successfully installed tomcat and jdk using following script !define PRODUCT_NAME "App Deploy" !define PRODUCT_VERSION "1.0" !define PRODUCT_PUBLISHER "ZippySoft" SetCompressor lzma ;!include "UserManagement.nsh" ; MUI 1.67 compatible ------ !include "MUI.nsh" ; MUI Settings !define MUI_ABORTWARNING ;!define MUI_ICON "${NSISDIR}\Contrib\Graphics\Icons\modern-install.ico" ; Welcome page !insertmacro MUI_PAGE_WELCOME ; Components page !insertmacro MUI_PAGE_COMPONENTS ; Instfiles page !insertmacro MUI_PAGE_INSTFILES ; Finish page !insertmacro MUI_PAGE_FINISH ; Language files !insertmacro MUI_LANGUAGE "English" ; Reserve files !insertmacro MUI_RESERVEFILE_INSTALLOPTIONS ; MUI end ------ Name "${PRODUCT_NAME} ${PRODUCT_VERSION}" OutFile "AppDeploy.exe" InstallDir "$PROGRAMFILES\App Deploy" ShowInstDetails show ;Section -SETTINGS ; SetOutPath "$INSTDIR" ; SetOverwrite ifnewer ;SectionEnd ;Section "JDK" SEC01 ; File "Prerequisites\jdk-1_5_0_15-windows-i586-p.exe" ; ExecWait "$INSTDIR\jdk-1_5_0_15-windows-i586-p.exe" ;SectionEnd ;System::Call 'Kernel32::SetEnvironmentVariableA(t, t) i("name", "value").r0' ;StrCmp $0 0 error ; ExecWait ProgThatReadsEnv.exe ; Goto done ;error: ; MessageBox MB_OK "Can't set environment variable" ;done: ;Section "Tomcat" SEC02 ; File "Prerequisites\apache-tomcat-6.0.16.exe" ; ExecWait "$INSTDIR\apache-tomcat-6.0.16.exe" ;SectionEnd Section "Data Submission Tool" SEC03 File "Prerequisites\DataSubmissionToolFinal.war" CopyFiles `$INSTDIR\DataSubmissionToolFinal.war` `c:\DataSubmissionToolFinal.war` StrCpy $0 "$INSTDIR\DataSubmissionToolFinal.war" ;Path of copy file from StrCpy $1 "c:\DataSubmissionToolFinal.war" ;Path of copy file to StrCpy $2 1 ; only 0 or 1, set 0 to overwrite file if it already exists System::Call 'kernel32::CopyFile(t r0, t r1, b r2) l' Pop $0 ; pops a bool. if overwrite is off and there is a file then error will be 1 SectionEnd There are no script errors but war file is not getting copied to c drive . How to do it? Also is it possible to identify path to JDK and Tomcat installation using NSIS ? Sorry if the question is too obvious, I am quite new to NSIS..

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• A error about "Address 0x0 is not stack'd, malloc'd or (recently) free'd" in c program under linux

  - by MaiTiano

  There is a piece of my program: height = atoi(argv[3]); width = atoi(argv[2]); sprintf(seqName,"%s", argv[1]); // strcpy(seqName, argv[1]); After compiling it, a exe file test is generated, then I use Valgrind to check it. Then I got the following message, however I cannot understand what it tends to tell me. Can anyone provide some kind help, Thanks. 1 contexts (suppressed: 13 from 8) 1 contexts (suppressed: 13 from 8) jl@ubuntu:~/work/dsr_analysis$ valgrind --tool=memcheck --leak-check=yes ./test ==28940== Memcheck, a memory error detector ==28940== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al. ==28940== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info ==28940== Command: ./test ==28940== ==28940== Invalid read of size 1 ==28940== at 0x40260CA: strcpy (mc_replace_strmem.c:311) ==28940== by 0x804A5C6: main (me_search.c:1428) ==28940== Address 0x0 is not stack'd, malloc'd or (recently) free'd ==28940== ==28940== ==28940== Process terminating with default action of signal 11 (SIGSEGV) ==28940== Access not within mapped region at address 0x0 ==28940== at 0x40260CA: strcpy (mc_replace_strmem.c:311) ==28940== by 0x804A5C6: main (me_search.c:1428) ==28940== If you believe this happened as a result of a stack ==28940== overflow in your program's main thread (unlikely but ==28940== possible), you can try to increase the size of the ==28940== main thread stack using the --main-stacksize= flag. ==28940== The main thread stack size used in this run was 8388608. ==28940== ==28940== HEAP SUMMARY: ==28940== in use at exit: 0 bytes in 0 blocks ==28940== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==28940== ==28940== All heap blocks were freed -- no leaks are possible ==28940== ==28940== For counts of detected and suppressed errors, rerun with: -v ==28940== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 13 from 8)1 contexts (suppressed: 13 from 8) 1 contexts (suppressed: 13 from 8)

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• pointer-to-pointer of derived class in multiple inheritance

  - by Abdul jalil

  i have 3 classes A,B and C. C is derived from A and B. i get pointer to pointer of class C and cast to A** , and B ** , the variable that hold the the B** has the address of A** in my example B ** BdoublePtr hold the address of A** .i am using the following code #include "conio.h" #include "stdio.h" #include "string.h" class A{ public: A() { strA=new char[30]; strcpy(strA,"class A"); } char *strA; }; class B { public: B() { strB=new char[30]; strcpy(strB,"class B"); } char *strB; }; class C :public A, public B { public: C() { strC=new char[30]; strcpy(strC,"class C"); } char *strC; }; int main(void) { C* ptrC=new C(); A * Aptr=(A*)ptrC; printf("\n class A value : %s",Aptr-strA); B * Bptr=(B*)ptrC; printf("\n class B value :%s",Bptr-strB); printf("\n\nnow with double pointer "); A ** AdoublePtr=(A **)&ptrC; Aptr=AdoublePtr; printf("\n class A value : %s",Aptr-strA); B * BdoublePtr=(B **)&ptrC; Bptr=*BdoublePtr; printf("\n class B value : %s",Bptr-strB); getch(); return 0; }

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• How to determine 2D unsigned short pointers array length in c++

  - by tuman

  Hello, I am finding it difficult to determine the length of the columns in a 2D unsigned short pointer array. I have done memory allocation correctly as far as I know. and can print them correctly. plz see the following code segment: int number_of_array_index_required_for_pointer_abc=3; char A[3][16]; strcpy(A[0],"Hello"); strcpy(A[1],"World"); strcpy(A[2],"Tumanicko"); cout<<number_of_array_index_required_for_pointer_abc*sizeof(unsigned short)<<endl; unsigned short ** pqr=(unsigned short **)malloc(number_of_array_index_required_for_pointer_abc*sizeof(unsigned short)); for(int i=0;i<number_of_array_index_required_for_pointer_abc;i++) { int ajira = strlen(A[i])*sizeof(unsigned short); cout<<i<<" = "<<ajira<<endl; pqr[i]=(unsigned short *)malloc(ajira); cout<<"alocated pqr[i]= "<<sizeof pqr<<endl; int j=0; for(j=0;j<strlen(A[i]);j++) { pqr[i][j]=(unsigned short)A[i][j]; } pqr[i][j]='\0'; } for(int i=0;i<number_of_array_index_required_for_pointer_abc;i++) { //ln= (sizeof pqr[i])/(sizeof pqr[0]); //cout<<"Size of pqr["<<i<<"]= "<<ln<<endl; // I want to know the size of the columns i.e. pqr[i]'s length instead of finding '\0' for(int k=0;(char)pqr[i][k]!='\0';k++) cout<<(char)pqr[i][k]; cout<<endl; }

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• What's the meaning of 'char (*p)[5];'?

  - by jpmelos

  people. I'm trying to grasp the differences between these three declarations: char p[5]; char *p[5]; char (*p)[5]; I'm trying to find this out by doing some tests, because every guide of reading declarations and stuff like that has not helped me so far. I wrote this little program and it's not working (I've tried other kinds of use of the third declaration and I've ran out of options): #include <stdio.h> #include <string.h> #include <stdlib.h> int main(void) { char p1[5]; char *p2[5]; char (*p3)[5]; strcpy(p1, "dead"); p2[0] = (char *) malloc(5 * sizeof(char)); strcpy(p2[0], "beef"); p3[0] = (char *) malloc(5 * sizeof(char)); strcpy(p3[0], "char"); printf("p1 = %s\np2[0] = %s\np3[0] = %s\n", p1, p2[0], p3[0]); return 0; } The first and second works alright, and I've understood what they do. What is the meaning of the third declaration and the correct way to use it? Thank you!

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• Can printf change its parameters??

  - by martani_net

  EDIT: complete code with main is here http://codepad.org/79aLzj2H and once again this is were the weird behavious is happening for (i = 0; i<tab_size; i++) { //CORRECT OUTPUT printf("%s\n", tableau[i].capitale); printf("%s", tableau[i].pays); printf("%s\n", tableau[i].commentaire); //WRONG OUTPUT //printf("%s --- %s --- %s |\n", tableau[i].capitale, tableau[i].pays, tableau[i].commentaire); } I have an array of the following strcuture struct T_info { char capitale[255]; char pays[255]; char commentaire[255]; }; struct T_info *tableau; This is how the array is populated int advance(FILE *f) { char c; c = getc(f); if(c == '\n') return 0; while(c != EOF && (c == ' ' || c == '\t')) { c = getc(f); } return fseek(f, -1, SEEK_CUR); } int get_word(FILE *f, char * buffer) { char c; int count = 0; int space = 0; while((c = getc(f)) != EOF) { if (c == '\n') { buffer[count] = '\0'; return -2; } if ((c == ' ' || c == '\t') && space < 1) { buffer[count] = c; count ++; space++; } else { if (c != ' ' && c != '\t') { buffer[count] = c; count ++; space = 0; } else /* more than one space*/ { advance(f); break; } } } buffer[count] = '\0'; if(c == EOF) return -1; return count; } void fill_table(FILE *f,struct T_info *tab) { int line = 0, column = 0; fseek(f, 0, SEEK_SET); char buffer[MAX_LINE]; char c; int res; int i = 0; while((res = get_word(f, buffer)) != -999) { switch(column) { case 0: strcpy(tab[line].capitale, buffer); column++; break; case 1: strcpy(tab[line].pays, buffer); column++; break; default: strcpy(tab[line].commentaire, buffer); column++; break; } /*if I printf each one alone here, everything works ok*/ //last word in line if (res == -2) { if (column == 2) { strcpy(tab[line].commentaire, " "); } //wrong output here printf("%s -- %s -- %s\n", tab[line].capitale, tab[line].pays, tab[line].commentaire); column = 0; line++; continue; } column = column % 3; if (column == 0) { line++; } /*EOF reached*/ if(res == -1) return; } return ; } Edit : trying this printf("%s -- ", tab[line].capitale); printf("%s --", tab[line].pays); printf("%s --\n", tab[line].commentaire); gives me as result -- --abi -- Emirats arabes unis I expect to get Abu Dhabi -- Emirats arabes unis -- Am I missing something?

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• Custom string class (C++)

  - by Sanctus2099

  Hey guys. I'm trying to write my own C++ String class for educational and need purposes. The first thing is that I don't know that much about operators and that's why I want to learn them. I started writing my class but when I run it it blocks the program but does not do any crash. Take a look at the following code please before reading further: class CString { private: char* cstr; public: CString(); CString(char* str); CString(CString& str); ~CString(); operator char*(); operator const char*(); CString operator+(const CString& q)const; CString operator=(const CString& q); }; First of all I'm not so sure I declared everything right. I tried googleing about it but all the tutorials about overloading explain the basic ideea which is very simple but lack to explain how and when each thing is called. For instance in my = operator the program calls CString(CString& str); but I have no ideea why. I have also attached the cpp file below: CString::CString() { cstr=0; } CString::CString(char *str) { cstr=new char[strlen(str)]; strcpy(cstr,str); } CString::CString(CString& q) { if(this==&q) return; cstr = new char[strlen(q.cstr)+1]; strcpy(cstr,q.cstr); } CString::~CString() { if(cstr) delete[] cstr; } CString::operator char*() { return cstr; } CString::operator const char* () { return cstr; } CString CString::operator +(const CString &q) const { CString s; s.cstr = new char[strlen(cstr)+strlen(q.cstr)+1]; strcpy(s.cstr,cstr); strcat(s.cstr,q.cstr); return s; } CString CString::operator =(const CString &q) { if(this!=&q) { if(cstr) delete[] cstr; cstr = new char[strlen(q.cstr)+1]; strcpy(cstr,q.cstr); } return *this; } For testing I used a code just as simple as this CString a = CString("Hello") + CString(" World"); printf(a); I tried debugging it but at a point I get lost. First it calls the constructor 2 times for "hello" and for " world". Then it get's in the + operator which is fine. Then it calls the constructor for the empty string. After that it get's into "CString(CString& str)" and now I'm lost. Why is this happening? After this I noticed my string containing "Hello World" is in the destructor (a few times in a row). Again I'm very puzzeled. After converting again from char* to Cstring and back and forth it stops. It never get's into the = operator but neither does it go further. printf(a) is never reached. I use VisualStudio 2010 for this but it's basically just standard c++ code and thus I don't think it should make that much of a difference

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• a c++ program for task scheduling [closed]

  - by scheduling

  This is the code which I made but I am not able to correct the mistake in the code. Please correct the mistake in my code. #include<unistd.h> #include<stdio.h> #include<stdlib.h> #include<time.h> #include<string.h> int main() { char *timetoken; char currtime[7]; char schedtime[7]; int i; struct tm *localtimeptr; strcpy(schedtime,"15:25:00"); while(6!=9) { time_t lt; sleep(1); lt = time(NULL); localtimeptr = localtime(<); timetoken=strtok(asctime(localtimeptr)," "); for(i=1;i<5;i++) timetoken=strtok('\0'," "); if(i==3) { strcpy(currtime,timetoken); } } printf("The current time is: %s\n",currtime); printf("We are waiting for: %s\n",schedtime); if(!strcmp(currtime,schedtime)) { printf("Time to do stuff \n"); system("C:\PROJECT X"); } getch(); return 0; }

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• a c++ code for scheduling tasks [closed]

  - by scheduling

  This code has no errors but then when i execute it, there is no output and the program automatically shuts down saying the program has stopped working. #include<unistd.h> #include<stdio.h> #include<stdlib.h> #include<time.h> #include<string.h> int main() { char *timetoken; char currtime[7]; char schedtime[7]; int i; struct tm *localtimeptr; strcpy(schedtime,"15:25:00"); while(6!=9) { time_t lt; sleep(1); lt = time(NULL); localtimeptr = localtime(lt); timetoken=strtok(asctime(localtimeptr)," "); for(i=1;i<5;i++) timetoken=strtok('\0'," "); if(i==3) { strcpy(currtime,timetoken); } } printf("The current time is: %s\n",currtime); printf("We are waiting for: %s\n",schedtime); if(!strcmp(currtime,schedtime)) { printf("Time to do stuff \n"); system("C:\PROJECT X"); } getch(); return 0; }

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• Which functions in the C standard library commonly encourage bad practice?

  - by Ninefingers

  Hello all, This is inspired by this question and the comments on one particular answer in that I learnt that strncpy is not a very safe string handling function in C and that it pads zeros, until it reaches n, something I was unaware of. Specifically, to quote R.. strncpy does not null-terminate, and does null-pad the whole remainder of the destination buffer, which is a huge waste of time. You can work around the former by adding your own null padding, but not the latter. It was never intended for use as a "safe string handling" function, but for working with fixed-size fields in Unix directory tables and database files. snprintf(dest, n, "%s", src) is the only correct "safe strcpy" in standard C, but it's likely to be a lot slower. By the way, truncation in itself can be a major bug and in some cases might lead to privilege elevation or DoS, so throwing "safe" string functions that truncate their output at a problem is not a way to make it "safe" or "secure". Instead, you should ensure that the destination buffer is the right size and simply use strcpy (or better yet, memcpy if you already know the source string length). And from Jonathan Leffler Note that strncat() is even more confusing in its interface than strncpy() - what exactly is that length argument, again? It isn't what you'd expect based on what you supply strncpy() etc - so it is more error prone even than strncpy(). For copying strings around, I'm increasingly of the opinion that there is a strong argument that you only need memmove() because you always know all the sizes ahead of time and make sure there's enough space ahead of time. Use memmove() in preference to any of strcpy(), strcat(), strncpy(), strncat(), memcpy(). So, I'm clearly a little rusty on the C standard library. Therefore, I'd like to pose the question: What C standard library functions are used inappropriately/in ways that may cause/lead to security problems/code defects/inefficiencies? In the interests of objectivity, I have a number of criteria for an answer: Please, if you can, cite design reasons behind the function in question i.e. its intended purpose. Please highlight the misuse to which the code is currently put. Please state why that misuse may lead towards a problem. I know that should be obvious but it prevents soft answers. Please avoid: Debates over naming conventions of functions (except where this unequivocably causes confusion). "I prefer x over y" - preference is ok, we all have them but I'm interested in actual unexpected side effects and how to guard against them. As this is likely to be considered subjective and has no definite answer I'm flagging for community wiki straight away. I am also working as per C99.

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• warning: incompatible implicit declaration of built-in function ‘xyz’

  - by Alex Reynolds

  I'm getting a number of these warnings when compiling a few binaries: warning: incompatible implicit declaration of built-in function ‘strcpy’ warning: incompatible implicit declaration of built-in function ‘strlen’ warning: incompatible implicit declaration of built-in function ‘exit’ To try to resolve this, I have added #include <stdlib.h> at the top of the C files associated with this warning, in addition to compiling with the following flags: CFLAGS = -fno-builtin-exit -fno-builtin-strcat -fno-builtin-strncat -fno-builtin-strcpy -fno-builtin-strlen -fno-builtin-calloc I am using GCC 4.1.2: $ gcc --version gcc (GCC) 4.1.2 20080704 What should I do to resolve these warnings? Thanks for your advice.

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• NSIS Check Textbox empty not working

  - by Hernán

  I'm trying to display a page in NSIS to obtain two different values. I want both to be not empty. The page actually displays altough I can't get my page leave function to check properly for empty fields. Function CCInstallOpts ReserveFile "cc_installopt.ini" !insertmacro MUI_INSTALLOPTIONS_EXTRACT "cc_installopt.ini" !insertmacro MUI_INSTALLOPTIONS_DISPLAY "cc_installopt.ini" FunctionEnd My page leave function where I validate fields (4 and 5 ) is : Function CCInstallOptsLeave Push $R0 Push $R1 !insertmacro MUI_INSTALLOPTIONS_READ $R0 "cc_installopt.ini" "Field4" "State" !insertmacro MUI_INSTALLOPTIONS_READ $R1 "cc_installopt.ini" "Field5" "State" StrCmp $R0 "" mustcomplete StrCmp $R1 "" mustcomplete StrCpy $CC_CyberID $R0 StrCpy $CC_VCode $R1 goto exitfunc mustcomplete: MessageBox MB_OK|MB_ICONEXCLAMATION "Empty not allowed" Abort exitfunc: Pop $R1 Pop $R0 FunctionEnd Note that I want to store the entered values into $CC_VCode and $CC_CyberID variables to be later used on different files (I've defined both as:) Var /GLOBAL CC_VCode Var /GLOBAL CC_CyberID Thanks in advance.

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• Find IP address in iphone

  - by Ruchir Shah

  Hi, I want to find IP address in an application. I am able to find it. But, problem is, it works fins in iphone os 2.0 or so. But, in iphone os 3.0 it is giving me a warning: warning: no '+currentHost' method found warning: (Messages without a matching method signature) I am using this code, and it works fine with os version 2.0. -(NSString*)getAddress { char iphone_ip[255]; strcpy(iphone_ip,"127.0.0.1"); // if everything fails NSHost* myhost = [NSHost currentHost]; if (myhost) { NSString *ad = [myhost address]; if (ad) strcpy(iphone_ip,[ad cStringUsingEncoding: NSISOLatin1StringEncoding]); } return [NSString stringWithFormat:@"%s",iphone_ip]; } How to find IP address in iphone os 3.0 or greater os version? Thanks in advance.

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• C -Segmentation fault !

  - by FILIaS

  It seems at least weird to me... The program runs normally.But after I call the enter() function for the 4th time,there is a segmentation fault!I would appreciate any help. With the following function enter() I wanna add user commands' datas to a list. [Some part of the code is already posted on another question of me, but I think I should post it again...as it's a different problem I'm facing now.] /* struct for all the datas that user enters on file*/ typedef struct catalog { char short_name[50]; char surname[50]; signed int amount; char description[1000]; struct catalog *next; }catalog,*catalogPointer; catalogPointer current; catalogPointer head = NULL; void enter(void) //user command: i <name> <surname> <amount> <description> { int n,j=2,k=0; char temp[1500]; char *short_name,*surname,*description; signed int amount; char* params = strchr(command,' ') + 1; //strchr returns a pointer to the 1st space on the command.U want a pointer to the char right after that space. strcpy(temp, params); //params is saved as temp. char *curToken = strtok(temp," "); //strtok cuts 'temp' into strings between the spaces and saves them to 'curToken' printf("temp is:%s \n",temp); printf("\nWhat you entered for saving:\n"); for (n = 0; curToken; ++n) //until curToken ends: { if (curToken) { short_name = malloc(strlen(curToken) + 1); strncpy(short_name, curToken, sizeof (short_name)); } printf("Short Name: %s \n",short_name); curToken = strtok(NULL," "); if (curToken) { surname = malloc(strlen(curToken) + 1); strncpy(surname, curToken,sizeof (surname)); } printf("SurName: %s \n",surname); curToken = strtok(NULL," "); if (curToken) { //int * amount= malloc(sizeof (signed int *)); char *chk; amount = (int) strtol(curToken, &chk, 10); if (!isspace(*chk) && *chk != 0) fprintf(stderr,"Warning: expected integer value for amount, received %s instead\n",curToken); } printf("Amount: %d \n",amount); curToken = strtok(NULL,"\0"); if (curToken) { description = malloc(strlen(curToken) + 1); strncpy(description, curToken, sizeof (description)); } printf("Description: %s \n",description); break; } if (findEntryExists(head, surname,short_name) != NULL) //call function in order to see if entry exists already on the catalog printf("\nAn entry for <%s %s> is already in the catalog!\nNew entry not entered.\n",short_name,surname); else { printf("\nTry to entry <%s %s %d %s> in the catalog list!\n",short_name,surname,amount,description); newEntry(&head,short_name,surname,amount,description); printf("\n**Entry done!**\n"); } // Maintain the list in alphabetical order by surname. } catalogPointer findEntryExists (catalogPointer head, char num[],char first[]) { catalogPointer p = head; while (p != NULL && strcmp(p->surname, num) != 0 && strcmp(p->short_name,first) != 0) { p = p->next; } return p; } catalogPointer newEntry (catalog** headRef,char short_name[], char surname[], signed int amount, char description[]) { catalogPointer newNode = (catalogPointer)malloc(sizeof(catalog)); catalogPointer first; catalogPointer second; catalogPointer tmp; first=head; second=NULL; strcpy(newNode->short_name, short_name); strcpy(newNode->surname, surname); newNode->amount=amount; strcpy(newNode->description, description); while (first!=NULL) { if (strcmp(surname,first->surname)>0) second=first; else if (strcmp(surname,first->surname)==0) { if (strcmp(short_name,first->short_name)>0) second=first; } first=first->next; } if (second==NULL) { newNode->next=head; head=newNode; } else //SEGMENTATION APPEARS WHEN IT GETS HERE! { tmp=second->next; newNode->next=tmp; first->next=newNode; } } UPDATE: SegFault appears only when it gets on the 'else' loop of InsertSort() function. I observed that segmentation fault appears when i try to put on the list names that are after it. For example, if in the list exists: [Name:b Surname:b Amount:6 Description:b] [Name:c Surname:c Amount:5 Description:c] [Name:d Surname:d Amount:4 Description:d] [Name:e Surname:e Amount:3 Description:e] [Name:g Surname:g Amount:2 Description:g] [Name:x Surname:x Amount:1 Description:x] and i put: " x z 77 gege" there is a segmentation but if i put "x a 77 gege" it continues normally....

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• C -Segmentation fault after the 4th call of the function!

  - by FILIaS

  It seems at least weird to me... The program runs normally.But after I call the enter() function for the 4th time,there is a segmentation fault!I would appreciate any help. With the following function enter() I wanna add user commands' datas to a list. [Some part of the code is already posted on another question of me, but I think I should post it again...as it's a different problem I'm facing now.] /* struct for all the datas that user enters on file*/ typedef struct catalog { char short_name[50]; char surname[50]; signed int amount; char description[1000]; struct catalog *next; }catalog,*catalogPointer; catalogPointer current; catalogPointer head = NULL; void enter(void) //user command: i <name> <surname> <amount> <description> { int n,j=2,k=0; char temp[1500]; char *short_name,*surname,*description; signed int amount; char* params = strchr(command,' ') + 1; //strchr returns a pointer to the 1st space on the command.U want a pointer to the char right after that space. strcpy(temp, params); //params is saved as temp. char *curToken = strtok(temp," "); //strtok cuts 'temp' into strings between the spaces and saves them to 'curToken' printf("temp is:%s \n",temp); printf("\nWhat you entered for saving:\n"); for (n = 0; curToken; ++n) //until curToken ends: { if (curToken) { short_name = malloc(strlen(curToken) + 1); strncpy(short_name, curToken, sizeof (short_name)); } printf("Short Name: %s \n",short_name); curToken = strtok(NULL," "); if (curToken) { surname = malloc(strlen(curToken) + 1); strncpy(surname, curToken,sizeof (surname)); } printf("SurName: %s \n",surname); curToken = strtok(NULL," "); if (curToken) { //int * amount= malloc(sizeof (signed int *)); char *chk; amount = (int) strtol(curToken, &chk, 10); if (!isspace(*chk) && *chk != 0) fprintf(stderr,"Warning: expected integer value for amount, received %s instead\n",curToken); } printf("Amount: %d \n",amount); curToken = strtok(NULL,"\0"); if (curToken) { description = malloc(strlen(curToken) + 1); strncpy(description, curToken, sizeof (description)); } printf("Description: %s \n",description); break; } if (findEntryExists(head, surname,short_name) != NULL) //call function in order to see if entry exists already on the catalog printf("\nAn entry for <%s %s> is already in the catalog!\nNew entry not entered.\n",short_name,surname); else { printf("\nTry to entry <%s %s %d %s> in the catalog list!\n",short_name,surname,amount,description); newEntry(&head,short_name,surname,amount,description); printf("\n**Entry done!**\n"); } // Maintain the list in alphabetical order by surname. } catalogPointer findEntryExists (catalogPointer head, char num[],char first[]) { catalogPointer p = head; while (p != NULL && strcmp(p->surname, num) != 0 && strcmp(p->short_name,first) != 0) { p = p->next; } return p; } catalogPointer newEntry (catalog** headRef,char short_name[], char surname[], signed int amount, char description[]) { catalogPointer newNode = (catalogPointer)malloc(sizeof(catalog)); catalogPointer first; catalogPointer second; catalogPointer tmp; first=head; second=NULL; strcpy(newNode->short_name, short_name); strcpy(newNode->surname, surname); newNode->amount=amount; strcpy(newNode->description, description); //SEGMENTATION ON THE 4TH RUN OF PROGRAM STOPS HERE depending on the names each time it gets! while (first!=NULL) { if (strcmp(surname,first->surname)>0) second=first; else if (strcmp(surname,first->surname)==0) { if (strcmp(short_name,first->short_name)>0) second=first; } first=first->next; } if (second==NULL) { newNode->next=head; head=newNode; } else { tmp=second->next; newNode->next=tmp; first->next=newNode; } }

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• Jumping into argv?

  - by jth

  Hi, I`am experimenting with shellcode and stumbled upon the nop-slide technique. I wrote a little tool that takes buffer-size as a parameter and constructs a buffer like this: [ NOP | SC | RET ], with NOP taking half of the buffer, followed by the shellcode and the rest filled with the (guessed) return address. Its very similar to the tool aleph1 described in his famous paper. My vulnerable test-app is the same as in his paper: int main(int argc, char **argv) { char little_array[512]; if(argc>1) strcpy(little_array,argv[1]); return 0; } I tested it and well, it works: jth@insecure:~/no_nx_no_aslr$ ./victim $(./exploit 604 0) $ exit But honestly, I have no idea why. Okay, the saved eip was overwritten as intended, but instead of jumping somewhere into the buffer, it jumped into argv, I think. gdb showed up the following addresses before strcpy() was called: (gdb) i f Stack level 0, frame at 0xbffff1f0: eip = 0x80483ed in main (victim.c:7); saved eip 0x154b56 source language c. Arglist at 0xbffff1e8, args: argc=2, argv=0xbffff294 Locals at 0xbffff1e8, Previous frame's sp is 0xbffff1f0 Saved registers: ebp at 0xbffff1e8, eip at 0xbffff1ec Address of little_array: (gdb) print &little_array[0] $1 = 0xbfffefe8 "\020" After strcpy(): (gdb) i f Stack level 0, frame at 0xbffff1f0: eip = 0x804840d in main (victim.c:10); saved eip 0xbffff458 source language c. Arglist at 0xbffff1e8, args: argc=-1073744808, argv=0xbffff458 Locals at 0xbffff1e8, Previous frame's sp is 0xbffff1f0 Saved registers: ebp at 0xbffff1e8, eip at 0xbffff1ec So, what happened here? I used a 604 byte buffer to overflow little_array, so he certainly overwrote saved ebp, saved eip and argc and also argv with the guessed address 0xbffff458. Then, after returning, EIP pointed at 0xbffff458. But little_buffer resides at 0xbfffefe8, that`s a difference of 1136 byte, so he certainly isn't executing little_array. I followed execution with the stepi command and well, at 0xbffff458 and onwards, he executes NOPs and reaches the shellcode. I'am not quite sure why this is happening. First of all, am I correct that he executes my shellcode in argv, not little_array? And where does the loader(?) place argv onto the stack? I thought it follows immediately after argc, but between argc and 0xbffff458, there is a gap of 620 bytes. How is it possible that he successfully "lands" in the NOP-Pad at Address 0xbffff458, which is way above the saved eip at 0xbffff1ec? Can someone clarify this? I have actually no idea why this is working. My test-machine is an Ubuntu 9.10 32-Bit Machine without ASLR. victim has an executable stack, set with execstack -s. Thanks in advance.

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