我一直在构建一个使用libcurl发送电子邮件的小型测试程序。最终目标是将其实现为更大软件的远程通知系统。我主要使用this和this作为指南。
程序一直运行到回调函数。调试器显示curl_callback正在接收＆＃39;字符串＆＃39; TESTMESSAGE.email正确。然后再拨打curl_callback两次（共三次）并挂起。
根据我的理解，curl使用回调函数迭代＆＃39;字符串＆＃39;，读取每个字符。根据我在调试器中看到的情况，情况似乎并非如此。
我认为问题在于我如何将我的信息传递给卷曲，但我对curl如何验证这一点没有足够的理解。我所看到的许多例子和论坛似乎都相互矛盾，是准备和传递信息的最佳方式。
注意：使用curl_global_init()是因为这里开发的函数将被实现为多线程程序。
/* Define message structures */
typedef struct emailMsg {
const char *toEmail;
const char *toName;
const char *fromEmail;
const char *fromName;
const char *subject;
const char *body;
const char **email;
size_t pos;
} emailMsg;
int sendEmail(emailMsg *data);
static size_t curl_callback(void *buffer, size_t size, size_t nmemb, void *instream);
char *payload[6];
#include <header.h>
int main(void){
curl_global_init(CURL_GLOBAL_NOTHING);
struct emailMsg TESTMESSAGE;
/* Definitions */
TESTMESSAGE.toEmail = "<toEmail@somedomain.com>";
TESTMESSAGE.toName = "toName";
TESTMESSAGE.fromEmail = "<fromEmail@somedomain.com>";
TESTMESSAGE.fromName = "fromName";
TESTMESSAGE.subject = "Test Message";
TESTMESSAGE.body = "THIS IS A TEST MESSAGE.\r\n"
"\r\n"
"DISREGARD IT AND HAVE A NICE DAY!";
sendEmail(&TESTMESSAGE);
return(0);
}
int sendEmail(emailMsg *data){
size_t bodySize = strlen(data->body) + 3;
char *body = malloc(bodySize);
snprintf(body, bodySize, "%s%s", data->body, "\r\n");
size_t subjectSize = strlen(data->subject) + 12;
char *subject = malloc(subjectSize);
snprintf(subject, subjectSize, "%s%s%s", "Subject: ", data->subject, "\r\n");
size_t receiverSize = strlen(data->toName) + strlen(data->toEmail) + 10;
char *receiver = malloc(receiverSize);
snprintf(receiver, receiverSize, "%s%s (%s)%s", "To: ", data->toEmail, data->toName, "\r\n");
size_t senderSize = strlen(data->fromEmail) + strlen(data->fromName) + 12;
char *sender = malloc(senderSize);
snprintf(sender, senderSize, "%s%s (%s)%s", "From: ", data->fromEmail, data->fromName, "\r\n");
size_t timeSize = 40;
char *timeString = malloc(timeSize);
time_t rawtime = 0;
time(&rawtime);
struct tm *timeinfo = localtime(&rawtime);
strftime (timeString, timeSize, "Date: %a, %d %b %Y %T %z\r\n", timeinfo);
/* Create payload (string) */
size_t total_length = timeSize + receiverSize + senderSize + subjectSize + bodySize + 1;
char *payload = (char*)malloc(total_length);
memset(payload,0,strlen(payload));
strcat(payload, timeString);
strcat(payload, receiver);
strcat(payload, sender);
strcat(payload, subject);
strcat(payload, body);
strcat(payload, "\0");
data->email = &payload;
CURL *curl;
CURLcode res = CURLE_OK;
struct curl_slist *recipients = NULL;
data->pos = 0;
curl = curl_easy_init();
if (curl){
curl_easy_setopt(curl, CURLOPT_URL, "smtp://somemta");
curl_easy_setopt(curl, CURLOPT_MAIL_FROM, data->fromEmail);
recipients = curl_slist_append(recipients, data->toEmail);
curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
curl_easy_setopt(curl, CURLOPT_READFUNCTION, curl_callback);
curl_easy_setopt(curl, CURLOPT_READDATA, data);
curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
/* useful for debugging encryped traffic */
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
/* send the message */
res = curl_easy_perform(curl);
/* Check for errors */
if(res != CURLE_OK){
fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
};
/* Free receipients list and cleanup */
curl_slist_free_all(recipients);
curl_easy_cleanup(curl);
};
return((int)res);
}
static size_t curl_callback(void *buffer, size_t size, size_t nmemb, void *instream){
/*
* Pass N bytes of data to libcurl for the transfer requested.
* This is done 'size' by 'size'.
*
* Parameters:
* void *buffer: Pointer to the buffer
* size_t size: Size of each item
* size_t nmemb: Number of items
* void *instream: Pointer address of data
*/
/* Check for invalid arguments */
if((size == 0) || (nmemb == 0) || ((size * nmemb) < 1)){
return(0);
};
emailMsg *upload = (emailMsg*)instream;
const char *email = upload->email[upload->pos];
if(email){
size_t len = strlen(email);
if(len > size * nmemb){
return(CURL_READFUNC_ABORT);
};
memcpy(buffer, email, len);
upload->pos++;
return(len);
};
return(0);
}
感谢nephtes帮助指出我的逻辑中的缺陷以及该程序的其他一些问题。您的解决方案帮助我意识到通过将字符串连接成一个，我正在删除CURL正在寻找的NULL元素以正确终止上载。工作来源如下。
header.h#define MTA "somemta"
/* Define message structures */
typedef struct emailMsg {
const char *toEmail;
const char *toName;
const char *fromEmail;
const char *fromName;
const char *subject;
const char *body;
size_t pos;
char *email[];
} emailMsg;
int sendEmail(emailMsg *data);
static size_t curl_callback(void *buffer, size_t size, size_t nmemb, void *instream);
char *payload;
#include <header.h>
int main(void){
curl_global_init(CURL_GLOBAL_NOTHING
struct emailMsg TESTMESSAGE;
/* Definitions */
TESTMESSAGE.toEmail = "<toEmail@somedomain.com>";
TESTMESSAGE.toName = "toName";
TESTMESSAGE.fromEmail = "<fromEmail@somedomain.com>";
TESTMESSAGE.fromName = "fromName";
TESTMESSAGE.subject = "Test Message";
TESTMESSAGE.body = "THIS IS A TEST MESSAGE.\r\n"
"\r\n"
"DISREGARD IT AND HAVE A NICE DAY!";
/* Process and send message */
sendEmail(&TESTMESSAGE);
/* Return zero for success */
return(0);
}
int sendEmail(emailMsg *data){
int i;
size_t sizes[6];
/* Date */
/* Calculate string size */
sizes[0] = 39;
/* Allocate memory (+1 for NULL) */
data->email[0] = malloc(sizes[0] + 1);
/* Compose string */
time_t rawtime = 0;
time(&rawtime);
struct tm *timeinfo = localtime(&rawtime);
strftime (data->email[0], sizes[0] + 1, "Date: %a, %d %b %Y %T %z\r\n", timeinfo);
/* Receiver */
/* Calculate string size */
sizes[1] = strlen(data->toName) + strlen(data->toEmail) + 9;
/* Allocate memory (+1 for NULL) */
data->email[1] = malloc(sizes[1] + 1);
/* Compose string */
snprintf(data->email[1], sizes[1] + 1, "%s%s (%s)%s", "To: ", data->toEmail, data->toName, "\r\n");
/* Sender */
/* Calculate string size */
sizes[2] = strlen(data->fromEmail) + strlen(data->fromName) + 11;
/* Allocate memory (+1 for NULL) */
data->email[2] = malloc(sizes[2] + 1);
/* Compose string */
snprintf(data->email[2], sizes[2] + 1, "%s%s (%s)%s", "From: ", data->fromEmail, data->fromName, "\r\n");
/* Subject */
/* Calculate string size */
sizes[3] = strlen(data->subject) + 11;
/* Allocate memory (+1 for NULL) */
data->email[3] = malloc(sizes[3] + 1);
/* Compose string */
snprintf(data->email[3], sizes[3] + 1, "%s%s%s", "Subject: ", data->subject, "\r\n");
/* Body */
/* Calculate string size */
sizes[4] = strlen(data->body) + 2;
/* Allocate memory (+1 for NULL) */
data->email[4] = malloc(sizes[4] + 1);
/* Compose string */
snprintf(data->email[4], sizes[4] + 1, "%s%s", data->body, "\r\n");
/* NULL terminated */
sizes[5] = 1;
data->email[5] = "";
/* Reset counter */
data->pos = 0;
printf("%s", data->email);
/* CURL initialization */
CURL *curl;
CURLcode res = CURLE_OK;
struct curl_slist *recipients = NULL;
curl = curl_easy_init();
if (curl){
curl_easy_setopt(curl, CURLOPT_URL, MTA);
curl_easy_setopt(curl, CURLOPT_MAIL_FROM, data->fromEmail);
recipients = curl_slist_append(recipients, data->toEmail);
curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
curl_easy_setopt(curl, CURLOPT_READFUNCTION, curl_callback);
curl_easy_setopt(curl, CURLOPT_READDATA, data);
curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
/* useful for debugging encryped traffic */
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
/* send the message */
res = curl_easy_perform(curl);
/* Free receipients list and cleanup */
curl_slist_free_all(recipients);
curl_easy_cleanup(curl);
};
/* Return CURL response */
return((int)res);
}
static size_t curl_callback(void *buffer, size_t size, size_t nmemb, void *instream){
/*
* Pass N bytes of data to libcurl for the transfer requested.
* This is done 'size' by 'size'.
*
* Parameters:
* void *buffer: Pointer to the buffer
* size_t size: Size of each item
* size_t nmemb: Number of items
* void *instream: Pointer address of data
*/
/* Check for invalid arguments */
if((size == 0) || (nmemb == 0) || ((size * nmemb) < 1)){
return(0);
};
/* Assign instream to local structure */
emailMsg *upload = (emailMsg*)instream;
/* Assign current position to local variable */
const char *email = upload->email[upload->pos];
/* Run until NULL reached */
if(email){
/* Find length of string */
size_t len = strlen(email);
/* len > expected message */
if(len > size * nmemb){
return(CURL_READFUNC_ABORT);
};
/* Copy to buffer */
memcpy(buffer, email, len);
/* Increment */
upload->pos++;
/* Return the number of bytes written */
return(len);
};
/* Signify end of upload */
return(0);
}
答案 0 :(得分：1)
这是您在curl_easy_perform()
char *payload = (char*)malloc(total_length);
data->email = &payload;
以下是您在回调中所做的事情：
const char *email = upload->email[upload->pos]
问题是upload->email（又名data->email）不是一个数组，但你却像对待它一样。索引0没问题，但其他任何东西都会指向一些随机内存位置。
您需要做的是使email成为一个简单的char*缓冲区而不是char**，并使用upload->pos作为该缓冲区的位置索引，将其值增加为您将数据复制到回调参数中提供的缓冲区。