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Lukas Forsberg
2025-12-14 21:34:10 +01:00
parent 8df3c5479b
commit 6f1d51cabc
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include/crow/multipart.h Normal file
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#pragma once
#include <string>
#include <vector>
#include <sstream>
#include "crow/http_request.h"
#include "crow/returnable.h"
#include "crow/ci_map.h"
#include "crow/exceptions.h"
namespace crow
{
/// Encapsulates anything related to processing and organizing `multipart/xyz` messages
namespace multipart
{
const std::string dd = "--";
/// The first part in a section, contains metadata about the part
struct header
{
std::string value; ///< The first part of the header, usually `Content-Type` or `Content-Disposition`
std::unordered_map<std::string, std::string> params; ///< The parameters of the header, come after the `value`
operator int() const { return std::stoi(value); } ///< Returns \ref value as integer
operator double() const { return std::stod(value); } ///< Returns \ref value as double
};
/// Multipart header map (key is header key).
using mph_map = std::unordered_multimap<std::string, header, ci_hash, ci_key_eq>;
/// Find and return the value object associated with the key. (returns an empty class if nothing is found)
template<typename O, typename T>
inline const O& get_header_value_object(const T& headers, const std::string& key)
{
if (headers.count(key))
{
return headers.find(key)->second;
}
static O empty;
return empty;
}
/// Same as \ref get_header_value_object() but for \ref multipart.header
template<typename T>
inline const header& get_header_object(const T& headers, const std::string& key)
{
return get_header_value_object<header>(headers, key);
}
///One part of the multipart message
///
/// It is usually separated from other sections by a `boundary`
struct part
{
mph_map headers; ///< (optional) The first part before the data, Contains information regarding the type of data and encoding
std::string body; ///< The actual data in the part
operator int() const { return std::stoi(body); } ///< Returns \ref body as integer
operator double() const { return std::stod(body); } ///< Returns \ref body as double
const header& get_header_object(const std::string& key) const
{
return multipart::get_header_object(headers, key);
}
};
/// Multipart map (key is the name parameter).
using mp_map = std::unordered_multimap<std::string, part, ci_hash, ci_key_eq>;
/// The parsed multipart request/response
struct message : public returnable
{
ci_map headers; ///< The request/response headers
std::string boundary; ///< The text boundary that separates different `parts`
std::vector<part> parts; ///< The individual parts of the message
mp_map part_map; ///< The individual parts of the message, organized in a map with the `name` header parameter being the key
const std::string& get_header_value(const std::string& key) const
{
return crow::get_header_value(headers, key);
}
part get_part_by_name(const std::string& name)
{
mp_map::iterator result = part_map.find(name);
if (result != part_map.end())
return result->second;
else
return {};
}
/// Represent all parts as a string (**does not include message headers**)
std::string dump() const override
{
std::stringstream str;
std::string delimiter = dd + boundary;
for (unsigned i = 0; i < parts.size(); i++)
{
str << delimiter << crlf;
str << dump(i);
}
str << delimiter << dd << crlf;
return str.str();
}
/// Represent an individual part as a string
std::string dump(int part_) const
{
std::stringstream str;
part item = parts[part_];
for (auto& item_h : item.headers)
{
str << item_h.first << ": " << item_h.second.value;
for (auto& it : item_h.second.params)
{
str << "; " << it.first << '=' << pad(it.second);
}
str << crlf;
}
str << crlf;
str << item.body << crlf;
return str.str();
}
/// Default constructor using default values
message(const ci_map& headers_, const std::string& boundary_, const std::vector<part>& sections):
returnable("multipart/form-data; boundary=CROW-BOUNDARY"), headers(headers_), boundary(boundary_), parts(sections)
{
if (!boundary.empty())
content_type = "multipart/form-data; boundary=" + boundary;
for (auto& item : parts)
{
part_map.emplace(
(get_header_object(item.headers, "Content-Disposition").params.find("name")->second),
item);
}
}
/// Create a multipart message from a request data
explicit message(const request& req):
returnable("multipart/form-data; boundary=CROW-BOUNDARY"),
headers(req.headers),
boundary(get_boundary(get_header_value("Content-Type")))
{
if (!boundary.empty())
{
content_type = "multipart/form-data; boundary=" + boundary;
parse_body(req.body);
}
else
{
throw bad_request("Empty boundary in multipart message");
}
}
private:
std::string get_boundary(const std::string& header) const
{
constexpr char boundary_text[] = "boundary=";
size_t found = header.find(boundary_text);
if (found != std::string::npos)
{
std::string to_return(header.substr(found + strlen(boundary_text)));
if (to_return[0] == '\"')
{
to_return = to_return.substr(1, to_return.length() - 2);
}
return to_return;
}
return std::string();
}
void parse_body(std::string body)
{
std::string delimiter = dd + boundary;
// TODO(EDev): Exit on error
while (body != (crlf))
{
size_t found = body.find(delimiter);
if (found == std::string::npos)
{
// did not find delimiter; probably an ill-formed body; throw to indicate the issue to user
throw bad_request("Unable to find delimiter in multipart message. Probably ill-formed body");
}
std::string section = body.substr(0, found);
// +2 is the CRLF.
// We don't check it and delete it so that the same delimiter can be used for The last delimiter (--delimiter--CRLF).
body.erase(0, found + delimiter.length() + 2);
if (!section.empty())
{
part parsed_section(parse_section(section));
part_map.emplace(
(get_header_object(parsed_section.headers, "Content-Disposition").params.find("name")->second),
parsed_section);
parts.push_back(std::move(parsed_section));
}
}
}
part parse_section(std::string& section)
{
struct part to_return;
size_t found = section.find(crlf + crlf);
std::string head_line = section.substr(0, found + 2);
section.erase(0, found + 4);
parse_section_head(head_line, to_return);
to_return.body = section.substr(0, section.length() - 2);
return to_return;
}
void parse_section_head(std::string& lines, part& part)
{
while (!lines.empty())
{
header to_add;
const size_t found_crlf = lines.find(crlf);
std::string line = lines.substr(0, found_crlf);
std::string key;
lines.erase(0, found_crlf + 2);
// Add the header if available
if (!line.empty())
{
const size_t found_semicolon = line.find("; ");
std::string header = line.substr(0, found_semicolon);
if (found_semicolon != std::string::npos)
line.erase(0, found_semicolon + 2);
else
line = std::string();
size_t header_split = header.find(": ");
key = header.substr(0, header_split);
to_add.value = header.substr(header_split + 2);
}
// Add the parameters
while (!line.empty())
{
const size_t found_semicolon = line.find("; ");
std::string param = line.substr(0, found_semicolon);
if (found_semicolon != std::string::npos)
line.erase(0, found_semicolon + 2);
else
line = std::string();
size_t param_split = param.find('=');
std::string value = param.substr(param_split + 1);
to_add.params.emplace(param.substr(0, param_split), trim(value));
}
part.headers.emplace(key, to_add);
}
}
inline std::string trim(std::string& string, const char& excess = '"') const
{
if (string.length() > 1 && string[0] == excess && string[string.length() - 1] == excess)
return string.substr(1, string.length() - 2);
return string;
}
inline std::string pad(std::string& string, const char& padding = '"') const
{
return (padding + string + padding);
}
};
} // namespace multipart
} // namespace crow