Get all information between the same multiple tags from XML file in C

Question

Summary:

• I developed an app which is supposed to: read an XML File (without using any XML library), get some words between specific tags and print those words on the screen using the basic printf().

My XML File looks like this:

<Server>  
    <Host>ip1</Host>  
    <User>user1</User>  
    <Pass>pass1</Pass>  
</Server>  
<Server>  
    <Host>ip2</Host>  
    <User>user2</User>  
    <Pass>pass2</Pass>  
</Server>

Now, my code is able to get: ip1, user1, pass1.

How can I modify my code, so that I can also get ip2, user2, pass2 then ip3, user3, pass3 and so on until I reach the end of the file ?

The code is the next one:

int getContent()
{
    //variables for reading the XML file
    char *buffer=0;
    long length;
    FILE *xmlFile=fopen("C:/Users/IEUser/AppData/Roaming/recentservers.xml","r");

    //constants for parsing XML
    const char *HOSTSTART = "<Host>";
    const char *HOSTEND = "</Host>";

    const char *USERSTART = "<User>";
    const char *USEREND = "</User>";

    const char *PASSSTART = "<Pass encoding=\"base64\">";
    const char *PASSEND = "</Pass>";

    char *target_host = NULL,*target_user = NULL,*target_pass = NULL, *start, *end;

    //read the xml file
    if(xmlFile)
    {
        fseek(xmlFile,0,SEEK_END);
        length=ftell(xmlFile);
        fseek(xmlFile,0,SEEK_SET);

        buffer=malloc(length);
        if(buffer)
        {
            fread(buffer,1,length,xmlFile);
        }
        fclose(xmlFile);
    }

    //get the HOST
    if(buffer)
    {
        if(start=strstr(buffer,HOSTSTART))
        {
            start += strlen(HOSTSTART);
            if(end=strstr(start, HOSTEND))
            {
                target_host = (char *)malloc(end-start+1);
                memcpy(target_host,start,end-start);
                target_host[end-start]='\0';
            }
        }
        if(target_host)
            printf("%s\n",target_host);
        //free(target_host);
    }

    //get the USER
    if(buffer)
    {
        if(start=strstr(buffer,USERSTART))
        {
            start += strlen(USERSTART);
            if(end=strstr(start, USEREND))
            {
                target_user = (char *)malloc(end-start+1);
                memcpy(target_user,start,end-start);
                target_user[end-start]='\0';
            }
        }
        if(target_user)
            printf("%s\n",target_user);
        //free(target_user);
    }

    //get the PASS
    if(buffer)
    {
        if(start=strstr(buffer,PASSSTART))
        {
            start += strlen(PASSSTART);
            if(end=strstr(start, PASSEND))
            {
                target_pass = (char *)malloc(end-start+1);
                memcpy(target_pass,start,end-start);
                target_pass[end-start]='\0';
            }
        }
        if(target_pass)
            printf("%s\n",target_pass);
        //free(target_pass);
    }
    // here I would like a for which will printf as many target information as they are in that XML File
    printf("%s | %s | %s",target_host,target_user,target_pass);
    printf("\n\n");
    return 0;
}

int main()
{
    getContent();
    return 0;
}

---

//EDIT1:

int readTag(char *buffer, const char *tagStart, const char *tagEnd){
    int start, end;
    char *target = NULL;
    start = 0;
    end = 0;
    if(start=strstr(buffer,tagStart))
    {
        start += strlen(tagStart);
        if(end=strstr(start, tagEnd))
        {
            target = malloc(end-start+1); //don't cast malloc
            memcpy(target,start,end-start);
            target[end-start]='\0';
            printf("Target between tag %s and %s = %s", tagStart, tagEnd, target);
            //sendTargetToGET(tagStart, tagEnd, target);
            free(target);
        }
    }
    return (end - start); // returns nr characters between the tags
}

int getTagID(char *buffer){
    const char *HOSTSTART = "<Host>";
    const char *HOSTEND = "</Host>";

    const char *USERSTART = "<User>";
    const char *USEREND = "</User>";

    const char *PASSSTART = "<Pass encoding=\"base64\">";
    const char *PASSEND = "</Pass>";

    if(strstr(buffer, HOSTSTART) != NULL && strstr(buffer, HOSTEND) != NULL)
    {
        return 1;
    }
    else if(strstr(buffer, USERSTART) != NULL && strstr(buffer, USEREND) != NULL)
    {
        return 2;
    }
    else if(strstr(buffer, PASSSTART) != NULL && strstr(buffer, PASSEND) != NULL)
    {
        return 3;
    }
    else 
        return 0;
}

int main()
{
    char *buffer=0;

    const char *HOSTSTART = "<Host>";
    const char *HOSTEND = "</Host>";

    const char *USERSTART = "<User>";
    const char *USEREND = "</User>";

    const char *PASSSTART = "<Pass encoding=\"base64\">";
    const char *PASSEND = "</Pass>";
    FILE *xmlFile=fopen("C:/Users/IEUser/AppData/Roaming/recentservers.xml","r");

    int tagID = 0;
    while (fgets(buffer, sizeof(buffer), xmlFile) != NULL)
    {
         tagID = getTagID(buffer);

         if(tagID == 1)
         {
             readTag(buffer, HOSTSTART, HOSTEND);
         }
         else if(tagID == 2)
         {
             readTag(buffer, USERSTART, USEREND);
         }
         else if(tagID == 3)
         {

         }
    }
    return 0;
}

I've got an assertion failure unfortunately and I don't know what is the reason

Answer 1

What I would suggest is:

1) Put the tag read parts in a function so you can don't have the same code for every tag:

int readTag(char *buffer, const char *tagStart, const char *tagEnd){
    int start, end;
    char *target = NULL;
    start = 0;
    end = 0;
    if(start=strstr(buffer,tagStart))
    {
        start += strlen(tagStart);
        if(end=strstr(start, tagEnd))
        {
            target = malloc(end-start+1); //don't cast malloc
            memcpy(target,start,end-start);
            target[end-start]='\0';
            printf("Target between tag %s and %s = %s", tagStart, tagEnd, target);
            //sendTargetToGET(tagStart, tagEnd, target);
            free(target);
        }
    }
    return (end - start); // returns nr characters between the tags
}

2) Read the file line by line, check if the line contains tags you need (maybe with a function) and call the associated tag read function.

int tagID = 0;
while (fgets(buffer, sizeof(buffer), xmlFile) != NULL){
     tagID = getTagID(buffer);

     if(tagID == 1){//or use an enum here
         readTag(buffer, HOSTSTART, HOSTEND);
     }else if(tagID == 2){
         readTag(buffer, USERSTART, USEREND);
     }else if(tagID == 3){ //and so on
     }
}

int getTagID(char *buffer){
    if(strstr(buffer, HOSTSTART) != NULL && strstr(buffer, HOSTEND) != NULL){
        return 1;
    }else if(strstr(buffer, USERSTART) != NULL && strstr(buffer, USERSTART) != NULL){
        return 2;
    }else if(/*and so on*/){
    }else return 0;
}